We synthesized a mesoporous film based on TiO2-reduced graphene oxide(RGO)hybrids using a one-step vapor-thermal method without the need for an additional annealing process.The vapor-thermally prepared TiO2-graphene h...We synthesized a mesoporous film based on TiO2-reduced graphene oxide(RGO)hybrids using a one-step vapor-thermal method without the need for an additional annealing process.The vapor-thermally prepared TiO2-graphene hybrid(VTH)features unique structures with an ultra-large specific surface area of^260 m^2 g^-1 and low aggregation,giving rise to enhanced light harvesting and increased charge generation and separation efficiency.It was observed that a mesoporous film with uniform pore distribution is simultaneously obtained during the VTH growth process.When a 5.0 wt%RGO VTH film was used as the active layer in photocatalysis,the highest photocatalytic activity for degradation of methyl orange was achieved.For another,when a 0.75 wt%RGO VTH film was used as the photoanode in a dye-sensitized solar cell,the power conversion efficiency reached 7.58%,which represents an increase of 73.1%compared to a solar cell using an a photoanode of pure TiO2 synthesized by a traditional solvothermal method.It is expected that this facile method for the synthesis of TiO2/graphene hybrid mesoporous films will be useful in practical applications for preparing other metal oxide/graphene hybrids with ultra-high photocatalytic activity and photovoltaic performance.展开更多
CO_(2)hydrogenation to value-added light olefins(C_(2-4)=)is crucial for the utilization and cycling of global carbon resource.Moderate CO_(2)activation and carbon chain growth ability are key factors for iron-based c...CO_(2)hydrogenation to value-added light olefins(C_(2-4)=)is crucial for the utilization and cycling of global carbon resource.Moderate CO_(2)activation and carbon chain growth ability are key factors for iron-based catalysts for efficient CO_(2)conversion to target C_(2-4)=products.The electronic interaction and confinement effect of electron-deficient graphene inner surface on the active phase are effective to improve surface chemical properties and enhance the catalytic performance.Here,we report a core-shell FeCo alloy catalyst with graphene layers confinement prepared by a simple sol-gel method.The electron transfer from Fe species to curved graphene inner surface modifies the surface electronic structure of the active phaseχ-(Fe_(x)Co_(1-x))_(5)C_(2)and improves CO_(2)adsorption capacity,enhancing the efficient conversion of CO_(2)and moderate C-C coupling.Therefore,the catalyst FeCoK@C exhibits C_(2-4)=selectivity of 33.0%while maintaining high CO_(2)conversion of 52.0%.The high stability without obvious deactivation for over 100 h and unprecedented C_(2-4)=space time yield(STY)up to 52.9 mmolCO_(2)·g^(-1)·h^(-1)demonstrate its potential for practical application.This work provides an efficient strategy for the development of high-performance CO_(2)hydrogenation catalysts.展开更多
The unique properties of TiO_(2)-sulfur(TiO_(2)-S)modified graphene nanocomposite electrode(GPE/TiO_(2)-S)in the electrochemical sensing of formaldehyde compound has been evaluated.We prepared TiO_(2)-S by hydrotherma...The unique properties of TiO_(2)-sulfur(TiO_(2)-S)modified graphene nanocomposite electrode(GPE/TiO_(2)-S)in the electrochemical sensing of formaldehyde compound has been evaluated.We prepared TiO_(2)-S by hydrothermal method and modified the graphene nanocomposite electrode by applying electrochemical cyclic voltammetry(CV)approach.The TiO_(2)-S nanocomposite was characterized by X-ray diffraction(XRD),while the GPE/TiO_(2)-S was examined by scanning electron microscopy(FESEM)and X-Ray fluorosense(XRF)techniques.TiO_(2)-S has a grain size of 19.32 nm.The surface morphology of the GPE/TiO_(2)-S nanocomposite shows a good,intact,and tightly porous structure with TiO_(2)-S covers the graphene surface.The content of optimized GPE/TiO_(2)-S electrodes is 41.5%of graphene,37.8%of TiO_(2),and 12.4%of sulfur that was prepared by mixing 1 g of TiO_(2)-S with 0.5 g of graphene and 0.3 mL paraffin.The GPE/TiO_(2)-S electrode produces a high anodic current(I_(pa))of 800μA and a high cathodic current(I_(pc))of-600μA at a scan rate of 0.1 V·s^(-1)using an electrolyte0.01 mol·L^(-1)K_3[Fe(CN)_6]solution containing 150 mg·L^(-1)formaldehyde.The limit of detection can reach as low as 9.7 mg·L^(-1)with stability with Horwitz ratio value as low as 0.397.The composite electrode also exhibits excellent slectivity properties by showing clear formaldehyde sugnal in the presence of high concentration of interfering agent.GPE/TiO_(2)-S electrode should find potential application of formaldehyde detection in food industries.展开更多
Manipulating catalyst structures to control product selectivity while maintaining high activity presents a considerable challenge in CO_(2)hydrogenation.Combining density functional theory calculations and microkineti...Manipulating catalyst structures to control product selectivity while maintaining high activity presents a considerable challenge in CO_(2)hydrogenation.Combining density functional theory calculations and microkinetic analysis,we proposed that graphene-supported isolated Pt atoms(Pt1/graphene)and Pt_(2)dimers(Pt_(2)/graphene)exhibited distinct selectivity in CO_(2)hydrogenation.Pt_(1)/graphene facilitated the conversion of CO_(2)into formic acid,whereas Pt_(2)/graphene favored methanol generation.The variation in product selectivity arose from the synergistic interaction of Pt_(2)dimers,which facilitated the migration of H atoms between two Pt atoms and promoted the transformation from*COOH intermediates to*C(OH)_(2)intermediates,altering the reaction pathways compared to isolated Pt atoms.Additionally,an analysis of the catalytic activities of three Pt_(1)/graphene and three Pt_(2)/graphene structures revealed that the turnover frequencies for formic acid generation on Pt_(1ii)/graphene and methanol generation on Pt_(2i)/graphene were as high as 744.48 h-1and 789.48 h^(-1),respectively.These values rivaled or even surpassed those previously reported in the literature under identical conditions.This study provides valuable insights into optimizing catalyst structures to achieve desired products in CO_(2)hydrogenation.展开更多
