Organic semiconductor materials have demonstrated extensive potential in the field of gas sensors due to the advantages including designable chemical structure,tunable physical and chemical properties.Through density ...Organic semiconductor materials have demonstrated extensive potential in the field of gas sensors due to the advantages including designable chemical structure,tunable physical and chemical properties.Through density functional theory(DFT)calculations,researchers can investigate gas sensing mechanisms,optimize,and predict the electronic structures and response characteristics of these materials,and thereby identify candidate materials with promising gas sensing applications for targeted design.This review concentrates on three primary applications of DFT technology in the realm of organic semiconductor-based gas sensors:(1)Investigating the sensing mechanisms by analyzing the interactions between gas molecules and sensing materials through DFT,(2)simulating the dynamic responses of gas molecules,which involves the behavior on the sensing interface using DFT combined with other computational methods to explore adsorption and diffusion processes,and(3)exploring and designing sensitive materials by employing DFT for screening and predicting chemical structures,thereby developing new sensing materials with exceptional performance.Furthermore,this review examines current research outcomes and anticipates the extensive application prospects of DFT technology in the domain of organic semiconductor-based gas sensors.These efforts are expected to provide valuable insights for further indepth exploration of DFT applications in sensor technology,thereby fostering significant advancements and innovations in the field.展开更多
Frequency combs[1, 2] consisting of equally-spaced frequencylines can be fully described by two frequencies, i.e., carrieroffset (fCEO) and repetition rate (frep). Once the two frequenciesare stabilized, the frequency...Frequency combs[1, 2] consisting of equally-spaced frequencylines can be fully described by two frequencies, i.e., carrieroffset (fCEO) and repetition rate (frep). Once the two frequenciesare stabilized, the frequency comb is well defined. Frequencycombs can be used for various applications, i.e., metrology,spectroscopy, timing, communications, absolute distancemeasurements, and so on, due to their two importantcharacteristics, i.e., stabilized frequency lines and ultra-shortoptical pulses (if the mode-locking is obtained) as shown inFig. 1.展开更多
We have experimentally studied the mode-locking dynamics of a polarization-maintaining figure-of-eight laser which has a semiconductor optical amplifier as gain medium. Self-starting mode-locking at the fundamental re...We have experimentally studied the mode-locking dynamics of a polarization-maintaining figure-of-eight laser which has a semiconductor optical amplifier as gain medium. Self-starting mode-locking at the fundamental repetition rate of 18 MHz is obtained at the lasing threshold, and further increasing the bias current leads to the progressive emission of additional optical pulses in each round trip and eventually to mode-locked emission at increasingly high harmonics of the fundamental repetition rate, up to 2.45 GHz. The intensity autocorrelation of the amplified mode-locked pulses has a full width at half-maximum duration of 382 fs, which corresponds to a pulse duration of 247 fs.展开更多
The rational fabrication of heterostructures is one of efficient strategies for improving photocatalytic performance of semiconductor photocatalysts.Very recently,Domen and co-workers found that Ta_(3)N_(5) single cry...The rational fabrication of heterostructures is one of efficient strategies for improving photocatalytic performance of semiconductor photocatalysts.Very recently,Domen and co-workers found that Ta_(3)N_(5) single crystals grown on the surface of KTaO_(3) can accomplish photocatalytic overall water splitting for the first time.In order to comprehend the underlying mechanism of this photocatalytic system,we have performed a systematic study based on density functional theory first-principles calculations.Ta_(3)N_(5)(010)/KTaO_(3)(110)slab models have been built according to experimental observations by considering two common terminations of KTaO_(3)(110)surface,named as Ta_(3)N_(5)/O_(2) and Ta_(3)N_(5)/KTaO.The formations of interfacial bonds are thermodynamically stable,showing a covalent interaction between two components of a heterostructure.Ta_(3)N_(5)/O_(2) has a higher mobility of photogenerated charge carriers and lower recombination rate of charge carriers than Ta_(3)N_(5)/KTaO.The light absorption of heterostructures displays the feature of KTaO_(3) in the short wavelength region and the characteristic of Ta_(3)N_(5) in the long wavelength region.The calculated band offsets show that Ta_(3)N_(5)/O_(2) and Ta_(3)N_(5)/KTaO have distinct Type-II band alignments,with Ta_(3)N_(5) as the accumulator of photoinduced electrons in the former and the collector of photogenerated holes in the latter,respectively.The difference in charge density and electrostatic potential between two components acts as a driving force to promote the transfer of electrons and holes to different domains of the interface,which is beneficial to extend the lifetime of photoinduced carriers.Our results demonstrate that the function of Ta_(3)N_(5) in Ta_(3)N_(5)/KTaO_(3) photocatalytic system is determined by the termination property of KTaO_(3)(110)surface,which provides a likely reason of the observed photocatalytic activity of overall water splitting achieved by Ta_(3)N_(5) synthesized by using KTaO_(3) as a precursor for the nitridation reaction.展开更多
