Exciton behavior is crucial to the exploitation of light-emitting conjugated polymer(LCPs)for optoelectronic devices.Singlet excitons are easily trapped by the intrinsically defect structures.Herein,we set a polyfluor...Exciton behavior is crucial to the exploitation of light-emitting conjugated polymer(LCPs)for optoelectronic devices.Singlet excitons are easily trapped by the intrinsically defect structures.Herein,we set a polyfluorenol(PPFOH)as an example to systematically investigate its photophysical behavior to check the role of defect structures in LCPs.According to time-resolved photoluminescence analysis,the feature emission peaks from individual chain of PPFOH in diluted DMF solution is effectively avoided the influence of fluorenone formation,but the residual green-band emission at 550nm is easily observed in the PL spectra of PPFOH dilute toluene solution obtained delay 1.5 ns,confirmed the formation of“vip”physical aggregation-induced defect structure.Remarkably,efficient and ultrafast energy transfer from individual chain to defect structure is observed in PPFOH films.Interestingly,the efficient energy transfer happened for the film obtained from DMF solution(200 ps)than those of toluene ones(600 ps).Meanwhile,compared to relatively stable green-band emission in PPFOH film from toluene solution,red-shifted emission peak(11 nm)of PPFOH film from DMF solutions exposed to saturated DNT vapor also confirmed their different aggregation-induced green-band emission.Therefore,this aggregation defect structures are influenced on the photophysical property of LCPs in solid states.展开更多
Although the Haber–Bosch process supports the growth of modern agriculture with abundant ammonia and fertilizer production,substantial energy consumption and enormous greenhouse emissions demand an alternative and su...Although the Haber–Bosch process supports the growth of modern agriculture with abundant ammonia and fertilizer production,substantial energy consumption and enormous greenhouse emissions demand an alternative and sustainable approach.Here,we report a novel approach that combines the nonphotosynthetic bacterium Shewanella oneidensis MR-1(S.oneidensis MR-1)with cadmium sulfide(CdS)nanoparticles(NPs)to enable the photosynthesis of ammonium(NH_(4)+)from nitrate(NO_(3)^(-))using photoexcited electrons as donors.The NO_(3)^(-)reduction efficiency reached almost 100%,with an NH_(4)^(+)production selectivity of over 90%.The maximum instantaneous quantum efficiency was 3.01%under light irradiation.The reverse metal-reducing(Mtr)pathway is responsible for the transfer of photoexcited electrons to intracellular compartments.Parallel reaction monitoring analysis illustrated that NO_(3)^(-)to NH_(4)^(+)was produced via the dissimilatory nitrate reduction to ammonium(DNRA)pathway in S.oneidensis MR-1.This study provides a facile strategy for light-driven ambient NH4+synthesis and solar-to-chemical conversion.展开更多
Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast pho...Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast photogenerated electron-hole recombination.To tackle these issues,herein,we propose a new strategy to modify Cd_(x) Zn_(1-x) S nanoreactors by the simultaneous utilization of ionic-liquid-assisted morphology engineering and MXene-incorporating method.That is,we designed and synthesized a novel hierarchi-cal Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction composite through the in-situ deposition of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets on unique IL-modified Ti_(3) C_(2) MXenes by a one-pot solvothermal method for efficiently PHE.The unique construction strategy tailors the thickness of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets and prevents them from stacking and agglomeration,and especially,optimizes their charge transfer pathways during the photocatalytic process.Compared with pristine Cd_(0.8) Zn_(0.2) S nanosheets,Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) has abun-dant photogenerated electrons available on the Ti_(3) C_(2) surface for proton reduction reaction,owing to the absence of deep-trapped electrons,suppression of electron-hole recombination in Cd_(0.8) Zn_(0.2) S and high-efficiency charge separation at the Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction interface.Moreover,the hy-drophilicity,electrical conductivity,visible-light absorption capacity,and surficial hydrogen desorption of Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) heterostructure are significantly improved.As a result,the heterostructure exhibits out-standing photocatalytic stability and super high apparent quantum efficiency,being rendered as one of the best noble-metal-free Cd-Zn-S-based photocatalysts.This work illustrates the mechanisms of mor-phology control and heterojunction construction in controlling the catalytic behavior of photocatalysts and highlights the great potential of the IL-assisted route in the synthesis of high-performance MXene-based heterostructures for photocatalytic hydrogen evolution.展开更多
We investigate the carrier, phonon, and spin dynamics in the ferromagnetic semiconductor(In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^(*)(~40 K) and T^(†)(~200 K) in the p...We investigate the carrier, phonon, and spin dynamics in the ferromagnetic semiconductor(In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^(*)(~40 K) and T^(†)(~200 K) in the photoexcited carrier dynamics, which can be attributed to the electron-spin and spin-lattice scattering processes influenced by the magnetic phase transition and modifications in magnetic anisotropy. The magnetization change can be revealed by the dynamics of coherent acoustic phonon. We also observe abrupt changes in the photoinduced spin dynamics near T^(*)and T^(†), which not only illustrate the spin-related scatterings closely related to the long-range magnetic order, but also reveal the D'yakonov–Perel and Elliott–Yafet mechanisms dominating at temperatures below and above T^(†), respectively. Our findings provide important insights into the nonequilibrium properties of the photoexcited(In,Fe)Sb.展开更多
