Strain-Modulated Engineering of High-Entropy Vanadium-Based Chalcogenide for Sustainable Water Oxidation

High-entropy metal chalcogenides (HEMC), stabilized by their high configurational entropy and multi-element disorder, have emerged as promising materials for electrocatalysis. However, synthesizing high-entropy sulfide catalysts via bottom-up routes remains challenging due to the thermodynamic incompatibility of multiple metals, which promotes unwanted phase segregation and hinders controlled self-assembly for optimal electrocatalytic performance. In this study, we tackle this challenge by systematically optimizing the solvothermal synthesis parameters, including solvent ratio, reductants, and stabilizers, to produce a single-phase, strain-engineered HEMC nanoflower/nanoflake (VMoFeCoNi)S_x, as strain engineering has the potential to modify the adsorption process and enhance electrocatalytic activity. The Williamson-Hall analysis reveals a compressive micro strain of 0.67%, manifested as a blue shift of the (220) reflection (44.34° → 44.47°) and a slight lattice contraction relative to the control samples. The optimized HEMC-based anode exhibits top-level oxygen evolution reaction (OER) performance in alkaline media, achieving overpotentials of 210 mV and 250 mV at current densities of 50 mA cm^-2 and 100 mA cm^-2, respectively. Notably, it retains excellent OER stability with minimal degradation at 200 mA cm^-2 over 120 h, demonstrating rapid reaction kinetics and durability at high current density, positioning it as a promising candidate for practical energy applications.