title: Rationally designed n-n heterojunction with highly efficient solar hydrogen evolution.
abstract: In most of the reported n-n heterojunction photocatalysts, both the conduction and valence bands of one semiconductor are more negative than those of the other semiconductor. In this work, we designed and synthesized a novel n-n heterojunction photocatalyst, namely CdS-ZnWO4 heterojunctions, in which ZnWO4 has more negative conduction band and more positive valence band than those of CdS. The hydrogen evolution rate of CdS-30 mol %-ZnWO4 reaches 31.46 mmol h(-1)  g(-1) under visible light, which is approximately 8 and 755 times higher than that of pure CdS and ZnWO4 under similar conditions, respectively. The location of the surface active sites is researched and a plausible mechanism of performance enhancement by the tuning of the structure is proposed based on the photoelectrochemical characterization. The results illustrate that this kind of nonconventional n-n heterojunctions is also suitable and highly efficient for solar hydrogen evolution.
authors.affiliation: Shanghai Electrochemical Energy Devices Research Center, School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240 (P. R. China).
authors.forename: Miao
authors.initials: M
authors.lastname: Xu
authors.forename: Tiannan
authors.initials: T
authors.lastname: Ye
authors.forename: Fang
authors.initials: F
authors.lastname: Dai
authors.forename: Jindi
authors.initials: J
authors.lastname: Yang
authors.forename: Jingmei
authors.initials: J
authors.lastname: Shen
authors.forename: Qingquan
authors.initials: Q
authors.lastname: He
authors.forename: Wenlong
authors.initials: W
authors.lastname: Chen
authors.forename: Na
authors.initials: N
authors.lastname: Liang
authors.forename: Jiantao
authors.initials: J
authors.lastname: Zai
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Qian
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D055668:Photochemical Processes; D012666:Semiconductors; D013440:Sulfides / Q000737:chemistry; D013472:Sunlight
chemical_list: D019187:Cadmium Compounds; D010087:Oxides; D013440:Sulfides; C034939:cadmium sulfide; D006859:Hydrogen
keywords: active sites; hydrogen; n-n heterojunction; photocatalysis; water splitting