Valence Engineering via Manganese‐Doping on Cobalt Nitride Nanoarrays for Efficient Electrochemically Paired Glycerol Valorization and H 2 Production

Integration of more thermodynamically favorable valorization of biomass (e.g., glycerol), compared to sluggish oxygen evolution, with H 2 production is of great significance for energy‐saving electrosynthesis of value‐added chemicals. However, its widespread deployment has been challenged by costly electrocatalysts and large overpotential reaching an industrial‐relevant current density (≥400 mA cm −2 ). Herein, carbon shell‐encapsulated manganese‐doped cobalt nitride nanoarrays immobilizing on nickel foam, denoted Mn‐CoN@C/NF, are crafted via hydrothermal method and ammoniation. As a bifunctional electrocatalyst, the Mn‐CoN@C/NF manifests extraordinary activity for glycerol oxidation reaction (GOR) with an ultralow potential of 1.37 V (versus RHE) at 400 mA cm −2 , in conjunction with H 2 evolution reaction (HER) with a low overpotential of 31 mV at 10 mA cm −2 . A record high Faradaic efficiency (97.7%) for formate production of GOR is delivered at 1.35 V (vs RHE). Impressively, a two‐electrode electrolyzer capitalizing on the Mn‐CoN@C/NF as catalysts reaches 800 mA cm −2 at 1.83 V, delivering an electricity‐saving efficiency of 15.0% compared to pure water splitting. DFT calculations substantiate that Mn species within Mn‐CoN not only optimize hydrogen adsorption kinetics for HER, but also elevate Co 3+ active sites’ density for GOR. This work offers an energy‐saving and efficient electrosynthesis avenue for coproduction of valuable chemicals.