Orchestrating the d-band and p-band centroids with local Lewis acid sites accelerates O2 evolution performance in ultralow Ru-doped NiFe LDH

Abstract

Accelerating the oxygen evolution reaction (OER) entails the dynamic stabilisation of its reaction intermediates to minimise energy barriers and enhance reaction kinetics. Nonetheless, optimisation of adsorption and desorption equilibria remains a formidable bottleneck. Our work highlights an ultralow Ru-doped NiFe LDH (0.43%, NRu3) framework coupled with tuned d-band and p-band centroid positions that deploys close to a quasi-industrial-scale current density of 746 mA cm⁻² in 1 M KOH (25 °C). EXAFS reveals a perturbed Ru–O environment, suggesting the presence of Lewis acid sites. These sites act as electron acceptors and metastabilise Ru, facilitating a better charge redistribution in NRu3. DFT calculations assert that the site of Ru doping, along with oxygen vacancies, plays a pivotal role in charge redistribution and optimisation of the centroid positions. Notably, NRu3 manifested extraordinary OER performance under both alkaline (η = 173 mV and Tafel slope 33.4 mV dec⁻¹) and simulated-seawater conditions (η = 196 mV and Tafel slope 51.2 mV dec⁻¹). Moreover, NRu3 displays an outstanding AEMWE performance, delivering a 66.7 fold enhancement in activity-to-price efficiency over the standard RuO₂ catalyst. Furthermore, a neural network (NN) driven multi-layer perceptron model was designed to predict the electrocatalytic activity across varying temperatures. Collectively, our work highlights the exceptional potential of NRu3 towards scalable and sustainable water-splitting technologies.