Nanoengineering construction of FeO/g-CN heterojunctions for cooperative enhanced photocatalytic CO 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 FeO/g-CN 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 CH production rate of 19.72 μmol g·h when exposed to visible light, demonstrating a reaction rate constant of 7.02∗10 min, which is 1.63 and 1.75 times greater than pure FeO and g-CN, respectively. Additionally, FC-8 exhibited an enhanced CO reduction rate, producing CH at 19.72 μmol g·h, surpassing FeO and g-CN 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 (O), superoxide radicals (O) and hydroxyl radicals (OH) drive RhB degradation, with O 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 CO transformation.