Synergistic effect of Fe vacancy engineering and integration of S, N, and C elements in SNC-TiO₂/Fe_vOCl nanocomposite for sustainable photocatalytic NH₃ synthesis

The nitrogen reduction reaction into value-added substances is a fundamental research area in the fields of renewable energy and sustainable chemistry, with the target of reducing greenhouse gas emissions and generating alternative fuels. The current research focuses on the synthesis of novel SNC-TiO₂/Fe_vOCl heterostructure through an easy calcination manner. The synthesized photocatalysts were utilized for nitrogen reduction under simulated sunlight illumination. The produced NH₃ over the optimum SNC-TiO₂/Fe_vOCl nanocomposite reached 29260 µmol L⁻¹ g⁻¹, indicating a considerable improvement compared with the TiO₂ and FeOCl counterparts, while the generation of NO₂⁻ and NO₃⁻ was minimal. Elevated light-driven nitrogen reduction reaction over SNC-TiO₂/Fe_vOCl was due to the tuning of the energy gap, hindering of electron-hole recombination, and effective charge segregation through the construction of a heterojunction between SNC-TiO₂ and Fe_vOCl. Moreover, the synergistic effect of Fe vacancy engineering and integration of S, C, and N elements augmented the active centers, which effectively strengthened the nitrogen activation and weakened the N≡N bond, thereby enhanced the selectivity of NH₃ synthesis. The synthesized SNC-TiO₂/Fe_vOCl was also reusable and durable, and its nitrogen fixation ability was still retained at 24340 µmol L⁻¹ g⁻¹ after six cycles. Our findings not only enabled a significant understanding of vacancy engineering, but also smoothed the route for the logical design of modified catalysts with excellent energy conversion abilities.