Strain engineering in gradient-structured metallic glasses for excellent overall water splitting

Metallic glasses (MGs) represent cutting-edge electrocatalysts due to their distinctive disordered atomic structure. However, enhancing the activity of MG catalysts poses a significant challenge. In this study, we present an innovative gradient structure design aimed at introducing strain effects into non-noble Ni₄₀Fe₄₀P₂₀ MG wires, resulting in a substantial enhancement of their water electrolysis efficiency. Our novel design strategy has been successfully implemented in various composition MG wires fabricated using the Taylor–Ulitovsky (TU) method. The gradient-structured metallic glasses (GS-MGs) enable the attainment of large and consistent surface tensile strain, which in turn modifies the electronic structure, leading to a remarkable improvement in catalytic performance. Furthermore, employing free-standing Ni₄₀Fe₄₀P₂₀ GS-MGs with a fully three-dimensional nanoporous structure as both cathode and anode in the overall water-splitting cell has achieved breakthrough performance in alkaline media. Notably, the cell exhibits significantly reduced potentials of only 1.378 V and 1.682 V at current densities of 10 mA cm⁻² and 1000 mA cm⁻², respectively, surpassing precious metal catalysts and previously reported advanced electrocatalysts. This study demonstrates that strain engineering induced by gradient structures is a universal and effective strategy for enhancing the catalytic performance of MGs. It introduces a new paradigm for the development of high-efficiency water splitting applications.