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

Photocatalytic overall water splitting is one of the most challenging reactions in modern chemistry. In addition, the O-2 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 O-2 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 H-2 and O-2 evolution rates of 14 and 7.2 mu mol 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.

Automated summary

This research develops a surface modification strategy to enhance the photocatalytic OER activity of carbon nitride, enabling the overall water splitting reaction. The introduction of high-density Co sites on the surface of carbon nitride significantly increases the photocatalytic O2 evolution rate. The modified Co/CNNS sample, in the presence of Pt as the reduction cocatalyst, is able to induce overall reactions with higher rates of H2 and O2 evolution.