Shivaji University

About: Shivaji University is a education organization based out in Kolhāpur, Maharashtra, India. It is known for research contribution in the topics: Thin film & Scanning electron microscope. The organization has 3078 authors who have published 5295 publications receiving 115397 citations.

Multifunctional zinc oxide thin films for high-performance UV photodetectors and nitrogen dioxide gas sensors

Abstract: In order to find new approaches for sensor devices; ZnO based gas sensors and UV photodetectors with higher sensitivity and responsivity were fabricated. ZnO thin films were synthesized by using inexpensive successive ionic layers by an adsorption and reaction method (SILAR) on the amorphous glass substrate. The fabricated metal���semiconductor–metal (MSM) UV photoconductive detector shows excellent photoresponse with fast response and recovery times (18 s and 24 s) under UV illumination (wavelength −365 nm and power density −1.8 μW cm−2) at 5 V bias voltage. The detector shows an ohmic nature between metal semiconductor contacts with spectral responsivity 185 A W−1. Gas sensing performance for detecting NO2 gas was studied at a relatively low operating temperature of 175 °C and 20.52 response was observed for the optimized film for a 60 ppm gas concentration. The sensor has good repeatability along with a quick response time, whereas it has a relatively high recovery time. The sensor is highly selective towards NO2 gas as compared to other gases, and has a lower detection limit of 10 ppm at an operating temperature of 175 °C. The present study opens up possibilities for the extensive study of ZnO thin film based sensor devices using a simple chemical deposition method (SILAR).

Dilute acid pretreatment of rice straw, structural characterization and optimization of enzymatic hydrolysis conditions by response surface methodology

Abstract: Efficient conversion of fermentable sugars from cheap lignocellulosic biomass is a current need in viable ethanol production technology. In the present study, agricultural waste biomass such as rice straw was pretreated by using 0.5% sulfuric acid for 60 min at 121 °C in an autoclave. A statistical experimental design like central composite design (CCD) was used for optimization of the enzymatic hydrolysis conditions to achieve a significant reducing sugar yield using commercial cellulase. The optimal conditions for acid pretreated rice straw were found to be 40 FPU g−1 enzymes loading, 17.50% biomass loading at 50 °C for 72 h. The reducing sugar yield was 0.359 g g−1, achieved at the optimized conditions. Experimental results under optimum conditions fit well with CCD model predictions. The structural and morphological changes in native and dilute acid treated rice straw substrate were evaluated by FTIR, XRD and SEM analysis. The XRD pattern of biomass revealed an increase in the crystallite size and crystallinity index of pretreated biomass. Scanning electron micrography reported surface porosity and a distorted structure due to pretreatment. HPTLC analysis of sugars like glucose and xylose in hydrolysate produced after enzymatic hydrolysis was determined.

LPG sensing properties of Pd-sensitized vertically aligned ZnO nanorods

Abstract: One-dimensional (1-D) vertically aligned ZnO nanorods are synthesized on glass substrate through a simple chemical route and their liquefied petroleum gas (LPG) sensing properties are studied. The morphology and structure of vertically aligned ZnO nanorods has been characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The LPG sensing properties of the vertically aligned ZnO nanorods are improved significantly after palladium (Pd) sensitization. The unsensitized vertically aligned ZnO nanorods exhibited the maximum response of 37% at 573 K upon exposure to 2600 ppm LPG, which improved to 60% at operating temperature of 498 K after the Pd sensitization. The Pd-sensitized vertically aligned ZnO nanorods showed more selectivity towards LPG as compared to CO2. Our results demonstrate that the chemically grown vertically aligned ZnO nanorods along with Pd sensitization are promising material for the fabrication of cost effective and high performance gas sensors.