Engineering Amorphous/Crystalline\nRod-like Core–Shell\nElectrocatalysts for Overall Water Splitting

Abstract

The design of bifunctional electrocatalysts for hydrogen\nand oxygen\nevolution reactions delivering excellent catalytic activity and stability\nis highly desirable, yet challenged. Herein, we report an amorphous\nRuO₂-encapsulated crystalline Ni_0.85Se nanorod\nstructure (termed as a/c-RuO₂/Ni_0.85Se) for\nenhanced HER and OER activities. The as-prepared a/c-RuO₂/Ni_0.85Se nanorods not only demonstrate splendid HER activity\n(58 mV@10 mA cm^–2 vs RHE), OER activity (233 mV@10\nmA cm^–2 vs RHE), and electrolyzer activity (1.488\nV@10 mA cm^–2 vs RHE for overall water splitting)\nbut also exhibit long-term stability with negligible performance decay\nafter 50 h continuous test for overall water splitting. In addition,\nthe variation of the d-band center (from the perspective of bonding\nand antibonding states) is unveiled theoretically by density functional\ntheory calculations upon amorphous RuO₂ layers coupling\nto clarify the increased hydrogen species adsorption for HER activity\nenhancement. This work represents a new pathway for the fabrication\nof bifunctional electrocatalysts toward green hydrogen generation.