Layered double hydroxides derived prussian blue analogue nanocage confining NiCoP nanoparticles as efficient bifunctional electrocatalyst

Abstract

Designing novel electrocatalysts with excellent catalytic activity for efficient water splitting is necessary to achieve the large-scale H2/O2 production from renewable resources. In this study, a facile hydrothermal method followed by low-temperature phosphorylation treatment was employed to fabricate a nanocage of prussian blue analogue encapsulating NiCoP nanoparticles (NiCoP@PBA), which was derived from the layered double hydroxide precursor. As a bifunctional non-precious metal electrocatalyst, NiCoP@PBA demonstrates superior performance in KOH electrolyte water splitting, with overpotentials of 59 mV for electrocatalytic hydrogen evolution reaction (HER) and 263 mV for oxygen evolution reaction (OER) at 10 mA cm−2. The catalyst also exhibits low Tafel slopes of 54 mV dec−1 for HER and 120 mV dec−1 for OER, reflecting efficient charge transfer kinetics. DFT simulations show that the Co–N moieties at the heterogeneous interface of NiCoP@PBA can optimize the surface electron distribution and energy states, thus facilitating efficient electron-hole pair separation, significantly enhancing catalytic activity for both HER and OER process, and significantly extending the electrocatalyst's service life. Our approach can be extended to more non-precious metal electrocatalysts, which is significant for the design of efficient bifunctional water splitting electrocatalysts.