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

• Synthesis of hollow structure {Cu(NH 4 ) 2 NiMo 6 O 24 H 6 }@HKUST-1 by simple solution method. • {Cu(NH 4 ) 2 NiMo 6 O 24 H 6 }@HKUST-1 possesses a large number of Single-Ni active points. • The assembled SSC has power density of 800.17 W kg −1 and light up one RLED for 4 min. • The assembled ASC has an energy density of 82.72 Wh kg −1 and can light up to 20 RLEDs. • The overpotentials of HER and OER are 192.98 mV ( η 100 ) and 405.38 mV ( η 100 ) We explore and synthesize hollow polyoxometalate-based metal–organic framework (POMOF) nanomaterial {Cu(NH 4 ) 2 NiMo 6 O 24 H 6 }@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 ( η 100 ) and 405.38 mV ( η 100 ). The double-layer capacitance ( C dl ) of HRBNU-2 is 269.23 mF cm −2 , reaching about 4.43 times of {Cu 2 (NH 4 ) 2 Mo 7 O 24 }@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.