Greatly Enhanced Methanol Oxidation Reaction of CoPt Truncated Octahedral Nanoparticles by External Magnetic Fields

Tunable behavior in electrocatalysis by external multifields, such as magnetic field, thermal field, and electric field, is the most promising strategy to expand the theory, design, and synthesis of state-of-the-art catalysts and the cell in the near future. Here, a systematic investigation for the effect of external magnetic field and thermal field on methanol oxidation reactions (MOR) in magnetic nanoparticles is reported. For Co₄₂Pt₅₈ truncated octahedral nanoparticles (TONPs), the catalytic performance in MOR is greatly increased to the maximum of 14.1% by applying a magnetic field up to 3000 Oe, and it shows a monotonical increase with increasing working temperature. The magnetic enhanced effect is closely related to the Co content of Co_xPt_100-x TONPs. Furthermore, the enhancement effect under a magnetic field is more obvious for Co₄₂Pt₅₈ TONPs annealed at 650 ℃. First-principle calculation points out that the magnetic fields can facilitate the dehydrogenation of both methanol and water by suppression of entropy of the electron spin and lowering of the activation barrier, where OH_ad intermediates on Co sites play a more important role. The application of magnetic fields together with thermal fields in MOR provides a new prospect to manipulate the performance of direct methanol fuel cells, which will accelerate their potential applications.