Enhanced photocatalytic ammonia generation from water and nitrogen by decorating BiOCl nanosheets with CoOOH oxygen evolution reaction cocatalyst

Abstract

Photocatalytic synthesis of ammonia from N2 and water consists of N2 reduction and water oxidation, but most research is focused only on the N2 reduction. Here, we demonstrated a strategy to improve ammonia generation by enhancing water oxidation through an oxygen evolution reaction (OER) cocatalyst. We employed cobalt oxyhydroxide as an OER cocatalyst for a well-known nitrogen reduction photocatalyst bismuth oxychloride (BiOCl). A series of cobalt-doped BiOCl (Co–BiOCl) nanoplatelets were synthesized through a combination of coprecipitation and hydrothermal synthesis with systematic variation in the percentage of added cocatalyst. The formation of a few atom clusters of cobalt oxyhydroxide was verified via X-ray diffraction, X-ray photoelectron spectroscopy, electron microscopy, Raman, and infrared spectroscopy. A 4.6-fold improvement in the ammonia production rate was realized with 5% Co–BiOCl. OER from water using Co–BiOCl was performed and correlated well with the ammonia generation. Enhancing water oxidation by loading of an OER cocatalyst points a promising and applicable method for better N2 fixation photocatalyst design.