Abstract

Investigation on Stability of Electroplated-Sulfurized CuInS₂-based Photocathode Modified with an In₂S₃ Layer for H₂ Evolution under Various pH Conditions

Gunawan¹, Abdul Haris¹, Hendri Widiyandari², Wilman Septina³ and Shigeru Ikeda⁴

DOI : http://dx.doi.org/10.13005/ojc/330202

Abstract:

We investigated photoelectrochemical water splitting properties of Pt-In₂S₃/CuInS₂ photocathodes from near neutral toward basic condition (pH 6, 9, and 13). Half-cell solar-to-hydrogen (HC-STH) of Pt-In₂S₃/CuInS₂ measured under 0.2 M NaH₂PO₄ was the highest when the pH of the solution was 13 (4.7% at 0.42 V vs. RHE) with a maximum photocurrent density of 16.3 mA cm^-2 (at 0 V vs. RHE) and onset potential of 0.9 V vs. RHE (defined as cathodic photocurrent of 0.1 mA cm^-2). However, it suffers from rapid degradation of the photocurrent over the time course when kept at 0 V vs. RHE under constant illumination. On the other hand, the photocathode showed relatively stable photocurrent when measured under near neutral condition (pH 6): HC-STH of 2.85% (at 0.28 V vs. RHE) with a maximum photocurrent density of 16.3 mA cm^-2 (at 0 V vs. RHE) and onset potential of 0.72 V vs. RHE were obtained from the photocathode. Passivation using In₂S₃ oxygen-free can stabilize the photocathode at alkaline pH (pH 13).