A nickel ion-incorporating zinc-mesoporous metal organic framework thin film nanocomposite modified glassy carbon electrode for electrocatalytic oxidation of methanol in alkaline media

Abstract

In this work, we have successfully synthesized zinc-mesoporous metal–organic framework thin films (Zn-mMOFTFs) on the surface of a glassy carbon electrode (GCE) by self-assembly accumulation and electrochemical potentiostatic techniques. Then the electrodeposited Zn-MOFTFs were incorporated with Ni ions through the immersion of the obtained electrode in Ni(II) solution to form the final modified electrode, Ni/Zn-mMOFTFs/GCE, which was characterized utilizing the various instrumental techniques. In electrochemical studies, the obtained modified electrode, Ni/Zn-mMOFTFs/GCE, showed enhanced electrocatalytic activity toward the oxidation of methanol (CH₃OH) in alkaline media. The values of catalytic rate constant (k) and the electron transfer coefficient (α) for the electrooxidation of CH₃OH on the Ni/Zn-mMOFTFs/GCE were obtained to be 1.43 × 10⁴ cm³ mol⁻¹ s⁻¹ and 0.56, respectively. The pseudo steady-state polarization method was employed for further investigation of the electrocatalytic oxidation of CH₃OH on the Ni/Zn-mMOFTFs/GCE and the rate constant of the reaction k₂Γ = 2.866 × 10⁻⁹ cm s⁻¹ and the ratio of k⁰₋₁/k⁰₁ = 2.08 × 10⁸ were determined. These results showed that the incorporation of the Ni(II) ions in the Zn-mMOFTFs produces a significant electrocatalytic activity toward the oxidation of CH₃OH and consequently opens a new way to design a high-performance capable electrocatalyst for direct CH₃OH fuel cell systems.