Surface states are expected to play a key role in broadband terahertz(THz) emitters, where photoexcited carrier distributions are confined within about 1 μm of the surface. Optical pump and THz probe spectroscopy was...Surface states are expected to play a key role in broadband terahertz(THz) emitters, where photoexcited carrier distributions are confined within about 1 μm of the surface. Optical pump and THz probe spectroscopy was used to study the dynamics of nonequilibrium charge carriers in both textured and non-textured GaAs substrates.Our findings show that the textured surface acts as an antireflective layer, greatly boosting the infrared pump laser's coupling efficiency into the semi-insulating GaAs substrate. Additionally, texturing introduces a trapassisted recombination pathway, speeding up carrier relaxation and thus reducing Joule heating. Under the same pumping and bias field conditions, the coarse-textured GaAs photoconductive antenna shows nearly 7.85 times stronger THz emission amplitude than the non-textured device, along with improvement in signal-to-noise ratio.At a fixed bias field, higher pump power increases photogenerated carrier density, causing bias field screening and subsequent saturation of THz emission. At fixed pump power, when the bias field reaches ~2.5 kV/cm, both THz emission and photocurrent spectra show a clear kink, signaling intervalley scattering from the Γ valley to the L(X) valleys under high electric fields.展开更多
We detect a relaxation process of excited SQ02 dye in the chlorobenzene solution and an- chor SQ02 on Al2O3 and TiO2 film, so as to investigate the photophysical properties of pristine SQ02 in the monodisperse system,...We detect a relaxation process of excited SQ02 dye in the chlorobenzene solution and an- chor SQ02 on Al2O3 and TiO2 film, so as to investigate the photophysical properties of pristine SQ02 in the monodisperse system, aggregation state, and the corresponding inter- facial electron transfer process. The experimental data show that the lifetime of SQ02 in the monondisperse system is ～2.0 ns, but that of SQ02 anchored on the Al2O3 film could obviously decrease to ～21 ps. The time of electron transfer from excited SQ02 to TiO2 film is estimated to be ～2.6 ps and the yield of electron injection is estimated to be ～89.1%, which matches the incident photon to current efficiency of dye-sensitized solar cell based on SQ02. In addition, some dyes are found to pack on the other dyes anchored on the nanocrystal film, and their relaxation time could reach ～60 ps. They couldn＇t participate in the interfacial electron transfer, since they are far away from the TiO2 interface.展开更多
Polarons are widely considered to play a crucial role in the charge transport and photocatalytic performance of materials,but the mechanisms of their formation and the underlying driving factors remain a matter of con...Polarons are widely considered to play a crucial role in the charge transport and photocatalytic performance of materials,but the mechanisms of their formation and the underlying driving factors remain a matter of controversy.This study delves into the formation of polarons in different crystalline forms of TiO_(2) and their connection with the materials'structure.By employing density functional theory calculations with on-site Coulomb interaction correction(DFT+U),we provide a detailed analysis of the electronic polarization behavior in the anatase and rutile forms of TiO_(2).We focus on the polarization properties of defect-induced and photoexcited excess electrons on various TiO_(2) surfaces.The results reveal that the defect electrons can form small polarons on the anatase TiO_(2)(101)surface,while on the rutile TiO_(2)(110)surface,both small and large polarons(hybrid-state polarons)are formed.Photoexcited electrons are capable of forming both small and large polarons on the surfaces of both crystal types.The analysis indicates that the differences in polaron distribution are primarily determined by the intrinsic properties of the crystals;the structural and symmetry differences between anatase and rutile TiO_(2) lead to the distinct polaron behaviors.Further investigation suggests that the polarization behavior of defect electrons is also related to the arrangement of electron orbitals around the Ti atoms,while the polarization of photoexcited electrons is mainly facilitated by the lattice distortions.These findings elucidate the formation mechanisms of different types of polarons and may contribute to understanding the performance of TiO_(2)in different fields.展开更多
By using soft X-ray spectroscopy, we investigate the inner-shell excitation and relaxation processes in atomic and ionic neon targets. Resonant X-ray emission spectroscopy was applied to neutral neon atom in the regio...By using soft X-ray spectroscopy, we investigate the inner-shell excitation and relaxation processes in atomic and ionic neon targets. Resonant X-ray emission spectroscopy was applied to neutral neon atom in the regions of the [1s]np （n = 3, 4,…, ε） excited states and [1s2p]3pmp （m = 3,4） doubly excited states to obtain the spectroscopic information on the [2p]np and [2p^2]3prnp final electronic states, where square brackets indicate hole states. The energy levels of the [2p^2]3prnp （m = 3,4） electronic states were spectroscopically measured for the first time. As for the ionic neon target, on the other hand, the photoion yield spectroscopy was adopted to survey the 1s→ np （n = 2, 3） resonant excitation and subsequent Auger decay processes for Ne^＋ target-ions. The observed Ne^2＋ photoion yield spectrum is successflllly explained by the theoretical calculations based on the nmlticonfiguration Dirac-Fock method展开更多
As one of the most compelling photovoltaic devices, halide perovskite (PVK) solar cells have achieved a new surprising record power conversion efficiency (PCE) of 25.8%in 2021 [1]. This demonstrates the great potentia...As one of the most compelling photovoltaic devices, halide perovskite (PVK) solar cells have achieved a new surprising record power conversion efficiency (PCE) of 25.8%in 2021 [1]. This demonstrates the great potential of halide PVK solar cells as a highly competitive substitute to replace silicon-based solar cells in the photovoltaic market [2–6].展开更多
Crafting charge transfer channels at titanium dioxide(TiO_(2))based photoanodes remain a pressing bottleneck in solar-to-chemical conversion technology.Despite the tremendous attempts,TiO_(2)as the promising photoanod...Crafting charge transfer channels at titanium dioxide(TiO_(2))based photoanodes remain a pressing bottleneck in solar-to-chemical conversion technology.Despite the tremendous attempts,TiO_(2)as the promising photoanode material still suffers from sluggish charge transport kinetics.Herein,we propose an assembly strategy that involves the axial coordination grafting metalloporphyrin-based photosensitizer molecules(MP)onto the surface-modified TiO_(2)nanorods(NRs)photoanode,forming the composite MP/TiO_(2)NRs photoelectrode.As expected,the resulted unique MPB/TiO_(2)NRs photoelectrode displays significantly improved photocurrent density as compared to TiO_(2)NRs alone and MPA/TiO_(2)NRs photoelectrode.Scanning photoelectrochemical microscopy(SPECM)and intensity modulated photocurrent spectroscopy(IMPS)were employed to systematically evaluate the continuous photoinduced electron transfer(PET)dynamics for MP/TiO_(2)NRs photoelectrode.According to the data fitting,it is found that the photoelectron transfer rate(keff)constant for the MPB/TiO_(2)NRs is about 2.6 times higher than that for the pure TiO_(2)NRs under light irradiation.The high kinetic constant for the MPB/TiO_(2)NRs was ascribed to that the conjugated molecules MPB of D-A structure can effectively accelerate intramolecular electrons transfer as well as promote electrons taking part in the reduction reaction of I3to Iin the novel charge transfer channel.The results demonstrated in this study are expected to shed some light on investigating the mechanism in the charge transfer process of artificial photosynthesis and constructing efficient photoelectrodes.展开更多
