Tailored Design of Iridium Single Atoms on Mn-Ni-Phytate with Robust Bifunctionality for Enhanced Anion Exchange Membrane Water Electrolysis

Abstract

The development of efficient and durable bifunctional electrocatalysts is essential to simplify electrode design and fabrication in anion exchange membrane water electrolyzers (AEMWEs). However, most existing bifunctional catalysts suffer from poor stability and struggle to achieve high activity for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) simultaneously. Herein, we report Ir@Mn-Ni-PA, phytic acid-modified Mn-doped Ni layered double hydroxide catalyst that incorporates atomically dispersed Ir sites through tailored design of single atoms. Synthesized via a simple hydrothermal method, the catalyst features hierarchical nanoarrays that enhance electron transport, mass diffusion, and hydrophilicity. Ir@Mn-Ni-PA exhibits excellent bifunctional activity, delivering low overpotentials of 65 mV for HER and 272 mV for OER at 10 mA cm-2, along with stability exceeding 100 h. When implemented in an AEMWE cell, it achieves a high current density of 1.64 A cm-2 at 2.0 V and remains stable for 300 h under industrially relevant conditions. Density functional theory calculations reveal that Ir atoms modulate the Mn-Ni-PA electronic structure, narrowing the bandgap and enhancing charge transfer, which improves water adsorption, dissociation, and catalytic activity. These results highlight the potential of atomic-level engineering for designing durable, high-performance bifunctional catalysts for sustainable energy conversion.