The synergistic effect Pt1-W dual sites as a highly active and durable catalyst for electrochemical methanol oxidation

Abstract

Downsizing precious metal catalysts such as Pt to the atomic level is considered effective and efficient in the catalysis industry. However, Pt single-atom alone cannot catalyze the MOR (methanol oxidation reaction) due to the requirement of Pt ensemble sites to activate C-O bonds. Herein, we report for the first Pt single atom dispersed on dual doped TiO2 (Pt1/ Ti0.8W0.2NxOy) as an effective and durable catalyst towards MOR. It is found that synergy between Pt1-WO3-x dual-active-sites enables the adsorption and dehydrogenation of methanol. Density functional theory (DFT) calculations reveal that W-site adsorbs methanol molecule and the synergistic cooperation between Pt1-W dual active sites in Pt1/Ti0.8W0.2NxOy contributes to the high catalytic activity, stability, and selectivity. The Pt1/ Ti0.8W0.2NxOy catalyst displays high MOR performance with a mass activity of 560 mA mg−1Pt at 0.82 V vs. RHE in an alkaline medium. This activity is 9.3 and 1.3 times higher than the corresponding Pt nanoparticle (2 wt% Pt/ Ti0.8W0.2NxOy) and 20% Pt/C catalysts, respectively. The lower Tafel slope (93 mV dec−1) and higher diffusion coefficient (1.5×10−12 cm2/s) indicate MOR is faster on Pt1/Ti0.82W0.18NxOy than the other catalysts. Furthermore, Pt1/ Ti0.8W0.2NxOy oxidizes methanol to formate with 90% selectivity, whereas 2 wt% Pt/Ti0.82W0.18NxOy to formaldehyde with 69% selectivity. Moreover, after 10 h, Pt1/ Ti0.8W0.2NxOy mass activity decayed only by 7.2%. In contrast, 2 wt% Pt/ Ti0.8W0.2NxOy and 20% Pt/C exhibited 23% and 43% of activity losses respectively.