Photoelectrocatalytic Conversion of Nitrates to Ammonia with Plasmon Hot Electrons

Abstract

Changes in agricultural practices enabled the circulation of N-containing species, making converting nitrate into ammonia (fertilizer) highly desirable. Herein, we propose a photosystem composed of NiO/Au plasmon/TiO2 that selectively produces ammonia from nitrates at neutral pH and room temperature with visible light via a combination of electrochemical and plasmon hot electrons (i.e., it is a photoelectrochemical process). The system effectively suppresses the undesirable hydrogen evolution reaction and converts the superfluous hot holes into atmospheric oxygen. The role of the hot electrons is to boost catalytic performance, enabling higher reaction rates at lower potentials. The process paves the way for agricultural practices that recycle nutrients, improving process circularity and reducing fertilizer costs.