Thermally Treated MoO ₃ Supports for Pt/C Catalysts: Enhancing the Methanol Electro‐Oxidation Efficiency

Abstract Direct methanol fuel cells (DMFCs) offer a promising clean energy solution but are limited by the high cost and performance challenges of platinum (Pt) based catalysts, including CO poisoning and sluggish methanol oxidation reaction (MOR) kinetics. This study investigates the enhancement of Pt in methanol electrocatalysts using MoO 3 supports, with a focus on the impact of calcination. MoO 3 nanorods are synthesized hydrothermally and used in two forms, as uncalcined and calcined, to support Pt (1:1 ratio). XRD, Raman, and XPS analysis confirmed the formation of α‐MoO 3 with mixed Mo⁶⁺/Mo⁵⁺ states and oxygen species, while TEM revealed well‐dispersed Pt nanoparticles averaging 4.5 nm on MoO 3 carbon matrix. Electrochemical tests show that the calcined MoO 3 ‐supported catalyst (PtM cal ) achieved an EASA of 54.02 m 2 /g, 1.4 and 1.7 times that of PtM and Pt/C. PtM cal delivered a peak current density of 17.84 mA cm − 2 for methanol oxidation, ≈ 1.6 and 4.7 times higher than PtM and Pt/C, with an onset potential of 285 mV and a Tafel slope of 135 mV dec −1 , indicating improved reaction kinetics. Overall, calcination of MoO 3 dramatically improves Pt‐MoO 3 heterojunction formation and activity, enhancing MOR performance in DMFCs, although the uncalcined PtM shows slightly better CO tolerance under reaction conditions.