The photochemical reaction of methylene blue (n-butyltriphenyl) borate, MBRBPh3 was examined. The ultrafast quenching rate and large negative value of Delta G indicated that the intra-ion pair ET plays an important ro...The photochemical reaction of methylene blue (n-butyltriphenyl) borate, MBRBPh3 was examined. The ultrafast quenching rate and large negative value of Delta G indicated that the intra-ion pair ET plays an important role in photoreaction of MBRBPh3. The sequent boron- carbon bond cleavage of butyltriphenylboranyl radical intermediate was found by GC-MS and photo-CIDNP studies.展开更多
Chiral metal-organic frameworks(CMOFs),characterized by their enantioselective porous architectures,intrinsic chirality,and precisely ordered active sites,have emerged as a transformative class of materials with appli...Chiral metal-organic frameworks(CMOFs),characterized by their enantioselective porous architectures,intrinsic chirality,and precisely ordered active sites,have emerged as a transformative class of materials with applications spanning asymmetric catalysis,enantiomeric separation,and chiral sensing.In this study,persulfurated arenes,as AIEgens with photoexcitation activity,were used as fluorescent dyes.Usingγ-cyclodextrin as a chiral template,we constructed a photo-responsive CMOF via intermolecular hydrogen bonding.The co-assembly process exhibited remarkable phenomena of chiral amplification and transfer,generating bright yellow fluorescence under mild UV irradiation at 365 nm.Deprotonated persulfurated arenes were used for comparative studies,and the resulting photoresponsive chiral metal-organic frameworks showed signals of reversed peaks at 400 and 460 nm.This study provides a novel construction strategy for chiral metal-organic frameworks featuring dual dynamic regulation mechanisms mediated by hydrogen bonding and photoirradiation.展开更多
Phototheranostics that performs real-time diagnosis and concurrent in situ therapy upon non-invasive photoexcitation is rapidly emerging as a promising frontier[1],by virtue of its notable advantages including minimal...Phototheranostics that performs real-time diagnosis and concurrent in situ therapy upon non-invasive photoexcitation is rapidly emerging as a promising frontier[1],by virtue of its notable advantages including minimal toxicity,precise diagnosis imaging capability,satisfactory therapeutic effect,and negligible drug resistance.Of particular interest is single organic small molecules synchronously possessing powerful second near-infrared fluorescence imaging(NIR-IIFLI)ability and prominent phototherapeutic outputs,owing to the high spatial resolution and imaging depth enabled by diminished tissue autofluorescence,reduced photon scattering,and low levels of photon absorption.展开更多
Ultrafast transient absorption spectrometry and DFT/TDDFT calculations reveal that following photoexcitation,carboranyl-and carboranyl-free alkylthioporphyrazines deactivate by the pathway S_(1)(π,π^(*))→Sn(C_(β)-...Ultrafast transient absorption spectrometry and DFT/TDDFT calculations reveal that following photoexcitation,carboranyl-and carboranyl-free alkylthioporphyrazines deactivate by the pathway S_(1)(π,π^(*))→Sn(C_(β)-2p_(z)/Sl.p.,π^(*))→ground state.The presence of quenching singlet excited states with predominantly C_(β)-2p_(z)/Sl.p.,π^(*)character immediately below the primarily photogenerated S_(1)(π,π^(*))state is a consequence of the electronic structure changes induced by the inherent flexibility of the alkylthio chains.展开更多
Transition metal dichalcogenide-fullerene(TMD/fullerene)van der Waals(vdW)heterojunctions are promising for photovoltaic applications due to the intriguing optoelectronic properties of their individual components.Howe...Transition metal dichalcogenide-fullerene(TMD/fullerene)van der Waals(vdW)heterojunctions are promising for photovoltaic applications due to the intriguing optoelectronic properties of their individual components.However,the fundamental understanding of the photophysical process,especially excited-state charge transfer and recombination,remains insufficient.Here,using ab initio nonadiabatic molecular dynamics,we investigated the photoexcitation dynamics across the interface composed of the MoSe_(2) monolayer and C_(60) molecules and compared it with the WSe_(2)/C_(60) heterojunction which has been experimentally demonstrated to be efficient for photovoltaic application.Our simulation results show that MoSe_(2)/C_(60) exhibits significantly faster electron transfer and a comparable charge recombination time to WSe_(2)/C_(60),demonstrating the more efficient charge separation in the MoSe_(2)/C_(60) heterojunction.The difference of electron transfer can be primarily explained in terms of the beneficial energy alignment and the enhanced electron-vibrational interaction.The electron-phonon coupling is stronger for the MoSe_(2)/C_(60) heterojunction because the thermal structural fluctuation is stronger due to the presence of lighter Mo and because the donor-acceptor overlap is larger arising from the smaller fluctuation of the interlayer distance.We further showed that the electron transfer in the MoSe_(2)/C_(60) heterojunction is several orders of magnitude faster than nonradiative charge recombination.The slow charge recombination is a result of the sufficiently large energy gap and the significantly reduced nonadiabatic couplings.Rapid charge transfer and slow charge recombination ensure that the MoSe_(2)/C_(60) heterostructure is an excellent candidate for applications in photovoltaics.Our atomistic investigation provides valuable insights into the photoexcitation dynamics across the interface formed by MoSe_(2) and C_(60),demonstrating the potential of the two components in optimizing the charge separation,which is highly relevant for photovoltaic and optoelectronic applications.展开更多
