A Simple and Efficient Non‐Noble Cathode Catalyst Based on Carbon Hollow Nanocapsules Containing Cobalt‐Based Materials for Anion Exchange Membrane Water Electrolyzer

Abstract An efficient approach for fabrication of non‐noble metal‐based electrocatalyst is desirable for designing the energy storage and conversion devices in real‐world usages due to low cost and excellent catalytic properties. The preparation of hollow carbon capsules (HCC) containing cobalt (Co)‐based electrocatalyst is reported by a simple synthesis process without using templates for the first time. Initially, cobalt phenylphosphonate (Co‐MOF) nanorods are fabricated through a simple hydrothermal approach. The as‐formed Co‐MOF is covered with a thin coating of polydopamine (DP‐Co‐MOF) through chemical polymerization of dopamine in Tris‐HCl (pH 8.5). The DP‐Co‐MOF is used as self‐degraded template for the formation of HCC under pyrolysis. The formation mechanism and hydrogen evolution reaction (HER) activity of HCC are investigated. The hollow structure derived under N 2 exhibits a low overpotential (295 mV at 100 mA cm −2 ) with excellent stability (90.98%) for 150 h, which is further verified by density functional theory (DFT) calculations. Finally, the designed anion exchange membrane (AEM) water electrolyzer based on C─Co─N as cathode delivers a current density of 500 mA cm −2 (at 2.19 V) and 1000 mAcm −2 (at 2.33 V) in 1.0 m KOH at 60 °C. The fabricated new Co‐based electrocatalyst is highly beneficial for the fabrication of cost‐effective and high‐performance AEMWEs.