Layered Heterostructures of Ultrathin Polymeric Carbon Nitride and ZnIn₂ S₄ Nanosheets for Photocatalytic CO₂ Reduction

The rational construction of heterostructures by using layered semiconductors with two-dimensional (2D) nanosheet configurations is promising to improve the efficiency of CO₂ photoreduction. Herein, the fabrication of layered heterojunction photocatalysts (PCN/ZnIn₂ S₄ ) by in situ growth of 2D ZnIn₂ S₄ nanosheets on the surfaces of ultrathin polymeric carbon nitride (PCN) layers is presented for greatly enhanced CO₂ conversion with visible light. The solution-processed self-assembly strategy renders the building of uniform and intimate junctions between PCN layers and ZnIn₂ S₄ subunits, which remarkably accelerates the separation and transfer of photogenerated charge carriers. In addition, the layered composites can also promote CO₂ adsorption and strengthen the visible-light absorption. Consequently, the optimized PCN/ZnIn₂ S₄ sheet-shaped composite shows reinforced photoactivity for deoxygenative CO₂ conversion, affording a high CO-production rate of 44.6 μmol h^-1 , which is 223 times higher than that of the pristine PCN nanosheets. Moreover, the heterojunction photocatalyst also exhibits high stability during repeated runs for five cycles.