Biomass Derived Biofluorescent Carbon Dots for Energy Applications: Current Progress and Prospects.

Biomass resources are often disposed of inefficiently and it causes environmental degradation. These wastes can be turned into bio-products using effective conversion techniques. The synthesis of high-value bio-products from biomass adheres to the principles of a sustainable circular economy in a variety of industries, including agriculture. Recently, fluorescent carbon dots (C-dots) derived from biowastes have emerged as a breakthrough in the field, showcasing outstanding fluorescence properties and biocompatibility. The C-dots exhibit unique quantum confinement properties due to their small size, contributing to their exceptional fluorescence. The significance of their fluorescent properties lies in their versatile applications, particularly in bio-imaging and energy devices. Their rapid and straight-forward production using green/chemical precursors has further accelerated their adoption in diverse applications. The use of green precursors for C-dot not only addresses the biomass disposal issue through a scientific approach, but also establishes a path for a circular economy. This approach not only minimizes biowaste, which also harnesses the potential of fluorescent C-dots to contribute to sustainable practices in agriculture. This review explores recent developments and challenges in synthesizing high-quality C-dots from agro-residues, shedding light on their crucial role in advancing technologies for a cleaner and more sustainable future.

Impact of the number of surface-attached tungsten diselenide layers on cadmium sulfide nanorods on the charge transfer and photocatalytic hydrogen evolution rate.

The selection of layered number and time-course destruction of layers may affect the charge transfer between 2D-to-1D heterostructure, making it possible to improve the efficiency of solar-to-hydrogen evolution. Herein, we demonstrate a simple, low-cost systematic protocol of 2D-WSe2 nanolayer numbers ranging from 7 to 60 aiding the ultrasonication time-course. The resultant nanolayers were assembled on the surface of 1D-CdS nanorods, which demonstrated an improved surface shuttling property. Consequently, a drastic improvement in photocatalytic solar-driven hydrogen evolution was observed (103.5 mmol h-1 g-1) with seven-layered WSe2 (few-layered WSe2) attached on CdS nanorods surface. This enhanced photocatalytic performance is attributed to the selection of layers on CdS surface that expose abundant active sites; along with suitable energy levels, this can facilitate increased charge transfer leading to feasible photocatalytic reactions. Significantly, the present study proposes an efficient and sustainable process to produce hydrogen and demonstrates the potential of numbered WSe2 nanosheets as a co-catalyst material.

Kinetic and thermodynamic study of finger millet straw pyrolysis through thermogravimetric analysis.

Pyrolysis kinetics of finger millet straw (FMS) was studied using a thermogravimetric analyzer under N2 environment. Physico-chemical characteristics of FMS were comparable with the established pyrolysis feedstocks. FMS thermally decomposed in three stages: drying, active pyrolysis, and char formation resulting in 70.37% overall weight loss. Average activation energy determined by Friedman and Starink methods was 177.80 and 172.18 kJ mol-1, respectively. Frequency factor was found to be in the range of 108 to 1029. Reaction pathway followed diffusion, nucleation, and order-based mechanisms. The pyrolysis of FMS was characterized by empirical modeling and predicted well with model adequacy of 97.55%. Thermodynamic parameters (ΔG and ΔH) revealed the non-spontaneous and endothermic nature of FMS pyrolysis. The biochar obtained at multiple heating rates were characterized for its physicochemical, functional, and morphological characteristics. The kinetic and thermodynamic analyses illustrate the feasibility of exploiting finger millet straw as a pyrolysis feedstock to derive biofuels.

Synergistic effect of nanocavities in anatase TiO2 nanobelts for photocatalytic degradation of methyl orange dye in aqueous solution.

Nanocavities are empty voids exposed on the surface of one dimensional TiO2 nanostructured material. Often, they exhibited beneficial optical and electrical properties that leads to efficient photocatalytic reactions. This study reports formation of nanocavities on anatase TiO2 nanobelts (TNB) through dehydroxylation of surface hydroxyl groups during calcination process (350-600°C). The morphological and crystal structure analysis of TNB-500, -550 and -600 displayed the nanobelts shape with high density of nano-size cavities and increase in average diameter with calcination temperature. The SAED patterns confirm the anatase TiO2 phase. The enhanced light absorption properties of biphasic anatase/TiO2-B and anatase TiO2 than H2Ti3O7 are attributed to transformation of crystal structure upon calcination process. The catalytic activity was evaluated for degradation of methyl orange dye in aqueous solution under solar light irradiation. The reaction variables such as calcination temperature, amount of catalyst and pH of the methyl orange dye solution were studied and discussed in detail. Under optimal experimental conditions TNB-550 photocatalyst displayed highest degradation performance about 8 folds higher than H2Ti3O7. The high performance is explained as due to synergistic properties of one dimensional anatase TiO2 with high density of nanocavities leading to one dimensional transfer of electrons and high absorption co-efficient in UV-A spectrum are suitable for efficient red-ox reactions.

Analysis of temporal jitter in a copper vapor laser system.

Temporal jitter in a magnetic pulse compression based copper vapor laser (CVL) system is analyzed by considering ripple present in the input dc power supply and ripple present in the magnetic core resetting power supply. It is shown that the jitter is a function of the ratio of operating voltage to the designed voltage, percentage ripple, and the total propagation delay of the magnetic pulse compression circuit. Experimental results from a CVL system operating at a repetition rate of 9 kHz are presented.

Characterization and analysis of a pulse power system based on Marx generator and Blumlein.

A pulse power system (1 MV, 50 kA, and 100 ns) based on Marx generator and Blumlein pulse forming line has been studied for characterization of a general system. Total erected Marx inductance and series resistance are calculated from modular testing of Marx generator and testing of Marx generator with Blumlein. The complete pulse power system has been tested with the termination of a liquid resistor load for finding the Blumlein characteristic impedance. Equivalent electrical circuits during the charging and discharging of the Blumlein are constructed from the characterized parameters of the system. These equivalent circuits can be used in the analysis of prepulse voltage and droop in the flat top of the main pulse in the pulse power systems based on Marx generator and Blumlein.