Ternary transition metal dichalcogenide alloys with spatially graded bandgaps are an emerging class of two-dimensional materials with unique features,which opens up new potential for device applications.Here,visible–...Ternary transition metal dichalcogenide alloys with spatially graded bandgaps are an emerging class of two-dimensional materials with unique features,which opens up new potential for device applications.Here,visible–near-infrared and self-powered phototransistors based on spatially bandgap-graded MoS2(1−x)Se2x alloys,synthesized by a simple and controllable chemical solution deposition method,are reported.The graded bandgaps,arising from the spatial grading of Se composition and thickness within a single domain,are tuned from 1.83 to 1.73 eV,leading to the formation of a homojunction with a builtin electric field.Consequently,a strong and sensitive gate-modulated photovoltaic effect is demonstrated,enabling the homojunction phototransistors at zero bias to deliver a photoresponsivity of 311 mA W−1,a specific detectivity up to^10^11 Jones,and an on/off ratio up to^10^4.Remarkably,when illuminated by the lights ranging from 405 to 808 nm,the biased devices yield a champion photoresponsivity of 191.5 A W−1,a specific detectivity up to^1012 Jones,a photoconductive gain of 10^6–10^7,and a photoresponsive time in the order of^50 ms.These results provide a simple and competitive solution to the bandgap engineering of two-dimensional materials for device applications without the need for p–n junctions.展开更多
In this study,Ni_(2)P-Cd_(0.9)Zn_(0.1)S(NPCZS)composites were synthesized by coupling tetrapod bundle Cd_(0.9)Zn_(0.1)S(CZS)and coralline-like Ni_(2)P(NP)via a simple calcination method.CZS shows outstanding activity ...In this study,Ni_(2)P-Cd_(0.9)Zn_(0.1)S(NPCZS)composites were synthesized by coupling tetrapod bundle Cd_(0.9)Zn_(0.1)S(CZS)and coralline-like Ni_(2)P(NP)via a simple calcination method.CZS shows outstanding activity in photocatalytic hydrogen evolution(1.31 mmol h^(‒1)),owing to its unique morphology and heterophase homojunctions(ZB/WZ),which accelerate the separation and transfer of photogenerated charges.After coupling with NP,the photoactivity of NPCZS was enhanced,and the maximum hydrogen evolution rate of 1.88 mmol h^(‒1)was reached at a NP content of 12 wt%,which was 1.43 times higher than that of pure CZS.The experimental results of the photocatalytic activity,viz.photoluminescence spectra,surface photovoltage spectra,and electrochemical test showed that the enhanced photoactivity of NPCZS should be attributed to the synergistic effects of the novel tetrapod-bundle morphology,heterophase homojunctions,and decoration of the NP co-catalyst.Moreover,the as-prepared NPCZS composites exhibited excellent photostability and recyclability.Herein,we propose a possible mechanism for the enhanced photocatalytic activity.展开更多
Both morphology and composition have a great influence on the properties and functions of materials,however,how to rational modulate both of them to achieve their synergistic effects has been a longstanding expectatio...Both morphology and composition have a great influence on the properties and functions of materials,however,how to rational modulate both of them to achieve their synergistic effects has been a longstanding expectation.Herein,we demonstrate a competitive assembling strategy for the construction of metal-free graphite carbon nitride(CN)homojunctions in which morphology and composition can be easily controlled simultaneously by only changing the ratio of assembly raw materials.These homojunctions are comprised of porous nanotubular S-doped CN(SCN)grafted with CN nanovesicles,which are derived from thermal polycondensation of melamine-thiocyanuric acid(M-T)/melamine-cyanuric acid(M-C)supramolecular hybrid blocks.This unique architecture and component engineering endows the novel SCN-CN homojunction with abundant active sites,enhanced visible trapping ability,and intimate interface contact.As a result,the synthesized SCN-CN homojunctions demonstrate high photocatalytic activity for hydrogen evolution and pollutant degradation.This developed strategy opens up intriguing opportu-nities for the rational construction of intricate metal-free heterostructures with controllable architecture and interfacial contact for applications in energy-related fields.展开更多
The density functional theory method is utilized to verify the electronic structures of SiC nanotubes(SiCNTs) and SiC nanoribbons(SiCNRs) one-dimensional(1D) van der Waals homojunctions(vdWh) under an applied axial st...The density functional theory method is utilized to verify the electronic structures of SiC nanotubes(SiCNTs) and SiC nanoribbons(SiCNRs) one-dimensional(1D) van der Waals homojunctions(vdWh) under an applied axial strain and an external electric field. According to the calculated results, the SiCNTs/SiCNRs 1D vdWhs are direct semiconductors with a type-II band alignment and robust electronic structures with different diameters or widths. Furthermore,the SiCNTs/SiCNRs 1D vdWhs are direct semiconductors with a type-I band alignment, respectively, in a range of[-0.3,-0.1] V/A and [0.1, 0.3] V/A and change into metal when the electric field intensity is equal to or higher than0.4 V/A. Interestingly, the SiCNTs/SiCNRs 1D vdWhs have robust electronic structures under axial strain. These findings demonstrate theoretically that the SiCNTs/SiCNRs 1D vdWhs can be employed in nanoelectronics devices.展开更多
Bi2O2Se thin film could be one of the promising material candidates for the next-generation electronic and optoelectronic applications. However, the performance of Bi2O2Se thin film-based device is not fully explored ...Bi2O2Se thin film could be one of the promising material candidates for the next-generation electronic and optoelectronic applications. However, the performance of Bi2O2Se thin film-based device is not fully explored in the photodetecting area. Considering the fact that the electrical properties such as carrier mobility, work function, and energy band structure of Bi2O2Se are thickness-dependent, the in-plane Bi2O2Se homojunctions consisting of layers with different thicknesses are successfully synthesized by the chemical vapor deposition(CVD) method across the terraces on the mica substrates,where terraces are created in the mica surface layer peeling off process. In this way, effective internal electrical fields are built up along the Bi2O2Se homojunctions, exhibiting diode-like rectification behavior with an on/off ratio of 102, what is more, thus obtained photodetectors possess highly sensitive and ultrafast features, with a maximum photoresponsivity of 2.5 A/W and a lifetime of 4.8 μs. Comparing with the Bi2O2Se uniform thin films, the photo-electric conversion efficiency is greatly improved for the in-plane homojunctions.展开更多
Effective bulk phase and surface charge separation is critical for charge utilization during the photo-catalytic energy conversion process.In this work,the ternary Ni_(2)P-NiS/twinned Mn_(0.5)Cd_(0.5)S(T-MCS)nanohybri...Effective bulk phase and surface charge separation is critical for charge utilization during the photo-catalytic energy conversion process.In this work,the ternary Ni_(2)P-NiS/twinned Mn_(0.5)Cd_(0.5)S(T-MCS)nanohybrids were successfully constructed via combining Ni_(2)P-NiS with T-MCS solid solution for visible light photocatalytic H_(2)evolution.T-MCS is composed of zinc blende Mn_(0.5)Cd_(0.5)S(ZB-MCS)and wurtzite Mn_(0.5)Cd_(0.5)S(WZ-MCS)and those two alternatively arranged crystal phases endow T-MCS with excellent bulk phase charge separation performance for the slight energy level difference between ZB-MCS and WZ-MCS.S-scheme carriers transfer route between NiS and T-MCS can accelerate the interfacial charge separation and retain the active electrons and holes,meanwhile,co-catalyst Ni_(2)P as electron receiver and proton reduction center can further optimize the H_(2)evolution reaction kinetics based on the surface Schottky barrier effect.The above-formed homo-heterojunctions can establish multiple charge transfer channels in the bulk phase of T-MCS and interface of T-MCS and Ni_(2)P-NiS.Under the synergistic effect of twinned homojunction,S-scheme heterojunction,and Schottky barrier,the ternary Ni_(2)P-NiS/T-MCS com-posite manifested an H_(2)production rate of 122.5 mmol h^(-1)g^(-1),which was 1.33,1.24,and 2.58 times higher than those of the NiS/T-MCS(92.4 mmol h^(-1)g^(-1)),Ni_(2)P/T-MCS(98.4 mmol h^(-1)g^(-1)),and T-MCS(47.5 mmol h^(-1)g^(-1)),respectively.This work demonstrates a promising strategy to develop efficient sul-fides photocatalyst toward targeted solar-driven H_(2)evolution through homo-heterojunction engineering.展开更多
