New Findings of Pseudocapacitive Behaviors in Cupric Tungstate Dihydrate

The pseudocapacitive behavior is a hot research topic in the electrochemical field. There are two most widely studied types of pseudocapacitors: (i) based on the redox reaction pseudocapacitance represented by RuO2 center dot xH(2)O, MnO2, and so on and (ii) the intercalation pseudocapacitive materials such as Nb2O5. It is important to study the pseudocapacitive mechanism and discover new materials with pseudocapacitive behavior for a dearer understanding of pseudocapacitive characteristics. Here, we discover and report the pseudocapacitive behavior of copper tungstate hydrate for the first time. Its cyclic voltammetry curve shape is similar to that of MXene (Ti3C2Tx), its potential window (-0.4 to 0.2 V) is also close to that of MXene, and its charge-discharge curve is almost an ideal isosceles triangle. These electrochemical analysis results indicate that the electrochemical behavior of CuWO4 is a new type of intercalation pseudocapacitive behavior. In addition, because of the higher density of CuWO4 (7.5 g cm(-3)), it exhibits an excellent volumetric specific capacitance of 743 F cm(-3) at 0.5 A g(-1) (similar to that of MXenes). The novel pseudocapacitive behavior of CuWO4 reported in this work facilitates the development of a new material system for pseudocapacitive research. The follow-up studies are more concerned with how the pseudocapacitive behavior of this material occurs.

Automated summary

Pseudocapacitive behavior is a popular research topic in the field of electrochemistry. This article reports the pseudocapacitive behavior of copper tungstate hydrate for the first time and compares it with MXene. Copper tungstate hydrate exhibits a new type of intercalation pseudocapacitive behavior and has a high volumetric specific capacitance.