The photoelectrochemistry of solution grown zinc oxide nanowire arrays

ZnO nanowire arrays were synthesized by a simple wet chemical method, and the effects of substrate, solution composition, and time on the attributes of the wire arrays were explored. Optimized wire arrays were used as photoanodes for water oxidation and in dye-sensitized solar cells with fast redox couples. The results for the wire arrays as photoanodes for water oxidation were compared to single crystals. Both ZnO electrodes exhibited poor cathodic kinetics with the aqueous solution, resulting in a non-ideal behavior of the semiconductor-liquid junction and substantial losses in the fill factor. Surprisingly, the wire arrays approached the efficiency of the single crystal, 0.18% vs 0.22% respectively. In the dye senitized solar cell, the ZnO nanowires developed a Schottky junction and allowed the use of fast redox couples. Unfortunately, the efficiencies measured were low, but results suggest the potential for substantial gains in the efficiency and versatility of the dye-sensitized solar cell.