The intramolecular magnetic interaction between a 4f electronic system in a dysprosium ion and a photoexcited macrocyclicπconjugate system in a 1:1 dysprosium-phthalocyaninato complex,[DyPc(cyclen)]Cl(Pc^(2-)=phthalo...The intramolecular magnetic interaction between a 4f electronic system in a dysprosium ion and a photoexcited macrocyclicπconjugate system in a 1:1 dysprosium-phthalocyaninato complex,[DyPc(cyclen)]Cl(Pc^(2-)=phthalocyaninato dianion,cyclen=1,4,7,10-tetraazacyclododecane),was investigated.Variable-temperature variable-field magnetic circular dichroism(VTVH-MCD)measurements of the Pc-Dy complex showed a reversal of the MCD pattern with decreasing temperature and a two-step dependence on the magnetic field.展开更多
Integrating the photocatalytic evolution of clean fuel hydrogen(H_(2))and high value-added products in a cooperative photoredox system is highly indispensable to achieve green and eco-sustainable development.Herein,an...Integrating the photocatalytic evolution of clean fuel hydrogen(H_(2))and high value-added products in a cooperative photoredox system is highly indispensable to achieve green and eco-sustainable development.Herein,an exquisite bifunctional core–shell Mo_(2)C@ZnIn_(2)S_(4) Schottky heterojunction is judiciously designed and constructed to simultaneously exploit photoexcited electron–hole pairs,achieving H_(2) production coupled with valuable furfuraldehyde(FAL)generation.The optimized Mo_(2)C@ZnIn_(2)S_(4) photocatalyst exhibits 24.1-fold improved H_(2)-yield and a superior FAL-production rate(11.33 mmol g^(−1) h^(−1))compared to blank ZnIn_(2)S_(4),and is also superior to Pt/ZnIn_(2)S_(4) and many previously reported photocatalysts.The boosted photocatalytic redox activity could be attributed to the synergistic effect of the distinctive hierarchical core–shell structure and the non-noble-metal cocatalyst Mo_(2)C,which results in a tightcontact heterointerface,a large specific surface area,abundant electron transport channels,and separate oxidation and reduction sites,thereby prominently promoting spatial photocarrier separation and migration kinetics.This study provides a deeper insight into the rational design of highly efficient bifunctional photocatalysts to steer photocarrier flows for the collaborative reactions of H_(2) evolution and biomass conversion.展开更多
Graphitic carbon nitride(g-C_(3)N_(4)),a layered conjugated organic polymer with suitable bandgap values of∼2.7 eV,has been a welcomed nanostructure for photocatalytic applications in energy conversion and environmen...Graphitic carbon nitride(g-C_(3)N_(4)),a layered conjugated organic polymer with suitable bandgap values of∼2.7 eV,has been a welcomed nanostructure for photocatalytic applications in energy conversion and environmental purification.Some drawbacks of the pure g-C_(3)N_(4)restrict the enhancement of photocatalytic performances,such as the limited solar-light harvesting ability,low surface area and rapid recombination rate of photoexcited electron–hole pairs.Interface engineering is considered as an effective strategy for addressing these issues by combining the superiorities of multi-components,as well as forming various kinds of interfaces.Broadly speaking,this enables the boosting of the light-response range,accelerate the transfer and separation of charge carriers,and inhibit the recombination of photoinduced electron–hole pairs.Unlike previous reviews,we herein summarize the interfaces-related topics of g-C_(3)N_(4)-based composite photocatalysts,including the methods to controllably devise and fabricate interfaces,the techniques to identify interfaces as well as the types and functions of the as-determined interface.Also,the relevant problems and ongoing challenges to design and understand interfaces of g-C_(3)N_(4)-based composite photocatalysts are put forward and highlighted.It is anticipated that this review could open a fresh pathway to further achievements of g-C_(3)N_(4)-based photocatalysts through better understanding and exploitation of interfaces.展开更多
Herein,we report an unprecedented molecular editing strategy for cycloketones that involves the precise translocation and removal of single oxygen atom enabled by dual photoexcited palladium and photoredox catalysis.I...Herein,we report an unprecedented molecular editing strategy for cycloketones that involves the precise translocation and removal of single oxygen atom enabled by dual photoexcited palladium and photoredox catalysis.In contrast to conventional ketone molecular editing strategies,which often rely on the loss of pre-functionalized groups or the addition of additional acylating agents,this approach facilitates the efficient recycling of pre-functionalized moieties.This is accomplished through a photoexcited palladium catalyzed N–O bond cleavage of cycloketone oxime esters,generating cyanoalkyl radicals and a palladium carboxylate complex.The subsequent photoredox-catalyzed deoxygenation,mediated by phosphoranyl radicals,then leads to the coupling of cyanoalkyl radicals,ultimately yielding the desired products.This molecular editing strategy features good atom economy due to precise skeletal modifications,broad compatibility with various functional groups,and significant potential for late-stage functionalization of pharmaceutical derivatives.展开更多
In recent years,photoinduced transition metal(TM)catalysis has garnered significant attention for advancing various asymmetric chemical transformations.Unlike traditional photocatalysis,photoexcited TM catalysis opera...In recent years,photoinduced transition metal(TM)catalysis has garnered significant attention for advancing various asymmetric chemical transformations.Unlike traditional photocatalysis,photoexcited TM catalysis operates through outer-sphere mechanisms,leveraging direct and strong substrate-metal interactions.The TM complex performs a dual role,both harvesting light and catalyzing chemical transformations,typically via single electron transfer pathways.This innovative approach establishes a multifunctional platform that facilitates the development of novel,particularly enantioselective,chemical transformations.Given that photoexcited TM asymmetric catalysis serves as an important complement to ground-state TM asymmetric catalysis,this review highlights recent advancements in photoexcited TM(Cu,Pd,Ir,Ti,etc.)asymmetric catalysis.展开更多
基金the National Natural Science Foundation of China(Nos.22105099,61874053)Natural Science Foundation of Jiangsu Province(No.BK20200700)the open research fund from Anhui Province Key Laboratory of Optoelectronic Materials Science and Technology(No.OMST202101).
