Superior photocatalytic hydrogen peroxide production over g-C3N4 with Ni(OH)2 as an oxidation cocatalyst

Abstract

Loading cocatalysts is an effective strategy to boost the photocatalytic performance of semiconductor photocatalysts. In this work, a novel Ni(OH)2/graphitic carbon nitride (g-C3N4) composite photocatalyst (NiCN) was successfully fabricated by via a facile deposition process for hydrogen peroxide (H2O2) production. In the composite, Ni(OH)2 serves mainly as an oxidation cocatalyst to efficiently capture photogenerated holes (h + ), thereby improving the separation efficiency of photoinduced charge carriers. As a result, the NiCN composite displays remarkably enhanced catalytic performance. Among them, the optimized NiCN-30 achieves the highest H2O2 yield of 1256.1 µM within 1 h (6250.5 μmol·g -1 ·h -1 ), which is 2.86 times higher than that of pristine g-C3N4. The superior activity of NiCN-30 is attributed to its greatly improved charge separation efficiency and favorable band structure compared with pure g-C3N4. Mechanistic studies confirm that ·O2 -is the dominant reactive intermediate, and the photocatalytic H2O2 generation over NiCN follows a two-step oxygen reduction reaction (ORR) pathway.