WO3/ZnIn2S4 heterojunction photoanodes grafting silane molecule for efficient photoelectrochemical water splitting

Abstract

Designing and fabricating semiconductor photoanodes with efficient charge separation and appropriate active sites for solar energy conversion is indubitably a promising alternative to overcome the environmental crisis and energy shortage. Herein, we report a heterojunction WO3/ZnIn2S4 (WO3/ZIS) grafting silane molecule (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, AESI) as photoanode with boosted photoelectrochemical (PEC) efficiency toward highly efficient water splitting. The type Ⅱ WO3/ZIS heterostructure are firstly synthesized by hydrothermal growth of WO3 nanosheets on the surface of fluorine-doped tine oxide (FTO)-coated glass, followed by depositing ZIS onto WO3 surface. After that, silane molecules are anchored on WO3/ZIS via chemical water bath method. It is demonstrated that forming WO3/ZIS heterostructure and grafting silane molecules would greatly enhance the charge separation efficiency and transfer mobility. In addition, silane molecules would offer enough reactive sites for water oxidization reaction. As a result, the obtained WO3/ZIS/AESI photoanode exhibits a photocurrent density of 1.51 mA cm−2 under simulated solar light irradiation, to be 74.6% enhanced than that of WO3. Moreover, the incident photon-to-current conversion efficiency (IPCE) at 365 nm increases from 39.1% to 50.6% for WO3 and WO3/ZIS/AESI, respectively. The present strategy provides inspiration for preparation of photoelectrode materials in water splitting.