Dual Z‐scheme ternary heterojunction photocatalyst with enhanced visible‐light photocatalytic degradation of organic pollutants

Abstract

Photocatalysis technology driven by solar energy is considered to be promising for solving energy crisis and environmental problems. Graphitic carbon nitride has been widely researched in the photocatalysis field due to its suitable band positions, non‐toxicity, easy synthesis, high stability, and low cost. However, the slow separation and rapid recombination of photogenerated carriers, the poor visible light response and the low specific surface area seriously limit the photocatalytic activity of g‐C3N4. Here, firstly, g‐C3N4 nanosheets with a large specific surface area of 152.2 m2 g−1 which provide more surface‐active sites for photocatalysis were prepared by secondary calcination method. Next, MoS2 and metal–organic framework (MIL‐101(Cr)) were tightly bonded on g‐C3N4 nanosheets to form ternary g‐C3N4/MoS2/MIL‐101(Cr) heterojunction photocatalyst. In which, a ternary dual Z‐scheme heterojunction photocatalyst composed of g‐C3N4, MoS2, and MIL‐101(Cr) was constructed to facilitate the separation and the migration of photogenerated charges. At the same time, MoS2 enhanced the visible light response of the ternary photocatalyst. The optimal ternary photocatalyst displayed the highest activity for methyl orange degradation (degradation efficiency of 98% in 60 min) under visible light irradiation. Finally, a photocatalytic mechanism of a dual Z‐scheme electron transfer channel and h+‐·O2− double oxidation sites were proposed and discussed.