Self-supporting high-entropy Co-Cr-Fe-Ni-Nb oxide electrocatalyst with nanoporous structure for oxygen evolution reaction

Microscopic brittleness is a disadvantage of nanoporous metallic electrocatalysts. Design of nanoporous high-entropy alloys is a promising way to solve this problem due to the excellent intrinsic mechanical properties of high-entropy alloys. In this paper, the nanoporous high-entropy Co-Cr-Fe-Ni-Nb oxide electrocatalyst with self-supporting structure are prepared by melt-spinning and chemical dealloying. Due to the different cooling rates, the copper roller surface shows the disordered vermicular nanoporous structure, while the free surface shows the ordered dendritic nanoporous structure. The CoCrFeNiNb-1 sample with ordered nanoporous structure has lower overpotential (η10 = 251 mV and η100 = 304 mV) and smaller Tafel slope (42.7 mV dec–1) for catalyzing oxygen evolution reaction (OER). The nanoporous Co-Cr-Fe-Ni-Nb catalyst contains abundant active reactants with different valence states, such as metallic, oxides, hydroxides and oxyhydroxides which greatly improves the catalytic activity. Besides, the CoCrFeNiNb-1 sample with ordered nanoporous structure exhibits the good long-term durability.