Novel NiCoP nanoarray modified by NiFeCo layered double hydroxide quantum dots as highly efficient bifunctional electrocatalysts in anion exchange membrane water electrolysis

Abstract

Enhancing the activity of non-precious metal electrocatalysts is crucial for advancing anion exchange membrane (AEM) electrolyzer technology. In this study, we synthesized an NiFeCo layered double hydroxide quantum dots (LDHQDs)-modified NiCoP nanoarray (NiCoP NA) via a hydrothermal–phosphorization–electrostatic adsorption process (LDHQDs/NiCoP NA). The LDHQDs/NiCoP NA demonstrates overpotentials of 75 and 263 mV, respectively, to achieve current densities of 10 and 1000 mA cm⁻² for the hydrogen evolution reaction. For the oxygen evolution reaction, reaching current densities of 10 and 1000 mA cm⁻² requires 203 and 330 mV, respectively. For overall water splitting, the LDHQDs/NiCoP NA electrocatalyst demonstrated remarkable performance, achieving a high current density of 1000 mA cm⁻² at 1.69 V. Furthermore, an AEM electrolyzer utilizing the LDHQDs/NiCoP NA as the anodic and cathodic electrocatalyst requires only 2 V to reach 574 mA cm⁻² and 2.28 V to reach 1000 mA cm⁻². The excellent electrocatalytic activity of the LDHQDs/NiCoP NA is due mainly to the large electrochemically active surface area of LDHQDs and the strong electronic coupling effect between the NiCoP NA and LDHQDs, which results in metallic conductivity and appropriate d-band centers. This study presents a practical methodology for developing highly efficient electrocatalysts through the utilization of LDHQDs.