Lattice hydrogen transfer in titanium hydride enhances electrocatalytic nitrate to ammonia conversion

The electrocatalytic reduction of nitrate toward ammonia under mild conditions addresses many challenges of the Haber-Bosch reaction, providing a sustainable method for ammonia synthesis, yet it is limited by sluggish reduction kinetics and multiple competing reactions. Here, the titanium hydride electrocatalyst is synthesized by electrochemical hydrogenation reconstruction of titanium fiber paper, which achieves a large ammonia yield rate of 83.64 mg h^-1 cm^-2 and a high Faradaic efficiency of 99.11% with an ampere-level current density of 1.05 A cm^-2 at -0.7 V versus the reversible hydrogen electrode. Electrochemical evaluation and kinetic studies indicate that the lattice hydrogen transfer from titanium hydride promotes the electrocatalytic performance of nitrate reduction reaction and the reversible equilibrium reaction between lattice hydrogen and activate hydrogen not only improves the electrocatalytic activity of nitrate reduction reaction but also demonstrates notable catalytic stability. These finding offers a universal design principle for metal hydrides as catalysts for effectively electrochemical ammonia production, highlighting their potential for sustainable ammonia synthesis.