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

Abstract

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.