Charge-neutral method(CNM)is extensively used in investigating the performance of catalysts and the mechanism of N_(2)electrochemical reduction(NRR).However,disparities remain between the predicted potentials required...Charge-neutral method(CNM)is extensively used in investigating the performance of catalysts and the mechanism of N_(2)electrochemical reduction(NRR).However,disparities remain between the predicted potentials required for NRR by the CNM methods and those observed experimentally,as the CNM method neglects the charge effect from the electrode potential.To address this issue,we employed the constant electrode potential(CEP)method to screen atomic transition metal-N-graphene(M_(1)/N-graphene)as NRR electrocatalysts and systematically investigated the underlying catalytic mechanism.Among eight types of M_(1)/N-graphene(M_(1)=Mo,W,Fe,Re,Ni,Co,V,Cr),W_(1)/N-graphene emerges as the most promising NRR electrocatalyst with a limiting potential as low as−0.13 V.Additionally,the W_(1)/N-graphene system consistently maintains a positive charge during the reaction due to its Fermi level being higher than that of the electrode.These results better match with the actual circumstances compared to those calculated by conventional CNM method.Thus,our work not only develops a promising electrocatalyst for NRR but also deepens the understanding of the intrinsic electrocatalytic mechanism.展开更多
Graphene has enormous potential to capture CO_(2)due to its unique properties and cost-effectiveness.However,graphene-based adsorbents have drawbacks of lower CO_(2)adsorption capacity and poor selectivity.This work d...Graphene has enormous potential to capture CO_(2)due to its unique properties and cost-effectiveness.However,graphene-based adsorbents have drawbacks of lower CO_(2)adsorption capacity and poor selectivity.This work demonstrates a one-step rapid and sustainable N_(2)/H_(2)plasma treatment process to prepare graphene-based sorbent material with enhanced CO_(2)adsorption performance.Plasma treatment directly enriches amine species,increases surface area,and improves textural properties.The CO_(2)adsorption capacity increases from 1.6 to 3.3 mmol/g for capturing flue gas,and from 0.14 to 1.3 mmol/g for direct air capture (DAC).Importantly,the electrothermal property of the plasma-modified aerogels has been significantly improved,resulting in faster heating rates and significantly reducing energy consumption compared to conventional external heating for regeneration of sorbents.Modified aerogels display improved selectivity of 42 and 87 after plasma modification for 5 and 10 min,respectively.The plasma-treated aerogels display minimal loss between 17%and 19% in capacity after 40 adsorption/desorption cycles,rendering excellent stability.The N_(2)/H_(2)plasma treatment of adsorbent materials would lower energy expenses and prevent negative effects on the global economy caused by climate change.展开更多
The production of hydrogen peroxide(H_(2)O_(2))via artificial photosynthesis using single-atom semiconductor photocatalysts represents a promising green and sustainable technology.However,its efficiency is still limit...The production of hydrogen peroxide(H_(2)O_(2))via artificial photosynthesis using single-atom semiconductor photocatalysts represents a promising green and sustainable technology.However,its efficiency is still limited by sluggish water oxidation kinetics,poor photogenerated charge separation,and insufficient O_(2)adsorption and activation capabilities.Herein,uniformly dispersed single-atom catalysts(SACs)with a Co-N_(4)coordination structure have been synthesized by thermally transforming cobalt phthalocyanine(CoPc)assemblies pre-anchored on phosphate functionalized reduced graphene oxide(Co@rGO-P),and then used to construct heterojunctions with perylenetetracarboxylic acid(PTA)nanosheets for photocatalytic H_(2)O_(2)production by an in-situ growth method.The optimized Co@rGO-P/PTA achieved an H_(2)O_(2)production rate of 1.4 mmol g^(-1)h^(-1)in pure water,with a 12.9-fold enhancement compared to pristine PTA nanosheets exhibiting competitive photoactivity among reported perylene-based materials.Femtosecond transient absorption spectra,in-situ diffuse reflectance infrared Fourier transform spectra and theoretical calculations reveal that the exceptional performance is attributed to the enhanced electron transfer from PTA to rGO via the phosphate bridge and then to the Co-N_(4),and to the promoted O_(2)adsorption and activation at Co-N_(4)active sites.This work provides a feasible and effective strategy for designing highly efficient single-atom semiconductor heterojunction photocatalysts for H_(2)O_(2)production.展开更多
In this study,the holey graphene was prepared by microwave-assisted chemical etching.The three-dimensional(3D)holey graphene hydrogel was obtained through hydrothermal self-assembly method,followed by the introduction...In this study,the holey graphene was prepared by microwave-assisted chemical etching.The three-dimensional(3D)holey graphene hydrogel was obtained through hydrothermal self-assembly method,followed by the introduction of FeCo_(2)S_(4)particles.The resulting holey graphene hydrogel,characterized by high specific surface area and abundant pores combined with FeCo_(2)S_(4)with high pseudocapacitance by interfacial interaction,shortened the mass transport path and enhanced the specific capacitance.The findings reveal that the holey graphene hydrogel/FeCo_(2)S_(4)(FeCo_(2)S_(4)/HGH)composite exhibits high specific capacitance and impressive rate capability(413.4 F·g^(-1)at 1 A·g^(-1),300.4 F·g^(-1)at 6 A·g^(-1)).The symmetric supercapacitor operated within a stable potential window of 0.1-1.6 V,achieving specific capacitance of 127.5 F·g^(-1)at 1 A·g^(-1),and can deliver 37.1 Wh·kg^(-1)at a power density of 1499 W·kg^(-1).Besides,under the current density of 3 A·g^(-1),the supercapacitor retained 90.8%of its capacitance after 5000 cycles,demonstrating exceptional cycle stability.This study presents an efficient method for fabricating advanced integrated supercapacitors electrodes with enhanced energy density.展开更多
Low-cost Fe-based disordered rock salt(DRX)Li_(2)FeTiO_(4)is capable of providing high capacity(295 mA h g^(-1))by redox activity of cations(Fe^(2+)/Fe^(4+)and Ti^(3+)/Ti^(4+))and anionic oxygen.However,DRX structures...Low-cost Fe-based disordered rock salt(DRX)Li_(2)FeTiO_(4)is capable of providing high capacity(295 mA h g^(-1))by redox activity of cations(Fe^(2+)/Fe^(4+)and Ti^(3+)/Ti^(4+))and anionic oxygen.However,DRX structures lack transport channels for ions and electrons,resulting in sluggish kinetics,poor electrochemical activity,and cyclability.Herein,graphene conductive carbon network permeated Li_(2)FeTiO_(4)(LFT/C/G)nanofibers are successfully prepared by a facile sol-gel assisted electrospinning method.Ultrafine Li_(2)FeTiO_(4)nanoparticles(2 nm)and one-dimensional(1D)structure provide abu ndant active sites and unobstructed diffu sion channels,accelerating ion diffusion.In addition,introducing graphene reduces the band gap and Li^(+)diffusion barrier and improves the dynamic properties of Li_(2)FeTiO_(4),thus achieving a relatively mild interfacial reaction and reversible redox reaction.As expected,the LFT/C/1.0G cathode delivers a remarkable discharge capacity(238.5 mA h g^(-1)),high energy density(508.8 Wh kg^(-1)),and excellent rate capability(51.2 mA hg^(-1)at 1.0 A g^(-1)).Besides,the LFT/C/1.0G anode also displays a high capacity(514.5 mA h g^(-1)at 500 mA g^(-1))and a remarkable rate capability(243.9 mA h g^(-1)at 8 A g^(-1)).Moreover,the full batteries based on the LFT/C/1.0G symmetric electrode demonstrate a reversible capacity of 117.0 mA h g^(-1)after 100 cycles at 50 mA g^(-1).This study presents useful insights into developing cost-effective DRX cathodes with durable and fast lithium storage.展开更多
