Nanoengineering construction of Fe2O3/g-C3N4 heterojunctions for cooperative enhanced photocatalytic CO2 reduction and pollutant degradation

Abstract

Developing heterojunction photocatalysts represents a promising strategy to improve photocatalytic efficiency in wastewater treatment and address the greenhouse effect. This investigation involved the creation of a new Fe₂O₃/g-C₃N₄ heterojunction photocatalyst (FC-X) through a simple hydrothermal process to overcome these obstacles. The optimized FC-8 composite exhibited a high photocatalytic activity, achieving a 95.5 % degradation of RhB within 180 min and a CH₄ production rate of 19.72 μmol g⁻¹·h⁻¹ when exposed to visible light, demonstrating a reaction rate constant of 7.02∗10⁻³ min⁻¹, which is 1.63 and 1.75 times greater than pure Fe₂O₃ and g-C₃N₄, respectively. Additionally, FC-8 exhibited an enhanced CO₂ reduction rate, producing CH₄ at 19.72 μmol g⁻¹·h⁻¹, surpassing Fe₂O₃ and g-C₃N₄ by 1.91 and 8.12 times, respectively. Structural, optical, and electrochemical characterizations confirmed that the enhanced performance originates from efficient charge separation and a lower carrier recombination rate at the heterojunction interface. Active species trapping experiments showed singlet oxygen (¹O₂), superoxide radicals (O₂^•-) and hydroxyl radicals (^•OH) drive RhB degradation, with ¹O₂ being the dominant contributor. The FC-8 photocatalyst also exhibited excellent stability, retaining over 90 % efficiency after four cycles. This study introduces an encouraging approach to developing heterojunction photocatalysts aimed at sustainable wastewater treatment and CO₂ transformation.