Preparation of Single-Ni atom active points by anchoring Anderson polyoxometalate in HKUST-1 for efficient Symmetric/ Asymmetric device energy storage and electrocatalytic overall water splitting

Abstract

We explore and synthesize hollow polyoxometalate-based metal–organic framework (POMOF) nanomaterial {Cu(NH4)2NiMo6O24H6}@HKUST-1 (HRBNU-2) with single-atom sites (SASs) by one-step solution method. It exhibits high specific capacitance (978.50F g−1) in neutral electrolyte. Symmetrical/Asymmetrical devices can light four Red Light Emitting Diodes (RLEDs)/one RLED on for 14 min. For electrocatalytic water splitting, the overpotentials of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline medium are 192.98 mV (η100) and 405.38 mV (η100). The double-layer capacitance (Cdl) of HRBNU-2 is 269.23 mF cm−2, reaching about 4.43 times of {Cu2(NH4)2Mo7O24}@HKUST-1 (HRBNU-3) and about 12.70 times of HKUST-1. Moreover, the device assembled by HRBNU-2 as cathode and anode, requires only 1.61 V cell voltage to achieve current density of 10 mA cm−2 and obtain stability of 100 h. Meanwhile, comparative study of HRBNU-3 system with similar structural composition is synthesized to illustrate that the synergy of SASs(Ni) and Mo in well-defined structures plays important role in the study of efficient overall water splitting and supercapacitance performance.