Precious-metal-free rGO/NiMnB nanoarchitectonics with covalent metal support interaction for efficient and durable alkaline water splitting

Abstract

To accelerate the widespread adoption of green hydrogen energy, developing cost-effective, sustainable electrocatalysts that can replace precious metals is essential. This study introduces a bifunctional electrocatalyst for overall water splitting, comprising 2D reduced graphene oxide (rGO) integrated with NiMnB nanosheets into a tailored nanohybrid (rGO/Ni1.5Mn0.5B). The integration enhances both crystal growth and catalytic activity by promoting rapid nucleation and efficient electron transport. Synthesized via a one-pot hydrothermal process, the rGO/Ni1.5Mn0.5B electrode exhibits a crystalline 2D nanosheet-like morphology, ensuring high electroactive surface area and strong contact with electrolyte. In 1.0 M KOH, the catalyst achieves an overpotential of 159 mV for hydrogen evolution reaction (HER) and 170 mV for oxygen evolution reaction (OER), outperforming RuO2 at 10 mA/cm2. DFT calculations reveal that the strong orbital coupling between Ni, Mn, and the rGO matrix enhances metal-support interactions, boosting catalytic performance. The symmetric cell demonstrates overall water splitting cell voltage of 1.49 V at 10 mA/cm2 with excellent durability over 20 h under industrial conditions. Additionally, the long-term durability performance was evaluated using time series modelling with a long short-term memory algorithm. With superior electronic, structural, and electrochemical properties, rGO/Ni1.5Mn0.5B offers a scalable solution for next-generation industrial water splitting and sustainable hydrogen production.Graphical abstract A bifunctional, precious-metal-free rGO/NiMnB nanohybrid exhibits enhanced alkaline water splitting performance via covalent metal-support interactions. Synergistic orbital coupling at the Fermi level promotes efficient electron transfer, leading to low overpotentials for HER and OER. DFT analysis supports the observed catalytic activity and stability under industrial conditions.