title: Oxyhydroxide Nanosheets with Highly Efficient Electron-Hole Pair Separation for Hydrogen Evolution.
abstract: The facile electron-hole pair recombination in earth-abundant transition-metal oxides is a major limitation for the development of highly efficient hydrogen evolution photocatalysts. In this work, the thickness of a layered β-CoOOH semiconductor that contains metal/hydroxy groups was reduced to obtain an atomically thin, two-dimensional nanostructure. Analysis by ultrafast transient absorption spectroscopy revealed that electron-hole recombination is almost suppressed in the as-prepared 1.3 nm thick β-CoOOH nanosheet, which leads to prominent electron-hole separation efficiencies of 60-90 % upon irradiation at 350-450 nm, which are ten times higher than those of the bulk counterpart. X-ray absorption spectroscopy and first-principles calculations demonstrate that [HO-CoO6-x] species on the nanosheet surface promote H(+) adsorption and H2 desorption. An aqueous suspension of the β-CoOOH nanosheets exhibited a high hydrogen production rate of 160 μmol g(-1)  h(-1) even when the system was operated for hundreds of hours.
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China.
authors.forename: Junheng
authors.initials: J
authors.lastname: Huang
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, P. R. China.
authors.forename: Qichao
authors.initials: Q
authors.lastname: Shang
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China.
authors.forename: Fumin
authors.initials: F
authors.lastname: Tang
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, P. R. China.
authors.forename: Qun
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China. qhliu@ustc.edu.cn.
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Liu
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China.
authors.forename: Shan
authors.initials: S
authors.lastname: Jiang
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China.
authors.forename: Fengchun
authors.initials: F
authors.lastname: Hu
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, P. R. China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Luo
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China. yaot@ustc.edu.cn.
authors.forename: Tao
authors.initials: T
authors.lastname: Yao
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China.
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Pan
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China.
authors.forename: Zhihu
authors.initials: Z
authors.lastname: Sun
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China. sqwei@ustc.edu.cn.
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Wei
keywords: XAFS spectroscopy; cobalt; hydrogen evolution; nanosheets