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Showing papers on "Iodide published in 2018"


Journal ArticleDOI
TL;DR: A distorted black CsPbI3 film is reported by exploiting the synergistic effect of hydroiodic acid and phenylethylammonium iodide additives to achieve device efficiency beyond 15% with high light soaking stability.
Abstract: As the black cesium lead iodide (CsPbI3) tends to transit into a yellow δ-phase at ambient, it is imperative to develop a stabilized black phase for photovoltaic applications. Herein, we report a distorted black CsPbI3 film by exploiting the synergistic effect of hydroiodic acid (HI) and phenylethylammonium iodide (PEAI) additives. It is found that the HI induces formation of hydrogen lead iodide (HPbI3+x), an intermediate to the distorted black phase with appropriate band gap of 1.69 eV; while PEAI provides nucleation for optimized crystallization. More importantly, it stabilizes the distorted black phase by hindering phase transition via its steric effects. Upon optimization, we have attained solar cell efficiency as high as 15.07%. Specifically, the bare cell without any encapsulation shows negligible efficiency loss after 300 h of light soaking. The device keeps 92% of its initial cell efficiency after being stored for 2 months under ambient conditions.

358 citations


Journal ArticleDOI
TL;DR: The underlying microscopic mechanism to be promoting the oriented growth of the perovskites crystals and reducing the defect concentration is unveiled, and the role of lead iodide is proposed.
Abstract: The presence of excess lead iodide in halide perovskites has been key for surpassing 20% photon-to-power conversion efficiency. To achieve even higher power conversion efficiencies, it is important to understand the role of remnant lead iodide in these perovskites. To that end, we explored the mechanism facilitating this effect by identifying the impact of excess lead iodide within the perovskite film on charge diffusion length, using electron-beam-induced current measurements, and on film formation properties, from grazing-incidence wide-angle X-ray scattering and high-resolution transmission electron microscopy. Based on our results, we propose that excess lead iodide in the perovskite precursors can reduce the halide vacancy concentration and lead to formation of azimuthal angle-oriented cubic α-perovskite crystals in-between 0° and 90°. We further identify a higher perovskite carrier concentration inside the nanostructured titanium dioxide layer than in the capping layer. These effects are consistent with enhanced lead iodide-rich perovskite solar cell performance and illustrate the role of lead iodide. Excess lead iodide in the mixed halide perovskites solar cells leads to high device performance but its origin remains elusive. Here Park et al. unveil the underlying microscopic mechanism to be promoting the oriented growth of the perovskites crystals and reducing the defect concentration.

247 citations


Journal ArticleDOI
TL;DR: The real composition of the perovskites is revealed, where dimethylammonium partially take place of cesium cation at the A-site, where the DMA cation is now revealed as an alternative A site cation.
Abstract: All-inorganic perovskites have a special place in halide perovskite family because of their potential for better stability. However, the representative cesium lead iodide (CsPbI3) is metastable and spontaneously converts to the non-perovskite structure at room temperature. Here, we demonstrate that what appears to be all-inorganic CsPbI3 stabilized in its perovskite form using the purported intermediate known as hydrogen lead iodide (HPbI3) is, in fact, the hybrid perovskite cesium dimethylammonium lead iodide (Cs1−xDMAxPbI3, x = 0.2 to 0.5). Thus, many of the reported all-inorganic perovskites are actually still hybrid organic-inorganic perovskites, as strongly evidenced by a wide battery of experimental techniques presented here. Solar cells based on the representative composition Cs0.7DMA0.3PbI3 can achieve an average power conversion efficiency of 9.27 ± 1.28% (max 12.62%). These results provide an alternative angle to look at previous results pertaining all-inorganic CsPbI3 while the DMA cation is now revealed as an alternative A site cation. Hydriodic acid or hydrogen lead iodide is widely used to stabilize all-inorganic perovskite cesium lead iodide to make high performing solar cells. Here Ke et al. reveal the real composition of the perovskites, where dimethylammonium partially take place of cesium cation at the A-site.