Response surface methodology(RSM)was employed to optimize the control parameters of TiO_(2)/graphene with exposed{001}facets during synthesis,and its enhanced photocatalytic activities were evaluated in the photodegra...Response surface methodology(RSM)was employed to optimize the control parameters of TiO_(2)/graphene with exposed{001}facets during synthesis,and its enhanced photocatalytic activities were evaluated in the photodegradation of toluene.Experimental results were in good agreement with the predicted results obtained using RSM with a correlation coefficient(R^(2))of 0.9345.When 22.06 mg of graphite oxide(GO)and 2.09 mL of hydrofluoric acid(HF)were added and a hydrothermal time of 28 h was used,a maximum efficiency in the degradation of toluene was achieved.X-ray diffraction(XRD),transmission electron microscopy(TEM),and scanning electron microscopy(SEM)were employed to characterize the obtained hybrid photocatalyst.The electron transferred between Ti and C retarded the combination of electron–hole pairs and hastened the transferring of electrons,which enhanced the photocatalytic activity.展开更多
As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solut...As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solution process to prepare freestanding TiO_2/graphene hydrogel electrode with tunable density and porous structures. By incorporating room temperature ionic liquids（RTILs）, even upon drying, the non-volatile RTILs that remained in the gel film would preserve the efficient ion transport channels and prevent the electrode from closely stacking, to develop dense yet porous structures. As a result, the dense TiO_2/graphene gel film as an electrode for lithium ion battery displayed a good gravimetric electrochemical performance and more importantly a high volumetric performance.展开更多
A layer of graphene(GR)particles was successfully deposited at the interface between Co(OH)2 nanoparticles and TiO2 nanotubes,aiming to improve the photoelectrochemical performance of the large-bandgap semiconductor T...A layer of graphene(GR)particles was successfully deposited at the interface between Co(OH)2 nanoparticles and TiO2 nanotubes,aiming to improve the photoelectrochemical performance of the large-bandgap semiconductor TiO2.The obtained Co(OH)2/GR/TiO2 was extensively characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),UV–vis absorption spectra and photoluminescence(PL)emission spectra.Electrochemical impedance spectra,photogenerated potential-time(E-t),photocurrent density-time(i-t)and i-E curves and open circuit potential(OCP)curves were measured to investigate the photoelectrochemical activities and photogenerated cathodic protection properties.The results revealed that Co(OH)2/GR/TiO2 exhibits excellent photoelectrochemical and photogenerated cathodic performance due to synergistic effect between Co(OH)2 and graphene.Co(OH)2 and graphene co-modified TiO2 photoanode could provide an effective protection for 304 stainless steel(304 SS)in 3.5 wt%Na Cl solution for 12 h,which would be promising for future practical applications in the field of marine corrosion protection.展开更多
We report the construction of a graphene/tourmaline/TiO2(G/T/TiO2)composite system with enhanced charge‐carrier separation,and therefore enhanced photocatalytic properties,based on tailoring the surface‐charged stat...We report the construction of a graphene/tourmaline/TiO2(G/T/TiO2)composite system with enhanced charge‐carrier separation,and therefore enhanced photocatalytic properties,based on tailoring the surface‐charged state of graphene and/or by introducing an external electric field arising from tourmaline.A simple two‐step hydrothermal method was used to synthesize G/T/TiO2composites and poly(diallyldimethylammonium chloride)‐G/T/TiO2composites.In the photocatalytic degradation of2‐propanol(IPA),the catalytic activity of the composite containing negatively charged graphene was higher than of the composite containing positively charged graphene.The highest acetone evolution rate(223?mol/h)was achieved using the ternary composite with the optimum composition,i.e.,G0.5/T5/TiO2(0.5wt%graphene and5wt%tourmaline).The involvement of tourmaline and graphene in the composite is believed to facilitate the separation and transportation of electrons and holes photogenerated in TiO2.This synergetic effect could account for the enhanced photocatalytic activity of the G/T/TiO2composite.A mechanistic study indicated that O2??radicals and holes were the main reactive oxygen species in photocatalytic degradation of IPA.展开更多
Optical polarizers,which allow the transmission of specific polarization states,are essential components in modern optical systems.Here,we experimentally demonstrate integrated photonic polarizers incorporating reduce...Optical polarizers,which allow the transmission of specific polarization states,are essential components in modern optical systems.Here,we experimentally demonstrate integrated photonic polarizers incorporating reduced graphene oxide(rGO)films.2D graphene oxide(GO)films are integrated onto silicon waveguides and microring resonators(MRRs)with precise control over their thicknesses and sizes,followed by GO reduction via two different methods including uniform thermal reduction and localized photothermal reduction.We measure devices with various lengths,thicknesses,and reduction degrees of GO films.The results show that the devices with rGO exhibit better performance than those with GO,achieving a polarization-dependent loss of~47 dB and a polarization extinction ratio of~16 dB for the hybrid waveguides and MRRs with rGO,respectively.By fitting the experimental results with theory,it is found that rGO exhibits more significant anisotropy in loss,with an anisotropy ratio over 4 times that of GO.In addition,rGO shows higher thermal stability and greater robustness to photothermal reduction than GO.These results highlight the strong potential of rGO films for implementing high-performance polarization selective devices in integrated photonic platforms.展开更多
