Electrolysis of seawater for hydrogen production on large-scale has garnered great attention as a breakthrough technological leap. Developing efficiency and cost-effective electrocatalysts remains at the forefront of this field. However, the seawater electrolysis encounters challenges arising from metal deposition and chlorine chemistry. Herein, we unveil a fluorine doping strategy for FeCoNiCuZn high entropy materials, showcasing a performance of 1.56 V at 50 mA·cm^–2 with long-term durability exceeding 1000 h in alkaline seawater. Experimental and theoretical evidence proves that the improvement is ascribed to F incorporation strengthens Lewis acid sites, which can absorb OH^– to resist cation deposition and Cl^– attack. The synergy effect between F and metal species further optimizes the intermediate adsorption energies by tuning the electronic structure. Significantly, the general efficacy of this approach is exhibited in a series of transition metal based high entropy materials with similar enhancements, among them, the FeCoNiCuZnCr and FeCoNiCuCr electrocatalysts demonstrate an even better HER and OER performance, respectively. This systematic study presents an in-depth perspective for designing efficient, robust high entropy electrocatalysts with high corrosion resistance in alkaline seawater electrolysis.

While the past years have witnessed great achievement in pseudocapacitors, the inauguration of electrode materials of high-performance still remains a formidable challenge. Moreover, the capacity and rate capability of the electrode depends largely on its electrical conductivity, which ensures fast charge transfer kinetics in both the grain bulk and grain boundaries. Here, nickel hydroxides with oxygen vacancies are facilely fabricated via a hydrothermal method. The active materials exhibit a high specific capacitance of 3250 F·g⁻¹ and a high areal of capacitance of 14.98 F·cm⁻² at 4.6 mA·cm⁻². The asymmetric supercapacitor device based on our material delivers a high energy density of ~ 71.6 Wh·kg⁻¹ and a power density of ~ 17,300 W·kg⁻¹ and could retain ~ 95% of their initial capacitance even after 30,000 cycles. In addition, the defect-rich hydroxides demonstrate higher electrical conductivity as well as dielectric constant, which is responsible for the superior pseudocapacitive performance. Our new scientific strategy in terms of taking the advantages of oxygen vacancies might open up new opportunities for qualified pseudocapacitive materials of overall high performances not only for nickel hydroxides but also for other metal hydroxides/oxides.