2D/2D Heterostructure of Metal-Free Ultrathin Graphdiyne/Carbon Nitride Nanosheets for Enhanced Photocatalytic Reduction of Carbon Dioxide with Water

In this study, a 2D/2D graphdiyne/carbon nitride (GD/CN) heterojunction was prepared by electrostatic self-assembly. Density functional theory calculations and physical characterization proved that the GD/CN structure was stable and exhibited strong interactions between the CN and GD. Efficient separation of photogenerated holes and electrons was realized for the GD/CN, which benefited from the efficient charge transfer facilitated by the large and tight interface. In situ X-ray photoelectron spectroscopy and energy band structure analysis verified that the photogenerated electrons generated on CN were transferred to GD under illumination. In situ diffuse reflectance Fourier transform infrared spectroscopy further confirmed the high CO2 chemisorption capacity and the conversion mechanism of the GD/CN. As a result, the CO and CH4 yields of the 2% GD/CN under ultraviolet light increased by 5.8 and 11.8 times that of pure CN with good cycle stability. This work illuminates the design and preparation of efficient and environmentally friendly photocatalysts for the robust photoreduction of CO2.