A recent progress in new emerging two-dimensional(2 D)materials has provided promising opportunity for gas sensing in ultra-low detectable concentration.In this work,we have demonstrated a flexible NO2 gas sensor with...A recent progress in new emerging two-dimensional(2 D)materials has provided promising opportunity for gas sensing in ultra-low detectable concentration.In this work,we have demonstrated a flexible NO2 gas sensor with porous structure graphene on polyethylene terephthalate substrates operating at room temperature.The gas sensor exhibited good performance with response of 1.2%and a fast response time within 30 s after exposure to50×10^-9 NO2 gas.As porous structure of graphene increased the surface area,the sensor showed high sensitivity of ppb level for NO2 detection.Au nanoparticles were decorated on the surface of the porous structure graphene skeleton,resulting in an incensement of response compared with pristine graphene.Au nanoparticles-decorated graphene exhibits not only better sensitivity(1.5-1.6 times larger than pristine graphene)for NO2 gas detection,but also fast response.The sensor was found to be robust and sensitive under the cycling bending test,which could also be ascribed to the merits of graphene.This porous structure graphene-based gas sensor is expected to enable a simple and inexpensive flexible gas sensing platform.展开更多
Titanium dioxide(TiO2) has gained burgeoning attention for potassium-ion storage because of its large theoretical capacity,wide availability,and environmental benignity.Nevertheless,the inherently poor conductivity gi...Titanium dioxide(TiO2) has gained burgeoning attention for potassium-ion storage because of its large theoretical capacity,wide availability,and environmental benignity.Nevertheless,the inherently poor conductivity gives rise to its sluggish reaction kinetics and inferior rate capability.Here,we report the direct graphene growth over TiO2 nanotubes by virtue of chemical vapor deposition.Such conformal graphene coatings effectively enhance the conductive environment and well accommodate the volume change of TiO2 upon potassiation/depotassiation.When paired with an activated carbon cathode,the graphene-armored TiO2 nanotubes allow the potassium-ion hybrid capacitor full cells to harvest an energy/power density of 81.2 Wh kg-1/3746.6 W kg-1.We further employ in situ transmis sion electron microscopy and ope rando X-ray diffraction to probe the potassium-ion storage behavior.This work offers a viable and versatile solution to the anode design and in situ probing of potassium storage technologies that is readily promising for practical applications.展开更多
Conversion-type anode materials are highly desirable for Na-ion batteries(NIBs)due to their high theoretical capacity.Nevertheless,the active materials undergo severe expansion and pulverization during the sodiation,r...Conversion-type anode materials are highly desirable for Na-ion batteries(NIBs)due to their high theoretical capacity.Nevertheless,the active materials undergo severe expansion and pulverization during the sodiation,resulting in inferior cycling stability.Herein,a self-supporting three-dimensional(3D)graphene sponge decorated with Fe_(2)O_(3)nanocubes(rGO@Fe_(2)O_(3))is constructed.Specifically,the 3D graphene sponge with resilience and high porosity benefits to accommodate the volume expansion of the Fe_(2)O_(3)nanocubes and facilitates the rapid electrons/ions transport,enabling spatial confinement to achieve outstanding results.Besides,the free-standing rGO@Fe_(2)O_(3)can be directly used as an electrode without additional binders and conductive additives,which helps to obtain a higher energy density.Based on the total mass of the rGO@Fe_(2)O_(3)material,the rGO@Fe_(2)O_(3)anode presents a specific capacity of 859 mAh/g at 0.1 A/g.It also delivers an impressive cycling performance(327 mAh/g after 2000 cycles at 1 A/g)and a superior rate capacity(162mAh/g at 20 A/g).The coin-type Na_(3)V_(2)(PO_(4))_(3)@C//rGO@Fe_(2)O_(3)NIB exhibits an energy density of 265.3Wh/kg.This unique 3D ionic/electronic conductive network may provide new strategies to design advanced conversion-type anode materials for high-performance NIBs.展开更多
Ag/TiO2/freeze-dried graphene nanocomposites have been prepared via a facile one-step solvothermal method for the photocatalytic degradation of Rh B under visible light irradiation. During the solvothermal process, re...Ag/TiO2/freeze-dried graphene nanocomposites have been prepared via a facile one-step solvothermal method for the photocatalytic degradation of Rh B under visible light irradiation. During the solvothermal process, reduction of graphene oxide and loading of Ag/TiO2nanoparticles on graphene sheets were achieved. Investigation of chemical state of products showed that covering of Ag/TiO2surface with higher weight ratio of graphene resulting in that Ag metals in Ag/TiO2were oxidized to Ag2 O in nanocomposite structure after solvothermal process. Degree of photocatalytic activity enhancement strongly depends on the coverage of Ag/TiO2surface by porous graphene. The sample of 1 wt% porous graphene hybridized Ag/TiO2showed the highest photocatalytic activity, which is related to high migration efficiency of photoinduced of electrons and reduction of electron–hole recombination rate due to high electrical conductivity of graphene. Expanding of absorption to visible light region was ascribed to surface plasmon resonance effect of Ag metals and presence of graphene. Investigation of photocatalytic performance of formic acid as a dye-less organic pollutant showed that dye sensitization effect of Rh B molecules during evaluation of photocatalytic performance was negligible.展开更多
文摘We synthesized a mesoporous film based on TiO2-reduced graphene oxide(RGO)hybrids using a one-step vapor-thermal method without the need for an additional annealing process.The vapor-thermally prepared TiO2-graphene hybrid(VTH)features unique structures with an ultra-large specific surface area of^260 m^2 g^-1 and low aggregation,giving rise to enhanced light harvesting and increased charge generation and separation efficiency.It was observed that a mesoporous film with uniform pore distribution is simultaneously obtained during the VTH growth process.When a 5.0 wt%RGO VTH film was used as the active layer in photocatalysis,the highest photocatalytic activity for degradation of methyl orange was achieved.For another,when a 0.75 wt%RGO VTH film was used as the photoanode in a dye-sensitized solar cell,the power conversion efficiency reached 7.58%,which represents an increase of 73.1%compared to a solar cell using an a photoanode of pure TiO2 synthesized by a traditional solvothermal method.It is expected that this facile method for the synthesis of TiO2/graphene hybrid mesoporous films will be useful in practical applications for preparing other metal oxide/graphene hybrids with ultra-high photocatalytic activity and photovoltaic performance.
