Extrasmall Ligand-Free Pt Nanoparticles as Dual-Function Catalysts for Methanol-Assisted Water Splitting Systems

The synthesis of ultrasmall-sized nanoparticles (NPs) has attracted serious attention in the past several years because of the largely increased surface-to-volume ratio of these NPs. Ligands are necessarily used to synthesize these NPs. However, the traditional ligands employed in the colloidal synthesis process would be strongly adsorbed on the surface of the metal NPs, leading to incomplete exposure of catalytically active sites. Here, we develop an efficient solid-state method to synthesize carbon-supported extrasmall ligand-free Pt nanoparticles (Pt SNPs/C) or Pd SNPs/C on a large scale (up to gram equivalent). The strong interfacial interaction between the modified carbon support and inorganometallic precursor is believed to successfully prepare this Pt SNPs/C catalyst. In particular, the fabricated Pt SNPs/C catalyst is ligand-free, which is carefully verified by different techniques (thermogravimetric analysis, X-ray photoelectron spectroscopy, and “electrochemical surface area (ECSA)” measurement). Because of the higher ECSA, Pt SNPs/C exhibits better catalytic activities toward methanol oxidation and hydrogen evolution than commercial Pt/C. By applying the catalyst as both the anode and cathode in a methanol-assisted water splitting system, the cell displays much better efficiency to produce highly valued hydrogen compared to that of commercial Pt/C components.