Design of an amorphous TaOx multifunctional interfacial layer on photocathodes for photoelectrochemical H-2 evolution

Abstract

A novel TaOx multifunctional layer which is transparent and co-catalytically active was applied to photoelectrodes for hydrogen production. We found that amorphous TaOx was in situ transformed into amorphous TaOx/Ta(OH)(x) in the photoelectrochemical reaction, which is a more active form for hydrogen evolution. The TaOx/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/TaOx were revealed by electrochemical impedance spectroscopy and IPCE analysis. The TaOx 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.