207 citations


Journal ArticleDOI
TL;DR: It is shown that TMA can facilitate homogeneous film formation of a SnI2 (+SnF2 ) layer by effectively forming intermediate SnY2 -TMA complexes, thereby enabling the formation of dense and compact FASnI3 film with large crystalline domain (>1 µm).
Abstract: Recently, the evolved intermediate phase based on iodoplumbate anions that mediates perovskite crystallization has been embodied as the Lewis acid-base adduct formed by metal halides (serve as Lewis acid) and polar aprotic solvents (serve as Lewis base). Based on this principle, it is proposed to constitute efficient Lewis acid-base adduct in the SnI2 deposition step to modulate its volume expansion and fast reaction with methylammonium iodide (MAI)/formamidinium iodide (FAI) (FAI is studied hereafter). Herein, trimethylamine (TMA) is employed as the additional Lewis base in the tin halide solution to form SnY2 -TMA complexes (Y = I- , F- ) in the first-step deposition, followed by intercalating with FAI to convert into FASnI. It is shown that TMA can facilitate homogeneous film formation of a SnI2 (+SnF2 ) layer by effectively forming intermediate SnY2 -TMA complexes. Meanwhile, its relatively larger size and weaker affinity with SnI2 than FA+ ions will facilitate the intramolecular exchange with FA+ ions, thereby enabling the formation of dense and compact FASnI3 film with large crystalline domain (>1 µm). As a result, high power conversion efficiencies of 4.34% and 7.09% with decent stability are successfully accomplished in both conventional and inverted perovskite solar cells, respectively.

196 citations


Journal ArticleDOI
TL;DR: A series of crosslinked anion exchange membranes (AEMs) were prepared through ring-opening metathesis polymerization (ROMP) of tetraalkylammonium-functionalized norbornene derivatives.

162 citations


Journal ArticleDOI
TL;DR: The temperature-dependent structure evolution of the hybrid halide perovskite compounds, FASnI3 and FAPbBr3, has been monitored using high-resolution synchrotron X-ray powder diffraction to suggest dynamic motion is occurring in the inorganic sublattice due to the flexibility of the in organic network and dynamic lone pair stereochemical activity on the B-site.
Abstract: The temperature-dependent structure evolution of the hybrid halide perovskite compounds, formamidinium tin iodide (FASnI3, FA+ = CH[NH2]2+) and formamidinium lead bromide (FAPbBr3), has been monitored using high-resolution synchrotron X-ray powder diffraction between 300 and 100 K. The data are consistent with a transition from cubic Pm3m (No. 221) to tetragonal P4/mbm (No. 127) for both materials upon cooling; this occurs for FAPbBr3 between 275 and 250 K, and for FASnI3 between 250 and 225 K. Upon further cooling, between 150 and 125 K, both materials undergo a transition to an orthorhombic Pnma (No. 62) structure. The transitions are confirmed by calorimetry and dielectric measurements. In the tetragonal regime, the coefficients of volumetric thermal expansion of FASnI3 and FAPbBr3 are among the highest recorded for any extended inorganic crystalline solid, reaching 219 ppm K–1 for FASnI3 at 225 K. Atomic displacement parameters of all atoms for both materials suggest dynamic motion is occurring in the...

120 citations


Journal ArticleDOI
TL;DR: In this article, two kinds of bio-chars derived from seaweed, such as sargassum and enteromorpha, are modified by halides impregnation.

119 citations


Journal ArticleDOI
TL;DR: For the first time, the fabrication of solar cells exploiting methylammonium antimony sulfur diiodide (MASbSI2) perovskite structures, as light harvesters, are reported on.
Abstract: The use of divalent chalcogenides and monovalent halides as anions in a perovskite structure allows the introduction of 3+ and 4+ charged cations in the place of the 2+ metal cations. Herein we report for the first time on the fabrication of solar cells exploiting methylammonium antimony sulfur diiodide (MASbSI2) perovskite structures, as light harvesters. The MASbSI2 was prepared by annealing under mild temperature conditions, via a sequential reaction between antimony trisulfide (Sb2S3), which is deposited by the chemical bath deposition (CBD) method, antimony triiodide (SbI3), and methylammonium iodide (MAI) onto a mesoporous TiO2 electrode, and then annealed at 150 °C in an argon atmosphere. The solar cells fabricated using MASbSI2 exhibited power conversion efficiencies (PCE) of 3.08%, under the standard illumination conditions of 100 mW/cm2.

