Layered Double Hydroxide Templated Synthesis of Amorphous NiCoFeB as a Multifunctional Electrocatalyst for Overall Water Splitting and Rechargeable Zinc–Air Batteries

Layered double hydroxides (LDHs) stand out as versatile structural platforms for modulating the electronic structure of highly reactive earth‐abundant transition metal‐based electrocatalysts for the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and the oxygen reduction reaction (ORR). Herein, a Ni‐Co‐Fe LDH, electrodeposited on a Ni nanocones (NiNCs)‐decorated Ni foam, acts as a morphology driving template to direct the facile constant potential electrosynthesis of NiCoFeB from a K2B4O7 solution. The amorphous tri‐metal borate (TMB) displays excellent trifunctional electrocatalytic activities toward the HER (overpotential at 10 mA cm−2, η10 = 174 mV vs RHE), OER (η10 = 208 mV), as well as ORR (half‐wave potential = 0.723 V) with a low ΔEOER−ORR of 770 mV, and excellent durability of over 110 h in alkaline solutions. A zinc–air battery based on the TMB@NiNC dual oxygen catalyst cathode exhibits a high open‐circuit voltage of 1.477 V, a power density of 107 mW cm−2, a specific energy of 918 W h kgZn−1 and an outstanding cycling stability of over 1330 cycles at 10 mA cm−2, which outperforms the commercial noble metal benchmarks. These results demonstrate that LDHs are efficient sacrificial templates for the preparation of high‐performance multifunctional multi‐metal borate electrocatalysts for energy‐related applications. An amorphous tri‐metal borate, in situ synthesized from a Ni‐Co‐Fe layered double hydroxide as a sacrificial template, shows impressive hydrogen evolution, oxygen evolution, and oxygen reduction activities. The electrochemically active sites of the metal species are rationally designed into one multifunctional structure. The electrosynthesized catalyst also displays excellent activity and outstanding durability as the cathode in rechargeable Zn–air batteries.