Doping strain induced bi-Ti3+ pairs for efficient N2 activation and electrocatalytic fixation

The electrochemical N 2 fixation to produce ammonia is attractive but significantly challenging with low yield and poor selectivity. Herein, we first used density function theory calculations to reveal adjacent bi-Ti 3+ pairs formed on anatase TiO 2 as the most active electrocatalytic centers for efficient N 2 lying-down chemisorption and activation. Then, by doping of anatase TiO 2 with Zr 4+ that has similar d -electron configuration and oxide structure but relatively larger ionic size, the adjacent bi-Ti 3+ sites were induced and enriched via a strained effect, which in turn enhanced the formation of oxygen vacancies. The Zr 4+ -doped anatase TiO 2 exhibited excellent electrocatalytic N 2 fixation performances, with an ammonia production rate (8.90 µg·h −1 ·cm −2 ) and a Faradaic efficiency of 17.3% at −0.45 V versus reversible hydrogen electrode under ambient aqueous conditions. Moreover, our work suggests a viewpoint to understand and apply the same-valance dopants in heterogeneous catalysis, which is generally useful but still poorly understood.