文摘Exciton behavior is crucial to the exploitation of light-emitting conjugated polymer(LCPs)for optoelectronic devices.Singlet excitons are easily trapped by the intrinsically defect structures.Herein,we set a polyfluorenol(PPFOH)as an example to systematically investigate its photophysical behavior to check the role of defect structures in LCPs.According to time-resolved photoluminescence analysis,the feature emission peaks from individual chain of PPFOH in diluted DMF solution is effectively avoided the influence of fluorenone formation,but the residual green-band emission at 550nm is easily observed in the PL spectra of PPFOH dilute toluene solution obtained delay 1.5 ns,confirmed the formation of“vip”physical aggregation-induced defect structure.Remarkably,efficient and ultrafast energy transfer from individual chain to defect structure is observed in PPFOH films.Interestingly,the efficient energy transfer happened for the film obtained from DMF solution(200 ps)than those of toluene ones(600 ps).Meanwhile,compared to relatively stable green-band emission in PPFOH film from toluene solution,red-shifted emission peak(11 nm)of PPFOH film from DMF solutions exposed to saturated DNT vapor also confirmed their different aggregation-induced green-band emission.Therefore,this aggregation defect structures are influenced on the photophysical property of LCPs in solid states.
基金supported by the National Key Research and Development Project(2019YFA0705804).
文摘Although the Haber–Bosch process supports the growth of modern agriculture with abundant ammonia and fertilizer production,substantial energy consumption and enormous greenhouse emissions demand an alternative and sustainable approach.Here,we report a novel approach that combines the nonphotosynthetic bacterium Shewanella oneidensis MR-1(S.oneidensis MR-1)with cadmium sulfide(CdS)nanoparticles(NPs)to enable the photosynthesis of ammonium(NH_(4)+)from nitrate(NO_(3)^(-))using photoexcited electrons as donors.The NO_(3)^(-)reduction efficiency reached almost 100%,with an NH_(4)^(+)production selectivity of over 90%.The maximum instantaneous quantum efficiency was 3.01%under light irradiation.The reverse metal-reducing(Mtr)pathway is responsible for the transfer of photoexcited electrons to intracellular compartments.Parallel reaction monitoring analysis illustrated that NO_(3)^(-)to NH_(4)^(+)was produced via the dissimilatory nitrate reduction to ammonium(DNRA)pathway in S.oneidensis MR-1.This study provides a facile strategy for light-driven ambient NH4+synthesis and solar-to-chemical conversion.
基金financial supports pro-vided by the National Natural Science Foundation of China(No.21905279)the Natural Science Foundation of Fujian Province(No.2020J05086).
文摘Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast photogenerated electron-hole recombination.To tackle these issues,herein,we propose a new strategy to modify Cd_(x) Zn_(1-x) S nanoreactors by the simultaneous utilization of ionic-liquid-assisted morphology engineering and MXene-incorporating method.That is,we designed and synthesized a novel hierarchi-cal Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction composite through the in-situ deposition of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets on unique IL-modified Ti_(3) C_(2) MXenes by a one-pot solvothermal method for efficiently PHE.The unique construction strategy tailors the thickness of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets and prevents them from stacking and agglomeration,and especially,optimizes their charge transfer pathways during the photocatalytic process.Compared with pristine Cd_(0.8) Zn_(0.2) S nanosheets,Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) has abun-dant photogenerated electrons available on the Ti_(3) C_(2) surface for proton reduction reaction,owing to the absence of deep-trapped electrons,suppression of electron-hole recombination in Cd_(0.8) Zn_(0.2) S and high-efficiency charge separation at the Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction interface.Moreover,the hy-drophilicity,electrical conductivity,visible-light absorption capacity,and surficial hydrogen desorption of Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) heterostructure are significantly improved.As a result,the heterostructure exhibits out-standing photocatalytic stability and super high apparent quantum efficiency,being rendered as one of the best noble-metal-free Cd-Zn-S-based photocatalysts.This work illustrates the mechanisms of mor-phology control and heterojunction construction in controlling the catalytic behavior of photocatalysts and highlights the great potential of the IL-assisted route in the synthesis of high-performance MXene-based heterostructures for photocatalytic hydrogen evolution.
基金supported by the National Key R&D Program of China (Grant No. 2024YFA1408502)the National Natural Science Foundation of China (Grant Nos. 92365102, 62027807, 12474107, and 12174383)+1 种基金the Chinese Academy of Sciences project for Yong Scientists in Basic Research (Grant No. YSBR-030)the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2024A1515011600)。
文摘We investigate the carrier, phonon, and spin dynamics in the ferromagnetic semiconductor(In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^(*)(~40 K) and T^(†)(~200 K) in the photoexcited carrier dynamics, which can be attributed to the electron-spin and spin-lattice scattering processes influenced by the magnetic phase transition and modifications in magnetic anisotropy. The magnetization change can be revealed by the dynamics of coherent acoustic phonon. We also observe abrupt changes in the photoinduced spin dynamics near T^(*)and T^(†), which not only illustrate the spin-related scatterings closely related to the long-range magnetic order, but also reveal the D'yakonov–Perel and Elliott–Yafet mechanisms dominating at temperatures below and above T^(†), respectively. Our findings provide important insights into the nonequilibrium properties of the photoexcited(In,Fe)Sb.
