Design of an amorphous TaOx multifunctional interfacial layer on photocathodes for photoelectrochemical H2 evolution

Abstract

A novel TaO_x multifunctional layer which is transparent and co-catalytically active was applied to photoelectrodes for hydrogen production. We found that amorphous TaO_x was in situ transformed into amorphous TaO_x/Ta(OH)_x in the photoelectrochemical reaction, which is a more active form for hydrogen evolution. The TaO_x/Ta(OH)_x multifunctional layer enhanced not only charge separation but also stability and HER kinetics when it was deposited on a p-type CuInS₂ model photocathode. The new band alignment and the widened depletion region of CuInS₂/TaO_x were revealed by electrochemical impedance spectroscopy and IPCE analysis. The TaO_x deposited CuInS₂ photocathode shows a higher photocurrent at −0.3 V vs. RHE compared to CuInS₂ or even Pt-decorated CuInS₂. A novel multifunctional layer was successfully designed and demonstrated for photocathodes without noble metals, which can minimize the structure of photoelectrodes.