文摘CO_(2)hydrogenation to value-added light olefins(C_(2-4)=)is crucial for the utilization and cycling of global carbon resource.Moderate CO_(2)activation and carbon chain growth ability are key factors for iron-based catalysts for efficient CO_(2)conversion to target C_(2-4)=products.The electronic interaction and confinement effect of electron-deficient graphene inner surface on the active phase are effective to improve surface chemical properties and enhance the catalytic performance.Here,we report a core-shell FeCo alloy catalyst with graphene layers confinement prepared by a simple sol-gel method.The electron transfer from Fe species to curved graphene inner surface modifies the surface electronic structure of the active phaseχ-(Fe_(x)Co_(1-x))_(5)C_(2)and improves CO_(2)adsorption capacity,enhancing the efficient conversion of CO_(2)and moderate C-C coupling.Therefore,the catalyst FeCoK@C exhibits C_(2-4)=selectivity of 33.0%while maintaining high CO_(2)conversion of 52.0%.The high stability without obvious deactivation for over 100 h and unprecedented C_(2-4)=space time yield(STY)up to 52.9 mmolCO_(2)·g^(-1)·h^(-1)demonstrate its potential for practical application.This work provides an efficient strategy for the development of high-performance CO_(2)hydrogenation catalysts.
基金the financial support from the Ministry of Education,Culture,Research and Technology of the Republic of Indonesia under the Applied Research award(DIPA023.17.1.690523/2023)the World Class Professor award grant 2023。
文摘The unique properties of TiO_(2)-sulfur(TiO_(2)-S)modified graphene nanocomposite electrode(GPE/TiO_(2)-S)in the electrochemical sensing of formaldehyde compound has been evaluated.We prepared TiO_(2)-S by hydrothermal method and modified the graphene nanocomposite electrode by applying electrochemical cyclic voltammetry(CV)approach.The TiO_(2)-S nanocomposite was characterized by X-ray diffraction(XRD),while the GPE/TiO_(2)-S was examined by scanning electron microscopy(FESEM)and X-Ray fluorosense(XRF)techniques.TiO_(2)-S has a grain size of 19.32 nm.The surface morphology of the GPE/TiO_(2)-S nanocomposite shows a good,intact,and tightly porous structure with TiO_(2)-S covers the graphene surface.The content of optimized GPE/TiO_(2)-S electrodes is 41.5%of graphene,37.8%of TiO_(2),and 12.4%of sulfur that was prepared by mixing 1 g of TiO_(2)-S with 0.5 g of graphene and 0.3 mL paraffin.The GPE/TiO_(2)-S electrode produces a high anodic current(I_(pa))of 800μA and a high cathodic current(I_(pc))of-600μA at a scan rate of 0.1 V·s^(-1)using an electrolyte0.01 mol·L^(-1)K_3[Fe(CN)_6]solution containing 150 mg·L^(-1)formaldehyde.The limit of detection can reach as low as 9.7 mg·L^(-1)with stability with Horwitz ratio value as low as 0.397.The composite electrode also exhibits excellent slectivity properties by showing clear formaldehyde sugnal in the presence of high concentration of interfering agent.GPE/TiO_(2)-S electrode should find potential application of formaldehyde detection in food industries.
基金supported by the National Key Research and Development Program(No.2022YFA1505800)the National Natural Science Foundation of China(No.22373092)+5 种基金CAS Project for Young Scientists in Basic Research(No.YSBR-051)China Association for Science and Technology(No.YESS20200031)the Start-up Funding of Central South University(No.502045005)Industry-University-Research Cooperation Projects with Zhejiang NHU Co.,Ltd.Ningbo Fengcheng Advanced Energy Materials Research Institutesupported by USTC Tang Scholarship。
文摘Manipulating catalyst structures to control product selectivity while maintaining high activity presents a considerable challenge in CO_(2)hydrogenation.Combining density functional theory calculations and microkinetic analysis,we proposed that graphene-supported isolated Pt atoms(Pt1/graphene)and Pt_(2)dimers(Pt_(2)/graphene)exhibited distinct selectivity in CO_(2)hydrogenation.Pt_(1)/graphene facilitated the conversion of CO_(2)into formic acid,whereas Pt_(2)/graphene favored methanol generation.The variation in product selectivity arose from the synergistic interaction of Pt_(2)dimers,which facilitated the migration of H atoms between two Pt atoms and promoted the transformation from*COOH intermediates to*C(OH)_(2)intermediates,altering the reaction pathways compared to isolated Pt atoms.Additionally,an analysis of the catalytic activities of three Pt_(1)/graphene and three Pt_(2)/graphene structures revealed that the turnover frequencies for formic acid generation on Pt_(1ii)/graphene and methanol generation on Pt_(2i)/graphene were as high as 744.48 h-1and 789.48 h^(-1),respectively.These values rivaled or even surpassed those previously reported in the literature under identical conditions.This study provides valuable insights into optimizing catalyst structures to achieve desired products in CO_(2)hydrogenation.
