Reduction Of Iodide Research Articles

Minimizing Interfacial Recombination in 1.8eVTriple-Halide Perovskites for 27.5% Efficient All-Perovskite Tandems.

All-perovskite tandem solar cells show great potential to enable the highest performance at reasonable costs for a viable market entry in the near future. In particular, wide-bandgap (WBG) perovskites with higher open-circuit voltage (VOC ) are essential to further improve the tandem solar cells' performance. Here, a new 1.8eV bandgap triple-halide perovskite composition in conjunction with a piperazinium iodide (PI) surface treatment is developed. With structural analysis, it is found that the PI modifies the surface through a reduction of excess lead iodide in the perovskite and additionally penetrates the bulk. Constant light-induced magneto-transport measurements are applied to separately resolve charge carrier properties of electrons and holes. These measurements reveal a reduced deep trap state density, and improved steady-state carrier lifetime (factor 2.6) and diffusion lengths (factor 1.6). As a result, WBG PSCs achieve 1.36V VOC , reaching 90% of the radiative limit. Combined with a 1.26eV narrow bandgap (NBG) perovskite with a rubidium iodide additive, this enables a tandem cell with a certified scan efficiency of 27.5%.

Synergistic effect of interface and defect engineering of MoC/MoO2 nano dot encapsulated N-doped carbon nanoflowers for highly durable dye-sensitized solar cells

The design and fabrication of advanced counter electrodes (CEs) for dye-sensitized solar cells (DSSCs) are limited by the scarcity of active sites and poor durability. Herein, we report the controlled preparation of a heterostructured nanoreactor CE based on defect-rich N-doped carbon nanoflowers (NCF) encapsulating MoC/MoO2 nano dots (NDs) in a well-defined heterophase (MoC/MoO2-NCF). The MoC/MoO2 NDs were uniformly dispersed on the NCF, and the NCF limited the size of the MoC/MoO2 NDs and prevented their agglomeration, thus maximizing the electrochemically active surface area of MoC/MoO2. Moreover, the synergistic effect between the MoC/MoO2 interface and the N-defects is conducive to the full exposure of the active sites. Furthermore, theoretical calculations revealed that the MoC/MoO2 heterojunction played a unique role in modulating the electronic structure and regulating the adsorption energy of tri-iodide in the iodide reduction reaction. The MoC/MoO2-NCF CEs in DSSCs demonstrated a power conversion efficiency (PCE) of 9.92% and high durability, exceeding the PCE (8.36%) and durability of Pt CEs. Overall, this study offers insights into the controlled synthesis of high-performance Mo-based composite CE materials for DSSCs.

Trends of clandestine laboratories manufacturing methamphetamine in New Zealand between 2009-2021: Evolution, enforcement, legislative, and COVID-19 effects.

The most common method of domestic methamphetamine manufacture encountered in New Zealand is the hydrogen iodide (HI) reduction of pseudoephedrine/ephedrine. While the overall method used to manufacture methamphetamine has remained consistent, the processes and chemicals utilized have evolved. Understanding the reason for any changes to methamphetamine manufacturing trends can assist jurisdictions with predicting the potential effects of enforcement and legislative initiatives. This paper presents data and trends amassed from suspected clandestine laboratories, associated with the manufacture of methamphetamine, in New Zealand between 2009 and 2021, along with data on methamphetamine, pseudoephedrine, and ephedrine seizures at the border. The data have shown that clandestine manufacturers in New Zealand have evolved the methamphetamine manufacturing process over the years. These changes in trends can largely be attributed to various enforcement and legislative effects and the COVID-19 pandemic response. Effects that enforcement, legislation, and the COVID-19 pandemic response may have had on the precursors, chemicals and equipment encountered are discussed.

