Correction: Speedy one-pot electrochemical synthesis of giant octahedrons from in situ generated pyrrolidinyl PAMAM dendrimer.

Correction for 'Speedy one-pot electrochemical synthesis of giant octahedrons from in situ generated pyrrolidinyl PAMAM dendrimer' by Anup Singhania et al., Soft Matter, 2020, 16, 9140-9146, DOI: 10.1039/D0SM00819B.

Speedy one-pot electrochemical synthesis of giant octahedrons from in situ generated pyrrolidinyl PAMAM dendrimer.

A novel electrochemical synthesis via a radical generation pathway is described here for the generation of a quaternary megamer structure from secondary dendrimers. The reaction is rapid and completes in <5 min. We have used lower/higher generation poly(amido)amine (PAMAM) dendrimers with carboxylic acid groups at the terminals. A precise electrocatalytic reaction at >3.5 V activates the carboxylic groups to undergo anodic oxidation (-e-) and produce radical carboxylate anions on the dendrimer surface. The reaction further goes through a decarboxylative elimination. Successive self-assembly creates billions of polydispersed and extremely stable ∼500 nm octahedron nanostructures, which we failed to destroy even by using a 20 kV electron beam. This is a new route for the speedy synthesis of important futuristic materials of well-defined shape. It has applications in building designer organic crystals for solar cells, organic electronics, rapid protein gelation, rapid protein crystallization, etc.

Fabrication and Characterization of Graphene Nanofibers by Electrospinning Technique and Its Electrochemical Properties.

Graphene has proved to be superior material for its exceptional physicochemical properties. However engineering graphene macroscopic structures by manipulating microscopic structures has faced a great challenge. Towards this here we report a fabrication method of graphene nanofiber by using simple electrospinning method. Fourier transform infrared and Raman spectroscopic characterizations confirmed the transformation from GO to reduced graphene for the nanofiber material. Estimated surface area of this material is as high as 526 m²g-1 with pores having size around 20 nm. Specific-capacitance of these nanofibers for current-density of 1 Ag-1 is 144.2 Fg-1, which will be useful for the advancement of devices for storing energy.

Functionalization of Silicon Nanostructures for Energy-Related Applications.

Silicon (Si) is used in various application fields such as solar cells and electric devices. Functionalization of Si nanostructures is one way to further improve the properties of these devices such as these. This Review summarizes recent results of solar cell and Li-ion battery applications using Si-related nanostructures. In solar cell applications, the light trapping effect is increased and the carrier recombination rate is decreased due to the short carrier collection path achieved by radially constructed p-n junction in Si nanowires, resulting in higher power conversion efficiency. The nonradiative energy transfer effect created by nanocrystalline Si is a novel way of improving solar cell properties. Si-related nanostructures are also anticipated as new anode materials with higher capacity in Li-ion batteries. Si-related nanocomposite materials which show densely packed microparticle structures agglomerated with small nanoparticles are described here as a promising challenge. These unique structures show higher capacity and longer cycle properties.

A simultaneous one pot synthesis of two fractal structures via swapping two fractal reaction kinetic states.

We introduce a new class of fractal reaction kinetics wherein two or more distinct fractal structures are synthesized as parts of a singular cascade reaction in a single chemical beaker. Two examples: sphere ↔ spiral & triangle ↔ square fractals, grow 10(6) orders from a single dendrimer (8 nm) to the visible scale.

Effect of Shell Growth and Doping Conditions of Core-Shell Homojunction Si Nanowire Solar Cells.

Effects of shell growth and doping conditions on the structural, optical and photovoltaic properties of core-shell homojunction Si nanowire (SiNW) arrays have been investigated. Core-shell nanowires were fabricated using a combination of metal-catalyzed electroless etching (MCEE) and thermal chemical vapor deposition (CVD) techniques. SiNWs formed by MCEE technique readily bundles with each other, disturbing the formation of radial p-n junctions surrounding them. CVD has made it possible to form uniform p-type Si shell layers on n-type SiNWs formed by MCEE technique. Results of SEM and Raman measurements reveal that electrical active B concentration can be increased with increase of shell thickness by increasing doping gas fluxes and growth time while keeping good crystallinity. Reflectivity measurements show an increase of light reflection in the visible range with increasing shell thickness. The short circuit current (I(sc)) and fill factor (FF) closely depend on the shell growth time and the dopant gas flux for the growth of shell layers. These results show doping conditions to be a key parameter for core-shell homojunction SiNW solar cells.

High Efficiency Hybrid Solar Cells Using Nanocrystalline Si Quantum Dots and Si Nanowires.

We report on an efficient hybrid Si nanocrystal quantum dot modified radial p-n junction thinner Si solar cell that utilizes the advantages of effective exciton collection by energy transfer from nanocrystal-Si (nc-Si) quantum dots to underlying radial p-n junction Si nanowire arrays with excellent carrier separation and propagation via the built-in electric fields of radial p-n junctions. Minimization of recombination, optical, and spectrum losses in this hybrid structure led to a high cell efficiency of 12.9%.

