Formic acid photodegradation is one of the most important reactions in organic pollution control, and helps to improve the hydrogen generation efficiency in titanium dioxide catalyzed water photodecomposition. Based o...Formic acid photodegradation is one of the most important reactions in organic pollution control, and helps to improve the hydrogen generation efficiency in titanium dioxide catalyzed water photodecomposition. Based on density functional theory and Reax FF molecular dynamics, the adsorption, diffusion and activation of formic acid on the different anatase TiO_2(101),(001),(010) surfaces are investigated.The result shows that the adsorption of COOH on anatase TiO_2 surface shrinks the energy gap between the dehydrogenation intermediate COOH and HCOO. On the anatase TiO_2(101) surface, the formic acid breaks the O–H bond at the first step with activation energy 0.24 eV, and the consequent break of α-H become much easier with activation energy 0.77 eV. The dissociation of α-H is the determination step of the HCOOH decomposition.展开更多
Titanium dioxide(TiO2)has been extensively investigated as a photocatalyst for water splitting to produce H2.However,an overall water splitting by using anatase TiO2 is extremely difficult due to the short lifetime of...Titanium dioxide(TiO2)has been extensively investigated as a photocatalyst for water splitting to produce H2.However,an overall water splitting by using anatase TiO2 is extremely difficult due to the short lifetime of holes.In this work,we propose that a surface energy decrease from{001}to{101}of anatase TiO2 is able to drive an epitaxial growth.A novel anatase TiO2 homostructure has been successfully synthesized via a facile hydrothermal route,where{101}semi-pyramid nanoparticles epitaxially grew on the both sides of the{001}nanosheets.The epitaxial relationship between the nanoparticles and the nanosheets has been characterized to be{001}//{001}of anatase TiO2.For the first time,it is interesting to find that the homostructure with 12 wt%of{101}semi-pyramid can significantly improve the H2 evolution rate by nearly 5 times compared to the pure nanosheets under the ultraviolet irradiation.More importantly,such homostructure enables 10.78μmol g-1h-1 of O2 production whereas the pure nanosheets cannot evolve detectable O2 gas.Meanwhile,the time-resolved photoluminescence analysis indicates that the mean lifetime of the holes is increased from 2.20 ns of the nanosheets to 3.59 ns of the homostructure,accounting for the observed overall water splitting.The findings suggest that constructing a homostructure by a surface energy strategy could be promising towards overall water splitting,which may be applicable to other photocatalytic materials.展开更多
基金supported by the National Natural Science Foundation of China(NSFC-2117622)
文摘Formic acid photodegradation is one of the most important reactions in organic pollution control, and helps to improve the hydrogen generation efficiency in titanium dioxide catalyzed water photodecomposition. Based on density functional theory and Reax FF molecular dynamics, the adsorption, diffusion and activation of formic acid on the different anatase TiO_2(101),(001),(010) surfaces are investigated.The result shows that the adsorption of COOH on anatase TiO_2 surface shrinks the energy gap between the dehydrogenation intermediate COOH and HCOO. On the anatase TiO_2(101) surface, the formic acid breaks the O–H bond at the first step with activation energy 0.24 eV, and the consequent break of α-H become much easier with activation energy 0.77 eV. The dissociation of α-H is the determination step of the HCOOH decomposition.
基金the National Natural Science Foundation of China[Nos.U1809217 and 51472218]State Key Laboratory of Crystal Materials(KF1807)Fundamental Research Funds for the Central Universities[2019XZZX005-4-01]。
文摘Titanium dioxide(TiO2)has been extensively investigated as a photocatalyst for water splitting to produce H2.However,an overall water splitting by using anatase TiO2 is extremely difficult due to the short lifetime of holes.In this work,we propose that a surface energy decrease from{001}to{101}of anatase TiO2 is able to drive an epitaxial growth.A novel anatase TiO2 homostructure has been successfully synthesized via a facile hydrothermal route,where{101}semi-pyramid nanoparticles epitaxially grew on the both sides of the{001}nanosheets.The epitaxial relationship between the nanoparticles and the nanosheets has been characterized to be{001}//{001}of anatase TiO2.For the first time,it is interesting to find that the homostructure with 12 wt%of{101}semi-pyramid can significantly improve the H2 evolution rate by nearly 5 times compared to the pure nanosheets under the ultraviolet irradiation.More importantly,such homostructure enables 10.78μmol g-1h-1 of O2 production whereas the pure nanosheets cannot evolve detectable O2 gas.Meanwhile,the time-resolved photoluminescence analysis indicates that the mean lifetime of the holes is increased from 2.20 ns of the nanosheets to 3.59 ns of the homostructure,accounting for the observed overall water splitting.The findings suggest that constructing a homostructure by a surface energy strategy could be promising towards overall water splitting,which may be applicable to other photocatalytic materials.
