Hierarchical Core-Shell Structural Ni2p/Nimoo4@Cop/Fep2 Nanorods as Difunctional Electrocatalysts for Efficient Overall Water Splitting

Abstract

The designing of efficient and stable electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is vital for boosting the efficiency of overall water splitting. Here, we reported an original design and synthesis of quaternary non-noble metal-based hierarchical core-shell structural nanorods (Ni2P/NiMoO4@CoP/FeP2) by hydrothermal reaction, in-situ coating reaction and phosphating processes. The unique core-shell structure increased the number of active sites, which provided favorable conditions for electrochemical catalytic reactions, and the metal phosphide/metal oxide also speeded up the rate of water splitting. In addition, the synergistic effect between metal phosphides also optimized the electrochemical catalytic performance of Ni2P/NiMoO4@CoP/FeP2 in the alkaline solution. Ni2P/NiMoO4@CoP/FeP2 displayed prominent electrocatalytic performance for HER and OER with overpotentials of 105 and 216 mV at 10 mA cm−2 and small Tafel slopes of 74.4 and 77.8 mV dec−1 in 1.0 M KOH, respectively. When the as-prepared materials were loaded to the anode and cathode of the two-electrode overall water splitting device, only a cell voltage of 1.56 V was required to reach a current density of 10 mA cm−2 and the materials also exhibited good long-term stability.

Keywords: Metal phosphides, Hierarchical core-shell structure, Difunctional electrocatalysts, HER, OER, Overall water splitting