Topological morphology that dominates the surface electronic properties of nanostructures plays a key role in producing desired materials for versatile functions and applications in many fields,but its modulation for ...Topological morphology that dominates the surface electronic properties of nanostructures plays a key role in producing desired materials for versatile functions and applications in many fields,but its modulation for specific functions remains a big challenge.Herein,we report an acid-induced method to prepare S-doped graphitic carbon nitride/graphitic carbon nitride(S-CN/CN)homojunction by simply pyrolyzing a supramolecular precursor synthesized from melamine and H_(2)SO_(4).The topological morphology and electronic structure of CN homojunction can be easily adjusted only by changing the ratio of raw materials.Moreover,the topological morphology of S-CN/CN homojunction can be further adjusted from hollow cocoon to 2D nanosheets by changing the annealing conditions.The optimized S-CN/CN homojunction shows highly efficient in charge transfer and separation and exhibits superior OER activity and high ability to degrade organic pollutants.Impressively,S-CN/CN nanosheets only demand low overpotential of301 m V to drive a current density of 10 m Acm^(-2)in 1 M KOH media,and the corresponding Tafel slope is only 57.71 m V/dec,which is superior to the most advanced precious metal Ir O_(2)catalyst.Moreover,under visible light irradiation,its photodegradation kinetic rate of Rh B is 2.38,which is 47.6 times higher than that of bulk CN.This work provides useful guidance for designing and developing efficient multifunctional metal-free catalysts.展开更多
A novel visible light‐responsive homogeneous catalyst based on Bi2WO6 quantum dots(QDs‐BWO)/Bi2WO6 nanosheets(N‐BWO)was successfully fabricated through a simple hydrothermal method.A variety of techniques were empl...A novel visible light‐responsive homogeneous catalyst based on Bi2WO6 quantum dots(QDs‐BWO)/Bi2WO6 nanosheets(N‐BWO)was successfully fabricated through a simple hydrothermal method.A variety of techniques were employed to investigate the morphology,structure,and electronic properties of the samples.The photocatalytic performance of the QDs/N‐BWO materials was investigated by monitoring the degradation of 4‐chlorophenol and rhodamine B under visible light irradiation.The as‐fabricated QDs/N‐BWO materials showed higher photocatalytic activity than both QDs‐BWO and N‐BWO.The results reveal that the incorporation of the QDs improved the separation efficiency of electron‐hole pairs,leading to enhanced photocatalytic activity.Moreover,the results of quenching experiments show that·O2– species played a major role in the degradation process.This work provides an important reference for the fabrication of homogeneous catalysts with high performance in the degradation of different types of pollutants.展开更多
Low-temperature processed electron transport layer(ETL)of TiO_(2)that is widely used in planar perovskite solar cells(PSCs)has inherent low carrier mobility,resulting in insufficient photogenerated elec-tron transport...Low-temperature processed electron transport layer(ETL)of TiO_(2)that is widely used in planar perovskite solar cells(PSCs)has inherent low carrier mobility,resulting in insufficient photogenerated elec-tron transport and thus recombination loss at buried interface.Herein,we demonstrate an effective strategy of laser embedding of p-n homojunctions in the TiO_(2)ETL to accelerate electron transport in PSCs,through localized build-in electric fields that enables boosted electron mobility by two orders of magnitude.Such embedding is found significantly helpful for not only the enhanced crystallization quality of TiO_(2)ETL,but the fabrication of perovskite films with larger-grain and the less-trap-states.The embedded p-n homojunction enables also the modulation of interfacial energy level between perovskite layers and ETLs,favoring for the reduced voltage deficit of PSCs.Benefiting from these merits,the formamidinium lead iodide(FAPbI_(3))PSCs employing such ETLs deliver a champion efficiency of 25.50%,along with much-improved device stability under harsh conditions,i.e.,maintain over 95%of their initial efficiency after operation at maximum power point under continuous heat and illumination for 500 h,as well as mixed-cation PSCs with a champion efficiency of 22.02%and over 3000 h of ambient storage under humidity stability of 40%.Present study offers new possibilities of regulating charge transport layers via p-n homojunction embedding for high performance optoelectronics.展开更多
Localized CdS homojunctions with optimal ratio of high and low index facets are constructed to dy-namically boost H_(2)O splitting into H_(2)energy by hydrothermal method in combination with calcination.By density fun...Localized CdS homojunctions with optimal ratio of high and low index facets are constructed to dy-namically boost H_(2)O splitting into H_(2)energy by hydrothermal method in combination with calcination.By density functional theory,hall effect,and in situ diffuse reflectance infrared Fourier transform spec-troscopy,it is revealed that photo-irradiated e^(−)and h^(+)can be spatially separated and directionally trans-ferred to the reductive high-index facet{002}and oxidative low-index facet{110}of localized CdS homo-junction induced by Fermi level difference of both high and low index facets to dehydrogenate ^(∗)-OH and coupled ^(∗)-O intermediates for H_(2)and O_(2)yield,respectively,along with a solar conversion into hydrogen of 1.93%by AM 1.5 G irradiation at 65℃.The study work suggests a scientific perspective on the optimal ratio of high and low index facets to understand photo-generated charge carrier transfer dynamically and their photocatalytic principle for H_(2)O splitting reaction in kinetics.展开更多
Metal-semiconductor ohmic contacts are required to reduce the energy dissipation for two-dimensional (2D) electronic devices, and phase engineering of 2D transition-metal dichalcogenides (TMDCs) is a promising approac...Metal-semiconductor ohmic contacts are required to reduce the energy dissipation for two-dimensional (2D) electronic devices, and phase engineering of 2D transition-metal dichalcogenides (TMDCs) is a promising approach for building ohmic contacts. Here, 2D in-plane 1T′-2H MoTe2 homojunctions were prepared by direct epitaxy via vapor deposition. The interface properties of in-plane 1T′-2H MoTe2 homojunction were investigated in detail by combining experiments, calculations and theories. The ohmic contact properties of 1T′-2H MoTe2 homojunction were proved according to Kelvin force probe microscopy and density functional theory calculations. The charge carriers robust transport in in-plane 1T′-2H MoTe2 homojunction without Fermi-level pinning can be well described by Poisson equation and band alignment. These results indicate that phase engineering of 2D TMDCs is promising to construct ohmic contacts for device applications.展开更多
