Assembling graphitic-carbon-nitride with cobalt-oxide-phosphate to construct an efficient hybrid photocatalyst for water splitting application

Abstract

A scalable method to load a cobalt-oxide-phosphate (CoPi) water oxidation electrocatalyst onto the surface of a mesoporous graphitic-carbon-nitride (mpg-CNx) semiconductor is reported. This procedure resulted in significant enhancement of photocatalytic activity of the mpg-CNx in water oxidation. The optimal loading gave an oxygen evolution rate of up to approximately 1 mmol O2 gcat−1 h−1 under 100 mW cm−2 visible light illumination in a pH 7 phosphate buffer containing Ag+ or Na2S2O8 as an electron scavenger which was 400 times faster compared with that of the untreated mpg-CNx catalyst. Under visible light illumination and by employing a hole scavenger e.g. methanol, CoPi was converted into a H2-CoCat HER electrocatalyst which significantly promoted the H2 generation photocatalytic activities of mpg-CNx. Without any electron/hole scavengers, the mpg-CNx–CoPi–H2-CoCat composite was able to catalyse the overall water splitting process.