Solution processed Cu2ZnSnSe4 nanoink for inexpensive Pt-free counter electrode in dye-sensitized solar cells

Morphology controllable Cu2ZnSnSe4 (CZTSe) nanoparticles (NPs) were successfully synthesized through hot injection method using oleic acid as solvent. The crystalline phase of the as-synthesized CZTSe NPs was confirmed with powder X-ray diffraction (XRD) and Raman results. The optical absorption spectra of CZTSe NPs exhibit a band gap of 1.21 eV. SEM analysis showed interconnected nanoflake-like morphology with higher surface area. The solid-state ligand exchanged CZTSe thin film without any toxic selenization process was used as counter electrode (CE) in dye-sensitized solar cells (DSSCs). The electrocatalytic activity of the CZTSe thin film for the reduction of iodide (I3−/I−) electrolyte was studied through cyclic voltammetry (CV) measurements. The DSSCs with ligand exchanged CZTSe CE exhibit an efficiency of 3.9% under 1 sun illumination, which is found to be higher than the Pt-based DSSC (3.5%) prepared in the same lab.

Tuned single atom coordination structures mediated by polarization force and sulfur anions for photovoltaics

Impeding high temperature sintering is challengeable for synthesis of carbon-supported single-atom catalysts (C-SACs), which requires high-cost precursor and strictly-controlled procedures. Herein, by virtue of the ultrastrong polarity of salt melts, sintering of metal atoms is effectively suppressed. Meanwhile, doping with inorganic sulfur anions not only produces sufficient anchoring sites to achieve high loading of atomically dispersed Co up to 13.85 wt.%, but also enables their electronic and geometric structures to be well tuned. When served as a cathode catalyst in dye-sensitized solar cells, the C-SAC with Co-N4-S2 moieties exhibits high activity towards the iodide reduction reaction (IRR), achieving a higher power conversion efficiency than that of conventional Pt counterpart. Density function theory (DFT) calculations revealed that the superior IRR activity was ascribed to the unique structure of Co-N4-S2 moieties with lower reaction barriers and moderate binding energy of iodine on the Co center, which was beneficial to I2 dissociation.

The modified IL-8 Luc assay, an in vitro skin sensitisation test, can significantly improve the false-negative judgment of lipophilic sensitizers with logKow values > 3.5.

False-negative judgment due to poor chemical solubility is a problem with in vitro skin sensitisation tests. Water-insoluble chemicals are typically dissolved in DMSO in most sensitisation tests but precipitate when diluted with medium beyond their solubility in water. Such tests lack procedures to rule out false-negative judgments due to poor solubility. The IL-8 Luc assay (OECD442E) is unique in that if chemicals do not dissolve at 20mg/mL in medium and have no effect on IL-8 luciferase activity (IL8LA), they are classified as indeterminate. The purpose of the present study was to reduce the number of indeterminate chemicals and improve assay performance. The IL-8 Luc assay can simultaneously examine glyceraldehyde 3-phosphate dehydrogenase luciferase activity (GAPLA) and IL8LA, and thus we examined the correlation between the reduction of GAPLA (defined as Inh-GAPLA) and the reduction of propidium iodide (PI)-excluding cells for three sensitizers and three non-sensitizers. We observed a significant correlation between luciferase activity driven by the GAPDH promoter of THP-G8 cells and the number of viable cells. Furthermore, chemicals providing an Inh-GAPLA value below 0.8 always reduced the ratio of PI-excluding cells to less than 0.6. Using the modified criteria, indeterminate chemicals are judged as negative if they provide Inh-GAPLA values below 0.8. This modification reduced the number of indeterminate chemicals and increased specificity, highlighting the unique advantage of the IL-8 Luc assay.

Solution-Processed Synthesis of Copper Oxide (Cu x O) Thin Films for Efficient Photocatalytic Solar Water Splitting.