In this theoretical work,we describe a mechanism for the coupling between a plane structure consisting of four quantum dots and a resonator.We systematically study the dependence of the quadruple coupling strength and...In this theoretical work,we describe a mechanism for the coupling between a plane structure consisting of four quantum dots and a resonator.We systematically study the dependence of the quadruple coupling strength and the qubit decoherence rate and point out the optimized operating position of the hybrid system.According to the transmission given by the input-output theory,the signatures in the resonator spectrum are predicted.Furthermore,based on the parameters already achieved in previous works,we prove that the device described in this paper can achieve the strong coupling limit,i.e.,this approach can be used for system extension under the existing technical conditions.Our results show an effective and promotable approach to couple quantum dot structures in plane with the resonator and propose a meaningful extension method.展开更多
SrTiO3 is a promising candidate photocatalyst for overall water splitting.Loading suitable cocatalysts,such as NiOx,the mixture of Ni and NiO,remarkably improve the photocatalytic activity.However,spatial locations an...SrTiO3 is a promising candidate photocatalyst for overall water splitting.Loading suitable cocatalysts,such as NiOx,the mixture of Ni and NiO,remarkably improve the photocatalytic activity.However,spatial locations and functions of components in NiOx/SrTiO3 are under debate.Here,using first-principles density functional theory(DFT)calculations,we investigate the initial growth of Nin(n=1–4)and(NiO)n(n=1,2 and 4)clusters on stoichiometric(100)surfaces of SrTiO3,and explore interfacial and electronic structures of composite photocatalysts.It is found that Nin clusters are easier to undergo aggregation on SrO-termination than on TiO2-termination.The adsorption of Nincluster on(100)surfaces elevates the Fermi level towards the conduction band,which may benefit the occurrence of hydrogen evolution reaction.The structural similarity between(NiO)n cluster and surface has an essential effect on the most stable adsorption configuration.For(NiO)n/SrTiO3 systems,the occupied states of(NiO)n cluster well overlap with those of(100)surfaces in the valence band maximum,which is in favor of the separation of photogenerated electrons and holes to SrTiO3 support and(NiO)n cluster,respectively.The detailed DFT analysis provides important insights into the growth of NiOx on surfaces of SrTiO3and presents an explanation on the different models of NiOx/SrTiO3 photocatalyst proposed by experimental groups.Our calculations build a basis for further investigations on the mechanism of photocatalytic water-splitting reaction in NiOx/SrTiO3composite system.展开更多
The light absorption properties of semiconductor-based photocatalysts to a large extent determine the relevant catalytic performance.Traditional strategies in broadening the light absorption range are usually accompan...The light absorption properties of semiconductor-based photocatalysts to a large extent determine the relevant catalytic performance.Traditional strategies in broadening the light absorption range are usually accompanied with unfavorable changes in redox ability and dynamics of photoinduced species that would confuse the comprehensive optimization.In this work,we propose a nontrivial excitonic transition regulation strategy for gaining sub-bandgap light absorption in low-dimensional semiconductor-based photocatalysts.Using bismuth oxybromide(BiOBr)as a model system,we highlight that the light absorption cut-off edge could be effectively extended up to 500 nm by introducing Bi vacancies.On the basis of theoretical simulations and spectroscopic analyses,we attributed the broadening of light absorption to the promotion of excitonic transition that is generally forbidden in pristine BiOBr system,associated with Bi-vacancy-induced excited-state symmetry breaking.In addition,Bi vacancy was demonstrated to implement negligible effects on other photoexcitation properties like excited-state energy-level profiles and kinetics.Benefiting from these features,the defective sample exhibits a notable advantage in gaining visible-light-driven photocatalytic reactions.展开更多
基金supported by National Natural Science Foundation of China(Nos.92263109 and 61904188)the Shanghai Rising-Star Program(No.22QA1410400)。
文摘Organic semiconductor materials have demonstrated extensive potential in the field of gas sensors due to the advantages including designable chemical structure,tunable physical and chemical properties.Through density functional theory(DFT)calculations,researchers can investigate gas sensing mechanisms,optimize,and predict the electronic structures and response characteristics of these materials,and thereby identify candidate materials with promising gas sensing applications for targeted design.This review concentrates on three primary applications of DFT technology in the realm of organic semiconductor-based gas sensors:(1)Investigating the sensing mechanisms by analyzing the interactions between gas molecules and sensing materials through DFT,(2)simulating the dynamic responses of gas molecules,which involves the behavior on the sensing interface using DFT combined with other computational methods to explore adsorption and diffusion processes,and(3)exploring and designing sensitive materials by employing DFT for screening and predicting chemical structures,thereby developing new sensing materials with exceptional performance.Furthermore,this review examines current research outcomes and anticipates the extensive application prospects of DFT technology in the domain of organic semiconductor-based gas sensors.These efforts are expected to provide valuable insights for further indepth exploration of DFT applications in sensor technology,thereby fostering significant advancements and innovations in the field.
