Investigation of Oxygen Evolution Reaction Activity in NiFe-LDH with Modulated Electron Density via PANI Coating

Water electrolysis is an efficient and environmentally friendly hydrogen production technology that emits no greenhouse gases. However, its overall efficiency is significantly constrained by the high overpotential associated with the oxygen evolution reaction (OER), and this remains the bottleneck in water splitting. Among various OER catalysts, NiFe-layered double hydroxide (NiFe-LDH) has emerged as a promising candidate due to its low cost and high intrinsic activity. Its catalytic performance, however, is limited by the strong binding of OH intermediates, which inhibits rapid reaction kinetics and restricts further improvements in efficiency. In this study, we designed and synthesized PANI@NiFe-LDH by coating polyaniline (PANI) onto the surface of NiFe-LDH to modulate its electronic structure and alleviate the adsorption strength of reaction intermediates. The intimate interfacial interaction between PANI and NiFeLDH effectively redistributed the electronic density. This in turn optimized the OH adsorption energy and led to faster OER kinetics. As a result, the PANI@NiFe-LDH exhibited significantly enhanced catalytic activity compared to pristine NiFe-LDH. Furthermore, when applied as anode catalyst in an anion exchange membrane water electrolysis (AEM electrolyzer), PANI@NiFe-LDH demonstrated excellent performance under alkaline conditions, confirming its practical applicability in sustainable hydrogen production systems. This work not only demonstrates an effective strategy to improve the OER performance of non-platinum group metal (non-PGM) based catalysts but also provides insights into the role of polymer coatings in tuning the surface electronic structure for AEM electrolyzer.