Rapid laser synthesis of medium-entropy alloy nanostructures for neutral seawater electrolysis

Abstract

Seawater electrolysis powered by surplus renewable energy has garnered significant attention as part of global efforts towards carbon neutrality and climate change mitigation. Current mainstream seawater electrolysis primarily relies on alkaline or acidic electrolytes, which presents ongoing challenges due to high costs and substantial maintenance requirements. As a result, neutral seawater electrolysis is emerging as a more attractive alternative, given its abundance. However, this approach remains a challenge due to the high salt content of seawater. In this work, we report the direct laser-induced synthesis of medium-entropy alloy nanoparticles (MEA NPs), FeNiCoRu, as a bifunctional electrocatalyst for neutral seawater electrolysis. The unique features of direct laser induction, including ultrahigh temperature and rapid heating/cooling rates, enable the formation of homogeneous FeNiCoRu MEA NPs without phase separation. The FeNiCoRu MEA NPs exhibit the highest catalytic activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) among their single, binary, and ternary counterparts. Specifically, overpotentials of −0.368 V and −0.448 V are required for the HER, while overpotentials of 0.559 V and 0.652 V are needed for the OER to deliver current densities of 10 mA cm⁻² and 50 mA cm⁻², respectively. When assembled into an electrolyzer, FeNiCoRu‖FeNiCoRu demonstrated an notable stability, with a voltage increase of only 0.161 V after 270 hours of continuous operation. The enhanced performance is attributed to the synergistic effects of the multi-elemental composition, particularly the role of Ru in reducing reaction barriers. Our findings demonstrate that direct laser-induced synthesis is a viable approach to develop advanced multi-component electrocatalysts, presenting a feasible solution for efficient neutral seawater electrolysis and the large-scale generation of green hydrogen.