Influence of bimetallic nanoparticles composition and synthesis temperature on the electrocatalytic activity of NiMn-incorporated carbon nanofibers toward urea oxidation

Abstract

High efficiency, cost effectivity and the availability of hydrogen are the advantages of electrolysis as a strategy for urea-containing wastewater treatment. Composition, morphology, and synthesis-temperature distinctly affect the performance of the functional electro-catalysts. NiMn-incorporated carbon nanofibers are introduced as effective electrocatalysts for urea oxidation process. Studying the influence of the metallic nanoparticles composition indicated that the nanofibers obtained from an electro-spun solution containing 10 wt% manganese acetate reveal the best performance in terms of both of onset potential and current density. Typically, the nanofibers obtained from electros-pun solutions having 0, 5, 10 and 15 wt% manganese acetate showed 540, 495, 430 and 510 mV (vs. RHE) and 56, 32, 79 and 29 mA/cm2 onset potentials and current densities, respectively at calcination temperature of 850 °C and 2 M urea solution. On the other hand, due to the impact on the crystallinity and final morphology, change in calcination temperature reflects the observable influence on the catalyst performance. At 2 M urea solution, the detected onset potentials and current densities were 590, 470, 430 and 440 mV, and 5, 22, 79 and 69 mA/cm2 for the nanofibers calcined at 550, 700, 850 and 1000 °C, respectively. Accordingly, these results indicated that the synthesis temperature must be maintained at 850 °C. Overall, the study emphasizes the importance of optimizing the bimetallic electrocatalysts composition and synthesis temperature. Moreover, it was detected that the carbon nanofibers prepared from poly(vinyl alcohol) reveal high electric conductivity compared to the commercial nanofibers obtained from the expensive polyacrylonitrile polymer.