Rapid evolution of perovskite solar cells (PSCs) performance and stability has inclined the research focus towards scalable bulk fabrication through high speed and cost-effective automated methods. ...For the first time, intense pulsed light (IPL) is utilized to rapidly fabricate efficient PSCs through swift annealing of both the SnO2 electron transport layer (ETL) and mixed triple cation perovskite thin films. The addition of di-iodomethane (CH2I2) alkyl-halide could enhance the PSC efficiency by retarding the crystallization and improving the surface morphology of the perovskite photoactive film through supplying iodine cleaved by ultraviolet energy during IPL process. The maximum efficiency and fill factor of the PSCs fabricated by IPL annealing were 12.56% and 78.3% for the rigid glass-FTO slides, and 7.6% and 64.75% for flexible PET-ITO substrates when processed in the ambient with relative humidity of 60%, respectively. The annealed materials were characterized through Scanning electron microscopy (SEM), UV–Vis, photoluminescence (PL), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. In addition, impedance spectroscopy (IS) and current-voltage measurements were conducted to study the functionality of fabricated cells. Our results delineated the feasibility of sequential step IPL annealing on rapid fabrication of efficient PSCs which is directly applicable for scalable roll-to-roll manufacturing.
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•Sequential step IPL annealing, SnO2, Perovskite film, Perovskite solar cell, Rapid thermal annealing.•Di-iodomethane (CH2I2) was shown to be compatible and improve the quality of fabricated films derived from other perovskite chemistries such as mixed triple cation precursors.•Pulse count and the heat flux per pulse was shown to play a significant role on SnO2 charge extraction.
Small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) techniques were applied to study the microstructure of several New Albany shales of different maturity. It has ...been established that the total porosity decreases with maturity and increases somewhat for post-mature samples. A new method of SANS data analysis was developed, which allows the extraction of information about the size range and number density of micropores from the relatively flat scattering intensity observed in the limit of the large scattering vector Q. Macropores and significant number of mesopores are surface fractals, and their structure can be described in terms of the polydisperse spheres (PDSP) model. The model-independent Porod invariant method was employed to estimate total porosity, and the results were compared with the PDSP model results. It has been demonstrated that independent evaluation of incoherent background is crucial for accurate interpretation of the scattering data in the limit of large Q-values. Pore volumes estimated by the N2 and CO2 adsorption, as well as via the mercury intrusion technique, have been compared with those measured by SANS/USANS, and possible reasons for the observed discrepancies are discussed.
Microbial enhanced coalbed methane (ME-CBM) recovery is critically examined as a viable technology for natural gas recovery from coalbed methane (CBM) reservoirs. Since the majority of gas-in-place ...(GIP) is stored as an adsorbed phase in fine pores of coal matrix, the nano-pore structure directly influences gas storage and transport properties. Only limited studies have quantified the alteration of the nano-pore structure due to ME-CBM treatment. This study examines the evolution of the pore structure using a combination of small angle X-ray scattering (SAXS), low-pressure N
and CO
adsorption (LPGA) and high-pressure methane adsorption methods. The results show that the surface fractal dimension decreases for the two bioconverted coals compared to the untreated coal. After bio-treatment, the mesopore surface area and pore volume decrease with the average pore diameter increases, while the micropore surface area increases with pore volume decreases. Both inaccessible meso-/micropore size distributions decrease after bioconversion, while the accessible micropore size distribution increases, making a portion of closed micropore network accessible. In addition, the methane adsorption capacities increase after bio-treatment, which is confirmed by the increase of micropore surface area. A conceptual physical model of methanogenesis is proposed based on the evolution of the pore structure.