This article reports a solution-processed synthesis of copper oxide (CuxO) to be used as a potential photocathode for solar hydrogen production in the solar water-splitting system. CuxO thin films were synthesized through the reduction of copper iodide (CuI) thin films by sodium hydroxide (NaOH), which were deposited by the spin coating method from CuI solution in a polar aprotic solvent (acetonitrile). The phase and crystalline quality of the synthesized CuxO thin films prepared at various annealing temperatures were investigated using various techniques. The X-ray diffraction and energy dispersive X-ray spectroscopy studies confirm the presence of Cu2O, CuO/Cu2O mixed phase, and pure CuO phase at annealing temperatures of 250, 300, and 350 °C, respectively. It is revealed from the experimental findings that the synthesized CuxO thin films with an annealing temperature of 350 °C possess the highest crystallinity, smooth surface morphology, and higher carrier density. The highest photocurrent density of −19.12 mA/cm2 at −1 V versus RHE was achieved in the photoelectrochemical solar hydrogen production system with the use of the CuxO photocathode annealed at a temperature of 350 °C. Therefore, it can be concluded that CuxO synthesized by the spin coating method through the acetonitrile solvent route can be used as an efficient photocathode in the solar water-splitting system.

Size-Dependent Liquid Crystal Behavior of Graphene Oxides for Preparation of Highly Ordered Graphene-Based Films

We report the preparation of a highly-oriented graphene-based film prepared from liquid crystal dispersion of graphene oxides (GOs). We observed that the liquid crystal behavior of GOs is highly affected by the lateral size of GO flakes: the critical concentration for liquid crystal formation decreased with the increase of the lateral size of GO flakes, which is in a good agreement with Onsager’s theory. As a result, we were able to obtain highly-ordered graphene assemblies with large-sized GO flakes (150 ± 29 μm) at relatively low concentrations. By applying the shear force, we were able to obtain highly-oriented films from liquid crystal GO flakes. After hydrogen iodide (HI) reduction, GO films showed excellent mechanical strength and electrical conductivity, which were 278% and 283% higher, respectively, than those of films made from smaller sized GO flakes (28 ± 24 μm).

Modifying nitrogen species of nitrogen-doped carbon nanotubes by thermal annealing to explore their role in the triiodide reduction reaction

Dye sensitized solar cells can convert solar energy into electricity. The counter electrode plays a critical role catalyzing the reduction of the redox electrolyte which transports electrons to the photo-anode. Nitrogen doped graphitic Carbon materials have great catalytic activity for the Iodide reduction reaction (IRR). However, several nitrogen species coexist and not all of them contribute equally to the IRR activity. Therefore, the need to correlate the nitrogen species proportions with the IRR activity of nitrogen doped carbon materials. It is challenging to vary the proportion of nitrogen species directly from synthesis parameters. Then, we make use of thermal treatments of nitrogen doped carbon nanotubes (CNx-CNTs) to modify the amount of nitrogen species to be able to compare and analyze their IRR activity. The thermal treatments resulted in the pyrrolic nitrogen disappearance and a considerable decrease of the pyridinic nitrogen, while enriching the quaternary nitrogen content of the samples. The best IRR performance was achieved for the sample enriched with quaternary nitrogen. Remarkably, the CNx-CNTs peak current density equate the platinum reference sample performance. Moreover, we incorporate the CNx-CNTs into a water based ink for potential applications in flexible counter electrodes printing, and its IRR activity is systematically explored.

Immobilized palladium complex into carbon-based nanomaterials: As catalyst for counter-electrode in the photovoltaics