ZnO-based n/p homojunctions were fabricated by sputtering from a single zinc nitride target at room temperature on metal or ITO-coated glass and Si substrates.A multi-target rf-sputtering system was used for the growt...ZnO-based n/p homojunctions were fabricated by sputtering from a single zinc nitride target at room temperature on metal or ITO-coated glass and Si substrates.A multi-target rf-sputtering system was used for the growth of all oxide films as multilayers in a single growth run without breaking the vacuum in the growth chamber.The nitrogen-containing films(less than 1.5 at.% of nitrogen)were n-type ZnO when deposited in oxygen-deficient Ar plasma(10%O_(2))and p-type ZnO when deposited in oxygen-rich Ar plasma(50%O_(2)).The all-oxide homojunction ITO/n-ZnO/p-ZnO/ITO/glass was fabricated in a single deposition run and exhibited visible transparency in the range of 75-85%.The n/p ZnO homojunctions,having metallic contacts,formed on conventionally processed substrates showed a fairly unstable behavior concerning the current-voltage characteristics.However,the same homojunctions formed on Si_(3)N_(4)-patterned substrates and stored in atmosphere for a period of five months were stable exhibiting a turn-on voltage of around 1.5 V.The realization of a room temperature sputtered transparent and stable ZnO homojunction paves the way to the realization of all-oxide transparent optoelectronic devices.展开更多
Lithium-sulfur(Li-S)batteries promise high energy density but suffer from low conductivity,polysulfide shuttling,and sluggish conversion kinetics.The construction of heterointerfaces is an effective strategy for enhan...Lithium-sulfur(Li-S)batteries promise high energy density but suffer from low conductivity,polysulfide shuttling,and sluggish conversion kinetics.The construction of heterointerfaces is an effective strategy for enhancing both polysulfide adsorption and conversion;however,the poor lattice compatibility in the heterointerface formed by different materials hinders interfacial charge transfer.In response to these challenges,herein,a biphasic homojunction of TiO_(2)enriched with oxygen vacancies and decorated with nitrogen-doped carbon nanotubes(B-TiO_(2-x)@NCNT)was designed to simultaneously enhance adsorption ability and catalytic activity.This homojunction interface composed of rutile(110)and anatase(101)plane exhibits excellent compatibility,and density functional theory(DFT)calculations reveal that this biphasic interface possesses a much higher binding energy to polysulfides compared to single-phase TiO_(2).Additionally,NCNTs are in situ grown on both interior and exterior surfaces of the hollow TiO_(2)nanospheres,facilitating rapid electron transfer for the encapsulated sulfur.The homojunction interface synergistically leverages the oxygen vacancies and highly conductive NCNTs to enhance the bidirectional catalytic activity for polysulfide conversion.Therefore,in this multifunctional sulfur-host,polysulfides are first strongly adsorbed at the homojunction interfaces and subsequently undergo smooth conversion,nucleation,and decomposition,completing a rapid sulfur redox cycle.The assembled Li-S battery delivered a high specific capacity of 1234.3 mAh g^(-1)at 0.2 C,long cycling stability for over 1000 cycles at 5 C with a low decay rate of 0.035%,and exciting areal capacity at a high sulfur loading of 5.6 mg cm^(-2)for 200cycles.展开更多
A strong built-in electric field(V_(bi))is the key to achieving rapid separation of photogenerated carriers in perovskite solar cells.This is particularly important for hole transport layer(HTL)free carbon-based perov...A strong built-in electric field(V_(bi))is the key to achieving rapid separation of photogenerated carriers in perovskite solar cells.This is particularly important for hole transport layer(HTL)free carbon-based perovskite solar cells(C-PSCs),which have a large interface energy level mismatch.The regulation of perovslite's surface energetics is an effective way to improve the V_(bi)and promote charge extraction,which is typically achieved by organic molecules.However,the insulating nature of organic molecules also negatively hinders charge transfer,resulting in a contradiction of"extraction-transport".Quantum dots(Q.Ds)have great potential for energetics regulation of perovskite film due to their semiconductor properties and inherent large dipole moments,but have not yet been explored.In this work,we propose a strategy of discrete embedding semiconductor QDs at the surface grain boundaries of the perovskite film to regulate surface energetics.The QDs change the energetics of the perovskite film surface,transforming the surface energetics from n-to p-type,thus constructing p-n homojunction at the interface.This significantly enhances the Vbi at the perovskite/carbon electrode interface,promoting hole extraction.In addition,the embedded discrete distribution of QDs at the upper surface grain boundaries ensures efficient transport of the extracted holes to the carbon electrode,overcoming the contradiction of"extraction-transport"for traditional energetics control strategies.Consequently,the fabricated planar HTL-free C-PSCs achieve an efficiency of 20.10%(certified 19.8%),which is one of the highest values reported for this kind of device.展开更多
Electrically tunable homojunctions based on ambipolar two-dimensional materials have attracted widespread attention in the field of intelligent vision.These devices exhibit inherent switchable positive and negative ph...Electrically tunable homojunctions based on ambipolar two-dimensional materials have attracted widespread attention in the field of intelligent vision.These devices exhibit inherent switchable positive and negative photovoltaic properties that effectively mimic the behavior of human retinal cells.However,the photovoltaic responsivity of most electrically tunable homojunctions remains significantly low due to the weak light absorption,making it challenging to meet the application requirements for high-sensitivity target detection in the field of intelligent vision.Here,we propose a gate-tunable photodiode based on two-dimensional ambipolar WSe_(2)with an asymmetric gate electrode,achieving high photovoltaic responsivity.By adjusting the gate voltage and keeping bias voltage zero,we can dynamically realize reconfigurable n-–p and n-–n homojunction states,as well as gate-tunable photovoltaic response characteristics that range from positive to negative.The maximum photovoltaic responsivity of the electrically tunable WSe_(2)homojunction is approximately 0.4 A/W,which is significantly larger than the previously reported value~0.1 A/W in homojunction devices.In addition,the responsivity can be further enhanced to approximately 1.0 A/W when the n-–p photodiode operates in reverse bias mode,enabling highsensitivity detection of targets.Our work paves the way for developing gate-tunable photodiodes with high photovoltaic responsivity and advancing high-performance intelligent vision technology.展开更多
The construction of crystalline/amorphous g-C_(3)N_(4)homojunctions presents a versatile strategy to obtain all-organic homojunction photocatalysts with better interface matching and lower interface charge carrier mov...The construction of crystalline/amorphous g-C_(3)N_(4)homojunctions presents a versatile strategy to obtain all-organic homojunction photocatalysts with better interface matching and lower interface charge carrier movement resistance for optimized photocatalytic activity.However,the process entails a complex multi-step workup,which compromises its feasibility.To overcome this challenge,this work provided an innovative Na_(2)CO_(3)-induced crystallinity modulation strategy to construct a Na-doped crystalline/amorphous g-C_(3)N_(4)S-scheme homojunction photocatalyst in a single step.The approach involves the initial pre-assembling of melamine and cyanuric acid molecules,and subsequent introduction of Na_(2)CO_(3)before the calcination.Na_(2)CO_(3)plays key roles to induce in-situ crystallinity modulation during the calcination and as a source for Na-doping.The prepared g-C_(3)N_(4)S-scheme homojunction photocatalyst demonstrated a prominent H_(2)O_(2)-production rate of 444.6μmol·L^(-1)·h^(-1),which is 6.1-fold higher than that of bulk g-C_(3)N_(4).The enhanced activity was attributed to the synergistic effect of charge carrier separation induced by the S-scheme homojunction system,and the optimized interfacial H_(2)O_(2)generation kinetics.The latter was fostered by the Na-doping.This study provides an innovative approach for the one-step construction of g-C_(3)N_(4)S-scheme homojunction and its integration in photocatalytic applications.展开更多