基金supported by the National Key Research and Development Program of China (Grant No.2023YFF0719200)the National Natural Science Foundation of China (Grant Nos.62322115,U24A20226,62588201,62435010,and 62335012)+2 种基金the 111 Project (Grant No.D18014)the Key project supported by Science and Technology Commission Shanghai Municipality (Grant No.YDZX20193100004960)Science and Technology Commission of Shanghai Municipality (Grant Nos.22JC1400200 and 21S31907400)。
文摘Surface states are expected to play a key role in broadband terahertz(THz) emitters, where photoexcited carrier distributions are confined within about 1 μm of the surface. Optical pump and THz probe spectroscopy was used to study the dynamics of nonequilibrium charge carriers in both textured and non-textured GaAs substrates.Our findings show that the textured surface acts as an antireflective layer, greatly boosting the infrared pump laser's coupling efficiency into the semi-insulating GaAs substrate. Additionally, texturing introduces a trapassisted recombination pathway, speeding up carrier relaxation and thus reducing Joule heating. Under the same pumping and bias field conditions, the coarse-textured GaAs photoconductive antenna shows nearly 7.85 times stronger THz emission amplitude than the non-textured device, along with improvement in signal-to-noise ratio.At a fixed bias field, higher pump power increases photogenerated carrier density, causing bias field screening and subsequent saturation of THz emission. At fixed pump power, when the bias field reaches ~2.5 kV/cm, both THz emission and photocurrent spectra show a clear kink, signaling intervalley scattering from the Γ valley to the L(X) valleys under high electric fields.
文摘We detect a relaxation process of excited SQ02 dye in the chlorobenzene solution and an- chor SQ02 on Al2O3 and TiO2 film, so as to investigate the photophysical properties of pristine SQ02 in the monodisperse system, aggregation state, and the corresponding inter- facial electron transfer process. The experimental data show that the lifetime of SQ02 in the monondisperse system is ～2.0 ns, but that of SQ02 anchored on the Al2O3 film could obviously decrease to ～21 ps. The time of electron transfer from excited SQ02 to TiO2 film is estimated to be ～2.6 ps and the yield of electron injection is estimated to be ～89.1%, which matches the incident photon to current efficiency of dye-sensitized solar cell based on SQ02. In addition, some dyes are found to pack on the other dyes anchored on the nanocrystal film, and their relaxation time could reach ～60 ps. They couldn＇t participate in the interfacial electron transfer, since they are far away from the TiO2 interface.
文摘Polarons are widely considered to play a crucial role in the charge transport and photocatalytic performance of materials,but the mechanisms of their formation and the underlying driving factors remain a matter of controversy.This study delves into the formation of polarons in different crystalline forms of TiO_(2) and their connection with the materials'structure.By employing density functional theory calculations with on-site Coulomb interaction correction(DFT+U),we provide a detailed analysis of the electronic polarization behavior in the anatase and rutile forms of TiO_(2).We focus on the polarization properties of defect-induced and photoexcited excess electrons on various TiO_(2) surfaces.The results reveal that the defect electrons can form small polarons on the anatase TiO_(2)(101)surface,while on the rutile TiO_(2)(110)surface,both small and large polarons(hybrid-state polarons)are formed.Photoexcited electrons are capable of forming both small and large polarons on the surfaces of both crystal types.The analysis indicates that the differences in polaron distribution are primarily determined by the intrinsic properties of the crystals;the structural and symmetry differences between anatase and rutile TiO_(2) lead to the distinct polaron behaviors.Further investigation suggests that the polarization behavior of defect electrons is also related to the arrangement of electron orbitals around the Ti atoms,while the polarization of photoexcited electrons is mainly facilitated by the lattice distortions.These findings elucidate the formation mechanisms of different types of polarons and may contribute to understanding the performance of TiO_(2)in different fields.
文摘By using soft X-ray spectroscopy, we investigate the inner-shell excitation and relaxation processes in atomic and ionic neon targets. Resonant X-ray emission spectroscopy was applied to neutral neon atom in the regions of the [1s]np （n = 3, 4,…, ε） excited states and [1s2p]3pmp （m = 3,4） doubly excited states to obtain the spectroscopic information on the [2p]np and [2p^2]3prnp final electronic states, where square brackets indicate hole states. The energy levels of the [2p^2]3prnp （m = 3,4） electronic states were spectroscopically measured for the first time. As for the ionic neon target, on the other hand, the photoion yield spectroscopy was adopted to survey the 1s→ np （n = 2, 3） resonant excitation and subsequent Auger decay processes for Ne^＋ target-ions. The observed Ne^2＋ photoion yield spectrum is successflllly explained by the theoretical calculations based on the nmlticonfiguration Dirac-Fock method
基金supported by the National Key R&D Program of China (2018YFE0208500)the Japan Science and Technology Agency (JST) Mirai program (JPMJMI17EA)。
文摘As one of the most compelling photovoltaic devices, halide perovskite (PVK) solar cells have achieved a new surprising record power conversion efficiency (PCE) of 25.8%in 2021 [1]. This demonstrates the great potential of halide PVK solar cells as a highly competitive substitute to replace silicon-based solar cells in the photovoltaic market [2–6].
基金We are thankful to the National Natural Science Foundation of China(22174110 and 22127803)the Industrial Support Plan of Gansu Provincial Department of Education(2021cyzc-01)the Special Fund Project for Guiding Local Scientific and Technological Development by the Central Government(2020-2060503-17).
