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.