Dual-functional nickel cobalt disulfide electrocatalyst for nitrogen-containing small-molecule electrooxidation

The high-potential and low-value oxygen byproducts of the oxygen evolution reaction (OER) constrain the production of green hydrogen. Replacing OER with nitrogen-containing small molecule oxidation reactions (NOR) reduces energy needs and enables environmental cleanup, as well as high-value chemical synthesis. This study constructs a three-dimensional crumpled NiCo₂S₄/nickel foam (NF) bifunctional catalyst via a hydrothermal synthesis of a precursor on NF, followed by a sulfidation strategy, achieving exceptional NOR performance in alkaline media. Urea oxidation reaction (UOR) drives 100 mA cm^-2 at a mere 1.35 V, while adiponitrile oxidation reaction (ADOR) achieves the same current density at 1.40 V, with a Faradaic efficiency 98 % for adiponitrile (ADN) production. In-situ Raman reveals a dynamic phase transformation mechanism: leaching of sulfur triggers the electrochemical formation of the active Ni(Co)OOH phase. Urea molecules undergo a chemisorption-reduction process, establishing a closed-loop, self-sustained redox cycle that ultimately stabilizes at the highly active NiCo-LDH interface. The catalyst exhibits less than 5 % decay during 30 h of constant-current testing, outperforming most reported non-precious metal systems. This study establishes a scalable materials design paradigm and elucidates the underlying mechanisms for integrated systems that concurrently facilitate hydrogen production, environmental remediation, and resource upgrading.