Vertically aligned TiO2/SrTiO3 core–shell heterostructured nanowire arrays with different shell thicknesses(5–40 nm)were fabricated on fluorine-doped tin oxide substrate via a hydrothermal process.Microstructural ch...Vertically aligned TiO2/SrTiO3 core–shell heterostructured nanowire arrays with different shell thicknesses(5–40 nm)were fabricated on fluorine-doped tin oxide substrate via a hydrothermal process.Microstructural characterization demonstrated that the TiO2 nanowires were uniformly coated by the singlecrystal SrTiO3 shell,where continuous and large-area interface could be clearly observed.By this means,significantly enhanced photoelectrochemical water splitting properties(0.78 mA·cm^-2 at 1.23 V vs.RHE)were successfully realized in well-designed sample(with a shell thickness of 5–10 nm)compared with those of pristine TiO2(0.38 mA·cm^-2 at 1.23 V vs.RHE).The improvement of photoelectrochemical properties was attributed to the improved charge injection and charge separation,which are calculated by the results of water oxidation and sulfite oxidation measurements.Based on these results,a mechanism was proposed that SrTiO3 shell acted as an electron–hole separation layer to improve the photocurrent density.On the other hand,the sample with an over-thick SrTiO3 shell(20–40 nm)exhibited slightly reduced photoelectrochemical properties(0.66 mA·cm^-2),which could be explained by the increase of the recombination rate in thethicker SrTiO3 shell.This work provided a facile strategy to improve and modulate the photoelectrochemical performance of heterostructured photoanodes.展开更多
The moisture instability and toxicity of lead have hindered the development of lead organometal halide perovskites(Pb-OHPs).Similar to Pb-OHPs,OHPs based on Pb-free elements,including Group VA metals Bi and Sb(denoted...The moisture instability and toxicity of lead have hindered the development of lead organometal halide perovskites(Pb-OHPs).Similar to Pb-OHPs,OHPs based on Pb-free elements,including Group VA metals Bi and Sb(denoted as M),exhibit optoelectronic properties due to their isoelectronic configuration and close chemistry of the lone-pair ns^(2) state.However,M-OHPs are mostly based on hydrophilic protonated organic countercations and possess low structural dimensionalities,which affect the moisture stability and disrupt continuous carrier transport,respectively.Herein,we demonstrate a“double-free”strategy to realize the rational synthesis of moisture-stable hypotoxic hybrid perovskites.A hydrogen-bond-free alkylated countercation was assembled with Pb-free OHP bearing an extended structure in one molecule.As a proof of concept,two double-free M-OHPs are synthesized,which show greatly improved moisture and photostability compared to their corresponding hydrogen-bond OHPs and the extensively studied MA_(3)M_(2)X_(9)(MA=CH_(3)NH_(3)^(+)).The photoconduction behaviors of both double-free OHPs display short rise and decay recovery time and exhibit excellent photocurrent reproducibility.Importantly,(1-methyl-4-phenylpyridin-1-ium)BiI_(4)(Me4ppi-BiI_(4))displays a comparable switching on/off ratio with MA_(3)Bi_(2)I_(9),and can endure 75% relative humidity(RH)for at least 243 days.The photophysical property measurements and theoretical calculations show that this remarkable photoconversion performance results from the relatively low exciton binding energy and greatly improved carrier mobility and concentration.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51232006, 51472218 and 11474249)the National Basic Research Program of China (No. 2015CB654900)
文摘Vertically aligned TiO2/SrTiO3 core–shell heterostructured nanowire arrays with different shell thicknesses(5–40 nm)were fabricated on fluorine-doped tin oxide substrate via a hydrothermal process.Microstructural characterization demonstrated that the TiO2 nanowires were uniformly coated by the singlecrystal SrTiO3 shell,where continuous and large-area interface could be clearly observed.By this means,significantly enhanced photoelectrochemical water splitting properties(0.78 mA·cm^-2 at 1.23 V vs.RHE)were successfully realized in well-designed sample(with a shell thickness of 5–10 nm)compared with those of pristine TiO2(0.38 mA·cm^-2 at 1.23 V vs.RHE).The improvement of photoelectrochemical properties was attributed to the improved charge injection and charge separation,which are calculated by the results of water oxidation and sulfite oxidation measurements.Based on these results,a mechanism was proposed that SrTiO3 shell acted as an electron–hole separation layer to improve the photocurrent density.On the other hand,the sample with an over-thick SrTiO3 shell(20–40 nm)exhibited slightly reduced photoelectrochemical properties(0.66 mA·cm^-2),which could be explained by the increase of the recombination rate in thethicker SrTiO3 shell.This work provided a facile strategy to improve and modulate the photoelectrochemical performance of heterostructured photoanodes.
基金the financial support by the Natural Science Foundation of Shandong Province(no.ZR2020MB014)the National Natural Science Foundation of China(no.21201080)+1 种基金the Fund of State Key Laboratory of Structural Chemistrythe Jinan Research Leader’s Studio(no.2019GXRC053)for financial support.
文摘The moisture instability and toxicity of lead have hindered the development of lead organometal halide perovskites(Pb-OHPs).Similar to Pb-OHPs,OHPs based on Pb-free elements,including Group VA metals Bi and Sb(denoted as M),exhibit optoelectronic properties due to their isoelectronic configuration and close chemistry of the lone-pair ns^(2) state.However,M-OHPs are mostly based on hydrophilic protonated organic countercations and possess low structural dimensionalities,which affect the moisture stability and disrupt continuous carrier transport,respectively.Herein,we demonstrate a“double-free”strategy to realize the rational synthesis of moisture-stable hypotoxic hybrid perovskites.A hydrogen-bond-free alkylated countercation was assembled with Pb-free OHP bearing an extended structure in one molecule.As a proof of concept,two double-free M-OHPs are synthesized,which show greatly improved moisture and photostability compared to their corresponding hydrogen-bond OHPs and the extensively studied MA_(3)M_(2)X_(9)(MA=CH_(3)NH_(3)^(+)).The photoconduction behaviors of both double-free OHPs display short rise and decay recovery time and exhibit excellent photocurrent reproducibility.Importantly,(1-methyl-4-phenylpyridin-1-ium)BiI_(4)(Me4ppi-BiI_(4))displays a comparable switching on/off ratio with MA_(3)Bi_(2)I_(9),and can endure 75% relative humidity(RH)for at least 243 days.The photophysical property measurements and theoretical calculations show that this remarkable photoconversion performance results from the relatively low exciton binding energy and greatly improved carrier mobility and concentration.