Inorganic/organic hybrid solar cells: optimal carrier transport in vertically aligned silicon nanowire arrays.

Inorganic/organic hybrid radial heterojunction solar cells that combine vertically-aligned n-type silicon nanowires (SiNWs) with poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) have great potential for replacing commercial Si solar cells. The chief advantage of such solar cells is that they exhibit higher absorbance for a given thickness than commercial Si solar cells, due to incident light-trapping within the NW arrays, thus enabling lower-cost solar cell production. We report herein on the effects of NW length, annealing and surface electrode on the device performance of SiNW/PEDOT:PSS hybrid radial heterojunction solar cells. The power conversion efficiency (PCE) of the obtained SiNW/PEDOT:PSS hybrid solar cells can be optimized by tuning the thickness of the surface electrode, and the etching conditions during NW formation and post-annealing. The PCE of 9.3% is obtained by forming efficient transport pathways for photogenerated charge carriers to electrodes. Our approach is a significant contribution to design of high-performance and low-cost inorganic/organic hybrid heterojunction solar cells.

Porous tubular rutile TiO2 nanofibers: synthesis, characterization and photocatalytic properties.

Electrospinning was employed to synthesize tubular TiO2 nanofibers. The as-spun fibers were subjected to heat treatment at 800 degrees C for 1 h in the air. By controlling the polymer concentration, pores measuring 30-60 nm were formed on the side walls of the tubular nanofibers. During annealing, the average nanofiber diameter shrank from 150 nm to 120 nm. The structural properties were characterized by XRD, Raman and FTIR spectroscopy. Further porous and tubular structures were confirmed by SEM and HRTEM. The specific surface area of porous tubular nanofibers (PTNFs) was measured using the Brunauer-Emmett-Teller (BET) method, which revealed a high surface area of 63 m2 g(-1). Photodegradation of methyl orange demonstrated that the PTNFs have higher photocatalytic activity than nonporous nanofibers. This enhanced photocatalytic activity can be attributed to the high surface area of the porous and tubular structures.

Is dye mixture more suitable rather than single dye to fabricate dye sensitized solar cell?

The steady state and time resolved spectroscopic studies reveal that two xanthene dyes Rhodamine 6G (R6G) and Rhodamine B (RB), used in the present investigations, form ground state hydrogen -bonded complexes with meso-tetrakis(4-carboxyphenyl) porphyrin (TCPP). However, it is apparent that upon photoexcitation the H-bonding complexes formed in the ground state decompose into the individual reacting components. This presumption was confirmed from the observation of the presence of only static quenching mode in the steady state fluorescence of the dyes in presence of porphyrin. The photoelectrochemical properties of the free dyes and the mixtures of each dye with porphyrin are investigated by measuring incident photon-to-current conversion efficiency (IPCE) using ZnO electrode and also with TiO2 electrode. It is seen that Rhodamine B-porphyrin mixture has attained maximum IPCE among the four samples studied at approximately 550 nm using ZnO electrode. Using TiO2 electrode, slight improvement in the value of IPCE was found for the same mixture. Therefore Rhodamine B-porphyrin mixture may act as a good sensitizer for converting solar energy to electrical energy.

Quenching of photoluminescence in ZnO QDs decorating multiwalled carbon nanotubes.

We report the controlled growth of ZnO quantum dots (QDs) on the sidewalls of multiwalled carbon nanotubes (MWCNTs) by a one-step process and study the effect on the photoluminescence (PL) properties of the ZnO QDs-MWCNT composite. The PL intensity of the composite is quenched and the lifetime is reduced compared to the only ZnO QDs. The origin of the PL quenching is discussed in terms of energy transfer, which is examined by varying the density and size of ZnO QDs by changing the molar concentration of the precursor solution for ZnO and the amount of MWCNT.

A novel and simple method to grow beaded nanochains of ZnO with superior photocatalytic activity.

We have demonstrated a novel and simple low-cost method to grow beaded nanochains of ZnO using an aqueous chemical growth method. Whatman filter paper (40) is used as the template. The filter paper is generally made up of cellulose fibers along which the growth of beaded ZnO nanoparticles (NPs) is initiated. When the filter paper is burnt at 700 degrees C temperature, the NPs appear as a beaded nanochain morphology while those synthesized without the filter paper form lumped nanostructures without any regular shape and size. A model has been proposed to explain the growth mechanism. A sharp and strong green emission has been observed for the template-grown sample in contrast to a broad and less intense hump of the without template-grown sample. The beaded nanochains shows 64% photocatalytic degradation of methyl orange (MO) under UV irradiation, which is much superior to a value of only 22% shown by the lumped sample. Not only can this low-cost simple template-based synthesis be applied to grow other nanostructures of similar morphology but is also promising for enhancing the properties in the multifunctional materials.