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.