The new [PdClL] type complex and immobilize carbon-based nanomaterials (multi-wall carbon nanotubes (MWCNTs) and graphene oxide (GO)) were fabricated with the basic synthesis route and characterized by 1H NMR, 13C NMR, FT-IR, EIS-MS, XRD, SEM-EDX, analysis techniques. The fabricated MWCNTs-supported [PdClL] (M1) and GO-supported [PdClL] (M2) organic/inorganic hybrid nanomaterials were carried out in the triiodide to iodide reduction reaction as counter electrodes (CEs) for photovoltaics (dye-sensitized solar cells, DSSCs). The hybrid nanomaterials (M1 and M2) as Pt-free CEs are compared to platinum, bare carbon nanotube and the power conversion efficiencies (PCEs) of the counter electrodes (M1 and M2) were enhanced with additive [PdClL]. The PCEs of the M1 and M2 were recorded as 1.88%, and 0.81%, respectively. And also, the performances indicated a relative efficiency (ƞrel) of ≈42% for MWCNTs-supported [PdClL] (M1), and ≈18% for GO-supported [PdClL] (M2) CEs regarding a platinum CEs set at 100%. This report shows that many hybrid nanomaterials with the immobilization process can be produced as cost-effectively and used as platinum-free electrodes in DSSC cells.

Alkyl-group grafting onto glassy carbon cathodes by reduction of primary monohaloalkanes: electrochemistry and X-ray photoelectron spectroscopy studies

Surface alkylation of glassy carbon (GC) and reticulated vitreous carbon (RVC) cathodes can occur when a primary alkyl monohalide is present in solution and when the electrode is polarized at potentials more negative than those required for reductive cleavage of the carbon–halogen bond, leading to the grafting of alkyl moieties onto the surface of the carbon cathode. Examination of electrode surfaces by means of X-ray photoelectron spectroscopy (XPS) has revealed that surface sp2:sp3 carbon ratios are approximately 4:1 for both pristine GC and RVC electrode materials that are commercially available. Further XPS analysis of these electrodes before and after reduction of perfluorobutyl iodide (C4F9I) provides substantial supporting evidence for a previously proposed mechanism for the grafting process that involves an SN2-like reaction between sp2-hybridized carbon (nucleophile) of the cathode and primary alkyl halides (electrophile) leading to conversion of sp2 sites to sp3 sites, with final surface sp2:sp3 carbon ratios that fall below 1:1. At the end of this paper, we discuss (mainly in qualitative terms) the ramifications of this surface modification of GC and RVC electrodes with respect to (a) bulk reduction of primary alkyl halides and (b) use and behavior of a well-known catalyst precursor (1,2,4,5-tetracyanobenzene).

A New Aspect for Band Gap Energy of Graphene-Mg2CuSnCoO6-Gallic Acid as a Counter Electrode for Enhancing Dye-Sensitized Solar Cell Performance

To develop counter electrodes (CEs) for dye-sensitized solar cells (DSSCs), band gap energy of quaternary semiconductor materials is of great interest. In the present study, a novel graphene sheet based on Mg2CuSnCoO6-Gallic acid nanomaterials (G/MCS@Gallic) was modified with a new Joule heating method, and a laser was applied for measuring band gap energy. Synergistic effect between graphene and Mg2CuSnCoO6-Gallic ensured excellent electron transport through the electrode and low band gap energy. The large surface area of the hybrid graphene materials rivaled the catalytic capability for iodide reduction. DSSCs achieved a maximum photoelectric conversion efficiency of 13.30% based on the 10% G/MCS@Gallic CE, which was higher than the platinum conversion efficiency. Thus, G/MCS@Gallic provides a novel, inexpensive, high-performance, and flexible cathode for solar cell applications.

First principles study of transition metals doped SiC for application as counter electrode in DSSC

The modification in material of counter electrode to improve the performance of dye sensitized solar cell based on first principles calculations is being reported. The slab models of pure SiC and its doping with Pt and Cr were investigated to study the catalytic activity on the basis of adsorption of triiodide and monoiodides as well as charge transfer from the slabs to the adsorbents. The iodide reduction reaction was modeled to study the splitting of tri-iodide into iodine and then into iodide ions which receive negative charge from the slabs. It was found that Cr doped SiC exhibited better activity to split the triiodide but poor action to further split the iodine into monoiodides when compared with pure SiC and Pt doped SiC slabs. The outcomes of this study revealed that TM doped SiC slabs may provide alternate materials to platinum for use as counter electrodes.

