N/S Codoped Porous Carbon Spheres by Extended Stöber Method for Highly Efficient Oxygen Reduction Reaction and Loaded with Pt for Methanol Oxidation Reaction

The development of efficient and stable electrocatalysts for direct methanol fuel cells (DMFCs) remains a challenge. Herein, nitrogen, sulfur codoped porous carbon spheres (N/S–Cs) were prepared by the extended Stöber method employing hexamethylenetetramine (HMTA) as both the nitrogen source and cross-linking agent and 4,4′-sulfonyldiphenol as the sulfur source. The results showed that N/S–Cs-800 has a large specific surface area (1098 m2 g–1) and plentiful nitrogen contents (6.96 wt %). Electrochemical tests demonstrated that N/S–Cs-800 exhibited excellent catalytic activity for oxygen reduction (Eonset = 0.995 V, E1/2 = 0.863 V) in alkaline media. Its long-term durability and high tolerance to methanol surpass that of the Pt/C catalyst. Furthermore, the ethylene glycol reduction method was used to load Pt nanoparticles on N/S–Cs-800 support for methanol oxidation. The mass activity was about 858.54 mA mgPt−1, and it showed good long-term stability and anti-CO poisoning ability. This work provides a feasible pathway to design high efficiency metal-free catalysts for DMFCs.