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

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.