Phase-Transition Engineering with Tuning of Defects in TiO2 for Highly Efficient Electrochemical Nitrogen Reduction

Titanium dioxide has recently received a lot of attention as a potential catalyst for the electrochemical nitrogen reduction reaction (NRR). However, the effect of surface reconstruction of titanium dioxide during the phase transition on electrocatalysis has attracted little attention. Here, we develop a facile one-pot phase-transition engineering strategy to implant defects in iron-doped titanium dioxide. Our engineering strategy shows advantages including a simple synthesis process, phase-transition efficiency, cost-effective materials, and scalability. The experimental results and density functional theory (DFT) calculations demonstrate that surface oxygen vacancies and doping Fe atoms play crucial roles as potential electrocatalytic sites for the NRR on Fe–TiO2 catalysts, which enables efficient inhibition of the hydrogen evolution reaction (HER). A high NH3 yield of 30.9 ± 0.4 μg h–1 mgcat.–1 and a Faradaic efficiency (FE) of 40.4 ± 1.1% at −0.4 V vs reversible hydrogen electrode are obtained for the NRR, outperforming most Ti-based catalysts reported previously. The formation and electrocatalytic NRR properties of Mn–TiO2, Co–TiO2, Ni–TiO2, and Cu–TiO2 are also verified.