基金Natural Science Foundation of Guangdong Province(No.2024A1515011094(C.Q Sun))National Natural Science Foundation of China(Nos.12304243(H.X.Fang),12150100(B.Wang))is gratefully acknowledged。
文摘Charge-neutral method(CNM)is extensively used in investigating the performance of catalysts and the mechanism of N_(2)electrochemical reduction(NRR).However,disparities remain between the predicted potentials required for NRR by the CNM methods and those observed experimentally,as the CNM method neglects the charge effect from the electrode potential.To address this issue,we employed the constant electrode potential(CEP)method to screen atomic transition metal-N-graphene(M_(1)/N-graphene)as NRR electrocatalysts and systematically investigated the underlying catalytic mechanism.Among eight types of M_(1)/N-graphene(M_(1)=Mo,W,Fe,Re,Ni,Co,V,Cr),W_(1)/N-graphene emerges as the most promising NRR electrocatalyst with a limiting potential as low as−0.13 V.Additionally,the W_(1)/N-graphene system consistently maintains a positive charge during the reaction due to its Fermi level being higher than that of the electrode.These results better match with the actual circumstances compared to those calculated by conventional CNM method.Thus,our work not only develops a promising electrocatalyst for NRR but also deepens the understanding of the intrinsic electrocatalytic mechanism.
基金Guangzhou (China) government postdoctoral program for providing financial support to conduct this worksupport from the National Natural Science Foundation of China (No. 72140008)funding from the European Union’s Horizon 2020 Research and Innovation program under grant agreement No. 101022484。
文摘Graphene has enormous potential to capture CO_(2)due to its unique properties and cost-effectiveness.However,graphene-based adsorbents have drawbacks of lower CO_(2)adsorption capacity and poor selectivity.This work demonstrates a one-step rapid and sustainable N_(2)/H_(2)plasma treatment process to prepare graphene-based sorbent material with enhanced CO_(2)adsorption performance.Plasma treatment directly enriches amine species,increases surface area,and improves textural properties.The CO_(2)adsorption capacity increases from 1.6 to 3.3 mmol/g for capturing flue gas,and from 0.14 to 1.3 mmol/g for direct air capture (DAC).Importantly,the electrothermal property of the plasma-modified aerogels has been significantly improved,resulting in faster heating rates and significantly reducing energy consumption compared to conventional external heating for regeneration of sorbents.Modified aerogels display improved selectivity of 42 and 87 after plasma modification for 5 and 10 min,respectively.The plasma-treated aerogels display minimal loss between 17%and 19% in capacity after 40 adsorption/desorption cycles,rendering excellent stability.The N_(2)/H_(2)plasma treatment of adsorbent materials would lower energy expenses and prevent negative effects on the global economy caused by climate change.
文摘The production of hydrogen peroxide(H_(2)O_(2))via artificial photosynthesis using single-atom semiconductor photocatalysts represents a promising green and sustainable technology.However,its efficiency is still limited by sluggish water oxidation kinetics,poor photogenerated charge separation,and insufficient O_(2)adsorption and activation capabilities.Herein,uniformly dispersed single-atom catalysts(SACs)with a Co-N_(4)coordination structure have been synthesized by thermally transforming cobalt phthalocyanine(CoPc)assemblies pre-anchored on phosphate functionalized reduced graphene oxide(Co@rGO-P),and then used to construct heterojunctions with perylenetetracarboxylic acid(PTA)nanosheets for photocatalytic H_(2)O_(2)production by an in-situ growth method.The optimized Co@rGO-P/PTA achieved an H_(2)O_(2)production rate of 1.4 mmol g^(-1)h^(-1)in pure water,with a 12.9-fold enhancement compared to pristine PTA nanosheets exhibiting competitive photoactivity among reported perylene-based materials.Femtosecond transient absorption spectra,in-situ diffuse reflectance infrared Fourier transform spectra and theoretical calculations reveal that the exceptional performance is attributed to the enhanced electron transfer from PTA to rGO via the phosphate bridge and then to the Co-N_(4),and to the promoted O_(2)adsorption and activation at Co-N_(4)active sites.This work provides a feasible and effective strategy for designing highly efficient single-atom semiconductor heterojunction photocatalysts for H_(2)O_(2)production.
基金Funded by the National Natural Science Foundation of China(No.51972242)the National College Students'Innovation and Entrepreneurship Training Program(No.202210488020)+2 种基金the Open Fund of the Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steel making(Wuhan University of Science and Technology)of China(No.KF-20-5)the Research Project of Yingcheng Xinjincheng Environmental Protection Technology Co.,Ltd(No.2023420612000754)the Program(No.BG20210227001)of High-end Foreign Experts of the State of the State Administration of Foreign Experts Affairs(SAFEA)。
文摘In this study,the holey graphene was prepared by microwave-assisted chemical etching.The three-dimensional(3D)holey graphene hydrogel was obtained through hydrothermal self-assembly method,followed by the introduction of FeCo_(2)S_(4)particles.The resulting holey graphene hydrogel,characterized by high specific surface area and abundant pores combined with FeCo_(2)S_(4)with high pseudocapacitance by interfacial interaction,shortened the mass transport path and enhanced the specific capacitance.The findings reveal that the holey graphene hydrogel/FeCo_(2)S_(4)(FeCo_(2)S_(4)/HGH)composite exhibits high specific capacitance and impressive rate capability(413.4 F·g^(-1)at 1 A·g^(-1),300.4 F·g^(-1)at 6 A·g^(-1)).The symmetric supercapacitor operated within a stable potential window of 0.1-1.6 V,achieving specific capacitance of 127.5 F·g^(-1)at 1 A·g^(-1),and can deliver 37.1 Wh·kg^(-1)at a power density of 1499 W·kg^(-1).Besides,under the current density of 3 A·g^(-1),the supercapacitor retained 90.8%of its capacitance after 5000 cycles,demonstrating exceptional cycle stability.This study presents an efficient method for fabricating advanced integrated supercapacitors electrodes with enhanced energy density.
基金supported by the National Natural Science Foundation of China(22278347)the Excellent Doctoral Student Research Innovation Project of Xinjiang University of China(XJU2022BS048)the Postgraduate Innovation Project of Xinjiang Uygur Autonomous Region of China(XJ2023G027).