The development of low-cost semiconductor photocatalysts for highly efficient and durable photocatalytic H2 evolution under visible light is very challenging.In this study,we combine low-cost metallic Ni3C cocatalysts...The development of low-cost semiconductor photocatalysts for highly efficient and durable photocatalytic H2 evolution under visible light is very challenging.In this study,we combine low-cost metallic Ni3C cocatalysts with twin nanocrystal Zn0.5Cd0.5S(ZCS)solid solution homojunctions for an efficient visible-light-driven H2 production by a simple approach.As-synthesized Zn0.5Cd0.5S-1%Ni3C(ZCS-1)heterojunction/homojunction nanohybrid exhibited the highest photocatalytic H2-evolution rate of 783μmol h‒1 under visible light,which is 2.88 times higher than that of pristine twin nanocrystal ZCS solid solution.The apparent quantum efficiencies of ZCS and ZCS-1 are measured to be 6.13%and 19.25%at 420 nm,respectively.Specifically,the homojunctions between the zinc blende and wurtzite segments in twin nanocrystal ZCS solid solution can significantly improve the light absorption and separation of photogenerated electron-hole pairs.Furthermore,the heterojunction between ZCS and metallic Ni3C NP cocatalysts can efficiently trap excited electrons from ZCS solid solution and enhance the H2-evolution kinetics at the surface for improving catalytic activity.This study demonstrates a unique one-step strategy for constructing heterojunction/homojunction hybrid nanostructures for a more efficient photocatalytic H2 evolution compared to other noble metal photocatalytic systems.展开更多
Black phosphorus(BP),an emerging two-dimensional material,is considered a promising candidate for next-generation electronic and optoelectronic devices due to in-plane anisotropy,high mobility,and direct bandgap.Howev...Black phosphorus(BP),an emerging two-dimensional material,is considered a promising candidate for next-generation electronic and optoelectronic devices due to in-plane anisotropy,high mobility,and direct bandgap.However,BP devices face challenges due to their limited stability,photo-response speed,and detection range.To enhance BP with powerful electrical and optical performance,the BP heterostructures can be created.In this review,the state-of-the-art heterostructures and their electrical and optoelectronic applications based on black phosphorus are discussed.Five parts introduce the performance of BP-based devices,including black phosphorus sandwich structure by hBN with better stability and higher mobility,black phosphorus homojunction by dual-gate structure for optical applications,black phosphorus heterojunction with other 2D materials for faster photo-detection,black phosphorus heterojunction integration with 3 D bulk material,and BP via Asdoping tunable bandgap enabling photo-detection up to 8.2μm.Finally,we discuss the challenges and prospects for BP electrical and optical devices and applications.展开更多
Transition metal dichalcogenides （TMDCs） have gained considerable attention because of their novel properties and great potential applications. The flakes of TMDCs not only have great light absorption from visible t...Transition metal dichalcogenides （TMDCs） have gained considerable attention because of their novel properties and great potential applications. The flakes of TMDCs not only have great light absorption from visible to near infrared, but also can be stacked together regardless of lattice mismatch like other two-dimensional （2D） materials. Along with the studies on intrinsic properties of TMDCs, the junctions based on TMDCs become more and more important in applications of photodetection. The junctions have shown many exciting possibilities to fully combine the advantages of TMDCs, other 2D materials, conventional and organic semiconductors together. Early studies have greatly enriched the application of TMDCs in photodetection. In this review, we investigate the efforts in photodetectors based on the junctions of TMDCs and analyze the properties of those photodetectors. Homojunctions based on TMDCs can be made by surface chemical doping, elemental doping and electrostatic gating. Heterojunction formed between TMDCs/2D materials, TMDCs/conventional semiconductors and TMDCs/organic semiconductor also deserve more attentions. We also compare the advantages and disadvantages of different junctions, and then give the prospects for the development of junctions based on TMDCs.展开更多
Transition metal dichalcogenides(TMDCs) belong to a subgroup of two-dimensional(2 D) materials which usually possess thickness-dependent band structures and semiconducting properties. Therefore, for TMDCs to be widely...Transition metal dichalcogenides(TMDCs) belong to a subgroup of two-dimensional(2 D) materials which usually possess thickness-dependent band structures and semiconducting properties. Therefore, for TMDCs to be widely used in electronic and optoelectronic applications, two critical issues need to be addressed, which are thickness-controllable fabrication and doping modulation of TMDCs. In this work, we successfully obtained monolayer WS2 and achieved its efficient doping by chemical vapor deposition and chemical doping, respectively. The n-and p-type dopings of the monolayer WS2 were achieved by drop coating electron donor and acceptor solutions of triphenylphosphine(PPh3) and gold chloride(AuCl_3), respectively, on the surface, which donates and captures electrons to/from the WS2 surface through charge transfer, respectively. Both doping effects were investigated in terms of the electrical properties of the fabricated field effect transistors. After chemical doping, the calculated mobility and density of electrons/holes are around 74.6/39.5 cm^2 · V^(-1) ·s^(-1)and 1.0 x 10^(12)/4.2 x 10^(11) cm^(-2), respectively. Moreover, we fabricated a lateral WS2 p-n homojunction consisting of nondoped n-type and p-doped p-type regions, which showed great potential for photodetection with a response time of 1.5 s and responsivity of 5.8 A/W at V_G = 0 V and V_D = 1 V under 532 nm light illumination.展开更多
基金supported by Grants from the UK EPSRC Future Compound Semiconductor Manufacturing Hub(EP/P006973/1)the financial support from EPSRC(EP/L018330/1,EP/N032888/1)+3 种基金the U.S.Army Research Laboratory under Cooperative Agreement Number W911NF-16-2-0120the “973 Program—the National Basic Research Program of China” Special Funds for the Chief Young Scientis(2015CB358600)the Excellent Young Scholar Fund from National Natural Science Foundation of China(21422103)the China Scholarship Council(CSC)
文摘Ternary transition metal dichalcogenide alloys with spatially graded bandgaps are an emerging class of two-dimensional materials with unique features,which opens up new potential for device applications.Here,visible–near-infrared and self-powered phototransistors based on spatially bandgap-graded MoS2(1−x)Se2x alloys,synthesized by a simple and controllable chemical solution deposition method,are reported.The graded bandgaps,arising from the spatial grading of Se composition and thickness within a single domain,are tuned from 1.83 to 1.73 eV,leading to the formation of a homojunction with a builtin electric field.Consequently,a strong and sensitive gate-modulated photovoltaic effect is demonstrated,enabling the homojunction phototransistors at zero bias to deliver a photoresponsivity of 311 mA W−1,a specific detectivity up to^10^11 Jones,and an on/off ratio up to^10^4.Remarkably,when illuminated by the lights ranging from 405 to 808 nm,the biased devices yield a champion photoresponsivity of 191.5 A W−1,a specific detectivity up to^1012 Jones,a photoconductive gain of 10^6–10^7,and a photoresponsive time in the order of^50 ms.These results provide a simple and competitive solution to the bandgap engineering of two-dimensional materials for device applications without the need for p–n junctions.
