H-Ni/ZnO system

Fig. 5.2. Schematic representation of H-Ni/ZnO system showing hydrogen adatom a of electronic energy eaa with bond energy ft attached to Ni surface atom at m = 0. Reprinted from Davison et al (1988) with permission from...

The cocatalyst, a combination of Cr and one other metal component, was loaded onto the as-prepared GaN ZnO by a co-impregnation method. In a typical preparation, the co-impregnation was performed by suspending 0.3-0.4 g of the photocatalyst powder in an aqueous solution containing an appropriate amount of Cr (N03)3 9H20 and the nitrate or chloride of the paired metal. The solution was then evaporated to dryness over a water bath followed by calcination in air at 623 K for 1 h. In the case of Ni or Ni-Cr cocatalysts, the impregnated catalyst was reduced by exposure to H2 (20 kPa) at 573 K for 2 h and then oxidized by exposure to O2 (10 kPa) at 473 K for 1 h in a closed gas circulation system to produce an Ni/NiO (core/shell) double structure [48]. 

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