Enhancing Benzylamine Electro‐Oxidation and Hydrogen Evolution Through in‐situ Electrochemical Activation of CoC₂O₄ Nanoarrays

The sluggish anodic oxygen evolution reaction (OER) seriously restricts the overall efficiency of water splitting. Here, we present an environmentally friendly and efficient aniline oxidation (BOR) to replace the sluggish OER, accomplishing the co-production of H₂ and high value-added benzonitrile (BN) at low voltages. Cobalt oxalates grown on cobalt foam (CoC₂O₄ ⋅ 2H₂O/CF) are adopted as the pre-catalysts, which further evolve into working electrocatalysts active for BOR and HER via appropriate electrochemical activation. Thereinto, cyclic voltammetry activation at positive potentials is performed to reconstruct cobalt oxalate via extensive oxidation, resulting in enriched Co(III) species and nanoporous structures beneficial for BOR, while chronoamperometry at negative potentials is introduced for the cathodic activation toward efficient HER with obvious improvement. The two activated electrodes can be combined into a two-electrode system, which achieves a high current density of 75 mA cm^-2 at the voltage of 1.95 V, with the high Faraday efficiencies of both BOR (90.0 %) and HER (90.0 %) and the satisfactory yield of BN (76.8 %).