Nanasaheb M. Shinde

Natural Carbonized Sugar as a Low-Temperature Ammonia Sensor Material: Experimental, Theoretical, and Computational Studies

Carbonized sugar (CS) has been synthesized via microwave-assisted carbonization of market-quality tabletop sugar bearing in mind the advantages of this synthesis method, such as being useful, cost-effective, and eco-friendly. The as-prepared CS has been characterized for its morphology, phase purity, type of porosity, pore-size distribution, and so on. The gas-sensing properties of CS for various oxidizing and reducing gases are demonstrated at ambient temperature, where we observe good selectivity toward liquid ammonia among other gases. The highest ammonia response (50%) of a CS-based sensor was noted at 80 °C for 100 ppm concentration. The response and recovery times of the CS sensor are 180 and 216 s, respectively. This unveiling ammonia-sensing study is explored through a plausible theoretical mechanism, which is further well-supported by computational modeling performed using density function theory. The effect of relative humidity on the CS sensor has also been studied at ambient temperature, which demonstrated that the minimum and maximum (20-100%) relative humidity values revealed 16 and 62% response, respectively.

Polycrystalline and Mesoporous 3-D Bi2O3 Nanostructured Negatrodes for High-Energy and Power-Asymmetric Supercapacitors: Superfast Room-Temperature Direct Wet Chemical Growth

Superfast (≤10 min) room-temperature (300 K) chemical synthesis of three-dimensional (3-D) polycrystalline and mesoporous bismuth(III) oxide (Bi2O3) nanostructured negatrode (as an abbreviation of negative electrode) materials, viz., coconut shell, marigold, honey nest cross section and rose with different surface areas, charge transfer resistances, and electrochemical performances essential for energy storage, harvesting, and even catalysis devices, are directly grown onto Ni foam without and with poly(ethylene glycol), ethylene glycol, and ammonium fluoride surfactants, respectively. Smaller diffusion lengths, caused by the involvement of irregular crevices, allow electrolyte ions to infiltrate deeply, increasing the utility of inner active sites for the following electrochemical performance. A marigold 3-D Bi2O3 electrode of 58 m2·g-1 surface area has demonstrated a specific capacitance of 447 F·g-1 at 2 A·g-1 and chemical stability of 85% even after 5000 redox cycles at 10 A·g-1 in a 6 M KOH electrolyte solution, which were higher than those of other morphology negatrode materials. An asymmetric supercapacitor (AS) device assembled with marigold Bi2O3 negatrode and manganese(II) carbonate quantum dots/nickel hydrogen-manganese(II)-carbonate (MnCO3QDs/NiH-Mn-CO3) positrode corroborates as high as 51 Wh·kg-1 energy at 1500 W·kg-1 power and nearly 81% cycling stability even after 5000 cycles. The obtained results were comparable or superior to the values reported previously for other Bi2O3 morphologies. This AS assembly glowed a red-light-emitting diode for 20 min, demonstrating the scientific and industrial credentials of the developed superfast Bi2O3 nanostructured negatrodes in assembling various energy storage devices.

Room-temperature successive ion transfer chemical synthesis and the efficient acetone gas sensor and electrochemical energy storage applications of Bi2O3 nanostructures

The acetone gas sensor and electrochemical supercapacitor applications of bismuth oxide (Bi2O3) nanostructures, synthesised using a facile and cost-effective quaternary-beaker mediated successive ion transfer wet chemical method and deposited onto soda-lime-glass (SLG) and Ni-foam substrates, respectively, are explored. The as-deposited Bi2O3 nanostructures on these substrates exhibit polycrystalline nature and a slight change in their surface appearance (i.e. upright-standing nanoplates on SLG and a curvy nanosheet structure on Ni-foam), suggesting the importance of the deposition substrate in developing Bi2O3 morphologies. The Bi2O3 nanoplate gas sensor on the SGL demonstrated a room temperature sensitivity of 41%@100 ppm for acetone gas, whereas the nanosheet structure of Bi2O3 on the Ni-foam elucidated a specific capacitance of 402 F g−1 at 2 mA cm−2, long-term cyclability, and rate capability with moderate chemical and environmental stability in a 6 M KOH electrolyte solution. The Bi2O3//graphite pencil-type asymmetric supercapacitor device revealed a specific capacitance as high as 43 F g−1, and an energy density of 13 W h kg−1 at 793 W kg−1 power density, turning a light emitting diode ON, with considerable full-brightness light intensity, during the process of discharging.