In-situ growth of ZIF-67-derived Co/wood-based carbon self-supporting electrocatalysts for stable hydrogen evolution at high current density

The hydrogen evolution reaction (HER) catalyst is limited by the substrate's stability and their interaction with the metal, resulting in high energy barriers at high current densities. In this work, Cobalt (Co)/wood-based carbon self-supporting catalysts were prepared based on the delignified natural wood, and Co-MOF (ZIF-67) was used as a stable Co metal layer by the loading-carbonization process. The distinctive microchannels of the carbonization wood substrate could provide more electrolyte contact interfaces, promoting good connectivity and stability between the wood cellulose skeleton and the embedded metal-organic framework. Additionally, Co nanoparticles with uniformly sized aggregate on the surface of the wood-derived carbon could create abundant interparticle voids, generating more active metal sites. The electronic structures of Co were regulated by changing the configuration of nitrogen on the supported ZIF-67 at different carbonization temperatures. These structures contribute to enhancing the catalytic surface activity and reducing the energy barrier during the HER process, thereby increasing the stability of the catalyst at high current density. The obtained ZIF-67/CW-800 exhibited impressive performance, with an overpotential of 293 mV (367 mV) at a current density of 200 mA cm−2 (500 mA cm−2), as well as Tafel slopes of 44.8 mV dec−1 in 1 M KOH, demonstrating excellent long-term stability. This work provides a theoretical basis for the preparation of HER catalysts that are low-cost, high-performance, and highly stable at high current densities. © 2024 Hydrogen Energy Publications LLC