Improving the electrocatalytic property of CoP for hydrogen evolution by constructing porous ternary CeO₂-CoP-C hybrid nanostructure via ionic exchange of MOF

Developing cheaper but efficient electrocatalysts toward hydrogen evolution reaction (HER) are highly desirable for the sustainable energy conversion techniques. The nanostructured CoP has been proved to be one of the most efficient non-noble metal HER catalyst. However, to further improve their performance in hydrogen evolution reaction (HER) is still a challenging task. In the present work, we prepare the nanohybrid CeO₂-CoP-C catalyst with high porosity through a co-ionic-exchange with Co and Ce ions using the metal-organic frameworks (MOFs) as template followed with a low-temperature phosphorization route. The high porosity of the catalysts is conductive to the diffusion and mass transfer of the reactants on the catalyst surface. Meanwhile, the doping of rare earth (RE) element modulates the electronic structure of the CoP nanoparticles, and the carbon skeleton left over from the annealed MOF is beneficial to the electronic conduction in the catalyst. Electrochemical tests showed that the ternary CeO₂-CoP-C/CC hybrid nanostructure presented overpotential of 71 mV at 10 mV cm⁻² (η₁₀), which is much higher than that of the binary CoP-C/CC catalysts (i.e., 132 mV). In addition, the ternary catalyst also presented a superior long-term durability in an acidic electrolyte. This work opens up a potential strategy for designing more efficient CoP-based catalysts toward electrochemical water splitting.