文摘In this study,Ni_(2)P-Cd_(0.9)Zn_(0.1)S(NPCZS)composites were synthesized by coupling tetrapod bundle Cd_(0.9)Zn_(0.1)S(CZS)and coralline-like Ni_(2)P(NP)via a simple calcination method.CZS shows outstanding activity in photocatalytic hydrogen evolution(1.31 mmol h^(‒1)),owing to its unique morphology and heterophase homojunctions(ZB/WZ),which accelerate the separation and transfer of photogenerated charges.After coupling with NP,the photoactivity of NPCZS was enhanced,and the maximum hydrogen evolution rate of 1.88 mmol h^(‒1)was reached at a NP content of 12 wt%,which was 1.43 times higher than that of pure CZS.The experimental results of the photocatalytic activity,viz.photoluminescence spectra,surface photovoltage spectra,and electrochemical test showed that the enhanced photoactivity of NPCZS should be attributed to the synergistic effects of the novel tetrapod-bundle morphology,heterophase homojunctions,and decoration of the NP co-catalyst.Moreover,the as-prepared NPCZS composites exhibited excellent photostability and recyclability.Herein,we propose a possible mechanism for the enhanced photocatalytic activity.
基金the National Natural Science Foundation of China(Nos.51772085,12072110)the Natural Science Foundation of Hunan Province(No.2020JJ4190).
文摘Both morphology and composition have a great influence on the properties and functions of materials,however,how to rational modulate both of them to achieve their synergistic effects has been a longstanding expectation.Herein,we demonstrate a competitive assembling strategy for the construction of metal-free graphite carbon nitride(CN)homojunctions in which morphology and composition can be easily controlled simultaneously by only changing the ratio of assembly raw materials.These homojunctions are comprised of porous nanotubular S-doped CN(SCN)grafted with CN nanovesicles,which are derived from thermal polycondensation of melamine-thiocyanuric acid(M-T)/melamine-cyanuric acid(M-C)supramolecular hybrid blocks.This unique architecture and component engineering endows the novel SCN-CN homojunction with abundant active sites,enhanced visible trapping ability,and intimate interface contact.As a result,the synthesized SCN-CN homojunctions demonstrate high photocatalytic activity for hydrogen evolution and pollutant degradation.This developed strategy opens up intriguing opportu-nities for the rational construction of intricate metal-free heterostructures with controllable architecture and interfacial contact for applications in energy-related fields.
基金Project supported by the National Natural Science Foundation of China(Grant No.11864011)the Youth Project of Scientific and Technological Research Program of Chongqing Education Commission,China(Grant Nos.KJQN202001207 and KJQN202101204)the Fund from the Educational Commission of Hubei Province,China(Grant No.T201914)。
文摘The density functional theory method is utilized to verify the electronic structures of SiC nanotubes(SiCNTs) and SiC nanoribbons(SiCNRs) one-dimensional(1D) van der Waals homojunctions(vdWh) under an applied axial strain and an external electric field. According to the calculated results, the SiCNTs/SiCNRs 1D vdWhs are direct semiconductors with a type-II band alignment and robust electronic structures with different diameters or widths. Furthermore,the SiCNTs/SiCNRs 1D vdWhs are direct semiconductors with a type-I band alignment, respectively, in a range of[-0.3,-0.1] V/A and [0.1, 0.3] V/A and change into metal when the electric field intensity is equal to or higher than0.4 V/A. Interestingly, the SiCNTs/SiCNRs 1D vdWhs have robust electronic structures under axial strain. These findings demonstrate theoretically that the SiCNTs/SiCNRs 1D vdWhs can be employed in nanoelectronics devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.61705066)the Open Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),China(Grant No.IPOC2018B004)the National Key Research and Development Program,China(Grant No.2016YFA0202401)
文摘Bi2O2Se thin film could be one of the promising material candidates for the next-generation electronic and optoelectronic applications. However, the performance of Bi2O2Se thin film-based device is not fully explored in the photodetecting area. Considering the fact that the electrical properties such as carrier mobility, work function, and energy band structure of Bi2O2Se are thickness-dependent, the in-plane Bi2O2Se homojunctions consisting of layers with different thicknesses are successfully synthesized by the chemical vapor deposition(CVD) method across the terraces on the mica substrates,where terraces are created in the mica surface layer peeling off process. In this way, effective internal electrical fields are built up along the Bi2O2Se homojunctions, exhibiting diode-like rectification behavior with an on/off ratio of 102, what is more, thus obtained photodetectors possess highly sensitive and ultrafast features, with a maximum photoresponsivity of 2.5 A/W and a lifetime of 4.8 μs. Comparing with the Bi2O2Se uniform thin films, the photo-electric conversion efficiency is greatly improved for the in-plane homojunctions.
基金supported by the National Natu-ral Science Foundation of China(Nos.22078261,21676213,and 11974276)Natural Science Basic Research Program of Shaanxi(No.2023-JC-YB-115)+1 种基金Shaanxi Key Science and Technology Innovation Team Project(No.2022TD-33)National College Student Inno-vation and Entrepreneurship Training Program(No.202210697069)for the financial support of this work.
