Development of an Efficient Photocathode CuO/Sb2S3 Heterojunction for Photoelectrochemical Water Splitting

Abstract

Developing an efficient photocathode system from the earth's abundant materials is essential for effectual Photoelectrochemical (PEC) water splitting. The charge transfer between heterojunctions is important in fabricating a novel composite, keeping cost-effectiveness, abundance, and PEC performance in mind. The p-type narrow band gap photocathode, CuO synthesized by hydrothermal method, was decorated with Sb2S3 by adopting the facile Chemical Bath Deposition (CBD) procedure to fabricate CuO/Sb2S3 heterojunction. The heterojunction shows better PEC performance contrary to the exposed CuO Photocathode. The improvement in the photocurrent density (Jph) of CuO/Sb2S3 with respect to CuO is due to the enhanced charge carrier generation and separation of the electron and holes. The composite CuO/Sb2S3 shows a higher Jph value ( -1 mA.cm-2 ) than CuO ( -0.3 mA.cm-2 ) photoelectrode at 0 VRHE in the 0.5 M Na2SO4 (pH 6.85). Sb2S3 works as a sensitizer, diminishing the recombination rate of the e-/h+ in the CuO photocathode. UV-Visible spectroscopy shows CuO/Sb2S3 composite with enhanced absorption spectrum compared to pristine CuO and Sb2S3 films. The photoluminescence (PL) emission spectra indicate less charge carrier recombination in the case of CuO/Sb2S3. As well as the Electrochemical impedance spectroscopy (EIS) studies show less charge transfer resistance in the case of CuO/Sb2S3 than CuO. This finding can help in developing new photocathodic materials with the composite of Cu-based binary oxides and chalcogenides, which is challenging to synthesize due to certain inbuilt restrictions with the materials and the experimental constraints.