Engineering Amorphous/Crystalline Rod-like Core-Shell Electrocatalysts for Overall Water Splitting.

The design of bifunctional electrocatalysts for hydrogen and oxygen evolution reactions delivering excellent catalytic activity and stability is highly desirable, yet challenged. Herein, we report an amorphous RuO 2 -encapsulated crystalline Ni 0.85 Se nanorod structure (termed as a/c-RuO 2 /Ni 0.85 Se) for enhanced HER and OER activities. The as-prepared a/c-RuO 2 /Ni 0.85 Se nanorods not only demonstrate splendid HER activity (58 mV@10 mA cm -2 vs RHE), OER activity (233 mV@10 mA cm -2 vs RHE), and electrolyzer activity (1.488 V@10 mA cm -2 vs RHE for overall water splitting) but also exhibit long-term stability with negligible performance decay after 50 h continuous test for overall water splitting. In addition, the variation of the d-band center (from the perspective of bonding and antibonding states) is unveiled theoretically by density functional theory calculations upon amorphous RuO 2 layers coupling to clarify the increased hydrogen species adsorption for HER activity enhancement. This work represents a new pathway for the fabrication of bifunctional electrocatalysts toward green hydrogen generation.