Photoelectrochemical water splitting on the Pt-In2S3/CuInS2 photoelectrode under solar light irradiation: Effects of electrolytes on the solar energy to hydrogen conversion

Abstract

An effective CuInS 2 for PEC water splitting was developed. Phosphate ions not only suppress the chemical bias for the HER process, but also reduce recombination center at the electrode/electrolyte interface. The HC-STH efficiency achieved 1.5% with faraday efficiency of 96 %. Solar energy to hydrogen (H 2 ) conversion system has been developed by the photoelectrochemical (PEC) water splitting. The CuInS 2 (CIS) photoelectrodes were successfully fabricated by electrodeposition (ED) of copper and indium metallic precursors on Mo-coated glass, followed by sulfurization under sulfur evaporation. The CIS was modified with In 2 S 3 by the chemical bath deposition (CBD), followed by photo-deposition of Pt particles. The Pt-In 2 S 3 /CIS photoelectrodes provided cathodic photocurrent by water splitting in the electrolyte solution under irradiation from the simulated sunlight (AM 1.5G). The half-cell solar-to-hydrogen (HC-STH) efficiencies by the Pt-In 2 S 3 /CIS achieved 1.5% at + 0.26 V vs. RHE with faraday efficiency of 96% in 0.5 M potassium phosphate (pH 7), while 0.16% at + 0.16 V vs. RHE in 0.5 M sodium sulfate (pH 7). It was clearly demonstrated that phosphate buffer solution play an important role in control of chemical bias by a removal of OH − as well as passivating surface defect sites, resulting in improvement of PEC water splitting.