Fabrication of a polyoxotungstate/metal–organic framework/phosphorus-doped reduced graphene oxide nanohybrid modified glassy carbon electrode by electrochemical reduction and its electrochemical properties

Abstract

Hybrid nanocomposites based on polyoxometalates (POMs), metal–organic frameworks (MOFs), and graphene oxide (GO) have a unique set of properties. They have specific properties such as high acidity, oxygen-rich surface, and good redox capability from POMs. In contrast, they do not have weaknesses of POMs such as a low surface area, and high solubility in aqueous media. Herein, a novel organic–inorganic nanohybrid compound based on H₃PW₁₂O₄₀ (PW₁₂), a Co-based MOF, and GO was prepared. The prepared hybrid nanocomposite (PW₁₂/MOF/GO) was characterized using different techniques. Then, a PW₁₂/MOF/GO nanocomposite modified glassy carbon electrode (GCE) was fabricated by the drop-casting method and next was dried at room temperature. Then, the PW₁₂/MOF/GO/GCE was subjected to electrochemical reduction at a constant potential of −1.5 V, in 0.1 M H₃PO₄ solution containing 0.10% w/v PW₁₂/MOF/GO additive. The morphology, electrochemical activity, and stability of the modified electrode (PW₁₂/MOF/P@ERGO/GCE) were studied with FE-SEM coupled with EDS, CV, and amperometry. The obtained results confirmed that the PW₁₂/MOF/P@ERGO/GCE could be effective in hydrogen evolution reaction (HER). The electrochemical activity of the PW₁₂/MOF/P@ERGO/GCE due to the desirable microstructure of the electrocatalyst (e.g. high active surface area and homogeneous distribution of the PW₁₂/MOF/P@ERGO), and also the synergistic effect of the blocks, is more than those of PW₁₂/GCE, MOF/GCE, PW₁₂/MOF/GCE, and P@ERGO/GCE. Moreover, the PW₁₂/MOF/P@ERGO/GCE showed an excellent long-term stability under the air atmosphere.