Preparation Of High Quality Carbon-supported Noble Metal Nanocrystals By Diethylene Glycol Method And Its Electrocatalytic Properties

Fuel cells have been one of the research hotspots in new energy sources due to thier high power efficiency, low pollution, abundant sources, and so on. However, the low catalytic activity and high cost of the electrocatalysts seriously hinder the commercial application of fuel cells. Therefore, it is important to improve the catalytic cactivity and efficiency, and decrease the loading mass of noble metal in fuel cells. To achieve this aim, it is desirable that noble metal nanoparticles (NPs) with small size are dispersed uniformly on the supports with good electronic conductivity and high specific surface area.In this dissertation, noble metal NPs with small particle size have been dispersed uniformly on the carbon supports (carbon black, carbon nanotubes (CNTs) and graphene) using diethylene glycol as the solvent and reductant. Moreover, as-prepared noble metal NPs/carbon catalysts show high electrocatalytic activity for methanol oxidation reaction.The main points are as follows:(1) Pd/C-DEG catalyst with high dispersion and small particle size was obtained using diethylene glycol (DEG) reduction method without surfactants. DEG efficiently acted as a solvent and reducing agent. Meanwhile, Pd/C-EG catalyst using ethylene glycol (EG) as reduction was also prepared. The as-prepared Pd/C DEG catalyst exhibited larger electrochemical active surface area and better electrocatalytic performance for the methanol oxidation reaction in an alkaline media. The high catalytic activity originated from the high dispersion and small particle size of the Pd NPs. Therefore, such Pd/C-DEG electrocatalyst has potential applications in alkaline direct methanol fuel cells.(2) The Pt NPs supported on carbon nanotubes (Pt/CNTs-DEG) catalyst was prepared by diethylene glycol reduction method. The prepared Pt/CNTs-DEG catalyst has a samll particle size and the narrow particle-size distribution. The Pt particle size is in the range of 2.8 to 3.5 nm. For comparison, Pt/CNTs-EG catalyst was prepared by EG reduction method at the same time. For the methanol oxidation reaction, the Pt/CNTs-DEG catalyst displayed improved electrocatalytic activity compared to Pt/CNTs-EG catalyst due to samller particle diameter and better dispersion(3) The reduced graphene oxide supported PtPd NPs catalyst (PtPd/rGO) was obtained using DEG reduction method. Electrochemical tests results showed that bimetallic PtPd/rGO catalysts had superior catalytic activity for the methanol oxidation reaction compared to the monometallic Pt/rGO or Pd/rGO catalysts. Moreover, the Pt1Pd3/rGO catalyst displayed the best catalystic activity for the the methanol oxidation reaction.