Core-shell structured tungstocuprate@silver homobenzotrizoate complex for supercapacitor and oxygen evolution reaction

It remains challenging to develop an efficient and inexpensive polyoxometalate (POM)-based MOFs (POMOFs) electrode material for supercapacitors and electrocatalytic oxygen evolution reaction to achieve efficient bifunctional performance. Herein, for the first time, the core-shell structured tungstocuprate@silver homo-benzotrizoate (Ag6[CuW12O40]@[{Ag(H2btc)}{Ag2(Hbtc)}]n) (shortened as HRBNU-1, where [{Ag(H2btc)} {Ag2(Hbtc)}]n is shortened as Ag-BTC, H3btc = 1,3,5-benzenetricarboxylic acid) complex with copper as het-eroatom was successfully synthesized using simple one-step solution method. The synergistic effect of this unique core-shell structure between Ag6[CuW12O40] and Ag-BTC can facilitate the interfacial electron transport on HRBNU-1. In a three-electrode system, the specific capacitance of HRBNU-1 is 533.6 F g-1 at 1 A g-1 with nickel foam as the collector, and higher than both precursors and as reported in the literature. Initial capacitance is retained at 92.4 % after 5000 cycles. The power density and energy density of the symmetrical supercapacitor assembled with nickel foam as collector are 474.7 W kg-1 and 35.7 Wh kg-1, respectively, at a voltage window of 1.0 V. Meanwhile, in the electrolyte solution of 1 M KOH, the oxygen evolution reaction overpotential is 235 mV at 10 mA cm-2 and a Tafel slope of 76 mV dec-1. Furthermore, compared with the traditional noble metal electrocatalyst, the prepared core-shell structured HRBNU-1 catalyst has good durability and catalytic activity. May be due to the central copper atom and tungsten of Ag6[CuW12O40] form a trimetal synergistic interaction with Ag+ in Ag-BTC through MMIDLINE HORIZONTAL ELLIPSISO bond, which enhances the catalytic activity of the metal active site. This work opens a new way for the application of POMOF in supercapacitors and electrocatalytic oxygen evolution reactions.

Automated summary

A core-shell structured tungstocuprate@silver homo-benzotrizoate complex was synthesized for the first time, showing efficient bifunctional performance in supercapacitors and electrocatalytic oxygen evolution reaction. Its unique structure facilitates interfacial electron transport and exhibits high specific capacitance, good durability, and catalytic activity.