Joule Heating Synthesis of MoO2 With Highly Exposed (101) Crystal Facets Promoted Water Dissociation to Improve Nitrate Reduction to Ammonia

The process of the electrocatalytic nitrate reduction reaction (NO3RR) holds great promise to produce ammonia with economic benefits while eliminating nitrate pollution. Nonetheless, the reaction involves multielectron transfer and easy desorption of intermediates, reducing the selectivity of the nitrate reduction reaction. Herein, a simple hydrothermal method along with a rapid Joule heating treatment was used to in situ grow MoO2 (MO/NF-JH) with (101) crystal facets exposed on nickel foam (NF). Compared to MoO2 (MO/NF-TH) with (−111) crystal facets exposed, MO/NF-JH exhibited excellent NO3RR activity with an NH3 yield of 3.28 mg h–1 cm–2 and a Faradaic efficiency of 96.29% in a neutral electrolyte at −0.55 V (vs RHE). DFT calculations indicated that MO/NF-JH with the main exposure of the (101) crystal facets was in favor of NO3– adsorption and NH3 desorption. Moreover, H2O dissociation was accelerated and *H retention ability was enhanced on (101) crystal facets, which provided a material basis for the *H-assisted pathway of electrocatalytic NO3RR.