Shravanti Joshi

Hexagonal CuO thin sheets synthesized via a facile biphasic solvent based co-precipitation route employing oleic acid as a surfactant for multiuse as a CO₂ sensor, and a natural sunlight active nanocatalyst for dye degradation and methanol generation.

Efficient CO ₂ gas detection and visible light photocatalysis performance shown by interleaved CuO/ZnO heterostructures ascribed primarily to the high surface area, p/n nano-interfaces and catalytic role of Ag.

Tetragonal BaTiO₃ spheroids synthesized by a facile hydrothermal route using Tween 80 were observed to be polydispersed with a diameter in the range of ∼15–75 nm. Thereon, BaTiO₃ spheroids were decorated with different percentages of Ag@CuO by wet impregnation, and their affinity toward carbon dioxide (CO₂) gas when employed as sensitive layers in a microsensor was investigated. The results revealed that the metal nanocomposite-based sensor had an exceptional stability and sensitivity toward CO₂ gas (6-fold higher response), with appreciable response and recovery times (3 and CuO. Such improved gas-sensing performances even at a very low concentration (∼700 ppm) is attributable to both the chemical and electrical contributions of Ag@CuO forming intermittent nanointerfaces with BaTiO₃ spheroids, exhibiting unique structural stability. The CO₂-sensing mechanism of CuO/BaTiO₃ nanocomposite was studied by the diffuse reflectance infrared Fourier transform spectroscopy technique that established the reaction of CO₂ with BaO and CuO to form the respective carbonate species that is correlated with the change in material resistance consequently monitored as sensor response.

3D hierarchical hollow ZnO microspheres were impregnated with CuO microleaves to form p-n heterojunctions. The synthesized p-type CuO/n-type ZnO composite was characterized for its composition and morphology. X-ray diffractograms confirmed formation of phase pure ZnO along with CuO in equimole ratio by a solution precipitation technique. FE-SEM micrographs revealed 3D ZnO hollow microspheres in the size range 3-8 μm formed of interleaved sheets, 10-20 nm thick as the primary building blocks. The results indicated an improved sensor response (S) of 44% at 320oC for a CO ₂ gas concentration of 10,000 ppm for the developed CuO/ZnO mixed metal oxide based sensor. The improved sensor response observed here, when compared with commercial ZnO powder decorated with CuO microleaves was attributed to the specific role of CuO in the sensing mechanism, formation of p-CuO/n-ZnO heterojunction and nanostructured sensitive layer, thus presenting CuO/ZnO composite as a candidate material for CO ₂ gas sensing.

The improved performance of the potentiometric CO₂sensor was attributed to the high crystallinity and tailored morphologies of the sensing and reference electrode nanomaterials.

Enhanced photocatalytic performance of a coupled p-type Cu ₂ O/n-type SnO ₂ nanocomposite primarily attributed to the hierarchical architecture and heterojunction formation.