Reconstructing the electronic structure of nickel selenide by Cu incorporation for enhanced alkaline hydrogen evolution reaction

Abstract

Nickel selenides are proven to be the efficient electrocatalysts in catalyzing hydrogen evolution reaction (HER) for alkaline water electrolysis, but their unsatisfying durability in alkaline medium opens up for the strategic exploration in improving the HER activity over time. Tuning the electronic structure of hydrothermally synthesized nickel selenide with electrodeposited Cu (NCS/NF) has proven fruitful beyond imagination in HER for the first time. Introduction of Cu enabled this newly developed catalyst to deliver current density of -10 mAcm-2 requiring a lower overpotential of only 45 mV due to the enhanced electron diffusivity with an extended surface area. The voltage-induced phase transition of nickel selenide with Cu exhibited 2.5fold increment in HER activity which enabled this activity tuned catalyst (AD NCS/NF) to surpass the state-of-the-art Pt at all potentials under identical conditions and when connected in two-cell configuration AD NCS/NF||NiFeLDH required cell voltage of only 1.48V for 50 mAcm-2. Further, XRD, XPS and XAS findings provide insights onto the voltage-induced structural reorganization of NCS/NF during the accelerated degradation test revealing the superior HER activity with the improvement of catalysts’ durability over time. This unique regulation of crystalline facets in NCS/NF with Se-enriched surface promotes the intrinsic activity for striking H2 production.