The loading of polyoxometalates based compound on reduced graphene oxide, a composite material for electrical energy storage and tetracycline removal

Abstract A polyoxometalate based composite material ( NiPW 12 NP/FrGO ) was synthesized successfully, in which the nanoparticle of a polyoxometalate compound ( NiPW 12 NP ) distributes on carboxylate group functionalized reduced graphene oxide ( FrGO ) homogenously. There exist intensive chemical bonds between NiPW 12 NP and FrGO , which guarantees the stability of this composite material. When employed as a cathode material, NiPW 12 NP/FrGO exhibits high specific capacitance, remarkable rate capability and long-term stability. When the current density is 4 A g −1 , a specific capacitance as high as 437.6 F g −1 is achieved by NiPW 12 NP/FrGO . With NiPW 12 NP/FrGO serving as cathode and MnO 2 acting as anode, a high performance asymmetric supercapacitor (ASC) is assembled, which possesses a high energy density of 12.96 W h·kg −1 at 0.67 kW kg −1 . It also shows a good rate capability, when the current density increases from 4 to 12 A g −1 , its specific capacitances decreases from 115.2 to 90.9 F g −1 , with 78.9% capacitance retention. After 5000 cycles charge-discharge experiments, 94.3% of its capacitance can be maintained, which exhibits good stability. Furthermore, NiPW 12 NP/FrGO composite material also shows excellent tetracycline adsorption ability with capacity 288.28 mg g −1 , the adsorption can be well described with Temkin model, which suggests electrostatic attraction dominates the adsorption process.