文摘Low-cost Fe-based disordered rock salt(DRX)Li_(2)FeTiO_(4)is capable of providing high capacity(295 mA h g^(-1))by redox activity of cations(Fe^(2+)/Fe^(4+)and Ti^(3+)/Ti^(4+))and anionic oxygen.However,DRX structures lack transport channels for ions and electrons,resulting in sluggish kinetics,poor electrochemical activity,and cyclability.Herein,graphene conductive carbon network permeated Li_(2)FeTiO_(4)(LFT/C/G)nanofibers are successfully prepared by a facile sol-gel assisted electrospinning method.Ultrafine Li_(2)FeTiO_(4)nanoparticles(2 nm)and one-dimensional(1D)structure provide abu ndant active sites and unobstructed diffu sion channels,accelerating ion diffusion.In addition,introducing graphene reduces the band gap and Li^(+)diffusion barrier and improves the dynamic properties of Li_(2)FeTiO_(4),thus achieving a relatively mild interfacial reaction and reversible redox reaction.As expected,the LFT/C/1.0G cathode delivers a remarkable discharge capacity(238.5 mA h g^(-1)),high energy density(508.8 Wh kg^(-1)),and excellent rate capability(51.2 mA hg^(-1)at 1.0 A g^(-1)).Besides,the LFT/C/1.0G anode also displays a high capacity(514.5 mA h g^(-1)at 500 mA g^(-1))and a remarkable rate capability(243.9 mA h g^(-1)at 8 A g^(-1)).Moreover,the full batteries based on the LFT/C/1.0G symmetric electrode demonstrate a reversible capacity of 117.0 mA h g^(-1)after 100 cycles at 50 mA g^(-1).This study presents useful insights into developing cost-effective DRX cathodes with durable and fast lithium storage.
基金supported by the National Natural Science Foundation of China(Nos.21406164,21466035 and 51203111)the National Basic Research Program of China("973"Program,Nos.2012CB720100 and 2014CB239300)
文摘Response surface methodology(RSM)was employed to optimize the control parameters of TiO_(2)/graphene with exposed{001}facets during synthesis,and its enhanced photocatalytic activities were evaluated in the photodegradation of toluene.Experimental results were in good agreement with the predicted results obtained using RSM with a correlation coefficient(R^(2))of 0.9345.When 22.06 mg of graphite oxide(GO)and 2.09 mL of hydrofluoric acid(HF)were added and a hydrothermal time of 28 h was used,a maximum efficiency in the degradation of toluene was achieved.X-ray diffraction(XRD),transmission electron microscopy(TEM),and scanning electron microscopy(SEM)were employed to characterize the obtained hybrid photocatalyst.The electron transferred between Ti and C retarded the combination of electron–hole pairs and hastened the transferring of electrons,which enhanced the photocatalytic activity.
基金supported by grants from the National Natural Science Foundation of China(21303251)Innovation Program of Shanghai Municipal Education Commission(16SG17)the Shenzhen Science and Technology Foundation(JCYJ201419122040621)
文摘As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solution process to prepare freestanding TiO_2/graphene hydrogel electrode with tunable density and porous structures. By incorporating room temperature ionic liquids（RTILs）, even upon drying, the non-volatile RTILs that remained in the gel film would preserve the efficient ion transport channels and prevent the electrode from closely stacking, to develop dense yet porous structures. As a result, the dense TiO_2/graphene gel film as an electrode for lithium ion battery displayed a good gravimetric electrochemical performance and more importantly a high volumetric performance.
基金supported financially by the National Natural Science Foundation of China(Nos.51622106 and 51871049)the Fundamental Research Funds for the Central Universities(No.160708001).
文摘A layer of graphene(GR)particles was successfully deposited at the interface between Co(OH)2 nanoparticles and TiO2 nanotubes,aiming to improve the photoelectrochemical performance of the large-bandgap semiconductor TiO2.The obtained Co(OH)2/GR/TiO2 was extensively characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),UV–vis absorption spectra and photoluminescence(PL)emission spectra.Electrochemical impedance spectra,photogenerated potential-time(E-t),photocurrent density-time(i-t)and i-E curves and open circuit potential(OCP)curves were measured to investigate the photoelectrochemical activities and photogenerated cathodic protection properties.The results revealed that Co(OH)2/GR/TiO2 exhibits excellent photoelectrochemical and photogenerated cathodic performance due to synergistic effect between Co(OH)2 and graphene.Co(OH)2 and graphene co-modified TiO2 photoanode could provide an effective protection for 304 stainless steel(304 SS)in 3.5 wt%Na Cl solution for 12 h,which would be promising for future practical applications in the field of marine corrosion protection.
基金supported by the National Basic Research Program of China (973 Program,2014CB239300)the National Natural Science Foundation of China (51572191)the Natural Science Foundation of Tianjin (13JCYBJC16600)~~
文摘We report the construction of a graphene/tourmaline/TiO2(G/T/TiO2)composite system with enhanced charge‐carrier separation,and therefore enhanced photocatalytic properties,based on tailoring the surface‐charged state of graphene and/or by introducing an external electric field arising from tourmaline.A simple two‐step hydrothermal method was used to synthesize G/T/TiO2composites and poly(diallyldimethylammonium chloride)‐G/T/TiO2composites.In the photocatalytic degradation of2‐propanol(IPA),the catalytic activity of the composite containing negatively charged graphene was higher than of the composite containing positively charged graphene.The highest acetone evolution rate(223?mol/h)was achieved using the ternary composite with the optimum composition,i.e.,G0.5/T5/TiO2(0.5wt%graphene and5wt%tourmaline).The involvement of tourmaline and graphene in the composite is believed to facilitate the separation and transportation of electrons and holes photogenerated in TiO2.This synergetic effect could account for the enhanced photocatalytic activity of the G/T/TiO2composite.A mechanistic study indicated that O2??radicals and holes were the main reactive oxygen species in photocatalytic degradation of IPA.
基金supported by the Australian Research Council Centre of Excellence Project in Optical Microcombs for Breakthrough Science(No.CE230100006)the Australian Research Council Discovery Projects Programs(Nos.P190103186 and FT210100806)+4 种基金Linkage Program(Nos.LP210200345 and LP210100467)the Swinburne ECR-SUPRA program,the Industrial Transformation Training Centres scheme(No.IC180100005)the National Natural Science Foundation of China(No.12404375)the Beijing Natural Science Foundation(No.Z180007)the Innovation Program for Quantum Science and Technology(No.2021ZD0300703).