文摘Effective bulk phase and surface charge separation is critical for charge utilization during the photo-catalytic energy conversion process.In this work,the ternary Ni_(2)P-NiS/twinned Mn_(0.5)Cd_(0.5)S(T-MCS)nanohybrids were successfully constructed via combining Ni_(2)P-NiS with T-MCS solid solution for visible light photocatalytic H_(2)evolution.T-MCS is composed of zinc blende Mn_(0.5)Cd_(0.5)S(ZB-MCS)and wurtzite Mn_(0.5)Cd_(0.5)S(WZ-MCS)and those two alternatively arranged crystal phases endow T-MCS with excellent bulk phase charge separation performance for the slight energy level difference between ZB-MCS and WZ-MCS.S-scheme carriers transfer route between NiS and T-MCS can accelerate the interfacial charge separation and retain the active electrons and holes,meanwhile,co-catalyst Ni_(2)P as electron receiver and proton reduction center can further optimize the H_(2)evolution reaction kinetics based on the surface Schottky barrier effect.The above-formed homo-heterojunctions can establish multiple charge transfer channels in the bulk phase of T-MCS and interface of T-MCS and Ni_(2)P-NiS.Under the synergistic effect of twinned homojunction,S-scheme heterojunction,and Schottky barrier,the ternary Ni_(2)P-NiS/T-MCS com-posite manifested an H_(2)production rate of 122.5 mmol h^(-1)g^(-1),which was 1.33,1.24,and 2.58 times higher than those of the NiS/T-MCS(92.4 mmol h^(-1)g^(-1)),Ni_(2)P/T-MCS(98.4 mmol h^(-1)g^(-1)),and T-MCS(47.5 mmol h^(-1)g^(-1)),respectively.This work demonstrates a promising strategy to develop efficient sul-fides photocatalyst toward targeted solar-driven H_(2)evolution through homo-heterojunction engineering.
基金the National Natural Science Foundation of China(Nos.51772085 and 11704116)Natural Science Foundation of Hunan Province(Nos.2020JJ4190 and 2019JJ50175)。
文摘Topological morphology that dominates the surface electronic properties of nanostructures plays a key role in producing desired materials for versatile functions and applications in many fields,but its modulation for specific functions remains a big challenge.Herein,we report an acid-induced method to prepare S-doped graphitic carbon nitride/graphitic carbon nitride(S-CN/CN)homojunction by simply pyrolyzing a supramolecular precursor synthesized from melamine and H_(2)SO_(4).The topological morphology and electronic structure of CN homojunction can be easily adjusted only by changing the ratio of raw materials.Moreover,the topological morphology of S-CN/CN homojunction can be further adjusted from hollow cocoon to 2D nanosheets by changing the annealing conditions.The optimized S-CN/CN homojunction shows highly efficient in charge transfer and separation and exhibits superior OER activity and high ability to degrade organic pollutants.Impressively,S-CN/CN nanosheets only demand low overpotential of301 m V to drive a current density of 10 m Acm^(-2)in 1 M KOH media,and the corresponding Tafel slope is only 57.71 m V/dec,which is superior to the most advanced precious metal Ir O_(2)catalyst.Moreover,under visible light irradiation,its photodegradation kinetic rate of Rh B is 2.38,which is 47.6 times higher than that of bulk CN.This work provides useful guidance for designing and developing efficient multifunctional metal-free catalysts.
文摘A novel visible light‐responsive homogeneous catalyst based on Bi2WO6 quantum dots(QDs‐BWO)/Bi2WO6 nanosheets(N‐BWO)was successfully fabricated through a simple hydrothermal method.A variety of techniques were employed to investigate the morphology,structure,and electronic properties of the samples.The photocatalytic performance of the QDs/N‐BWO materials was investigated by monitoring the degradation of 4‐chlorophenol and rhodamine B under visible light irradiation.The as‐fabricated QDs/N‐BWO materials showed higher photocatalytic activity than both QDs‐BWO and N‐BWO.The results reveal that the incorporation of the QDs improved the separation efficiency of electron‐hole pairs,leading to enhanced photocatalytic activity.Moreover,the results of quenching experiments show that·O2– species played a major role in the degradation process.This work provides an important reference for the fabrication of homogeneous catalysts with high performance in the degradation of different types of pollutants.
基金financially supported by the project of the National Natural Science Foundation of China(52202115 and 52172101)the China Postdoctoral Science Foundation(2022M722586)+2 种基金the Natural Science Foundation of Chongqing,China(CSTB2022NSCQ-MSX1085)the Shaanxi Science and Technology Innovation Team(2023-CX-TD-44)the Fundamental Research Funds for the Central Universities(3102019JC005 and G2022KY0604)。
文摘Low-temperature processed electron transport layer(ETL)of TiO_(2)that is widely used in planar perovskite solar cells(PSCs)has inherent low carrier mobility,resulting in insufficient photogenerated elec-tron transport and thus recombination loss at buried interface.Herein,we demonstrate an effective strategy of laser embedding of p-n homojunctions in the TiO_(2)ETL to accelerate electron transport in PSCs,through localized build-in electric fields that enables boosted electron mobility by two orders of magnitude.Such embedding is found significantly helpful for not only the enhanced crystallization quality of TiO_(2)ETL,but the fabrication of perovskite films with larger-grain and the less-trap-states.The embedded p-n homojunction enables also the modulation of interfacial energy level between perovskite layers and ETLs,favoring for the reduced voltage deficit of PSCs.Benefiting from these merits,the formamidinium lead iodide(FAPbI_(3))PSCs employing such ETLs deliver a champion efficiency of 25.50%,along with much-improved device stability under harsh conditions,i.e.,maintain over 95%of their initial efficiency after operation at maximum power point under continuous heat and illumination for 500 h,as well as mixed-cation PSCs with a champion efficiency of 22.02%and over 3000 h of ambient storage under humidity stability of 40%.Present study offers new possibilities of regulating charge transport layers via p-n homojunction embedding for high performance optoelectronics.
基金supported by the National Natural Science Foundation of China(No.51972177)the Natural Science Foundation of Ningbo City(No.2021J067)the SJLY2021010 of Ningbo University,Fan 3315 Plan,and Yongjiang Scholar Project.
文摘Localized CdS homojunctions with optimal ratio of high and low index facets are constructed to dy-namically boost H_(2)O splitting into H_(2)energy by hydrothermal method in combination with calcination.By density functional theory,hall effect,and in situ diffuse reflectance infrared Fourier transform spec-troscopy,it is revealed that photo-irradiated e^(−)and h^(+)can be spatially separated and directionally trans-ferred to the reductive high-index facet{002}and oxidative low-index facet{110}of localized CdS homo-junction induced by Fermi level difference of both high and low index facets to dehydrogenate ^(∗)-OH and coupled ^(∗)-O intermediates for H_(2)and O_(2)yield,respectively,along with a solar conversion into hydrogen of 1.93%by AM 1.5 G irradiation at 65℃.The study work suggests a scientific perspective on the optimal ratio of high and low index facets to understand photo-generated charge carrier transfer dynamically and their photocatalytic principle for H_(2)O splitting reaction in kinetics.
基金This work was supported by the Grants from National Natural Science Foundation of China(No.11874316)Scientific Research Fund of Hunan Provincial Education Department(No.18A059)+2 种基金the Hunan Provincial Innovation Foundation for Postgraduate(No.CX2018B321)the Project of Xiangtan Science and Technology Bureau(No.CXY-ZD20172002)Innovative Research Team in University(No.IRT 17R91).
