Oxygen-vacancy-rich Ce-doped MnO2/MWCNTs supported Pt catalyst for efficient photoelectrocatalytic methanol oxidation

Ce-doped MnO 2 with oxygen vacancies modulates Pt electronic structure. • Pt/Ce-MnO 2 /MWCNTs shows 9.69 A mg Pt -1 for methanol oxidation under light. • Electron-rich Pt surface shows weakened CO adsorption at 0.94 V vs. RHE. • Synergy of defect engineering and photocatalysis boosts MOR durability. The development of efficient and CO-tolerant anode catalysts is critical for advancing direct methanol fuel cells (DMFCs). Herein, we report a rationally designed photoelectrocatalyst comprising ultrafine Pt nanoparticles anchored on Ce-doped MnO 2 supported by highly conductive multi-walled carbon nanotubes (Pt/Ce-MnO 2 /MWCNTs). Ce incorporation induces abundant oxygen vacancies within the amorphous MnO 2 matrix, which modulate the local electronic structure and facilitate strong metal-support interactions. This results in electron-enriched Pt surfaces with weakened CO adsorption, as evidenced by negative shifts in Pt 4f binding energies and improved CO stripping performance. Under simulated solar illumination, the Pt/Ce-MnO 2 /MWCNTs catalyst delivers a mass activity of 9.69 A mg Pt -1 toward methanol oxidation, representing a 46.6% enhancement over that under dark conditions and exceeding undoped Pt/MnO 2 /MWCNTs and commercial Pt/C catalysts. This performance is attributed to the synergistic interplay of (i) oxygen-vacancy-mediated electronic modulation, (ii) efficient charge transport via the MWCNT network, and (iii) photoexcited charge carriers from Ce-MnO 2 that actively participate in oxidizing poisoning intermediates. The catalyst also exhibits CO tolerance with an onset potential of 0.94 V and good long-term durability, retaining 82.3% of its initial activity after 500 cycles. This work demonstrates strategies for designing high-performance DMFC anodes through defect engineering and light harvesting. Download: Download high-res image (150KB) Download: Download full-size image