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

A general strategy to simultaneouslypromote the NRR selectivityand activity of M-TiO2 through phase-transitionengineering to regulate oxygen vacancy and metal doping at the catalystsurface. Titanium dioxide has recently received a lot of attentionas apotential catalyst for the electrochemical nitrogen reduction reaction(NRR). However, the effect of surface reconstruction of titanium dioxideduring the phase transition on electrocatalysis has attracted littleattention. Here, we develop a facile one-pot phase-transition engineeringstrategy to implant defects in iron-doped titanium dioxide. Our engineeringstrategy shows advantages including a simple synthesis process, phase-transitionefficiency, cost-effective materials, and scalability. The experimentalresults and density functional theory (DFT) calculations demonstratethat surface oxygen vacancies and doping Fe atoms play crucial rolesas potential electrocatalytic sites for the NRR on Fe-TiO2 catalysts, which enables efficient inhibition of the hydrogenevolution reaction (HER). A high NH3 yield of 30.9 & PLUSMN;0.4 & mu;g h(-1) mg(cat.) (-1) and a Faradaic efficiency (FE) of 40.4 & PLUSMN; 1.1% at -0.4V vs reversible hydrogen electrode are obtained for the NRR, outperformingmost Ti-based catalysts reported previously. The formation and electrocatalyticNRR properties of Mn-TiO2, Co-TiO2, Ni-TiO2, and Cu-TiO2 are alsoverified.