First-principles Studies on the Structural and Electronic Modifications of Nitrogen Electrochemical Reduction on Anatase TiO₂(101) Surface

The conversion of dinitrogen (N₂) to ammonia (NH₃) through an electrochemical reduction process is attracting increasing attentions due to its great importance in both the biosphere and the fertilizer industry. In this work, we performed systematic density functional theory (DFT) studies on the nitrogen reduction reaction (NRR) mechanisms on both clean and O-decorated TiO₂(101) surfaces at an atomic scale.Our calculation results showed that the Ti_4C,VO2c site most likely serves as the active site for NRR process, and the V_O2c-decorated TiO₂(101) surface exhibits outstanding NRR catalytic activity through a mixed mechanism compared with the clean anatase TiO₂(101) surface. We further studied the effect of structural and electronic features on N₂ fixation and activation on TiO₂(101) surface. The introduction of surface oxygen vacancy should enhance the nitrogen adsorption obviously with an adsorption energy of -0.46 eV, and the tuning of Ti³⁺ concentration further changes the adsorption energy, such as to -0.65 eV if the concentrations of Ti³⁺ can be decreased to 4%. Our calculation results may provide some guidelines in the design of new catalysts for NRR.