Surface modification of carbon nitride with single Co sites via a solvent-driven strategy promoting high‐efficiency photocatalytic overall water splitting

Abstract

Photocatalytic overall water splitting is one of the most challenging reactions in modern chemistry. In addition, the O2 evolution reaction (OER) is considered to be the rate-determining step. Here we develop a surface modification strategy for carbon nitride (CN) to improve its photocatalytic OER activity, thus making the overall reaction possible. We take CN nanosheets (CNNS) as an example to demonstrate that the single Co sites with high density (3.0 wt%) can be obtained on the surface of CNNS via a simple organic-solvent driven deposition method. The photocatalytic O2 evolution rate of the as-synthesized Co/CNNS is significantly increased, up to about 46 times that of pristine CNNS. In the presence of Pt as the reduction cocatalyst, the Co/CNNS sample can induce overall reactions with H2 and O2 evolution rates of 14 and 7.2 μmol h−1, respectively, about five times those of CNNS. The abundant exposed Co atoms not only act as active sites to facilitate the surface water oxidation reaction, but also quickly trap the holes to promote the charge separation and transfer. This research reports a universal strategy of surface modification CNs to promote photocatalytic overall water splitting.