Boron and Nitrogen Co-doped Graphene Used As Counter Electrode for Iodine Reduction in Dye-Sensitized Solar Cells

A counter electrode (CE), which acts as an efficient catalyst, plays a pivotal role in dye-sensitized solar cells (DSSCs). Graphene doped by heteroatoms has been regarded as a material having a high reduction catalytic activity to develop efficient Pt-free alternative CE. However, the doping effects accounting for such a catalytic activity remain unknown. In this study, by means of density functional theory calculations, we determined the band gaps, formation energies, and regions of charge-induced impurities to examine the possibilities of B-doped, N-doped, and B–N co-doped graphene (BNG) sheets to replace platinum as CE. Our results demonstrated that the B–N co-doped graphene (BNG) is suitable to be used for CE owing to its small band gap, small formation energy, and having appropriate region of charge-induced impurities. In addition, we considered the iodide reduction reaction on the negatively charged BNG sheet. After injecting two extra electrons, the I2 molecule can strongly adsorb on the BNG surfac...

Free-standing reduced graphene oxide/polypyrrole films with enhanced electrochemical performance for flexible supercapacitors

Flexible all-solid-state supercapacitors with specific energy higher than 1 mW h cm−3 after long-term cycles remain a hot research topic in energy storage systems. In this paper, free-standing reduced graphene oxide/polypyrrole films are produced at the ice/ethanol interface following by hydrogen iodide reduction. The reduced graphene oxide/polypyrrole films are featured with high specific surface area, three-dimensional porosity, and tunable thickness and electronic conductivity. The typical flexible all-solid-state supercapacitor based on reduced graphene oxide/polypyrrole films exhibits a high volumetric specific capacitance of 17.3 F cm−3 and a high specific energy of 2.40 mW h cm−3 with corresponding specific power of 136.1 mW cm−3 at a current density of 3 mA cm−2 (ca. 10 A g−1). After 10,000 cycles at 3 mA cm−2, the capacitance retention of the typical flexible supercapacitor retains 73.2%. The enhanced electrochemical properties of the flexible supercapacitors are attributed to the high specific surface area, three-dimensional porosity, and the synergistic effect between reduced graphene oxide and polypyrrole with respect to the composite films.

Insight into singlet oxygen generation from metastable lattice of Treated-NaBiO3: A mechanism study

Nitric acid treated NaBiO3 (N-NBO) was observed to have the ability of yielding singlet oxygen (1O2) for degrading organic pollutants, and a mechanism study or insight into 1O2 generation from metastable lattice of treated-NBO was conducted. It was demonstrated that the acid treatment made Bi(V)O6 octahedron in NBO undergo drastic distortion, leading to the formation of a metastable Bi(III)O6 octahedron, which could store and release active oxygen as 1O2. As confirmed by characterization experiments, the 1O2-generating ability of N-NBO could be activated, deactivated and re-activated by different treatments, which corresponded to the formation, consummation and re-formation of the active metastable Bi(III)O6 octahedron. The formation of the metastable structure was related closely to the conversion of Bi5+ to Bi3+ in N-NBO, and its “collapse” eliminated the activity of the metastable Bi(III)O6 octahedron “pseudo-interface”. This structure was responsible for the release of active oxygen from the lattice in the form of 1O2, and the deactivated N-NBO could be re-activated by re-constructing this metastable structure through metal-ion doping and iodide reduction. A mechanism of 1O2 generation was proposed by considering the Bi(V)-Bi(III) conversion and the formation of the metastable Bi(III)O6 octahedron.

