Insight into the Crucial Factors for Photochemical Deposition of Cobalt Cocatalysts on g‑C3N4 Photocatalysts

Photochemical preparation of inexpensive hydrogen evolution cocatalysts is of great significance and is challenging. Currently, the crucial factors in the photochemical preparation of nonnoble metals are still unknown. In this work, taking Co/g-C3N4 composite photocatalysts as a case, complexing agents and sacrificial agents were found to be the crucial factors for the photochemical deposition process. Cobalt was supported on the electron outlet points of g-C3N4 for 1 h, and the ratio of Co in the Co/g-C3N4 composite photocatalyst can be regulated by changing the irradiation time of the preparation process. The optimized hydrogen evolution rate of Co/g-C3N4 was about 11.48 μmol h–1, which was 75 times more than pure g-C3N4. The photocatalytic H2 evolution rate was stable after 48 h. The mechanism for the high activity of Co/g-C3N4 composites was explored by surface photovoltage spectra and photoluminescence spectra. Co effectively promoted the separation of the photogenerated electrons and holes of g-C3N4 and improved the H2 production rate.