Construction of 2D/2D α-Fe2O3/g-C3N4 Z-scheme photocatalysts with SnO2 as an energy platform for directed charge transfer in cascade heterojunction: Photocatalytic CO2 reduction and pollutant degradation

Abstract

Developing an efficient visible-light-driven photocatalysts for conversion of atmospheric CO₂ into valuable fuels is a promising strategy to mitigate the escalating greenhouse gas, environmental, and energy crisis. This study presents an innovative design for a cascade Z-scheme comprising of dimensional matched SnO₂-α-Fe₂O₃/g-C₃N₄ (SO-FO/CN) nanosheets heterojunction. In this configuration, SnO₂ functions as an optimal energy platform that not only facilitates charge transfer and separation but also sustains sufficient thermodynamic energy for redox reactions and inhibits the undesired type-II charge transfer pathway. The optimized cascade Z-scheme exhibits a remarkable 20-fold improved photoactivity for CO₂ conversion to CH₄ and CO compared to bare g-C₃N₄ (CN). It also shows significantly improved photocatalytic activity for the degradation of toxic organic pollutants, 2,4-dichlorophenol (2,4-DCP) ∼6.6-fold and bisphenol A (BPA) ∼4.2-fold, respectively. The improved photocatalytic activity results from effective charge separation facilitated by the Z-scheme, along with a favorable energy platform and extended charge lifetime. This innovative strategy, which utilize an energy platform, presents a promising approach for designing an efficient Z-scheme heterojunction photocatalysts for solar-to-fuel conversion and pollutant degradation.