Octahedral CdS−ZnS composites were synthesized using a simple method of cation exchange and hydrothermal treatment, using Cd 3 (C 3 N 3 S 3 ) 2 (denoted as Cd 3 (TMT) 2 ) as a precursor and Zn 2+ for ion exchange. In the spontaneous ion exchange process, there is the formation of compact heterojunctions and three-dimensional octahedral structures. By controlling the ion exchange level, the composition of (Cd x Zn 1−x ) 3 (TMT) 2 hybrid nanomaterials can be regulated, and the composite can be used as a template to generate octahedral CdS−ZnS. Photocatalytic oxidation of toluene to benzaldehyde was used as a model reaction to evaluate the performance of the as-prepared samples, and the CZ-2 catalyst shows the highest photocatalytic activity, giving a benzaldehyde formation rate of 1078 μmol•g −1 •h −1 without the need of any solvent. The excellent performance is ascribed to the octahedral structure which is large in specific surface area and compact in heterojunctions. It is envisaged that the method is suitable for the generation of heterojunctions for photocatalytic purposes.

The activation of C−H bonds is an efficient approach for the production of value-added organics. The partial oxidation of hydrocarbons to oxygen-containing products at mild conditions is a profound challenge because the products are often more active than the substrates. In this context, a novel helical structure of monoclinic scheelite bismuth vanadate (BiVO 4 ) on the top of the silver (Ag) and amorphous carbon nitride (C 3 N 4 ) was prepared for the first time and used as an efficient photocatalyst for selective oxidation of low hydrocarbons at room temperature. Benefited from its unique structural features, the helical BiVO 4 /Ag/C 3 N 4 exhibits outstanding light absorption ability, efficient separation of photogenerated charge carriers, and high exposure of active sites. Using O 2 as an oxidant, the helical BiVO 4 /Ag/C 3 N 4 achieved high selectivity in the oxidation of different alkanes into the corresponding ketones or aldehydes (nearly 100% selectivity) at room temperature under visible light irradiation. This work not only discloses a facile method for the preparation of the helical composite but also provides an efficient way for the generation of value-added organics from low hydrocarbons at mild conditions.

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