Synergistic Enhancement of CO2 photoreduction through sulfur defects in (3D/2D) CdS-nanoflowers/CN Binary heterojunction photocatalyst under visible light

Abstract

Global warming is the biggest threat to the entire world owing to the continuous release of greenhouse gases such as CO₂ from various sources. Herein, we have utilized renewable energy for the conversion of CO₂ to valuable feedstocks through a semiconductor-mediated photocatalytic system. The cadmium sulfide nanoflowers (CS-NFs) decorated graphitic carbon nitride (CN) through a solvothermal route to form a Z-scheme CSCN heterojunction. The as-synthesized material has been characterized by various spectroscopic and microscopic tools. The optimal CSCN-0.5 (1:0.5) photocatalyst achieves a CO production rate of 130.9 μmol g^-1 under visible light irradiation of 4h (λ > 420 nm), doubling that of pristine CS-NFs and CN. CO, along with CH₄ (3.4 μmol g^-1) and C₂H₆ (2.9 μmol g^-1), is the sole product detected. Experimental results indicate that the CSCN-0.5 photocatalyst spatially separates electron-hole pairs, suppresses charge carrier recombination, and maintains robust redox ability, enhancing CO₂ photoreduction. The CO₂ reduction mechanism over CSCN heterojunction was also studied through in-situ DRIFTS and electron spin resonance (ESR) measurements. Therefore, CSCN proves that it could be used as a robust photocatalyst for the CO₂ reduction reactions towards C1 and C2 feedstocks.

Keywords: CN; CO production; CO(2) photoreduction; CS-NFs; Photocatalyst; Z-Scheme.