Ag2CO3/α-Fe2O3 n-n heterojunction photocatalyst for efficient degradation of orange G under visible light irradiation

Abstract

This study focuses on the development of an Ag₂CO₃/α-Fe₂O₃ composite with an n-n heterojunction structure using a facile precipitation method. The composite was systematically characterized using XRD, Raman, FTIR, SEM-EDS, BET, and UV–Vis DRS, confirming the successful integration of α-Fe₂O₃ nanorods with Ag₂CO₃, enhanced visible-light absorption (E_g = 1.97 eV vs. 2.37 eV for pure Ag₂CO₃), and increased surface area (10.2 m²/g vs. 1.3 m²/g for Ag₂CO₃). The composite exhibited superior photocatalytic performance, achieving 100 % degradation of Orange G (OG) within 60 min under visible light, 85 % mineralization efficiency, and excellent stability with minimal Ag⁰ formation. The observed improvements in photocatalytic performance indicate that the formation of an n-n heterojunction generates an internal electric field that facilitates efficient charge separation, as confirmed by photoluminescence and supported by scavenger studies (^⋅O₂⁻/h⁺ as dominant species). In addition, the Z-scheme charge transfer pathway significantly enhances the redox ability of the system. Moreover, α-Fe₂O₃ nanorods act as both charge-transfer mediators and protective shield against Ag₂CO₃ photocorrosion. These findings establish the Ag₂CO₃/α-Fe₂O₃ composite as a sustainable and efficient photocatalyst for organic pollutant remediation, effectively addressing the photocorrosion issue of Ag₂CO₃.