Thermally assisted photocatalytic conversion of CO2–H2O to C2H4 over carbon doped In2S3 nanosheets

Abstract

The development of an efficient photocatalyst for selective conversion of CO₂ to ethylene (C₂H₄) is highly desirable. Here, carbon-doped In₂S₃ nanosheet-based spheres (denoted as C-In₂S₃) are reported to be highly efficient for thermally assisted photocatalytic conversion of CO₂–H₂O to C₂H₄ at 150 °C without any cocatalysts or sacrificial agents. The total consumed electron number (TCEN) for CO₂ conversion over C-In₂S₃ can reach 472.7 μmol g⁻¹ h⁻¹. The selectivity and production rate of C₂H₄ over C-In₂S₃ are about 50% and 26.6 ± 4.1 μmol g⁻¹ h⁻¹, respectively, with a quantum efficiency of 13.3% at 420 nm. Meanwhile, no C₂H₄ can be detected over In₂S₃ without carbon doping. ¹³CO₂ and D₂O isotope labeling experiments confirm the carbon and hydrogen origins of C₂H₄. In situ experimental and theoretical studies reveal that carbon doping accelerates CO₂ adsorption and activation, lowering the energy barrier to form CH*, the key intermediate for C₂H₄, thus leading to high selectivity.