Ag2O-supported FePO4 heterojunctions: Facile fabrication and fast visible-light carbon dioxide photoreduction into methanol with superb recyclability

The conversion of carbon dioxide (CO₂) into clean fuels using semiconductor materials represents a sustainable and environmentally advantageous approach to energy generation. Extensive research is underway to develop robust and enduring photocatalysts for this purpose. This research focused on the synthesis of visible-light-responsive 1.0–4.0 wt% Ag₂O-decorated FePO₄ (FPO) nanocomposites using a surfactant-assisted sol-gel method and evaluated their ability to catalyze the photoconversion of CO₂ into methanol. The addition of trace amounts of Ag₂O expanded their visible-light absorption range, improved charge isolation, and enhanced mobility of photoexcited charges. This resulted in a bandgap reduction from 3.14 eV in pure FPO to 1.98 eV. Additionally, the surface structure examination revealed the production of mesoporous nanocomposites with a surface area ranging from 103 to 119 m²/g. Furthermore, a controlled dosage of 3 % Ag₂O-FPO at 1.6 g/L produced CH₃OH with a yield of 1612 μM g⁻¹ after 9 h of illumination, approximately 2.2 times higher than the pure FPO. This stable and reusable heterojunction maintains 94 % of its initial performance after 5 cycles. This research highlights the potential of phosphates-based heterojunctions for producing sustainable fuels under visible illumination conditions.