In this work, antibacterial, micro-structural, and fluorescence properties of silver (Ag) doped TiO
2
nanoparticles were studied to analyze the effect of silver for effective improvement in ...antibacterial properties of TiO
2
. Antibacterial properties of pure TiO
2
and Ag-TiO
2
was studied using
Escherichia coli
,
Pseudomonas aeruginosa
as Gram Negative and
Bacillus subtilis
,
Staphylococcus aureus
as Gram positive bacteria, as a model for Agar disc diffusion assay method. The concept of inhibition zone diameter was applied to observe the antibacterial activity of TiO
2
and Ag-TiO
2
. It was observed that the antibacterial activity of TiO
2
improves with doping of Ag. Fluorescence spectra confirm the red shift in band edge emission at excitation wavelength of 360 nm which shows effective fluorescence properties of these nanoparticles. Microstructures of these nanoparticles have studied with the help of transmission electron microscopy (TEM) and atomic force microscopy (AFM).
Carbon nanotube fiber (CNT fiber) synthesized through floating catalyst chemical vapor deposition (FC-CVD) is one of the strongest man-made fibers ever synthesized. The poor carbon conversion in the ...FC-CVD process is one of the major hurdles in its commercial deployment. In this work, we have employed a novel method of bi-directional catalyst injection where catalysts were injected from both inlet and outlet sides of the reactor. The injection of the catalyst from the outlet into the reactor reaction zone was possible by a backflow caused by the convection vortex as predicted by the computational fluid dynamics (CFD) analysis. Bi-directional catalyst injection was able to enhance the carbon conversion by 56% compared to conventional unidirectional injection. CNT fibers obtained in bi-directional catalyst injection are a mixture of multi-walled (MW) and single-walled (SW) CNTs whereas unidirectional catalyst injection resulted in MWCNTs only. The average CNT bundle diameter dimensions were similar in both unidirectional and bi-directional catalyst injection. The amorphous carbon content was lower for bi-directional catalyst injection. A mechanism for the improvement of carbon conversion in bi-direction catalyst injection has been proposed.
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A cost effective and facile sol–gel method is used to synthesize graphene oxide (GO)/Mn
3
O
4
nanocomposite (NC). The synthesized materials (GO and GO/Mn
3
O
4
nanocomposite) were analyzed using ...different characterization techniques. X-ray diffraction (XRD) analysis confirmed the presence of Mn
3
O
4
nanoparticles incorporated in the synthesized GO matrix. The stretching and bending vibrational modes corresponding to various functional groups (–OH, C–H, C–C, etc.) present in the FTIR spectra of the synthesized nanocomposite. The microstructural studies have been carried out through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that revealed the layered morphology of GO and uniform size distribution of Mn
3
O
4
nanoparticles over the GO layers. UV–visible measurement indicates a red shift in the GO/Mn
3
O
4
nanocomposite absorption edge as compared to the GO and associated band gap reduced from 4.46 eV (GO) to 2.95 eV (GO/Mn
3
O
4
) attributed to the
π
–
π
non-covalent electrostatic interactions. The electrochemical study revealed a high specific capacitance of GO/Mn
3
O
4
nanocomposite as compared to GO sheets, making it suitable candidate for supercapacitors.
Anatase TiO
2
hierarchical nanostructures with higher photocatalytic activity are of special importance in various applications. We have reported the synthesis of TiO
2
as water chestnut plants like ...morphology via facile hydrothermal method, by using Titanium (IV) butoxide (TBOT) as a precursor solution. It is found that TiO
2
nanoparticles work as seed and completely convert into water chestnut plants like structure or morphology, which are composed of crystallized anatase nanocrystals. X-ray diffraction spectra confirmed the presence of anatase phase of crystallized TiO
2
plants (TPs). The average life time delay for generated charge carriers in TPs was calculated to be around 2.45 ns, which reflects slow recombination of charge carriers. The prepared TPs show excellent photocatalytic performance when applied in photo degradation of Rhodamine B organic dye. The unique features exhibited by TPs make them a promising candidate for vast potential applications in field such as solar cells, photocatalysis, supercapacitor, lithium ion batteries and some related fields.
