Bimetallic nickel/manganese phosphate-carbon nanofiber electrocatalyst for the oxidation of formaldehyde in alkaline medium

The development of earth-abundant transition metal-based catalysts, supported by a conductive carbonaceous matrix, has received great attention in the field of conversion of formaldehyde derivatives into toxic-free species. Herein, we report a comprehensive investigation of bimetallic electrocatalyst activity towards the electrooxidation of formaldehyde. The bimetallic phosphate catalyst is prepared by co-precipitation of Ni and Mn phosphate precursors using a simple reflux approach. Then the bimetallic catalyst is produced by mixing the Ni/Mn with carbon fibres (CNFs). The structural properties and crystallinity of the catalyst were investigated by using several techniques, such as scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and Brunauer Emmett−Teller theory. The system performance was studied under potentiostatic conditions. Some theoretical thermodynamic and kinetic models were applied to assess the system performance. Accordingly, key electrochemical parameters, including surface coverage ( Γ ) of active species, charge transfer rate ( k s ), diffusion coefficient of the formaldehyde ( D ), and catalytic rate constant ( k cat ) were calculated at Γ = 1.690 × 10 −4 mmol cm −2 , k s = 1.0800 s −1 , D = 1.185 × 10 −3 cm 2 s −1 and k cat = 1.08 × 10 5 cm 3 mol −1 s −1 . These findings demonstrate the intrinsic electrocatalytic activity of formaldehyde electrooxidation on nickel/manganese phosphate- CNFs in alkaline medium. The catalytic performance of bimetallic Ni/Mn phosphate-carbon nanofiber composite catalyst is better than mono metallic catalysts toward electrooxidation of formaldehyde.