Electrodeposition Of Pt And Pt-Based Alloys From Ionic Liquid

Pt-based catalysts play a cruial role in the application of fuel cells,and are the most widely used ones for their outstanding stability. In order to develop a new method for the fabrication of fuel cell catalyst, this paper prepared Pt,PtCu and PtCuCe catalyst in a electrodeposition way in ionic liquids.and carried out a simple performance test.Firstly, seven different kinds of ionic liquids were screened by the metal salt solubility, and the properties of ionic liquids. [BMIM][TfO] and [DEME][BF₄] system were as-chosen as the eletrolyte for the electrodeposition of Pt-based alloys.Cyclic voltammetry studies have revealed the two-step reduction of H2 Pt Cl6 in the ionic liquid, which showed the Pt（Ⅳ）firstly reduced to Pt（Ⅱ） and then further reduced to Pt. [BMIM][TfO] was uesed to deposit Pt onto conductive glass substrate, and the effects of deposition potential and time on layer morphology and catalytic properties were studied. Results showed that more uniform particle size and thus relatively good catalytic performance were obtained when deposition was carried out under potential-2.0V for 30 min. In [DEME] [BF₄] system, through process optimization, Pt particles size of only 2.38 nm were achieved under-2.5V（vs Pt） for 480 s. In 0.5M sulfuric acid solution, cyclic voltammetry showed the Pt（100） and（110） catalytic peak. Diffusion coefficients were calculated from cyclic voltammetry studies under different scan rates, and results showed that the control process is the irreversible reduction of Pt（Ⅱ） to Pt.The deposition process of PtCu In [BMIM] [TfO] was studied. CuCl₂ was added to make it easier to deposit platinum. On a conductive glass substrate, with the deposition potential shifted negatively, alloy morphology transformed from particle to granular layer. When deposited for 3min 5min, better morphology and catalytic properties were obtained. PtCu alloy was derived when deposited under-1.5V, and after the dissolution of Cu in the deposited layer, a grid-like structure of Pt was obtained. When the deposition was carried out on carbon paper substrate, particles of PtCu alloy were derived. Particles with diameter of about 10 nm can be obtained under-1.5V for 120 s, and XPS revealed a Pt:Cu ratio of 5:2. With the addition of Ce Cl3, more peaks in cyclic voltammetry appeared. Then the effects of different time, different deposition potential and temperature on morphology of deposition layer were studied. Results showed potential had a minor effect on the morphology, and as deposition time increases, the deposition layer transferred from petal-like structure to film structure. and EDS revealed a Pt:Cu Ce ratio of 13.57:76.43:10.