Microwave assisted synthesis and characterization of silicon and phosphorous co-doped carbon as an electrocatalyst for oxygen reduction reaction

Abstract

Doped carbon materials have gained a lot of attention recently due to their wide array of applications. These doped carbon materials have a tremendous potential to replace expensive metal based electrocatalysts in fuel cells. A recently established microwave assisted technique, which does not make use of any inert or reducing gases, has been used to synthesize novel silicon (Si), phosphorous (P) co-doped carbon (SiPDC), as yet not reported in the literature. The method is simple, rapid and economical. Tannin, a renewable resource material is chosen as the carbon source, polyphosphoric acid is utilized as the dehydrating agent/P source and silicone oil is chosen as the Si source. Brunauer–Emmett–Teller analysis reveals the surface area of SiPDC to be 641.51 m² g⁻¹ and X-ray photoelectron spectroscopy confirms the doping of Si and P at 8.80% and 4.20% respectively. The doped carbon material is utilized for oxygen reduction reaction (ORR) in 0.1 M KOH. The mechanism of ORR is found to be a four electron reduction process based on rotating disk electrode studies. Electrochemical stability studies are performed to evaluate the effectiveness of the catalyst for practical applications.