Fabrication of TiO₂ with Ru-induced lattice strain for enhancing photocatalytic nitrogen fixation in gas–solid reaction system

Photocatalytic nitrogen (N₂) fixation is a promising strategy for green ammonia (NH₃) synthesis. However, the design of catalysts possessing high nitrogen adsorption capacity and efficient N₂ dissociation remains a significant challenge, owing to the poor solubility of N₂ in aqueous solutions coupled with its high chemical stability. Herein, we prepared Ru-TiO₂ with metal lattice strain and applied it to a gas–solid two-phase system (G-S). Compared to the conventional gas–liquid-solid three-phase system (G-L-S), the G-S system can effectively enhance N₂ adsorption and shorten the diffusive mass transfer path. Additionally, Ru-TiO₂ demonstrates improved N₂ adsorption capacity and activation efficiency, giving the maximum NH₃ production rate of 38.7 μmol g⁻¹ h⁻¹, which is about four times higher than that in the G-L-S system. Density functional theory results demonstrate that N₂ adsorption and activation are optimized over the lattice-strained Ru surface. This work provides an innovative approach to developing advanced photocatalysts and NRR systems.