Flash joule heating enabled construction of interface-rich nickel-cobalt alloy on coconut shell-derived carbon for...

Alkaline hydrogen evolution reaction (HER) has always faced the problem of slow hydrolysis kinetics. In this study, an interfacial-rich metastable NiCo alloy electrocatalyst was prepared in situ on coconut shell-derived porous carbon (CSC) by Flash Joule heating (FJH) technique. DFT calculations verified that the synchronization of metal reduction, alloying, and local graphitization processes of carbon support was achieved under millisecond thermal shock. Structural characterization revealed that the alloy nanoparticles were uniformly dispersed in the hierarchical porous carbon framework, providing efficient channels for charge transfer and reactant diffusion. In 1.0 M KOH solution, the deeply activated catalyst only produced an overpotential of 73 mV at a current density of 10 mA·cm^-2 and operated stably for 450 h at a high current density of 160 mA·cm^-2. The characterization after electrolysis showed that the surface reconstruction layer of the catalyst composed of hydroxyoxide and hydroxide provided real active sites for alkaline hydrogen evolution, and significantly improved the catalytic performance by improving the wettability and promoting water dissociation. The reconstructed layer with a thickness of about 6 nm can effectively protect the alloy from corrosion and loss, and enhance the long-term stability. The results show that instantaneous Joule heating is an effective strategy to construct durable Ni-Co-based electrocatalysts suitable for alkaline HER.