2D ultrathin ZnIn₂S₄ nanosheets anchored on octahedral TiO₂/Ti₃C₂ Z-scheme heterostructure for enhanced photocatalytic CO₂ reduction

The low carbon dioxide (CO₂) conversion efficiency of semiconductor heterojunction-based photocatalysts is a lingering issue in the field of solar energy-driven catalysis. In this study, sandwich-like hierarchical heterostructures of two-dimensional (2D) ultrathin ZnIn₂S₄ nanosheets and octahedral titanium dioxide (TiO₂) nanoparticles were grown in situ on Ti₃C₂ MXene via a hydrothermal method. Significantly, the ZnIn₂S₄@TiO₂/Ti₃C₂ ternary heterostructure shows better CO₂ reduction activity and the optimal catalyst has carbon monoxide (CO) and methane (CH₄) production rates of 59.8 and 23.44 μmol g⁻¹, respectively, within 8 h of simulated solar light illumination, which was greater than that pristine ZnIn₂S₄. These ultrathin ZnIn₂S₄ nanosheets and TiO₂/Ti₃C₂ Schottky-junctions assisted the heterostructures to reduce photogenerated electron–hole recombination and increase photogenerated charge-transfer and separation in a Z-scheme pathway. ZnIn₂S₄@TiO₂/Ti₃C₂ heterostructure photocatalysts have superior photocatalytic CO₂ conversion and good stability compared to pure ZnIn₂S₄. Thus, the suggested approach is to design a highly-efficient photocatalyst for environmental remediation.