文摘Metal-semiconductor ohmic contacts are required to reduce the energy dissipation for two-dimensional (2D) electronic devices, and phase engineering of 2D transition-metal dichalcogenides (TMDCs) is a promising approach for building ohmic contacts. Here, 2D in-plane 1T′-2H MoTe2 homojunctions were prepared by direct epitaxy via vapor deposition. The interface properties of in-plane 1T′-2H MoTe2 homojunction were investigated in detail by combining experiments, calculations and theories. The ohmic contact properties of 1T′-2H MoTe2 homojunction were proved according to Kelvin force probe microscopy and density functional theory calculations. The charge carriers robust transport in in-plane 1T′-2H MoTe2 homojunction without Fermi-level pinning can be well described by Poisson equation and band alignment. These results indicate that phase engineering of 2D TMDCs is promising to construct ohmic contacts for device applications.
基金partially supported by the EU Horizon 2020‘ASCENT’project,grant agreement No 654384(project 046)the“Materials and Processes for Energy and Environment Applications-AENAO”(MIS 5002556)project co-financed by Greece and EU(European Regional Development Fund)+1 种基金the EU's FP7/2007-2013 project“Oxide Materials Towards a Matured Post-silicon Electronics Era-ORAMA”(contract no.NMP3-LA-2010-246334)the project“Electronics Beyond Silicon Era”(ELBESIER)Erasmus+KА2 programme.
文摘ZnO-based n/p homojunctions were fabricated by sputtering from a single zinc nitride target at room temperature on metal or ITO-coated glass and Si substrates.A multi-target rf-sputtering system was used for the growth of all oxide films as multilayers in a single growth run without breaking the vacuum in the growth chamber.The nitrogen-containing films(less than 1.5 at.% of nitrogen)were n-type ZnO when deposited in oxygen-deficient Ar plasma(10%O_(2))and p-type ZnO when deposited in oxygen-rich Ar plasma(50%O_(2)).The all-oxide homojunction ITO/n-ZnO/p-ZnO/ITO/glass was fabricated in a single deposition run and exhibited visible transparency in the range of 75-85%.The n/p ZnO homojunctions,having metallic contacts,formed on conventionally processed substrates showed a fairly unstable behavior concerning the current-voltage characteristics.However,the same homojunctions formed on Si_(3)N_(4)-patterned substrates and stored in atmosphere for a period of five months were stable exhibiting a turn-on voltage of around 1.5 V.The realization of a room temperature sputtered transparent and stable ZnO homojunction paves the way to the realization of all-oxide transparent optoelectronic devices.
基金supported by the National Natural Science Foundation of China(Grant No.52372281)the Fundamental Research Funds for the Central Universities(2232020G-07)+3 种基金the foundation of Shanghai Institute of Technology(grant no.YJ2022-37)the Graduate Student Innovation Fund of Donghua University(CUSF-DH-D-2022007)the State Key Laboratory of Advanced Fiber Materials(KF2517)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning。
文摘Lithium-sulfur(Li-S)batteries promise high energy density but suffer from low conductivity,polysulfide shuttling,and sluggish conversion kinetics.The construction of heterointerfaces is an effective strategy for enhancing both polysulfide adsorption and conversion;however,the poor lattice compatibility in the heterointerface formed by different materials hinders interfacial charge transfer.In response to these challenges,herein,a biphasic homojunction of TiO_(2)enriched with oxygen vacancies and decorated with nitrogen-doped carbon nanotubes(B-TiO_(2-x)@NCNT)was designed to simultaneously enhance adsorption ability and catalytic activity.This homojunction interface composed of rutile(110)and anatase(101)plane exhibits excellent compatibility,and density functional theory(DFT)calculations reveal that this biphasic interface possesses a much higher binding energy to polysulfides compared to single-phase TiO_(2).Additionally,NCNTs are in situ grown on both interior and exterior surfaces of the hollow TiO_(2)nanospheres,facilitating rapid electron transfer for the encapsulated sulfur.The homojunction interface synergistically leverages the oxygen vacancies and highly conductive NCNTs to enhance the bidirectional catalytic activity for polysulfide conversion.Therefore,in this multifunctional sulfur-host,polysulfides are first strongly adsorbed at the homojunction interfaces and subsequently undergo smooth conversion,nucleation,and decomposition,completing a rapid sulfur redox cycle.The assembled Li-S battery delivered a high specific capacity of 1234.3 mAh g^(-1)at 0.2 C,long cycling stability for over 1000 cycles at 5 C with a low decay rate of 0.035%,and exciting areal capacity at a high sulfur loading of 5.6 mg cm^(-2)for 200cycles.
基金supported by the National Natural Science Foundation of China(NFSC No.22122805,U21A20310,22075090,and 22278164)the Science and Technology Program of Guangzhou,China(No.2024A04J1540)。
文摘A strong built-in electric field(V_(bi))is the key to achieving rapid separation of photogenerated carriers in perovskite solar cells.This is particularly important for hole transport layer(HTL)free carbon-based perovskite solar cells(C-PSCs),which have a large interface energy level mismatch.The regulation of perovslite's surface energetics is an effective way to improve the V_(bi)and promote charge extraction,which is typically achieved by organic molecules.However,the insulating nature of organic molecules also negatively hinders charge transfer,resulting in a contradiction of"extraction-transport".Quantum dots(Q.Ds)have great potential for energetics regulation of perovskite film due to their semiconductor properties and inherent large dipole moments,but have not yet been explored.In this work,we propose a strategy of discrete embedding semiconductor QDs at the surface grain boundaries of the perovskite film to regulate surface energetics.The QDs change the energetics of the perovskite film surface,transforming the surface energetics from n-to p-type,thus constructing p-n homojunction at the interface.This significantly enhances the Vbi at the perovskite/carbon electrode interface,promoting hole extraction.In addition,the embedded discrete distribution of QDs at the upper surface grain boundaries ensures efficient transport of the extracted holes to the carbon electrode,overcoming the contradiction of"extraction-transport"for traditional energetics control strategies.Consequently,the fabricated planar HTL-free C-PSCs achieve an efficiency of 20.10%(certified 19.8%),which is one of the highest values reported for this kind of device.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62375131,62204119,62122036,and 62304104)the Natural Science Foundation of Jiangsu Province(Grant No.BK20220947)the Funding of NJUST(Grant No.TSXK2022D008)。
文摘Electrically tunable homojunctions based on ambipolar two-dimensional materials have attracted widespread attention in the field of intelligent vision.These devices exhibit inherent switchable positive and negative photovoltaic properties that effectively mimic the behavior of human retinal cells.However,the photovoltaic responsivity of most electrically tunable homojunctions remains significantly low due to the weak light absorption,making it challenging to meet the application requirements for high-sensitivity target detection in the field of intelligent vision.Here,we propose a gate-tunable photodiode based on two-dimensional ambipolar WSe_(2)with an asymmetric gate electrode,achieving high photovoltaic responsivity.By adjusting the gate voltage and keeping bias voltage zero,we can dynamically realize reconfigurable n-–p and n-–n homojunction states,as well as gate-tunable photovoltaic response characteristics that range from positive to negative.The maximum photovoltaic responsivity of the electrically tunable WSe_(2)homojunction is approximately 0.4 A/W,which is significantly larger than the previously reported value~0.1 A/W in homojunction devices.In addition,the responsivity can be further enhanced to approximately 1.0 A/W when the n-–p photodiode operates in reverse bias mode,enabling highsensitivity detection of targets.Our work paves the way for developing gate-tunable photodiodes with high photovoltaic responsivity and advancing high-performance intelligent vision technology.
