Morphology-dependent highly active microcrystalline stannous oxalate photocatalysts with selectively exposed facets and low specific surface areas

To achieve high photocatalytic activity, the sizes of photocatalysts are usually reduced to nanoscales. However, nano-sized particles are difficult to be separated and recycled. In this paper, we successfully fabricate stannous oxalate microcrystals with selectively exposed facets and various morphologies (prismoids, tubes, rods and needles). The photocatalytic activities are comparative or even higher than that of commercial Degussa P25 nano titanium dioxide under both full spectrum light and ultra-violet irradiation, even though the stannous oxalate particles are in micrometer size. The exposure of {(1) over bar 01} polar facets could drive photogenerated charge separation, and thus accelerates photocatalysis. The photocatalytic activities of the optimized sample (fragmented prismoids) with specific surface areas about 1.18 m(2)/g are 2.49 and 2.67 times higher than that of the commercial Degussa P25 nano titanium dioxide (specific surface areas: 48.59 m(2)/g) under both full spectrum light and ultra-violet irradiation in methyl orange degradation, respectively. The micro/submicron-sized particles could be easily separated and recycled after waste water treatment, and catalysts can be synthesized with a large amount by a facile chemical precipitation method. Given these factors, micro/submicron sized stannous oxalate catalysts are expected to be a practical water cleaner.