Niobium Doping in Pt/C Electrocatalysts: Synthesis and Catalytic Activity for Methanol Oxidation

Fuel cells powered by renewable sources are gaining prominence for their high energy conversion efficiency and low pollutant emissions. These electrochemical devices convert chemical energy directly into electrical energy and utilize sustainable fuels, such as hydrogen and low-molecular-weight alcohols. However, challenges related to catalyst cost, efficiency, and carbon monoxide (CO) poisoning hinder the widespread adoption of alcohol fuel cells. This study investigates the role of niobium (Nb) in the catalytic performance of platinum (Pt)-based anodes. A PtNb/C electrocatalyst in a 3:1 ratio is synthesized by sodium borohydride reduction, followed by physical and electrochemical characterizations. The Pt₃Nb₁/C catalyst exhibits a lower onset potential (0.45 V) than commercial Pt/C (0.55 V), demonstrating superior electrocatalytic activity for the methanol oxidation reaction and improved CO tolerance. Structural analysis reveals that Nb is present as oxides (Nb _x O _y ), which induce electronic interactions with Pt, facilitating CO oxidation. At the electrochemically active area (63.2 m² g^-1 Pt₃Nb₁/C vs 51.8 m² g^-1 Pt/C), the Nb-doped catalyst demonstrates higher Pt utilization efficiency and oxidation current densities. These findings highlight the potential of Nb-based materials to enhance the performance and durability of Pt catalysts in fuel cell applications, contributing to the advancement of sustainable energy technologies.