Facile preparation of a methanol catalyst with ultra-high voltage efficiency and super-durability: Pt pollution introduction by composite electrodeposition

Noble metal catalysts are still the best methanol oxidation reaction (MOR) catalysts for direct methanol fuel cells nowadays, because the MOR onset potential of non-noble metal-based catalysts is much higher than that of Pt (usually greater than 1.35 V vs. RHE), so that the potential of the MOR is even higher than that of the oxygen reduction reaction and cannot form a cell. Here, we develop a high-performance non-noble-metal based (CoSn) MOR catalyst with a small amount (3.2 wt%) of Pt, which exhibits overpotential even lower than that of Pt/C (260 mV lower), unparalleled stability (retains 610 mA mg_Pt⁻¹ after chronoamperometry testing for 28 h, the best value for methanol oxidation reported to date) and high methanol oxidation activity (3680 mA mg_Pt⁻¹). We synthesize this CoSn-Pt catalyst by innovatively utilizing a Pt plate as a counter electrode (which is always avoided to prevent potential pollution of Pt in the past) to realize composite electrodeposition in a deep eutectic solvent.