(513bk) Hydrothermal Synthesis of Nico/S-Doped C3N4 As an Effective Bifunctional Catalyst for ORR and Mor in Alkaline Medium

The excessive use of fossil fuels for energy production has led to harmful environmental impact and a need for more sustainable and clean sources. Sources that are potentially sustainable include methanol, ethanol, hydrogen, ammonia, and formic acid as they can be linked back to biomass or bio-waste that use carbon dioxide during photosynthesis process. Methanol is one of the chemicals that can be fed directly into some fuel cells, such as direct methanol fuel cells (DMFC), in which methanol oxidation and oxygen reduction reactions occur at anode and cathode respectively. Platinum is often used as a catalyst for the two half-reactions, however, Pt is expensive and alternative cathode catalyst, mainly alloys or bi(multi)metals made of earth abundant elements, capable of driving oxygen reduction reaction with high activity and stability are seen as potential solutions. Herein, with the goal to synthesize new catalyst materials for MOR and ORR involving non-noble metals that could exhibit high activity and long-term stability towards the two reactions, we have synthesized four types of catalysts including Co, sulfur-doped Co, NiCo, and sulfur-doped NiCo. Hydrothermal method was used to encapsulate all the active phases by flat sheets of C₃N₄. The sulfur doped catalysts were found to be effective for both, ORR and MOR reaction. A detailed characterization of the final products was conducted, which includes transmission electron microscopy (TEM) and X-ray diffraction (XRD) along with their electrocatalytic activities and stabilities using cyclic voltammetry and chronoamperometry (CA), respectively.