A novel N-doped porous carbon-supported g-C3N4 composite for enhanced photocatalytic CO2 conversion

The solar light-driven CO₂ conversion into hydrocarbon fuels is regarded as one of the most crucial inventions to reduce CO₂ abundance in the atmosphere and fulfill energy needs. Graphitic carbon nitride (g-C₃N₄) has garnered considerable attention and emerges as a promising candidate for photocatalytic CO₂ reduction, owing to its visible light absorption, metal-free, and environmentally benign nature. However, its ability to effectively achieve this is currently hindered by several factors such as relatively low surface area, fast electron-hole recombination rate and limited CO₂ adsorption capacity, which also constrain its practical applicability. In this work, a novel photocatalyst was synthesized by incorporating a suitable amount of ZIF-8 derived N-doped porous carbon into g-C₃N₄ without affecting its light absorption capacity. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), nitrogen and CO₂ adsorption measurements, X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance absorption spectra (UV-DRS), and photoluminescence spectroscopy (PL). Compared to g-C₃N₄, the optimized photocatalyst exhibited a 54-fold increase in surface area, a 3.5-fold enhancement in CO₂ adsorption capacity, a reduced optical bandgap, and significantly superior photocatalytic activity for CO₂ reduction, achieving CH₄ production at 70.87 μmol h⁻¹ g⁻¹ and C₂H₆ production at 35.31 μmol h⁻¹ g⁻¹. The enhanced activity of the composites is attributed to the synergistic effect of the N-doped carbon and g-C₃N₄. Thus, this approach offers a promising strategy for the future development of C₃N₄-based catalysts for efficient solar to fuel conversion.