Solar-assisted urea oxidation at silicon photoanodes promoted by an amorphous and optically adaptive Ni-Mo-O catalytic layer

Abstract

Enabling Si to perform solar photoelectrocatalysis is a tedious task due to its low stability and because it requires interfacial catalytic layers that can impede light absorption. Here, we report the deposition of amorphous Ni-Mo-O (NMO) coatings onto metal-insulator-semiconductor silicon junctions and we use these surfaces as photoanodes for the urea oxidation reaction (UOR). The novelty is that these photoanodes stand out for two reasons. First, they allow unprecedented performance for photoelectrochemical UOR at silicon at low overpotentials: photovoltage of 400 mV, onset potential of 0.9 V vs. RHE, activity for hours, high faradaic and photoconversion efficiencies. Second, the deposited NMO coating exhibits an optically adaptive nature, that promotes considerable improvement of the maximum photocurrent in the presence of urea. This original behavior is promising for the future development of original photoelectrode architectures.