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Electrochemical processing has already manifested its prominence for obtaining well structured composite materials. The method is highly precise and is reduction potential driven. This methodology has resulted in a hierarchical Au–CuO nanocomposite from a chosen redox transformation reaction between the newly synthesized spherical and roughened Cu2O nanoparticles and HAuCl4. Thus the attractive shape as well as reducing capability of Cu2O made it promising as a starting material. The proposed redox transformation reaction does not need any additional reducing or stabilizing agents. The reduction potential value of CuO/Cu2O (+0.66 V vs. SHE) supports the quantitative reduction of Au(III) ions because of its higher reduction potential (+1.69 V vs. SHE) i.e., for the AuCl4−/Au half cell. The prescribed conditions, spontaneous redox reaction and the morphology of Cu2O nanoparticles help to produce the unique Au–CuO nanoflowers. The formation of Au–CuO nanocomposites from Cu2O nanospheres is characterised by several physical techniques such as XRD, XPS and FTIR. Finally the flower like Au–CuO nanocomposite shows higher SERS activity with 4-aminothiophenol (4-ATP) as a probe molecule than what is evident from the individual components (Au or Cu2O or CuO). Additionally the derived Au–CuO nanocomposite has also been found to be an effective catalyst for the clock reaction employing methylene blue and ascorbic acid in solution.

An inexpensive, facile wet chemical approach for fabrication of ZnO nanoflowers on glass, indium tin oxide coated glass, Si substrate, transparency sheet, and cotton wool as a thin film has been demonstrated for its several useful applications. The thin film on a glass slide is capable of showing superhydrophobicity and exhibits a water contact angle of 155 ± 3°. A remarkable reversible wettability of the film is achieved by UV illumination and dark storage.

A simplistic, elegant approach has been invoked for the gram level synthesis of cubooctahedral Zn3V2O8 without the assistance of any template or growth directing agent. By heating on a water bath, ZnSO4 and ammonium vanadate produce unique cubooctahedral Zn3V2O7(OH)2(H2O)2. Then, cubooctahedral Zn3V2O8 is generated upon heating Zn3V2O7(OH)2(H2O)2 at a temperature of 500 °C in air. Interestingly, the morphology of Zn3V2O7(OH)2(H2O)2 remains unaltered even after complete dehydration by heat treatment. The unusual robust morphology of Zn3V2O8 exhibits enhanced photocatalytic dye mineralization activity, leaving behind Zn3V2O7(OH)2(H2O)2 and also NH4VO3. Cationic, nonionic and anionic dye degradation has become effective with a high turn over number (TON). The synthesized nanomaterial, being robust and highly photoactive, finds valuable application in environmental remediation under UV irradiation. In a nutshell, the present work provides some new insights for a low-cost and high-yielding greener synthetic protocol to produce a well defined photocatalytic material bearing a unique structure to benefit potential applications in wastewater treatment.