基金supported by the "Hundred-Talent" Program of Chinese Academy of Sciencesthe National Natural Science Foundation of China(61875220,61575214,61404150,61405233,and 61704181)+1 种基金the National Key R&D Program of China(2017YFF0106302 and 2017YFA0701005)Shanghai Municipal Commission of Science and Technology(17YF1430000)
文摘Frequency combs[1, 2] consisting of equally-spaced frequencylines can be fully described by two frequencies, i.e., carrieroffset (fCEO) and repetition rate (frep). Once the two frequenciesare stabilized, the frequency comb is well defined. Frequencycombs can be used for various applications, i.e., metrology,spectroscopy, timing, communications, absolute distancemeasurements, and so on, due to their two importantcharacteristics, i.e., stabilized frequency lines and ultra-shortoptical pulses (if the mode-locking is obtained) as shown inFig. 1.
基金Ministerio de Economía y Competitividad(MINECO)(TEC2015-65212-C3-3-P)
文摘We have experimentally studied the mode-locking dynamics of a polarization-maintaining figure-of-eight laser which has a semiconductor optical amplifier as gain medium. Self-starting mode-locking at the fundamental repetition rate of 18 MHz is obtained at the lasing threshold, and further increasing the bias current leads to the progressive emission of additional optical pulses in each round trip and eventually to mode-locked emission at increasingly high harmonics of the fundamental repetition rate, up to 2.45 GHz. The intensity autocorrelation of the amplified mode-locked pulses has a full width at half-maximum duration of 382 fs, which corresponds to a pulse duration of 247 fs.
基金financially supported by the Natural Science Foundation of Liaoning Province(Grant No.2019-ZD-0304)the Educational Department of Liaoning Province(Grant No.LJ2019009)+1 种基金Liaoning BaiQianWan Talents Program,Doctoral Start-up Foundation of Liaoning Province(Grant No.20170520231)the open fund of the State Key Laboratory of Molecular Reaction Dynamics in Dalian Institute of Chemical Physics(Grant No.SKLMRDK202001),Chinese Academy of Sciences。
文摘The rational fabrication of heterostructures is one of efficient strategies for improving photocatalytic performance of semiconductor photocatalysts.Very recently,Domen and co-workers found that Ta_(3)N_(5) single crystals grown on the surface of KTaO_(3) can accomplish photocatalytic overall water splitting for the first time.In order to comprehend the underlying mechanism of this photocatalytic system,we have performed a systematic study based on density functional theory first-principles calculations.Ta_(3)N_(5)(010)/KTaO_(3)(110)slab models have been built according to experimental observations by considering two common terminations of KTaO_(3)(110)surface,named as Ta_(3)N_(5)/O_(2) and Ta_(3)N_(5)/KTaO.The formations of interfacial bonds are thermodynamically stable,showing a covalent interaction between two components of a heterostructure.Ta_(3)N_(5)/O_(2) has a higher mobility of photogenerated charge carriers and lower recombination rate of charge carriers than Ta_(3)N_(5)/KTaO.The light absorption of heterostructures displays the feature of KTaO_(3) in the short wavelength region and the characteristic of Ta_(3)N_(5) in the long wavelength region.The calculated band offsets show that Ta_(3)N_(5)/O_(2) and Ta_(3)N_(5)/KTaO have distinct Type-II band alignments,with Ta_(3)N_(5) as the accumulator of photoinduced electrons in the former and the collector of photogenerated holes in the latter,respectively.The difference in charge density and electrostatic potential between two components acts as a driving force to promote the transfer of electrons and holes to different domains of the interface,which is beneficial to extend the lifetime of photoinduced carriers.Our results demonstrate that the function of Ta_(3)N_(5) in Ta_(3)N_(5)/KTaO_(3) photocatalytic system is determined by the termination property of KTaO_(3)(110)surface,which provides a likely reason of the observed photocatalytic activity of overall water splitting achieved by Ta_(3)N_(5) synthesized by using KTaO_(3) as a precursor for the nitridation reaction.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.92265113,12074368,and 12034018).
