The weak visible light harvesting and high charge recombination are two main problems that lead to a low photocatalytic H2 generation of polymeric carbon nitride(p-CN).To date,the approaches that are extensively invok...The weak visible light harvesting and high charge recombination are two main problems that lead to a low photocatalytic H2 generation of polymeric carbon nitride(p-CN).To date,the approaches that are extensively invoked to address this problem mainly rely on heteroatom-doping and heterostructures,and it remains a grand challenge in regulating dopant-free p-CN for increasing H2 generation.Here,we report utilizing the inherent n-π^(*)electronic transition to simultaneously realize extended light absorption and reduced charge recombination on pCN nanosheets.Such n-π^(*)electronic transition yields a new absorption peak of 490 nm,which extends the light absorption edge of p-CN to approximately 590 nm.Meanwhile,as revealed by the photoluminescence(PL)spectra of p-CN at the single-particle level,the n-π*electronic transition gives rise to an almost quenched PL signal at room temperature,unravelling a dramatically reduced charge recombination.As a consequence,a remarkably improved photocatalytic performance is realized under visible light irradiation,with a H2 generation rate of 5553μmol g^(-1)·h^(-1),~12 times higher than that of pristine p-CN(460μmol·g^(-1)·h^(-1))in the absence of the n-π^(*)transition.This work illustrates the highlights of using the inherent n-π^(*)electronic transition to improve the photocatalytic performance of dopant-free carbon nitrides.展开更多
High-rate CO_(2)-to-CH_(4)photoreduction with high selectivity is highly attractive,which is a win-win strategy for mitigating the greenhouse effect and the energy crisis.However,the poor photocatalytic activity and l...High-rate CO_(2)-to-CH_(4)photoreduction with high selectivity is highly attractive,which is a win-win strategy for mitigating the greenhouse effect and the energy crisis.However,the poor photocatalytic activity and low product selectivity hinder the practical application.To precisely tailor the product selectivity and realize high-rate CO_(2)photoreduction,we design atomically precise Pd species supported on In_(2)O_(3)nanosheets.Taking the synthetic 1.30Pd/In_(2)O_(3)nanosheets as an example,the aberration-correction high-angle annular dark-field scanning transmission electron microscopy image displayed the Pd species atomically dispersed on the In_(2)O_(3)nanosheets.Raman spectra and X-ray photoelectron spectra established that the strong interaction between the Pd species and the In_(2)O_(3)substrate drove electron transfer from In to Pd species,resulting in electron-enriched Pd sites for CO_(2)activation.Synchrotronradiation photoemission spectroscopy demonstrated that the Pd species can tailor the conduction band edge of In_(2)O_(3)nanosheets to match the CO_(2)-to-CH_(4)pathway,instead of the CO_(2)-to-CO pathway,which theoretically accounts for the high CH_(4)selectivity.Moreover,in situ X-ray photoelectron spectroscopy unveiled that the catalytically active sites had a change from In species to Pd species over the 1.30Pd/In_(2)O_(3)nanosheets.In situ FTIR and EPR spectra reveal the atomically precise Pd species with rich electrons prefer to adsorb the electrophilic protons for accelerating the*COOH intermediates hydrogenation into CH_(4).Consequently,the 1.30Pd/In_(2)O_(3)nanosheets reached CO_(2)-to-CH_(4)photoconversion with 100%selectivity and 81.2μmol g^(−1)h^(−1)productivity.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(52072001,51872003,22102002)Anhui Provincial Natural Science Foundation(1908085J21 and 2108085QE192)Horizontal Cooperation Project of Fuyang Municipal Government-Fuyang Normal University(SXHZ202102).
文摘The weak visible light harvesting and high charge recombination are two main problems that lead to a low photocatalytic H2 generation of polymeric carbon nitride(p-CN).To date,the approaches that are extensively invoked to address this problem mainly rely on heteroatom-doping and heterostructures,and it remains a grand challenge in regulating dopant-free p-CN for increasing H2 generation.Here,we report utilizing the inherent n-π^(*)electronic transition to simultaneously realize extended light absorption and reduced charge recombination on pCN nanosheets.Such n-π^(*)electronic transition yields a new absorption peak of 490 nm,which extends the light absorption edge of p-CN to approximately 590 nm.Meanwhile,as revealed by the photoluminescence(PL)spectra of p-CN at the single-particle level,the n-π*electronic transition gives rise to an almost quenched PL signal at room temperature,unravelling a dramatically reduced charge recombination.As a consequence,a remarkably improved photocatalytic performance is realized under visible light irradiation,with a H2 generation rate of 5553μmol g^(-1)·h^(-1),~12 times higher than that of pristine p-CN(460μmol·g^(-1)·h^(-1))in the absence of the n-π^(*)transition.This work illustrates the highlights of using the inherent n-π^(*)electronic transition to improve the photocatalytic performance of dopant-free carbon nitrides.
基金the National Key R&D Program of China(2022YFA1502904,2019YFA0210004,2021YFA1501502)National Natural Science Foundation of China(22125503,21975242,U2032212,21890754)+1 种基金Youth Innovation Promotion Association of CAS(CX2340007003)Technical Talent Promotion Plan(TS2021002).
文摘High-rate CO_(2)-to-CH_(4)photoreduction with high selectivity is highly attractive,which is a win-win strategy for mitigating the greenhouse effect and the energy crisis.However,the poor photocatalytic activity and low product selectivity hinder the practical application.To precisely tailor the product selectivity and realize high-rate CO_(2)photoreduction,we design atomically precise Pd species supported on In_(2)O_(3)nanosheets.Taking the synthetic 1.30Pd/In_(2)O_(3)nanosheets as an example,the aberration-correction high-angle annular dark-field scanning transmission electron microscopy image displayed the Pd species atomically dispersed on the In_(2)O_(3)nanosheets.Raman spectra and X-ray photoelectron spectra established that the strong interaction between the Pd species and the In_(2)O_(3)substrate drove electron transfer from In to Pd species,resulting in electron-enriched Pd sites for CO_(2)activation.Synchrotronradiation photoemission spectroscopy demonstrated that the Pd species can tailor the conduction band edge of In_(2)O_(3)nanosheets to match the CO_(2)-to-CH_(4)pathway,instead of the CO_(2)-to-CO pathway,which theoretically accounts for the high CH_(4)selectivity.Moreover,in situ X-ray photoelectron spectroscopy unveiled that the catalytically active sites had a change from In species to Pd species over the 1.30Pd/In_(2)O_(3)nanosheets.In situ FTIR and EPR spectra reveal the atomically precise Pd species with rich electrons prefer to adsorb the electrophilic protons for accelerating the*COOH intermediates hydrogenation into CH_(4).Consequently,the 1.30Pd/In_(2)O_(3)nanosheets reached CO_(2)-to-CH_(4)photoconversion with 100%selectivity and 81.2μmol g^(−1)h^(−1)productivity.