文摘Optical polarizers,which allow the transmission of specific polarization states,are essential components in modern optical systems.Here,we experimentally demonstrate integrated photonic polarizers incorporating reduced graphene oxide(rGO)films.2D graphene oxide(GO)films are integrated onto silicon waveguides and microring resonators(MRRs)with precise control over their thicknesses and sizes,followed by GO reduction via two different methods including uniform thermal reduction and localized photothermal reduction.We measure devices with various lengths,thicknesses,and reduction degrees of GO films.The results show that the devices with rGO exhibit better performance than those with GO,achieving a polarization-dependent loss of~47 dB and a polarization extinction ratio of~16 dB for the hybrid waveguides and MRRs with rGO,respectively.By fitting the experimental results with theory,it is found that rGO exhibits more significant anisotropy in loss,with an anisotropy ratio over 4 times that of GO.In addition,rGO shows higher thermal stability and greater robustness to photothermal reduction than GO.These results highlight the strong potential of rGO films for implementing high-performance polarization selective devices in integrated photonic platforms.
基金financially supported by National Natural Science Foundation of China(No.61874137)。
文摘A recent progress in new emerging two-dimensional(2 D)materials has provided promising opportunity for gas sensing in ultra-low detectable concentration.In this work,we have demonstrated a flexible NO2 gas sensor with porous structure graphene on polyethylene terephthalate substrates operating at room temperature.The gas sensor exhibited good performance with response of 1.2%and a fast response time within 30 s after exposure to50×10^-9 NO2 gas.As porous structure of graphene increased the surface area,the sensor showed high sensitivity of ppb level for NO2 detection.Au nanoparticles were decorated on the surface of the porous structure graphene skeleton,resulting in an incensement of response compared with pristine graphene.Au nanoparticles-decorated graphene exhibits not only better sensitivity(1.5-1.6 times larger than pristine graphene)for NO2 gas detection,but also fast response.The sensor was found to be robust and sensitive under the cycling bending test,which could also be ascribed to the merits of graphene.This porous structure graphene-based gas sensor is expected to enable a simple and inexpensive flexible gas sensing platform.
基金financially supported by the National Natural Science Foundation of China(51702225,11774051,61574034,51672007)the National Basic Research Program of China(No.2016YFA0200103)the Natural Science Foundation of Jiangsu Province(BK20170336)。
文摘Titanium dioxide(TiO2) has gained burgeoning attention for potassium-ion storage because of its large theoretical capacity,wide availability,and environmental benignity.Nevertheless,the inherently poor conductivity gives rise to its sluggish reaction kinetics and inferior rate capability.Here,we report the direct graphene growth over TiO2 nanotubes by virtue of chemical vapor deposition.Such conformal graphene coatings effectively enhance the conductive environment and well accommodate the volume change of TiO2 upon potassiation/depotassiation.When paired with an activated carbon cathode,the graphene-armored TiO2 nanotubes allow the potassium-ion hybrid capacitor full cells to harvest an energy/power density of 81.2 Wh kg-1/3746.6 W kg-1.We further employ in situ transmis sion electron microscopy and ope rando X-ray diffraction to probe the potassium-ion storage behavior.This work offers a viable and versatile solution to the anode design and in situ probing of potassium storage technologies that is readily promising for practical applications.
基金supported by National Natural Science Foundation of China(Nos.52307239,52102300,52207234)the Natural Science Foundation of Hubei Province(Nos.2022CFB1003,2021CFA025).
文摘Conversion-type anode materials are highly desirable for Na-ion batteries(NIBs)due to their high theoretical capacity.Nevertheless,the active materials undergo severe expansion and pulverization during the sodiation,resulting in inferior cycling stability.Herein,a self-supporting three-dimensional(3D)graphene sponge decorated with Fe_(2)O_(3)nanocubes(rGO@Fe_(2)O_(3))is constructed.Specifically,the 3D graphene sponge with resilience and high porosity benefits to accommodate the volume expansion of the Fe_(2)O_(3)nanocubes and facilitates the rapid electrons/ions transport,enabling spatial confinement to achieve outstanding results.Besides,the free-standing rGO@Fe_(2)O_(3)can be directly used as an electrode without additional binders and conductive additives,which helps to obtain a higher energy density.Based on the total mass of the rGO@Fe_(2)O_(3)material,the rGO@Fe_(2)O_(3)anode presents a specific capacity of 859 mAh/g at 0.1 A/g.It also delivers an impressive cycling performance(327 mAh/g after 2000 cycles at 1 A/g)and a superior rate capacity(162mAh/g at 20 A/g).The coin-type Na_(3)V_(2)(PO_(4))_(3)@C//rGO@Fe_(2)O_(3)NIB exhibits an energy density of 265.3Wh/kg.This unique 3D ionic/electronic conductive network may provide new strategies to design advanced conversion-type anode materials for high-performance NIBs.
文摘Ag/TiO2/freeze-dried graphene nanocomposites have been prepared via a facile one-step solvothermal method for the photocatalytic degradation of Rh B under visible light irradiation. During the solvothermal process, reduction of graphene oxide and loading of Ag/TiO2nanoparticles on graphene sheets were achieved. Investigation of chemical state of products showed that covering of Ag/TiO2surface with higher weight ratio of graphene resulting in that Ag metals in Ag/TiO2were oxidized to Ag2 O in nanocomposite structure after solvothermal process. Degree of photocatalytic activity enhancement strongly depends on the coverage of Ag/TiO2surface by porous graphene. The sample of 1 wt% porous graphene hybridized Ag/TiO2showed the highest photocatalytic activity, which is related to high migration efficiency of photoinduced of electrons and reduction of electron–hole recombination rate due to high electrical conductivity of graphene. Expanding of absorption to visible light region was ascribed to surface plasmon resonance effect of Ag metals and presence of graphene. Investigation of photocatalytic performance of formic acid as a dye-less organic pollutant showed that dye sensitization effect of Rh B molecules during evaluation of photocatalytic performance was negligible.
