Synergistic effects of Ag/g-C3N4-incorporated bi-metallic ZnTi-LDH in CO2 photoreduction to hydrocarbons†

Abstract

Coupling solar energy with photocatalytic processes offers a viable route to address environmental challenges such as pollution remediation and CO₂ reduction. The strategic construction of heterojunctions enhances charge separation efficiency, thereby improving photocatalytic performance. Herein, a bi-metallic ZnTi-LDH/Ag/g-C₃N₄ heterojunction photocatalyst was rationally engineered to facilitate the photoreduction of CO₂ into value-added hydrocarbon compounds, offering potential utility across energy, chemical, and environmental sectors. The distinctive peaks in the XRD patterns, along with the elemental interactions analyzed through XPS and surface atomic ratio calculations based on the XPS results, further established the successful formation of ZnTi-LDH-Ag/gC₃N₄. The composite exhibited an absorbance range within the spectrum window of 400–500 nm with a narrow bandgap of 2.13 eV, indicating its potential for photocatalysis in the visible light region. PL spectra suggested that the interface has the potential to suppress electron–hole recombination compared to pristine ZnTi-LDH and Ag/gC₃N₄. The photoreduction studies of CO₂ using this interface composite demonstrated the successful generation of 36.66 mmol L⁻¹ of CH₃OH and 10.86 mmol L⁻¹ of HCOOH. Notably, the selectivity of CH₃OH was 91.01% compared to 8.99% of HCOOH. The stability and recyclability test revealed consistent generation of CH₃OH and HCOOH over three cyclic runs without alteration in the interface structures. The engineered photocatalyst composite demonstrates strong activity for visible-light-driven CO₂ conversion into valuable hydrocarbons, underscoring solar energy as a viable route for both carbon mitigation and sustainable resource synthesis.