Ni-single atom decorated mesoporous carbon electrocatalysts for hydrogen evolution reaction

Abstract

A single atom catalyst (SAC) is a type of heterogeneous catalyst in which individual metal atoms are dispersed on a support material, such as carbon, metal oxides, or zeolites, rather than forming nanoparticles or clusters. SACs have unique catalytic properties, such as high selectivity and activity, due to their high surface area and the exposed active metal sites, allowing them to interact more efficiently with the reactants. SACs also have the advantage of being more environmentally friendly and cost-effective than traditional catalysts, as they require smaller amounts of metal and can be easily recycled. In this study, we report the synthetic method of mesoporous single atom catalysts (MSACs) containing nickel (Ni), platinum (Pt), iridium (Ir), cobalt (Co), and iron (Fe) as metal-centered atoms for hydrogen evolution reaction (HER). MSACs are successfully synthesized with metal-chelation and soft-templating methods. The results show that highly uniform MSACs can be fabricated with high reproducibility. The metal contents in MSACs can be reduced to under 1wt%, keeping good HER reactivity. For HER, the Ni mesoporous single atom catalysts (Ni-MSACs) show 270 mV overpotential at 10 mA/cm2 at the initial polarization curve and reduces to 190 mV after 2,000 cycles, which outperforms Ni bulk catalyst (Ni plate). In contrast, porous pure carbon without Ni atoms shows inferior performance, indicating that Ni metal center plays an important role in the catalytic activity. The computational calculation using density functional theory (DFT) tells that Volmer-Heyrovsky pathway is dominant for HER using the Ni-MSACs. The performance of MSACs has a high potential for improvement of performance and extreme reduction of metal usage by doping nitrogen, phosphorous, and two or more metal atoms into MSACs.