电化学法制备晶面优势取向的微量铂电极

研究了用电化学方法在导电玻璃上沉积具有晶面优势取向的微量铂的方法。结果表明，用快速循环伏安法可以导电玻璃上电沉积得到亚微米级的、均匀分散的、具有晶面优势取向的铂微料。在快速扫描时，初期产生的铂微晶中，（100）面和（111）面的微晶产生的机会大致相等。由于（111）面的微晶的阳极溶解速度高于（100）面的，所以在反复多次循环扫描的沉积-溶解过程中（111）面的微晶微目减少，（100）面的微晶趋于优势取向。在较正的扫描下限和较短的扫描时间时得到的是二维微晶。对I3^-/I^-电化学反应来说，二维晶体和（100）面的电催化活性分别高于三维晶体和（111）面的。因此，可以控制循环伏安扫描的参数，在导电玻璃上得到高比表面的、二维的、具有晶面优势取向的微量铂沉积，制备高活性的新型光化学电池对电极。

ELECTRODEPOSITION OF PLATINUM WITH PREFERENTIAL CRYSTALLOGRAPHIC ORIENTATION ON CONDUCTING GLASS SHEET

Platinum was electrochemically deposited on surface of a conducting glass sheet to form a well adherent and high-active electrode for the new type photoelectrochemical cell. The very low loading platinum crystallites,which are in sub-micrometer scale, are facetted with preferential crystallographic orientation. The fast cyclic voltammetry was applied. Three potential scan ranges were evaluated: 0.67 ~+0.3 (vs. Hg2SO4/Hg, and the same below), 0.85~+0.3V and 1.00~+0.3V. In all of the three scan ranges the face (100) of crystallites become the preferential crystallographic orientation after long time cyclic scanning. The smaller cathodic overpotential favors the formation of a two-dimension crystallite. The overmuch negative potential limit (1.00V) makes a bad dispersion of platinum deposit on the surface of the glass sheet. Platinum deposits are concentrated on the upper part of the glass sheet. However, on the lower part of the electrode some well-shaped two-dimension platinum nano-structured crystals are formed. For the electrochemical reaction of --II/3 couple, the two-dimension platinum crystallites are more catalytically active than the three-dimension deposit; the crystal face (100) of platinum crystallites more catalytically active than the (111) face.