We report results of vibrational neutron spectroscopy investigation aimed to identify the state of hydrogen adsorbed in ultramicroporous carbon. The mobility of hydrogen confined in carbon pores was ...probed as a function of temperature and pressure using inelastic neutron scattering, and the molecular translational and rotational motions were studied. At low loading rotation of H2 molecules adsorbed in the smallest carbon pores (∼4–5 Å) is severely hindered, suggesting that the interaction between H2 and the host matrix is anisotropic. At higher loading, H2 molecules behave as a nearly free rotor, implying lower anisotropic interactions with adsorption sites. At 77 K where bulk H2 is a gas, deconvolution of elastic/quasielastic signal provide evidence of pressure-dependent fractions of immobile (solid-like) and partially mobile (liquid-like) hydrogen, which correlate with the excess adsorption isotherm at 77 K. Effective H2 density in pores changes from solid-like to liquid-like with increasing pressure at 77 K. Surprisingly, immobile and partially mobile H2 is present even at temperatures as high as ∼110 K where bulk hydrogen exists only in gas form.
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Anisotropic silver nanostructures having complex morphologies are of immense importance due to its application in plasmon-enhanced photocatalysis, transparent conducting electrodes, and ...surface-enhanced Raman spectroscopy (SERS). We report the generation of silver nanowires, nanobelts, and nanostructures having dendritic fibrous morphologies by galvanic replacement reaction on copper thin-film coated dendritic fibrous nanosilica (DFNS). DC magnetron sputtering was used to deposit copper thin- film on DFNS. Electron microscopy revealed that galvanically grown silver nanostructures followed the wrinkled fibrous morphology of DFNS. In addition to dendritic fibrous nanosilver (DFNAg), silver nanobelts, nanowires with high aspect ratio also grew over large areas when the silver precursor concentration and the copper film thickness were varied. The SERS performance of DFNAg substrates was evaluated using a self-assembled monolayer of
p
-aminothiophenol (
p
-ATP). The SERS and plasmon-enhanced photocatalytic performance of DFNAg were compared with a standard SERS substrate, Ag film on nanosphere (AgFON). The ensemble-averaged Raman enhancement factor for DFNAg was found to be of the order of 10
5
, on par with AgFON. Variation in Raman peak intensities revealed that plasmon-assisted photodimerization of
p-
ATP to
p,p′
-dimercaptoazobisbenzene was higher on DFNAg than AgFON which could be attributed to a high number of hot spots on DFNAg caused by its anisotropic structure.
Graphical abstract
•Co-HMS-X catalyst showed catalytic activity for direct styrene epoxidation reaction.•Al, Ga and Tl (0.25mol%) are used as promoters in Co-HMS-X catalyst.•The highly active Ga-Co-HMS-X (Co/Ga=4) had ...large number of acidic sites.•The catalyst is stable up to three cycles.•It could epoxide cyclooctene with reasonably good conversion.
Atom efficient synthesis of various value added products has been focused as an intense research area after Kyoto protocol. Styrene epoxidation is a challenging reaction as styrene epoxide is an important monomer for large number of polymers. It has been found that surface acidity and redox property of the catalyst has a major contribution to the catalytic activity for oxidation reaction. In this study Co-HMS-X catalyst was prepared and characterized by BET surface area and porosity measurement, SAXS, SANS, FESEM, HRTEM, UV–vis spectra, FTIR, 29Si NMR, H2-TPR and NH3-TPD techniques. It is observed that 5mol% Co-HMS-X showed highest catalytic activity for styrene epoxidation reaction using molecular O2 as an oxidant. Interestingly it is found that among three different dopant (Al, Ga, Tl), the Ga promoted Co-HMS-X catalyst (Si:Co:Ga=100:5:1.25) showed highest catalytic activity in terms of styrene conversion (100%) and styrene epoxide selectivity (68%). The unusual trend of Al, Ga and Tl towards the activity of Co-HMS-X (5mol%) catalyst has been discussed from the results obtained in the H2-TPR and NH3-TPD study.
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