Multiobjective optimization of a g-C3N4/Cd-Zn3In2S6 heterojunction for high-efficiency photocatalytic hydrogen evolution

Abstract

Finding efficient photocatalysts is the key to achieving sustainable hydrogen production. In this work, a rational design of Cd²⁺-doped Zn₃In₂S₆ (ZIS) and a heterojunction structure with g-C₃N₄ (GCN) was carried out to form a GCN/Cd/ZIS composite. The synergistic effect of Cd²⁺ doping and heterojunction construction in the photocatalytic hydrogen production process was probed. The results showed that doping Cd²⁺ modified the bandgap structure of ZIS and improved the photocatalytic activity. The heterojunction construction between Cd/ZIS and GCN also effectively promoted the separation and migration of photogenerated carriers, which significantly improved the hydrogen production performance of the GCN/Cd/ZIS composite. The hydrogen production rate of 15% Cd/ZIS and 5% GCN/Cd/ZIS was 2.45 mmol g⁻¹ h⁻¹, 3.34 mmol g⁻¹ h⁻¹, which was 4.3 and 5.9 times higher than that of ZIS (0.57 mmol g⁻¹ h⁻¹), respectively. This study provides strong evidence that doping and heterojunction construction can synergistically improve photocatalytic activity.