Silicon-silver dendritic nanostructures for the enhanced photoelectrochemical splitting of natural water

We report on the photoelectrochemical (PEC) splitting of natural water (pH 7) using silicon (Si) nanowires fitted with silver (Ag) dendrites (dendritic nanostructures) as working electrodes (photoanodes). A detailed study of the PEC water splitting process was carried out using linear sweep voltammetry, electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) measurements. The measured photocurrent density of 1.7 mA/cm² at an external voltage of ?0.6 V under white light illumination demonstrates the efficient decomposition of natural water using dendritic nanostructures as working electrodes. This decomposition is mainly attributed to a significant strengthening of the effective interface between working electrode surface/water and to a decline in the recombination of photoinduced carriers in the presence of Ag dendrites. We propose that the Schottky barrier between Si and Ag dendritic nanostructures favors enhanced photoinduced charge carrier separation. Photoinduced holes in Si are transferred to Ag dendrites (nano branches and leaves) that serve as a charge sink to effectively carry out the PEC oxidation of water. Photoinduced charge carrier separation enhancement was corroborated by the kinetics of our carrier recombination study. We obtained a reasonably long transient period of 80 s for the photoinduced carriers. EIS results show that the charge transfer resistance (150 Ω) of the dendritic nanostructure surface is low enough to promote interfacial charge transfer. This resistance generated a large carrier concentration of ～1.1 × 10²⁰ cm^?3 at the working electrode/water interface according to an M-S analysis. An applied bias-photon-to-current-conversion efficiency level of roughly 4% is reported, demonstrating the efficient PEC splitting of natural water.     

Thermal conductivity studies on magnetite nanofluids coated with short-chain and long-chain fatty acid surfactants

The effect of the length of surfactant molecules on the surface of the nanoparticles on the thermal conductivity of nanofluids is studied. Magnetite (\(\hbox {Fe}_{3}\hbox {O}_{4}\)) nanoparticles of comparable sizes are stabilized with short-chain capric acid (\(\hbox {C}_{9}\hbox {H}_{19}\hbox {COOH}\)) and long-chain stearic acid (\(\hbox {C}_{17}\hbox {H}_{35}\hbox {COOH}\)) molecules. Thermal conductivity of the two surfactant-coated magnetite nanoparticles dispersed in toluene is measured as a function of the concentration of the particles in the fluids and in the presence of a magnetic field. Studies showed that the critical concentration for thermal conductivity enhancement is lower for stearic-acid-coated fluid as compared with the capric-acid-coated fluid. Comparable enhancement in the thermal conductivity is observed at higher concentrations of the particles. Relatively larger enhancement in the thermal conductivity is observed for the capric-acid-coated fluid in a magnetic field. The difference in the enhancement in the thermal conductivity, depending on the chain length of the surfactant, is explained in terms of the inter-particle magnetic interactions and formation of clusters.     

Scalable microwave-assisted continuous flow synthesis of CuO nanoparticles and their thermal conductivity applications as nanofluids

We have demonstrated the novel and scalable synthesis of CuO nanoparticles by an integration of microwave and flow synthesis. The shape and size of CuO nanoparticles were tuned by changing the concentration of copper precursor. The production rate of CuO nanoparticles was found to be 5?g/h with 70% conversion of copper acetate into the CuO nanoparticles. The thermal conductivity of CuO nanofluid prepared in ethylene glycol showed linear enhancement with increase in the volume content of CuO nanoparticles produced in batch and flow reactors.     

Assessment of nutritional properties and phenolic characterization of freshly harvested Dendrocalamus hamiltoni shoots and processed bamboo candy

Food Science and Biotechnology - The free and bound phenolic constituents in Dendrocalamus hamiltonii shoots were evaluated and compared to processed bamboo candy. Preliminary proximate analysis...