Study Of Electro-catalyst With High Selectivity For Power Source

The structure of traditional fuel cells is complex. It is composed of two gas chambers, and high qutality sealing and unti-crossover membrane are required. Single-chamber fuel cells without unti-crossover membrane can simply shows much simple structure compared with traditional fuel cell, and thus reduced the seal costs. Explosion problem will be avoided and higher efficiency will be realized if liquid electrolyte/fuels is used. Because of the apparent advantages, the research in single-chamber fuel cell has transferred to liquid as electrolyte and fuel in recent years. The principle of the single-chamber fuel cells indicated that selectivity of the electro-catalysts has key influence on the performance of sigle-chamber fuel cells. The research and development of the catalyst with high selectivity had received widely concern. With high-selective electro-catalyst, electricity can be produced with midiium redox state because only reduction or oxidation catalytic reaction can occur on one electrode. This paper studied the feasibility of rare earth metal oxides (La2O3, etal), elemental metals(Ag, etal) and Pt-Pd/C and Pt-Ni/C composite as selective catalyst using H2O2both as fuel can oxidant.The property is characterized by d by XRD, SEM and electrochemical performance,respectively. And the above mentioned catalysts were also be tested in VOSO4system to verify the selective catalytic performance. The experimental results are as follows:(1) Rare earth metal oxides and tungsten carbide (WC) does not show selective catalytic activity in H2O2system. Platinum (Pt), palladium (Pd), silver (Ag) and nickel (Ni) appear different degrees of selectivity. From the point of the reversibility, as the catalytic electrode of the single "fuel" single-chamber battery, Pt is better than Pd, Ag and Ni. And from the point of battery performance, Pd-Pt>Ni-Ag>Pt-Ag. The highest open voltage of these batteries has reached0.098V. Catalysts mixed by the above unary catalysts using ball milling has little contribution to the selectivity of the catalyst, because the oxidation and reduction reactions between various components may offset each other or due to one kind of the activity of the catalysts. (2) The Pt-Pd/C catalyst and Pt-Ni/C catalyst with even distribution and particle size of several nanometers were successfully obtained by codeposition in liquid phase. Pt-Pd/C catalyst and Pt-Ni/C catalyst have high selectivity. The power density of the cell catalyzed by the as-synthesised catalyst shows a power density of3-4orders of magnitude higher than platinum-metal catalysts.(3) VOSO4can be oxidized or reduced by Ag, Ni, Pd, Pt, Pt-Ni/C and Pt-Pd/C. But the catalytic reaction in VOSO4system is reversible. Therefore, Ag, Ni, Pd, Pt, Pt-Ni/C and Pt-Pd/C can not used as the catalytic electrodes in the non-membrane cell using VOSO4as its electrolyte.It proved that H2O2is a good choice as the electrolyte of a single-chamber fuel cell, it also paved the road for the future research in single-chamber fuel cells.