文摘The construction of crystalline/amorphous g-C_(3)N_(4)homojunctions presents a versatile strategy to obtain all-organic homojunction photocatalysts with better interface matching and lower interface charge carrier movement resistance for optimized photocatalytic activity.However,the process entails a complex multi-step workup,which compromises its feasibility.To overcome this challenge,this work provided an innovative Na_(2)CO_(3)-induced crystallinity modulation strategy to construct a Na-doped crystalline/amorphous g-C_(3)N_(4)S-scheme homojunction photocatalyst in a single step.The approach involves the initial pre-assembling of melamine and cyanuric acid molecules,and subsequent introduction of Na_(2)CO_(3)before the calcination.Na_(2)CO_(3)plays key roles to induce in-situ crystallinity modulation during the calcination and as a source for Na-doping.The prepared g-C_(3)N_(4)S-scheme homojunction photocatalyst demonstrated a prominent H_(2)O_(2)-production rate of 444.6μmol·L^(-1)·h^(-1),which is 6.1-fold higher than that of bulk g-C_(3)N_(4).The enhanced activity was attributed to the synergistic effect of charge carrier separation induced by the S-scheme homojunction system,and the optimized interfacial H_(2)O_(2)generation kinetics.The latter was fostered by the Na-doping.This study provides an innovative approach for the one-step construction of g-C_(3)N_(4)S-scheme homojunction and its integration in photocatalytic applications.
文摘The development of low-cost semiconductor photocatalysts for highly efficient and durable photocatalytic H2 evolution under visible light is very challenging.In this study,we combine low-cost metallic Ni3C cocatalysts with twin nanocrystal Zn0.5Cd0.5S(ZCS)solid solution homojunctions for an efficient visible-light-driven H2 production by a simple approach.As-synthesized Zn0.5Cd0.5S-1%Ni3C(ZCS-1)heterojunction/homojunction nanohybrid exhibited the highest photocatalytic H2-evolution rate of 783μmol h‒1 under visible light,which is 2.88 times higher than that of pristine twin nanocrystal ZCS solid solution.The apparent quantum efficiencies of ZCS and ZCS-1 are measured to be 6.13%and 19.25%at 420 nm,respectively.Specifically,the homojunctions between the zinc blende and wurtzite segments in twin nanocrystal ZCS solid solution can significantly improve the light absorption and separation of photogenerated electron-hole pairs.Furthermore,the heterojunction between ZCS and metallic Ni3C NP cocatalysts can efficiently trap excited electrons from ZCS solid solution and enhance the H2-evolution kinetics at the surface for improving catalytic activity.This study demonstrates a unique one-step strategy for constructing heterojunction/homojunction hybrid nanostructures for a more efficient photocatalytic H2 evolution compared to other noble metal photocatalytic systems.
基金supported in part by Fundamental Research Project of National Institute of Metrology China under Grant AKYZZ2116in part by National Natural Science Foundation of China under Grant 62022047,Grant 61874065 and Grant 51861145202+4 种基金in part by the National Key R&D Program under Grant 2016YFA0200400in part by the Research Fund from Beijing Innovation Center for Future Chipthe Independent Research Program of Tsinghua University under Grant 20193080047in part by Young Elite Scientists Sponsorship Program by CAST under Grant 2018QNRC001in part by Fok Ying-Tong Education Foundation under Grant 171051。
文摘Black phosphorus(BP),an emerging two-dimensional material,is considered a promising candidate for next-generation electronic and optoelectronic devices due to in-plane anisotropy,high mobility,and direct bandgap.However,BP devices face challenges due to their limited stability,photo-response speed,and detection range.To enhance BP with powerful electrical and optical performance,the BP heterostructures can be created.In this review,the state-of-the-art heterostructures and their electrical and optoelectronic applications based on black phosphorus are discussed.Five parts introduce the performance of BP-based devices,including black phosphorus sandwich structure by hBN with better stability and higher mobility,black phosphorus homojunction by dual-gate structure for optical applications,black phosphorus heterojunction with other 2D materials for faster photo-detection,black phosphorus heterojunction integration with 3 D bulk material,and BP via Asdoping tunable bandgap enabling photo-detection up to 8.2μm.Finally,we discuss the challenges and prospects for BP electrical and optical devices and applications.
基金Project supported by the National Basic Research Program of China(Grant No.2014CB643903)the National Natural Science Foundation of China(Grant Nos.61225021,11474272,11174272,and 11404324)K.C.Wong Education Foundation
文摘Transition metal dichalcogenides （TMDCs） have gained considerable attention because of their novel properties and great potential applications. The flakes of TMDCs not only have great light absorption from visible to near infrared, but also can be stacked together regardless of lattice mismatch like other two-dimensional （2D） materials. Along with the studies on intrinsic properties of TMDCs, the junctions based on TMDCs become more and more important in applications of photodetection. The junctions have shown many exciting possibilities to fully combine the advantages of TMDCs, other 2D materials, conventional and organic semiconductors together. Early studies have greatly enriched the application of TMDCs in photodetection. In this review, we investigate the efforts in photodetectors based on the junctions of TMDCs and analyze the properties of those photodetectors. Homojunctions based on TMDCs can be made by surface chemical doping, elemental doping and electrostatic gating. Heterojunction formed between TMDCs/2D materials, TMDCs/conventional semiconductors and TMDCs/organic semiconductor also deserve more attentions. We also compare the advantages and disadvantages of different junctions, and then give the prospects for the development of junctions based on TMDCs.
基金Project supported by the National Natural Science Foundation of China(Grant No.21405109)Seed Foundation of State Key Laboratory of Precision Measurement Technology and Instruments,China(Grant No.1710)
文摘Transition metal dichalcogenides(TMDCs) belong to a subgroup of two-dimensional(2 D) materials which usually possess thickness-dependent band structures and semiconducting properties. Therefore, for TMDCs to be widely used in electronic and optoelectronic applications, two critical issues need to be addressed, which are thickness-controllable fabrication and doping modulation of TMDCs. In this work, we successfully obtained monolayer WS2 and achieved its efficient doping by chemical vapor deposition and chemical doping, respectively. The n-and p-type dopings of the monolayer WS2 were achieved by drop coating electron donor and acceptor solutions of triphenylphosphine(PPh3) and gold chloride(AuCl_3), respectively, on the surface, which donates and captures electrons to/from the WS2 surface through charge transfer, respectively. Both doping effects were investigated in terms of the electrical properties of the fabricated field effect transistors. After chemical doping, the calculated mobility and density of electrons/holes are around 74.6/39.5 cm^2 · V^(-1) ·s^(-1)and 1.0 x 10^(12)/4.2 x 10^(11) cm^(-2), respectively. Moreover, we fabricated a lateral WS2 p-n homojunction consisting of nondoped n-type and p-doped p-type regions, which showed great potential for photodetection with a response time of 1.5 s and responsivity of 5.8 A/W at V_G = 0 V and V_D = 1 V under 532 nm light illumination.
