Crystal-phase-controlled PtSn intermetallic nanowires for efficient methanol oxidation

Abstract

Developing highly efficient Pt-based methanol oxidation reaction (MOR) catalysts is pivotal for direct methanol fuel cells. Phase engineering of nanomaterials offers a promising strategy to improve their catalytic performance, yet achieving phase modulation in one-dimensional nanowires (NWs) remains a great challenge. Herein, we report a facile and one-pot synthesis approach for the crystal-phase-controlled Pt-Sn intermetallic nanowires (NWs), realizing the crystal-phases regulation of face-centered cubic Pt₃Sn intermetallic NWs (FCC-Pt₃Sn INTNWs) and hexagonal close-packed PtSn intermetallic NWs (HCP-PtSn INTNWs) by adjusting the amounts of Sn precursors. Notably, the FCC-Pt₃Sn INTNWs exhibit high mass and specific activities of 6.4 A mg_Pt^-1 and 11.8 mA cm^-2, respectively, surpassing its counterparts, the HCP-PtSn INTNWs and commercial Pt/C catalysts. After a 10,000 s durability test, the FCC-Pt₃Sn INTNWs still maintain a mass activity of 5.6 A mg_Pt^-1, which is 24.3 times higher than that of commercial Pt/C catalyst. This dramatic enhancement of MOR performance is primarily attributed to the phasecontrolled structure and accelerated removal of CO intermediates (CO*). Theoretical calculations and CO stripping experiments demonstrate that the FCC-Pt₃Sn INTNWs lower the energy barrier for converting CO* into COOH* by reducing CO* binding and enhancing OH adsorption, thus significantly improving the MOR activity, CO tolerance, and stability.