A green chemical approach for preparation of PtxCuy nanoparticles with a concave surface in molten salt for methanol and formic acid oxidation reactions

Molten salts are a kind of inorganic ionic liquid, which have advantages of a wide liquid range, negligible vapor pressure, good solubility characteristics, non-flammability, excellent thermal and chemical stability, and more importantly, they are low-cost and recyclable. These advantages have aroused an appealing green chemical approach to synthesize nanoparticles (NPs) with controlled morphologies. In the current research, we synthesized PtxCuy (x/y = 23/77, 51/49, 74/26, 83/17) nanoparticles with a concave and clean surface in the KNO3-LiNO3 molten salt system, in air, without using any organic solvent or capping agent. The as-prepared PtxCuy NPs were characterized by X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). The results indicated that the as-obtained PtxCuy alloy had a face-centered-cubic (fcc) polycrystal structure in which the lattice parameter and composition relationship followed Vegard's law in the Cu-poor regions. The results of CV on methanol and formic acid electrooxidation indicated that Pt74Cu26/C exhibited a remarkable enhancement in catalytic activities compared with the commercially used Pt/C catalyst.