Microwave-assisted the facile synthesis and photocatalytic properties of rhombic ZnO microstructures

ZnO rhombic microstructures were fabricated via microwave assisted approach using ZnCl2 and NaOH as raw materials by simply adjusting the ratios of [Zn2+]/[OH−] as 1:8 (pH of reaction mixture at 13.9). Controlling [Zn2+]/[OH−] as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, and 1:7 respectively (changing the pH of the precursor solution), ZnO microstructures with different morphologies were also synthesized. The characterization results revealed that as-obtained ZnO nanocrystals are of wurtzite structure and of the average grain sizes between 17 and 34 nm. In terms of BET surface areas, the photocatalytic activity of five typical ZnO samples was evaluated by degradations of methyl orange, and rhombic ZnO exhibited the better photocatalytic property, which could be attributed to its larger surface area, high crystallinity, and small particle size. Rhombic ZnO also showed good performance in photocatalytic eliminating Rhodamine-B. The synthesis and application of rhombic ZnO may contribute to development of photocatalyst for environmental issues.