Modulating the Oxidation State of Titanium via Dual Anions Substitution for Efficient N₂ Electroreduction

Abstract The electrocatalytic nitrogen reduction reaction (NRR) is a promising approach for renewable ammonia synthesis but remains significantly challenging due to the low yield and poor selectivity. Herein, a facile N and S dual anions substitution strategy is developed to tune the Ti oxidation states of TiO₂ nanohybrid catalyst (NS‐TiO₂/C), in which anatase TiO₂ nanoplates with dense Ti³⁺ active sites are uniformly dispersed on porous carbon derived from 2D Ti₃C₂T_x nanosheets. The catalyst NS‐TiO₂/C exhibits a superior ambient NRR efficiency with an NH₃ yield rate of 19.97 µg h⁻¹ mg⁻¹_cat and Faradaic efficiency of 25.49% and is coupled with a remarkable 50 h long‐term stability at −0.25 V versus RHE. Both experimental and theoretical results reveal that the N and S dual‐substitution effectively regulate the Ti oxidation state and electronical properties of the NS‐TiO₂/C via simultaneously forming interstitial and substitutional TiS and TiN bonds in the anatase TiO₂ lattice, inducing oxygen vacancies and dense Ti³⁺ active species as well as better electronic conductivity, which substantially facilitates N₂ chemisorption and activation, and reduces the energy barrier of the rate‐determining step, thereby essentially boosting NRR efficiency. This work provides a valuable approach to the rational design of advanced materials by modulating oxidation states for efficient electrocatalysis.