Joule Heating\nSynthesis of MoO<sub>2</sub> With Highly\nExposed (101) Crystal Facets Promoted Water Dissociation to Improve\nNitrate Reduction to Ammonia

The process of the electrocatalytic nitrate reduction\nreaction\n(NO<sub>3</sub>RR) holds great promise to produce ammonia with economic\nbenefits while eliminating nitrate pollution. Nonetheless, the reaction\ninvolves multielectron transfer and easy desorption of intermediates,\nreducing the selectivity of the nitrate reduction reaction. Herein,\na simple hydrothermal method along with a rapid Joule heating treatment\nwas used to <i>in situ</i> grow MoO<sub>2</sub> (MO/NF-JH)\nwith (101) crystal facets exposed on nickel foam (NF). Compared to\nMoO<sub>2</sub> (MO/NF-TH) with (−111) crystal facets exposed,\nMO/NF-JH exhibited excellent NO<sub>3</sub>RR activity with an NH<sub>3</sub> yield of 3.28 mg h<sup>–1</sup> cm<sup>–2</sup> and a Faradaic efficiency of 96.29% in a neutral electrolyte at\n−0.55 V (vs RHE). DFT calculations indicated that MO/NF-JH\nwith the main exposure of the (101) crystal facets was in favor of\nNO<sub>3</sub><sup>–</sup> adsorption and NH<sub>3</sub> desorption.\nMoreover, H<sub>2</sub>O dissociation was accelerated and *H retention\nability was enhanced on (101) crystal facets, which provided a material\nbasis for the *H-assisted pathway of electrocatalytic NO<sub>3</sub>RR.