Enhanced electron transfer ability via coordination in block copolymer/porphyrin/fullerene micelle

Inspired by structures of antenna-reaction centers in photosynthesis, the complex micelle was prepared from zinc tetra-phenyl porphyrin (ZnTPP), fullerene derivative (PyC60) and poly(ethylene glycol)-block-poly(e-caprolactone) (PEG-b-PCL). The core-shell structure made the hydrophobic donor-acceptor system work in aqueous. In micellar core, coordination interaction occurred between ZnTPP and PyC60 molecules which ensured the enhanced energy migration from the donor to the acceptor. The enhanced interaction between porphyrin and fullerene was confirmed by absorption, steady-state fluorescence and transient fluorescence. The generation of singlet oxygen and superoxide radical was detected by iodide method and reduction of nitro blue tetrazolium, respectively, which confirmed that electron transfer reaction in the complex micellar core occurred. Moreover, the complex micelle exhibited effective electron transfer performance in photodebromination of 2,3-dibromo-3-phenylpropionic acid. The complex micellar structure endowed the donor-acceptor system with improved stability under irradiation. This strategy could be helpful for designing new electron transfer platform and artificial photosynthetic system.

Cyclohexyl Bromide and Iodide: Direct Reduction at Vitreous Carbon Cathodes together with Nickel(I) Salen‐ and Cobalt(I) Salen‐Catalyzed Reductions in Dimethylformamide

AbstractCyclic voltammetry and controlled‐potential (bulk) electrolysis have been used to study the direct electrochemical reduction of cyclohexyl bromide (1) and cyclohexyl iodide (2) at glassy carbon cathodes in dimethylformamide (DMF) containing 0.10 M tetramethylammonium tetrafluoroborate (TMABF4). Direct reduction of 1 is a one‐step process that affords a carbanion intermediate, whereas 2 undergoes stepwise reduction to a radical and then a carbanion intermediate. Mixtures of cyclohexane, cyclohexene, and bicyclohexyl arise from bulk electrolyses of both 1 and 2. Catalytic reduction of 1 and 2 by nickel(I) salen and cobalt(I) salen electrogenerated at glassy carbon cathodes in DMF‐TMABF4 has been investigated with the aid of both cyclic voltammetry and bulk electrolysis. Products arising from these catalytic reductions are cyclohexane, cyclohexene, and bicyclohexyl, although significant amounts of unreduced 1 are found when cobalt(I) salen is utilized as the catalyst. Mechanistic aspects of the direct and catalyzed reductions of 1 and 2 are discussed.

Covalent Modification of Glassy Carbon Surfaces by Electrochemical Grafting of Aryl Iodides.

The reduction of an aryl iodide is generally believed to involve a clean-cut two-electron reduction to produce an aryl anion and iodide. This is in contradiction to what is observed if a highly efficient grafting agent, such as an aryldiazonium salt, is employed. The difference in behavior is explained by the much more extreme potentials required for reducing an aryl iodide, which facilitates the further reduction of the aryl radical formed as an intermediate. However, in this study we disclose that electrografting of aryl iodides is indeed possible upon extended voltammetric cycling. This implies that even if the number of aryl radicals left unreduced at the electrode surface is exceedingly small, a functionalization of the surface may still be promoted. In fact, the grafting efficiency is found to increase during the grafting process, which may be explained by the inhibiting effect the growing film exerts on the competing reduction of the aryl radical. The slow buildup of the organic film results in a well-ordered structure as shown by the well-defined electrochemical response from a grafted film containing ferrocenylmethyl groups. Hence, the reduction of aryl iodides allows a precisely controlled, albeit slow, growth of thin organic films.

The role of various carbon nanomaterials for dye-sensitized solar cells applications

This study investigates dye-sensitized solar cells (DSSCs) manufactured with carbon-based counter electrodes (carbon black, graphite and graphene). Specifically, it examine the effects of each commonly employed carbon allotrope on the subsequent photovoltaic performance. The fabricated carbon counter electrodes were extensively characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). DSSCs were also manufactured using counter electrodes produced by different mixtures of carbon allotropes. It was found that the addition of graphene into carbon black produces high photovoltaic performances in DSSCs by creating additional conduction paths and a high surface area for iodide reduction. It is potentially feasible that such a carbon configuration can be used as a counter electrode, replacing the more expensive Pt.