Effect of N-Doped Carbon on the Morphology and Oxygen Reduction Reaction (ORR) Activity of a Xerogel-Derived Mn(II)O Electrocatalyst

• Published in: Catalysts 2024-11, Vol.14 (11), p.792
• Main Authors: Peera, Shaik Gouse, Koutavarapu, Ravindranadh, Prasada Reddy, P. Siva, Koyyada, Ganesh, Alodhayb, Abdullah N., Pandiaraj, Saravanan, Kim, Seung Won, Tamtam, Mohan Rao
• Format: Article
• Language: English
• Subjects: Alternative energy; Biochemical fuel cells; Biomass; Carbon; Carbon content; Catalysts; Chemical reduction; Coffee; Electrocatalysts; Electrochemistry; Electrolytes; Electrolytic cells; Energy conversion; Fuel cells; Greenhouse gases; Heat treatment; Hydrogen; Investigations; Landfill; Manganese oxides; Metal air batteries; Metals; Morphology; Nanomaterials; Nanoparticles; Nitrogen; Oxidation; Oxygen reduction reactions; Physiochemistry; Reaction kinetics; Sol-gel processes; Surface area; Surface stability; X ray photoelectron spectroscopy; Xerogels
• ISSN: 2073-4344; 2073-4344
• DOI: 10.3390/catal14110792

This work synthesizes a xerogel from a sol–gel synthesis strategy and supports it on N-doped carbon support from spent coffee biomass (Mn(II)O/N-CC, hereafter MnO) as an efficient oxygen reduction reaction (ORR) catalyst in alkaline electrolytes. The effects of N-CC carbon content on MnO nanoparticle size, dispersion, distribution, morphology, and electrochemistry on ORR are discussed. The SEM and TEM measurements show that increasing the N-CC content during the MnO gelation reaction improved MnO dispersion and particle size during thermal treatment, increasing the ORR’s electrochemical active surface area. Several physiochemical and electrochemical characterizations show a clear relationship between N-CC catalysts and ORR activities. The best catalyst, MnO/N-CC-5, had an even distribution of 27 nm MnO nanoparticles on the N-CC support. The MnO/N-CC-5 catalyst had almost identical ORR kinetics and stability to those of the state-of-the-art Pt/C catalyst in 0.1 M KOH electrolytes, losing only 10 mV in half-wave potential after 5000 potential cycles and retaining 96% of current for over 10 h of continuous chronoamperometric stability. By measuring the electrochemical active surface areas of various catalysts by cyclic voltammetry at different scan rates and measuring the double layer capacitance (Cdl) and ECSA, MnO/N-CC-5 catalysts were shown to have enhanced ORR activity. The XPS analysis explains the ORR activity in terms of the Mn3+/Mn4+ ratio, and a mechanism was proposed. These findings suggest that the MnO/N-CC-5 catalyst could be a cathode catalyst in fuel cells, biofuel cells, metal–air batteries, and other energy conversion devices.