文摘Crafting charge transfer channels at titanium dioxide(TiO_(2))based photoanodes remain a pressing bottleneck in solar-to-chemical conversion technology.Despite the tremendous attempts,TiO_(2)as the promising photoanode material still suffers from sluggish charge transport kinetics.Herein,we propose an assembly strategy that involves the axial coordination grafting metalloporphyrin-based photosensitizer molecules(MP)onto the surface-modified TiO_(2)nanorods(NRs)photoanode,forming the composite MP/TiO_(2)NRs photoelectrode.As expected,the resulted unique MPB/TiO_(2)NRs photoelectrode displays significantly improved photocurrent density as compared to TiO_(2)NRs alone and MPA/TiO_(2)NRs photoelectrode.Scanning photoelectrochemical microscopy(SPECM)and intensity modulated photocurrent spectroscopy(IMPS)were employed to systematically evaluate the continuous photoinduced electron transfer(PET)dynamics for MP/TiO_(2)NRs photoelectrode.According to the data fitting,it is found that the photoelectron transfer rate(keff)constant for the MPB/TiO_(2)NRs is about 2.6 times higher than that for the pure TiO_(2)NRs under light irradiation.The high kinetic constant for the MPB/TiO_(2)NRs was ascribed to that the conjugated molecules MPB of D-A structure can effectively accelerate intramolecular electrons transfer as well as promote electrons taking part in the reduction reaction of I3to Iin the novel charge transfer channel.The results demonstrated in this study are expected to shed some light on investigating the mechanism in the charge transfer process of artificial photosynthesis and constructing efficient photoelectrodes.
文摘The photochemical reaction of methylene blue (n-butyltriphenyl) borate, MBRBPh3 was examined. The ultrafast quenching rate and large negative value of Delta G indicated that the intra-ion pair ET plays an important role in photoreaction of MBRBPh3. The sequent boron- carbon bond cleavage of butyltriphenylboranyl radical intermediate was found by GC-MS and photo-CIDNP studies.
基金supported by the National Natural Science Foundation of China(22105128)the Open Research Fund of the School of Chemistry and Chemical Engineering,Henan Normal University(2024Y12)。
文摘Chiral metal-organic frameworks(CMOFs),characterized by their enantioselective porous architectures,intrinsic chirality,and precisely ordered active sites,have emerged as a transformative class of materials with applications spanning asymmetric catalysis,enantiomeric separation,and chiral sensing.In this study,persulfurated arenes,as AIEgens with photoexcitation activity,were used as fluorescent dyes.Usingγ-cyclodextrin as a chiral template,we constructed a photo-responsive CMOF via intermolecular hydrogen bonding.The co-assembly process exhibited remarkable phenomena of chiral amplification and transfer,generating bright yellow fluorescence under mild UV irradiation at 365 nm.Deprotonated persulfurated arenes were used for comparative studies,and the resulting photoresponsive chiral metal-organic frameworks showed signals of reversed peaks at 400 and 460 nm.This study provides a novel construction strategy for chiral metal-organic frameworks featuring dual dynamic regulation mechanisms mediated by hydrogen bonding and photoirradiation.
文摘Phototheranostics that performs real-time diagnosis and concurrent in situ therapy upon non-invasive photoexcitation is rapidly emerging as a promising frontier[1],by virtue of its notable advantages including minimal toxicity,precise diagnosis imaging capability,satisfactory therapeutic effect,and negligible drug resistance.Of particular interest is single organic small molecules synchronously possessing powerful second near-infrared fluorescence imaging(NIR-IIFLI)ability and prominent phototherapeutic outputs,owing to the high spatial resolution and imaging depth enabled by diminished tissue autofluorescence,reduced photon scattering,and low levels of photon absorption.
文摘Ultrafast transient absorption spectrometry and DFT/TDDFT calculations reveal that following photoexcitation,carboranyl-and carboranyl-free alkylthioporphyrazines deactivate by the pathway S_(1)(π,π^(*))→Sn(C_(β)-2p_(z)/Sl.p.,π^(*))→ground state.The presence of quenching singlet excited states with predominantly C_(β)-2p_(z)/Sl.p.,π^(*)character immediately below the primarily photogenerated S_(1)(π,π^(*))state is a consequence of the electronic structure changes induced by the inherent flexibility of the alkylthio chains.
基金financial support of the National Natural Science Foundation of China(No.22373033)the Science and Technology Innovation Program of Hunan Province(No.2021RC3089)T.X.acknowledges the Innovation and Entrepreneurship Training Program for Undergraduates(No.s202210537081,No.D202305231555195730).
文摘Transition metal dichalcogenide-fullerene(TMD/fullerene)van der Waals(vdW)heterojunctions are promising for photovoltaic applications due to the intriguing optoelectronic properties of their individual components.However,the fundamental understanding of the photophysical process,especially excited-state charge transfer and recombination,remains insufficient.Here,using ab initio nonadiabatic molecular dynamics,we investigated the photoexcitation dynamics across the interface composed of the MoSe_(2) monolayer and C_(60) molecules and compared it with the WSe_(2)/C_(60) heterojunction which has been experimentally demonstrated to be efficient for photovoltaic application.Our simulation results show that MoSe_(2)/C_(60) exhibits significantly faster electron transfer and a comparable charge recombination time to WSe_(2)/C_(60),demonstrating the more efficient charge separation in the MoSe_(2)/C_(60) heterojunction.The difference of electron transfer can be primarily explained in terms of the beneficial energy alignment and the enhanced electron-vibrational interaction.The electron-phonon coupling is stronger for the MoSe_(2)/C_(60) heterojunction because the thermal structural fluctuation is stronger due to the presence of lighter Mo and because the donor-acceptor overlap is larger arising from the smaller fluctuation of the interlayer distance.We further showed that the electron transfer in the MoSe_(2)/C_(60) heterojunction is several orders of magnitude faster than nonradiative charge recombination.The slow charge recombination is a result of the sufficiently large energy gap and the significantly reduced nonadiabatic couplings.Rapid charge transfer and slow charge recombination ensure that the MoSe_(2)/C_(60) heterostructure is an excellent candidate for applications in photovoltaics.Our atomistic investigation provides valuable insights into the photoexcitation dynamics across the interface formed by MoSe_(2) and C_(60),demonstrating the potential of the two components in optimizing the charge separation,which is highly relevant for photovoltaic and optoelectronic applications.
