title: Vectorial electron transfer for improved hydrogen evolution by mercaptopropionic-acid-regulated CdSe quantum-dots-TiO2 -Ni(OH)2 assembly.
abstract: A visible-light-induced hydrogen evolution system based on a CdSe quantum dots (QDs)-TiO2 -Ni(OH)2 ternary assembly has been constructed under an ambient environment, and a bifunctional molecular linker, mercaptopropionic acid, is used to facilitate the interaction between CdSe QDs and TiO2 . This hydrogen evolution system works effectively in a basic aqueous solution (pH 11.0) to achieve a hydrogen evolution rate of 10.1 mmol g(-1)  h(-1) for the assembly and a turnover frequency of 5140 h(-1) with respect to CdSe QDs (10 h); the latter is comparable with the highest value reported for QD systems in an acidic environment. X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and control experiments demonstrate that Ni(OH)2 is an efficient hydrogen evolution catalyst. In addition, inductively coupled plasma optical emission spectroscopy and the emission decay of the assembly combined with the hydrogen evolution experiments show that TiO2 functions mainly as the electron mediator; the vectorial electron transfer from CdSe QDs to TiO2 and then from TiO2 to Ni(OH)2 enhances the efficiency for hydrogen evolution. The assembly comprises light antenna CdSe QDs, electron mediator TiO2 , and catalytic Ni(OH)2 , which mimics the strategy of photosynthesis exploited in nature and takes us a step further towards artificial photosynthesis.
authors.affiliation: Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry the Chinese Academy of Sciences, Beijing 100190 (P.R. China), Fax: (+86) 10-8254-3580; These authors contributed equally to this work.
authors.forename: Shan
authors.initials: S
authors.lastname: Yu
authors.forename: Zhi-Jun
authors.initials: ZJ
authors.lastname: Li
authors.forename: Xiang-Bing
authors.initials: XB
authors.lastname: Fan
authors.forename: Jia-Xin
authors.initials: JX
authors.lastname: Li
authors.forename: Fei
authors.initials: F
authors.lastname: Zhan
authors.forename: Xu-Bing
authors.initials: XB
authors.lastname: Li
authors.forename: Ye
authors.initials: Y
authors.lastname: Tao
authors.forename: Chen-Ho
authors.initials: CH
authors.lastname: Tung
authors.forename: Li-Zhu
authors.initials: LZ
authors.lastname: Wu
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry* / Q000528:radiation effects; D002384:Catalysis; D006859:Hydrogen / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D009532:Nickel / Q000737:chemistry* / Q000528:radiation effects; D045663:Quantum Dots / Q000737:chemistry* / Q000528:radiation effects; D018036:Selenium Compounds / Q000737:chemistry* / Q000528:radiation effects; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D019187:Cadmium Compounds; D006878:Hydroxides; D018036:Selenium Compounds; D013438:Sulfhydryl Compounds; C037473:nickel hydroxide; C009495:titanium dioxide; D009532:Nickel; D006859:Hydrogen; C058667:cadmium selenide; D014025:Titanium
keywords: electron transfer; hydrogen; nickel; photosynthesis; quantum dots