Sudarsan Raj

Effect of Au nanorods on potential barrier modulation in morphologically controlled Au@Cu2O core-shell nanoreactors for gas sensor applications.

In this work, Au@Cu2O core-shell nanoparticles (NPs) were synthesized by simple solution route and applied for CO sensing applications. Au@Cu2O core-shell NPs were formed by the deposition of 30-60 nm Cu2O shell layer on Au nanorods (NRs) having 10-15 nm width and 40-60 nm length. The morphology of Au@Cu2O core-shell NPs was tuned from brick to spherical shape by tuning the pH of the solution. In the absence of Au NRs, cubelike Cu2O NPs having ∼200 nm diameters were formed. The sensor having Au@Cu2O core-shell layer exhibited higher CO sensitivity compared to bare Cu2O NPs layer. Tuning of morphology of Au@Cu2O core-shell NPs from brick to spherical shape significantly lowered the air resistance. Transition from p- to n-type response was observed for all devices below 150 °C. It was demonstrated that performance of sensor depends not only on the electronic sensitization of Au NRs but also on the morphology of the Au@Cu2O core-shell NPs.

Facile preparation of ZnO nanosheets and its photocatalytic activity in the degradation of rhodamine B dye under UV irradiation

We have successfully synthesized high crystalline quality ZnO nanosheets (NSs) structures by a hydrothermal process. The detailed characterizations have shown that the ZnO nanostructures were well crystalline, uniform and had nanosheets-like morphology with an average size of 100-150 nm. The photocatalytic performance of ZnO NSs was examined for use in the degradation of rhodamine B dye, and exhibited ∼83.7% and 96.8% dye decomposition within 100 min and 140 min, respectively, under UV irradiation. The results were attributed to the high crystalline quality of ZnO NSs that produced reactive sites over the ZnO catalyst surface to decompose the rhodamine B dye.

Electrophoretic deposition of CdSe@CdZnS–ZnS multi core–shell QDs for quantum efficiency control of InGaN/GaN MQW LEDs

CdSe@CdZnS–ZnS multi core–shell quantum dots (MCSQDs) were deposited on fluorine doped tin oxide (FTO) glass substrates as well as InGaN/GaN MQW LEDs by electrophoretic deposition (EPD). The as synthesized QDs having particle size 6 nm with emission peak at 596 nm. The number of QDs deposited on the substrate increased with prolonged deposition times and applied voltages. Lower voltage (20 V) deposition on FTO glass showed linearity in photoluminescence (PL) peak intensity. The green emitted InGaN/GaN MQW LEDs showed the dual PL emission after EPD of CdSe@CdZnS–ZnS MCSQDs. Surface roughness and PL peak intensity nearby 596 nm showed a reverse relationship in QDs deposited InGaN/GaN MQW LEDs.