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.
