Cha Chuansin

Hydrogen production from catalytic hydrolysis of sodium borohydride solution using nickel boride catalyst

Abstract A highly stable and active nickel boride catalyst (NixB) was prepared and tested for the catalytic hydrolysis of alkaline NaBH4 solution. It was found that after heat treatment at 150°C in vacuum the NixB catalyst shows greatly enhanced catalytic activity and operational stability. In the experimental conditions, the hydrolysis reaction can produce 6.75 wt % hydrogen at 45°C and >4.0 wt % hydrogen even at room temperatures, exhibiting much higher hydrogen storage capacity than currently used alloys for hydrogen storage. Since the NixB catalyst is inexpensive and easy to prepare, it is feasible to use this catalyst in the construction of practical hydrogen generators for portable and in situ applications.

THE GENERAL CHARACTERISTICS OF MICROELECTRODES OF ANY PLANAR GEOMETRY UNDER STEADY-STATE CONDITIONS

Abstract The general characteristics of microelectrodes of any planar geometry under steady-state conditions are discussed. The exact expression for reversible i-E waves is obtained. Irreversible and quasi-reversible processes are also discussed. The approximate expressions for the steady-state voltammetric curves of irreversible electrode reactions are derived by both “uniform surface concentration” and “uniform flux” approaches.

Time-resolved electrochemical quartz crystal microbalance

Abstract A time-resolved electrochemical quartz crystal microbalance is described for the first time. In this equipment the frequency of the signal obtained equals the difference between the frequency of the working crystal resonator and the fixed frequency of a reference resonator. Taking this signal as the gate-controlling signal, a 16-bit synchronous counter counts the number of pulses from a stable high frequency time-base generator. The period of the signal with the differential frequency is measured as a function of time. After the measurement is complete, the data are transferred to the main memory of the host computer for further data processing. In this paper the mass change during the process of underpotential deposition of lead on a silver electrode is described with satisfactory accuracy and time resolution.

The preparation of a highly dispersed Pd + Ag/carbon electrocatalyst and its properties

Abstract A new method for the preparation of fairly dispersed Pd + Ag alloy catalysts on carbon is described. The method involves three steps: (1) the functionalization of the surface of activated carbon with I − preadsorption; (2) the coprecipitation of Pd 2+ and Ag + on the carbon surface; (3) the reduction of PdI 2 and AgI codeposits on the carbon surface. The majority of metal particles are in the size range 2–8 nm. The effects of different halogen ion preadsorption and different initial Pd:Ag ratios on Pd + Ag particle size distribution were studied by transmission electron microscopy. Pd + Ag particle crystal structure and its composition were studied by selected area diffraction and energy dispersive spectrometry analysis. The unique feature of this method is that the bimetallic alloys could be formed at room temperature. The results of the electrocatalytic reduction of oxygen on these catalysts showed that this new method can increase the catalytic activity of the catalysts, mainly as a result of a decrease in metal particle size.