Self-supporting W-doped NiFe/NiMo heterojunction as a high-performance and stable electrocatalyst for efficient overall water splitting.

Abstract

Developing bifunctional electrocatalysts for simultaneous catalysis of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at industrial current densities is a critical challenge in electrochemical water splitting. Herein, a hierarchically structured heterojunction electrode comprising W-doped NiFe layered double hydroxide (NiFe LDH) grown atop a NiMo alloy interlayer on nickel foam (NF) is fabricated via a two-step electrodeposition strategy. The NiMo underlayer acts as both an efficient HER-active component and a protective barrier against NF corrosion in harsh electrochemical environments. Remarkably, W incorporation into the NiFe LDH lattice enhances lattice oxygen activity and raises the oxygen vacancy concentration, thus triggering a low-overpotential lattice oxygen mechanism (LOM) for OER. Meanwhile, strong WO bonds help stabilize the Ni and Fe active sites, suppressing their dissolution and improving long-term durability. Consequently, the optimized W-NiFe/NiMo catalyst delivers overpotentials of only 170 and 233 mV to achieve a current density of 100 mA cm-2 for the HER and OER, respectively, and maintains stable operation for 500 h in alkaline electrolyte at current densities of 100 and 1000 mA cm-2. This study offers a practical route for designing durable, high-performance catalysts for overall water splitting.

Abstract as supplied by the indexing source. © the authors / publisher.