A sequential template strategy toward hierarchical hetero-metal phosphide hollow nanoboxes for electrocatalytic oxygen evolution

Engineering delicate structures/morphologies and coordinated components of electrocatalysts are of great importance to optimize physicochemical properties of materials and thus enhance their electrocatalytic performance. Herein, we demonstrate a facile sequential template-engaged strategy for fabricating Co–Ni–Fe phosphide hollow nanoboxes with hierarchical structures and desired hetero-metal compositions (Co–Ni–Fe–P HNBs). Starting from ZIF-67 templates, binary-metal Co–Ni and ternary-metal Co–Ni–Fe HNBs are sequentially synthesized and further phosphidated into hetero-metal Co–Ni–Fe–P HNBs. As-resultant Co–Ni–Fe–P HNBs endow multiple structural and compositional merits that expose abundant active sites, accelerate mass/ion diffusion and optimize adsorption energies of oxygen and hydroxyl groups, thus kinetically promoting electrocatalytic oxygen evolution reaction (OER). Specifically, Co–Ni–Fe–P HNBs disclose remarkable OER activity with an overpotential of 249 mV at 10 mA cm−2 and stability with 86% activity retained over 24 h, which represents one of the toppest values of OER electrocatalysts. This work thus paves an effective protocol to rationally engineer hierarchical and hetero-metal electrocatalysts towards targeted applications.