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Nano-ZnO/regenerated cellulose (NZRC) films were prepared via the formation of Zn5(OH)8Cl2·H2O/regenerated cellulose (ZHCRC) film from cellulose-ZnCl2 aqueous solution by using NaOH aqueous solution as both the regeneration agent and the reactant, and the subsequent transformation of the Zn5(OH)8Cl2·H2O into nano-ZnO at a low hydrothermal temperature of 100 °C. The morphology of nano-ZnO changed from hexagonal nanosheets to nanorods as the hydrothermal treatment extending from 0.5 to 4 h. The NZRC films exhibited excellent photocatalytic degradation efficiency for methyl orange and 1.53 × 10−5 mol methyl orange was completely degraded in 40 min by using 1 g of hexagonal catalyst. The NZRC film photocatalytic composites can be applied in the large-scale industrial treatment for degrading organic dye wastewater with good prospects.

2D ZnO nanosheets-regenerated cellulose (ZNSRC) photocatalytic composite thin films were prepared from ZnCl2 by using a two–step synthesis method at room temperature. The results show that during the formation of ZNSRC composite thin film, ZnCl2 first reacted with NaOH to form Zn5(OH)8Cl2·H2O which was then converted to ZnO. The 2D ZnO nanosheets are 350–450 nm in transverse size and 80 nm in thickness, dispersed on both the surface and inside of the ZNSRC thin films. The ZNSRC prepared by 13 h of reaction time has a characteristic of nanoporous 2D ZnO nanosheets and exhibits the best photocatalytic activity, as 1.53 × 10−5 mol methyl orange was completely degraded in 50 min by using 1 g catalyst. Thus, we can conclude that the ZNSRC photocatalytic composite thin films can be very useful for degrading organic dye wastewater.

The nano-ZnO/regenerated cellulose composite particles were prepared via a novel co-gelation and low temperature hydrothermal synthesis by using ZnCl2 aqueous solution as both solvent of cellulose and zinc source of ZnO nanoflakes. The reaction system was systematically studied and the optimal reaction conditions for growing the nano-ZnO/regenerated cellulose particles were determined to be liquid: solid ratio of 30:1, solution pH=7, and hydrothermal temperature of 120 °C. The composite particles consisted of regenerated cellulose in the center and hexagonal structured ZnO nanoflakes with thickness of 100 nm, on the surface. The nano-ZnO/regenerated cellulose composite particles were decomposed at 300 °C, and the total weight loss was 67%. This novel synthesis strategy can be very useful for preparing eco-friendly nano-ZnO/regenerated cellulose composite structure in photocatalytic industry.

ZnO tubes with diameters ranging from tens of nanometers to several microns were prepared via hydrothermal reactions using surfactants as structure-directing agents. All tubular ZnO materials are indexed to a hexagonal structure of wurtzite. The room-temperature photoluminescence spectra of ZnO tubes reveal a strong UV emission at around 387 nm and broad and a relative weak visible emission with main peak identified at 510–520 nm, depending on the size of ZnO tubes.