Improved N2 photo-fixation performance of nanocrystalline TiO2 films by photon localization effects and Fe doping

Abstract

The development of clean and sustainable nitrogen-fixing methods has always attracted significant attention for decades. In this work, we investigated a strategy to enhance the N₂ photo-fixation performance of titanium dioxide (TiO₂) films by leveraging the synergistic effect between photon localization effects and iron (Fe) doping. Introducing Fe ions into TiO₂ broadens its light absorption spectrum, making it extend into the visible light range, while improving charge separation capabilities. Our findings revealed that the photocatalytic ammonia generation of Fe-doped TiO₂ (FT) catalysts, with a Fe³⁺ concentration of 6%, could reach up to 1.5 times that of pure TiO₂. Besides, the photon localization effect of the SiO₂ opal photonic crystals (SOPC) could enhance the light harvesting efficiency of the photocatalysts. By coupling the SOPC layer and nanocrystalline FT films, the N₂ photo-fixation performance of FT/SOPC composite membranes was further promoted to 55.6 μmol g⁻¹ h⁻¹. This study offered a promising route for nitrogen fixation using solar energy.