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

초록

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.

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