Insights into defective TiO₂ in electrocatalytic N₂ reduction: combining theoretical and experimental studies

Artificial N2 fixation via the Haber-Bosch process requires high temperature and high pressure at the expense of CO2 release. Electrochemical NH3 synthesis is emerging as an environmentally friendly alternative that operates under ambient conditions, calling for electrocatalysts with efficient N2 reduction reaction (NRR) performance. In this paper, we experimentally and theoretically prove that defective TiO2 on Ti mesh (d-TiO2/TM) acts as an electrocatalyst for the NRR. In 0.1 M HCl, d-TiO2/TM achieves a much higher NH3 yield of 1.24 × 10-10 mol s-1 cm-2 and FE of 9.17% at -0.15 V (versus reversible hydrogen electrode) than pristine TiO2 (NH3 yield: 0.17 × 10-10 mol s-1 cm-2; FE: 0.95%). Notably, d-TiO2/TM also shows great electrochemical stability and durability. Theoretical investigation further reveals the possible catalytic mechanism involved.