Abstract
Electrooxidation of urea plays a substantial role in the elimination of urea-containing wastewater and industrial urea. Here, we report the electrodeposition of nickel hydroxide catalyst on commercial carbon paper (CP) electrodes from dimethyl sulphoxide solvent (Ni(OH)2-DMSO/CP) for urea electrooxidation under alkaline conditions. The physicochemical features of Ni(OH)2-DMSO/CP catalysts using scanning electron microscopy and X-ray photoelectron spectroscopy revealed that the Ni(OH)2-DMSO/CP catalyst shows nanoparticle features, with loading of <1 wt%. The cyclic voltammetry and electrochemical impedance spectroscopy revealed that the Ni(OH)2-DMSO/CP electrode has a urea oxidation onset potential of 0.33 V vs. Ag/AgCl and superior electrocatalytic performance, which is a more than 2-fold higher activity in comparison with the counterpart Ni(OH)2 catalyst prepared from the aqueous electrolyte. As expected, the enhancement in electrocatalytic activity towards urea was associated with the superficial enrichment in the electrochemically active surface area of the Ni(OH)2-DMSO/CP electrodes. The results might be a promising way to activate commercial carbon paper with efficient transition metal electrocatalysts, for urea electrooxidation uses in sustainable energy systems, and for relieving water contamination.
Highlights
The global increase in energy requirements has directed the search for alternate clean energy resources other than fossil fuels
Metal coatings obtained through an aqueous medium might have hydrogen, which is observed to cause higher internal stress and cracks in the coated films, and which undesirably upsets the mechanical features of the coatings [56]
0.33 M urea was examined by cyclic voltammetry experiments (CVs), chronoamperometric techniques (CA), and electrochemical impedance spectroscopy (EIS)
Summary
The global increase in energy requirements has directed the search for alternate clean energy resources other than fossil fuels. Despite the Ni-based electrocatalysts’ generally poor performance, UORs’ features, stabilities, and over-potential are quite high (greater than 0.9 V) [31,32,33,34,35] In this regard, Ni-based electrodes can drive the oxygen evolution reaction (OER) [36], whose influence as a competitive process further reduces the selectivity toward UORs. obtaining abundant efficient, robust, and inexpensive electrocatalysts provides a chance of overcoming these challenges by reducing the over-potential and improving the efficiency of UORs. At present, there are numerous methods applied to the synthesis of nickel-based electrodes, such as the sol-gel method [37], hydro/solvothermal method [38,39,40], microwaveassisted synthesis [41], and electrodeposition process [42,43,44]. The electrodeposition approach has been recognized as a simple, high purity, and cost-effective technique for the commercial production of electrocatalysts It represents one of the oldest surface engineering processes to make thin films, especially metals and their alloys, with various nanostructures, by controlling electrodeposition parameters [45,46,47]. DMSO/CP catalysts for UORs were examined and compared to Ni-electrodes deposited from the aqueous solution
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