基金supported by the JSPS KAKENHI Grant Number 21K18982 and partly achieved through the use of the supercomputer system SQUID at the Cybermedia Center,Osaka University.
文摘The intramolecular magnetic interaction between a 4f electronic system in a dysprosium ion and a photoexcited macrocyclicπconjugate system in a 1:1 dysprosium-phthalocyaninato complex,[DyPc(cyclen)]Cl(Pc^(2-)=phthalocyaninato dianion,cyclen=1,4,7,10-tetraazacyclododecane),was investigated.Variable-temperature variable-field magnetic circular dichroism(VTVH-MCD)measurements of the Pc-Dy complex showed a reversal of the MCD pattern with decreasing temperature and a two-step dependence on the magnetic field.
基金supported by the National Natural Science Foundation of China(Grant No.21571162).
文摘Integrating the photocatalytic evolution of clean fuel hydrogen(H_(2))and high value-added products in a cooperative photoredox system is highly indispensable to achieve green and eco-sustainable development.Herein,an exquisite bifunctional core–shell Mo_(2)C@ZnIn_(2)S_(4) Schottky heterojunction is judiciously designed and constructed to simultaneously exploit photoexcited electron–hole pairs,achieving H_(2) production coupled with valuable furfuraldehyde(FAL)generation.The optimized Mo_(2)C@ZnIn_(2)S_(4) photocatalyst exhibits 24.1-fold improved H_(2)-yield and a superior FAL-production rate(11.33 mmol g^(−1) h^(−1))compared to blank ZnIn_(2)S_(4),and is also superior to Pt/ZnIn_(2)S_(4) and many previously reported photocatalysts.The boosted photocatalytic redox activity could be attributed to the synergistic effect of the distinctive hierarchical core–shell structure and the non-noble-metal cocatalyst Mo_(2)C,which results in a tightcontact heterointerface,a large specific surface area,abundant electron transport channels,and separate oxidation and reduction sites,thereby prominently promoting spatial photocarrier separation and migration kinetics.This study provides a deeper insight into the rational design of highly efficient bifunctional photocatalysts to steer photocarrier flows for the collaborative reactions of H_(2) evolution and biomass conversion.
基金supported by the National Natural Science Foundation of China(Grant No.11674398).
文摘Graphitic carbon nitride(g-C_(3)N_(4)),a layered conjugated organic polymer with suitable bandgap values of∼2.7 eV,has been a welcomed nanostructure for photocatalytic applications in energy conversion and environmental purification.Some drawbacks of the pure g-C_(3)N_(4)restrict the enhancement of photocatalytic performances,such as the limited solar-light harvesting ability,low surface area and rapid recombination rate of photoexcited electron–hole pairs.Interface engineering is considered as an effective strategy for addressing these issues by combining the superiorities of multi-components,as well as forming various kinds of interfaces.Broadly speaking,this enables the boosting of the light-response range,accelerate the transfer and separation of charge carriers,and inhibit the recombination of photoinduced electron–hole pairs.Unlike previous reviews,we herein summarize the interfaces-related topics of g-C_(3)N_(4)-based composite photocatalysts,including the methods to controllably devise and fabricate interfaces,the techniques to identify interfaces as well as the types and functions of the as-determined interface.Also,the relevant problems and ongoing challenges to design and understand interfaces of g-C_(3)N_(4)-based composite photocatalysts are put forward and highlighted.It is anticipated that this review could open a fresh pathway to further achievements of g-C_(3)N_(4)-based photocatalysts through better understanding and exploitation of interfaces.
基金support from the National Natural Science Foundation of China(22171233)the Science and Technology Department of Sichuan Province(2023NSFSC1086)the Science and Technology Project of Luzhou City(2024RCX207)。
文摘Herein,we report an unprecedented molecular editing strategy for cycloketones that involves the precise translocation and removal of single oxygen atom enabled by dual photoexcited palladium and photoredox catalysis.In contrast to conventional ketone molecular editing strategies,which often rely on the loss of pre-functionalized groups or the addition of additional acylating agents,this approach facilitates the efficient recycling of pre-functionalized moieties.This is accomplished through a photoexcited palladium catalyzed N–O bond cleavage of cycloketone oxime esters,generating cyanoalkyl radicals and a palladium carboxylate complex.The subsequent photoredox-catalyzed deoxygenation,mediated by phosphoranyl radicals,then leads to the coupling of cyanoalkyl radicals,ultimately yielding the desired products.This molecular editing strategy features good atom economy due to precise skeletal modifications,broad compatibility with various functional groups,and significant potential for late-stage functionalization of pharmaceutical derivatives.
基金supported by the National Natural Science Foundation of China(22371119)。
文摘In recent years,photoinduced transition metal(TM)catalysis has garnered significant attention for advancing various asymmetric chemical transformations.Unlike traditional photocatalysis,photoexcited TM catalysis operates through outer-sphere mechanisms,leveraging direct and strong substrate-metal interactions.The TM complex performs a dual role,both harvesting light and catalyzing chemical transformations,typically via single electron transfer pathways.This innovative approach establishes a multifunctional platform that facilitates the development of novel,particularly enantioselective,chemical transformations.Given that photoexcited TM asymmetric catalysis serves as an important complement to ground-state TM asymmetric catalysis,this review highlights recent advancements in photoexcited TM(Cu,Pd,Ir,Ti,etc.)asymmetric catalysis.
