Integrating biomass and minerals into photocatalysts for efficient photocatalytic N2 fixation coupled with biomass conversion

Abstract

Photocatalytic nitrogen fixation is considered a promising strategy for addressing the energy crisis; however, it suffers from sluggish thermodynamics and kinetics. The photoredox coupling reaction has the potential to overcome the above obstacles by co-producing ammonia fuel and valuable chemicals. In this study, we propose a solar-driven catalysis system based on natural minerals and biomass waste for coupling photocatalytic N₂ reduction with biomass oxidation, thereby realizing the concept of “trash to treasure”. Specifically, Fe-modified attapulgite (Fe-ATP)-supported hydrothermal carbon (HTCC) nanosheets were synthesized by a microwave hydrothermal method to form an HTCC/Fe-ATP heterostructure mimicking a natural branch-leaf morphology. HTCC/Fe-ATP exhibited significantly improved carrier separation and transport efficiency due to the formation of its S-scheme heterostructure. Consequently, the 30% HTCC/Fe-ATP composite demonstrated remarkable photocatalytic N₂ fixation capability coupled with the conversion of benzyl alcohol under visible light. Notably, the ammonia production rate reached 102.8 μmol g⁻¹ h⁻¹, while the yield of benzaldehyde reached 155 μmol g⁻¹ h⁻¹, and the selectivity was close to 99%. The nanocomposite exposes abundant active sites for N₂ adsorption and effectively enhances visible light absorption. Furthermore, the presence of benzyl alcohol in the reaction system effectively improves the nitrogen fixation efficiency. This study presents a novel perspective for valorizing N₂ and biomass into value-added chemicals in a photo-driven catalysis system.