Study On The Fabrication Of Polyoxometalate-Functionalized Graphene Nanocomposite And Electrocatalytic Property

Polyoxometalates ?POMs? can undergo a stepwise multielectron reversible redox process without affecting their structures, which makes them as prospective candidates for electrocatalysis. At the same time, the defects of POMs for electrocatalytic applications are also very obvious, such as the low specific surface area and easy to gather in the water, which have seriously affected their electrocatalytic activity and stability. In order to extremely improve the electrocatalytic activity of POMs, suitable matrices are required to disperse or immobilize POMs. Graphene, consisting of sp2 carbon atoms packed into a dense honeycomb, has been applied in many research fields owing to its high surface area, superior electrical conductivity, high chemical stability and mechanical properties. Due to these excellent merits of graphene, it will become a unique candidate as support material for POMs to overcome its own defects in electrocatalytic applications.In our work, the well dispersed and porous PMo¹²-rGO nanocomposite was synthesized via a chemical reduction method by the facile and economical reducing agent of thiourea. By optimizing the amount of reducing agent of thiourea, PMo¹² are reduced to heteropoly blue, and then react with GO to assemble PMo¹² clusters onto the rGO by the strong interaction between rGO and PMo¹². The method is facile, economical and suitable for common POMs, which opens a new way to fabricate a wide range of hybrid materials using different type of polyoxometalates. The as-prepared PMo¹²-rGO nanocomposite exhibit high stability and excellent electrocatalytic activity towards the reduction of nitrite and hydrogen peroxide compared to individual PMo¹² catalysts, which could be mostly attributed to the following major factors.1. The high conductivity of rGO can accelerate the electron transfer between target molecule and electrode.2. The well dispersed PMo¹² with small size is benefit to their electrocatalytic activities.3. More important, the crumpled, porous and paper-like morphology structure of PMo¹²-rGO improve the active surface area of the electrode, which mainly enhanced the catalytic current density, and then improved the electrocatalytic activities of PMo¹².