Pomegranate-like Nickel–Iron Electrocatalyst Hosted on Shrimp Shell–Derived Carbon for Efficient Alkaline Hydrogen Evolution

The development of efficient, low-cost, and sustainable electrocatalysts is crucial for advancing clean hydrogen production and overcoming the limitations posed by the scarcity of noble metals. Herein, we present a zero-waste biorefinery strategy that upcycles shrimp shell waste into nitrogen-doped porous carbon via carbonization and activation, yielding a high specific surface area of 2841 m2 g–1 and providing abundant active sites for catalysis. Concurrently, we demonstrate that earth-abundant, cost-effective, and easily processable Ni-Fealloys spontaneously form catalytically active NiFe species upon electrochemical activation. The integration of Fe and Ni into the carbon matrix gives rise to a pomegranate-inspired catalyst with a hierarchical porous architecture, which facilitates ion transport and maximizes active site exposure, thereby enhancing overall catalytic performance. The optimal Hydrogen evolution reaction (HER) performance and durability were achieved at a surface Fe/Ni ratio of 1:2, attributed to the abundance of active sites and high catalytic efficiency. As a result, the as-prepared Ni-Fe electrocatalyst achieves an overpotential of 129.1 mV at 10 mA cm–2, a Tafel slope of 153 mV dec–1, and 98% Faradaic efficiency, with excellent structural integrity and consistent performance over 10,000 cycles in the hydrogen evolution reaction. It also demonstrates excellent operational stability over 100 h. The catalyst undergoes continuous structural reconstruction during operation, ensuring long-term stability and facilitating metal recycling. Moreover, its compatibility with solar energy-enabled water splitting highlights its potential for integration into renewable energy systems. This work presents a bioinspired, scalable electrocatalyst developed through a solvent-free synthesis that fully utilizes biomass and avoids toxic reagents, in alignment with green chemistry principles.