Mild construction of an Fe-B-O based flexible electrode toward highly efficient alkaline simulated seawater splitting.

It is essential to construct self-supporting electrodes based on earth-abundant iron borides in a mild and economical manner for grid-scale hydrogen production. Herein, a series of highly efficient, flexible, robust, and scalable Fe-B-O@FeB modified on hydrophilic cloth (denoted as Fe-B-O@FeB/HC, 10 cm × 10 cm) are fabricated by mild electroless plating. The overpotentials and Tafel slope values for the hydrogen and oxygen evolution reactions are 59 mV and 57.62 mV dec and 181 mV and 65.44 mV dec, respectively; only 1.462 V is required to achieve 10 mA cm during overall water splitting (OWS). Fe-B-O@FeB/HC maintains its high catalytic activity for more than 7 days at an industrial current density (400 mA cm), owing to the loosened popcorn-like Fe-B-O@FeB that is firmly loaded on a 2D-layered and mechanically robust substrate along with its fast charge and mass transfer kinetics. The chimney effect of core-shell borides@(oxyhydro)oxides enhances the OWS performance and protects the inner metal borides from further corrosion. Moreover, the flexible Fe-B-O@FeB/HC electrode has a low cost for grid-scale hydrogen production ($2.97 kg). The proposed strategy lays a solid foundation for universal preparation, large-scale hydrogen production and practical applications thereof.