文摘In this theoretical work,we describe a mechanism for the coupling between a plane structure consisting of four quantum dots and a resonator.We systematically study the dependence of the quadruple coupling strength and the qubit decoherence rate and point out the optimized operating position of the hybrid system.According to the transmission given by the input-output theory,the signatures in the resonator spectrum are predicted.Furthermore,based on the parameters already achieved in previous works,we prove that the device described in this paper can achieve the strong coupling limit,i.e.,this approach can be used for system extension under the existing technical conditions.Our results show an effective and promotable approach to couple quantum dot structures in plane with the resonator and propose a meaningful extension method.
基金financially supported by the National Natural Science Foundation of China under Grant 21473183
文摘SrTiO3 is a promising candidate photocatalyst for overall water splitting.Loading suitable cocatalysts,such as NiOx,the mixture of Ni and NiO,remarkably improve the photocatalytic activity.However,spatial locations and functions of components in NiOx/SrTiO3 are under debate.Here,using first-principles density functional theory(DFT)calculations,we investigate the initial growth of Nin(n=1–4)and(NiO)n(n=1,2 and 4)clusters on stoichiometric(100)surfaces of SrTiO3,and explore interfacial and electronic structures of composite photocatalysts.It is found that Nin clusters are easier to undergo aggregation on SrO-termination than on TiO2-termination.The adsorption of Nincluster on(100)surfaces elevates the Fermi level towards the conduction band,which may benefit the occurrence of hydrogen evolution reaction.The structural similarity between(NiO)n cluster and surface has an essential effect on the most stable adsorption configuration.For(NiO)n/SrTiO3 systems,the occupied states of(NiO)n cluster well overlap with those of(100)surfaces in the valence band maximum,which is in favor of the separation of photogenerated electrons and holes to SrTiO3 support and(NiO)n cluster,respectively.The detailed DFT analysis provides important insights into the growth of NiOx on surfaces of SrTiO3and presents an explanation on the different models of NiOx/SrTiO3 photocatalyst proposed by experimental groups.Our calculations build a basis for further investigations on the mechanism of photocatalytic water-splitting reaction in NiOx/SrTiO3composite system.
基金supported by the National Key Research and Development Program of China(Nos.2022YFA1502903 and 2021YFA1501502)the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB36000000 and XDB0450102)+3 种基金the National Natural Science Foundation of China(22275179)the Anhui Provincial Key Research and Development Program(No.2022a05020054)the Youth Innovation Promotion Association of CAS(No.Y2021123)the Fundamental Research Funds for the Central Universities(No.WK2060000039)。
文摘The light absorption properties of semiconductor-based photocatalysts to a large extent determine the relevant catalytic performance.Traditional strategies in broadening the light absorption range are usually accompanied with unfavorable changes in redox ability and dynamics of photoinduced species that would confuse the comprehensive optimization.In this work,we propose a nontrivial excitonic transition regulation strategy for gaining sub-bandgap light absorption in low-dimensional semiconductor-based photocatalysts.Using bismuth oxybromide(BiOBr)as a model system,we highlight that the light absorption cut-off edge could be effectively extended up to 500 nm by introducing Bi vacancies.On the basis of theoretical simulations and spectroscopic analyses,we attributed the broadening of light absorption to the promotion of excitonic transition that is generally forbidden in pristine BiOBr system,associated with Bi-vacancy-induced excited-state symmetry breaking.In addition,Bi vacancy was demonstrated to implement negligible effects on other photoexcitation properties like excited-state energy-level profiles and kinetics.Benefiting from these features,the defective sample exhibits a notable advantage in gaining visible-light-driven photocatalytic reactions.