111 citations


Journal ArticleDOI
TL;DR: In this article, two isoxazolidine derivatives, namely 5-(benzo[d][1,3]dioxol-5-ylmethyl)-2-tetradecyl (BDMTI) and 5-(4-hydroxy-3-methoxybenzyl)-2 -hexylmethyl (HMBTI), were synthesized and characterized using FTIR, C-NMR, H-NPM, and elemental analysis.
Abstract: Two isoxazolidine derivatives namely 5-(benzo[d][1,3]dioxol-5-ylmethyl)-2-tetradecyl isoxazolidine (BDMTI) and 5-(4-hydroxy-3-methoxybenzyl)-2-tetradecyl isoxazolidine (HMBTI) were synthesized and characterized using FTIR, C-NMR, H-NMR, and elemental analysis. The synthesized compounds were evaluated as corrosion inhibitors for API 5L X60 steel in 1 M HCl in the temperature range of 25–60 °C using gravimetric and electrochemical (Electrochemical Impedance Spectroscopy (EIS), Potentiodynamic Polarization (PDP) and Linear Polarization Resistance (LPR)) techniques. The effect of addition of a small amount of iodide ions on the corrosion inhibition performance of the compounds was also assessed. In addition, quantum chemical calculations and Monte Carlo simulations were employed to correlate the electronic properties of the compounds with the corrosion inhibition effect as well as to evaluate the adsorption/binding of the inhibitor molecules on the steel surface. Experimental results show that the two compounds inhibited the corrosion of carbon steel in an acid environment with HMBTI showing superior performance. The corrosion inhibition effect was found to be dependent on the inhibitors' concentration and temperature. Addition of iodide ions improves the inhibition efficiency considerably due to co-adsorption of the iodide ions and the inhibitors on the steel surface which was competitive in nature as confirmed from the synergistic parameter (S1) which was less than unity at higher temperature. Experimental and theoretical results are in good agreement.

102 citations


Journal ArticleDOI
TL;DR: In this paper, the authors studied the layered material butylammonium methylamptonium lead iodide (C4H9NH3)2(CH3NH3n−1PbnI3n+1) for values of n ranging from 1 to 4.
Abstract: Solution-processable organic metal halide Ruddlesden–Popper phases have shown promise in optoelectronics because of their efficiencies in solar cells along with increased material stability relative to their three-dimensional counterparts (CH3NH3PbI3). Here, we study the layered material butylammonium methylammonium lead iodide (C4H9NH3)2(CH3NH3)n−1PbnI3n+1 for values of n ranging from 1 to 4. Thin films cast from solution show a gradual change in the crystalline texture of the two-dimensional lead iodide layers from being parallel to the substrate to perpendicular with increasing n. Contactless time-resolved microwave conductivity measurements show that the average recombination rate order increases with n and that the yield–mobility products and carrier lifetimes of these thin films are much lower than that of CH3NH3PbI3, along with increased higher-order recombination rate constants.

91 citations


Journal ArticleDOI
TL;DR: In this article, three corrosion inhibitors with different anionic carbon chain lengths, 1-vinyl-3methylimidazolium iodide ([VMIM]I), 1-vyl-three-proply-dimitriou-dimethyl iodide (VPIMI) and 1-VBIM]I, were studied on the corrosion of X70 steel in 0.5 mM H2SO4 solution at 298 K.

Journal ArticleDOI
TL;DR: In this article, a time-dependent density functional theory-based theoretical formalism is taken advantage of to assess the many-body excited states of pristine and defective perovskites in their pristine state and in the presence of point chemical defects.
Abstract: DOI: 10.1002/aenm.201702754 cells has been raised from 3.8% in the first report[2] to over 20% today.[3] Such an unprecedented improvement has been triggered by the unique features of hybrid perovskites that make them attractive for solar-cell applications, including large optical absorption coefficients and high charge carrier mobility.[1] Despite these remarkable advances, the mechanism for photoinduced electron– hole (e–h) pair dissociation and transport in lead perovskites is still controversial. Exciton binding energies of 5–16 meV have been reported in MAPbI3, so only a fraction of weakly bound excitons likely coexist with free charge carriers at room temperature under solar illumination conditions.[5] It has been argued that e–h separation could be further assisted by fluctuations in the energy landscape associated with the positional dynamics of MA cations in pristine materials.[6–8] In polycrystalline films prepared from precursor solutions, defects are not as benign as initially thought,[9] as suggested by the recent demonstration of the grain-to-grain variation in photoluminescence (PL) intensity.[10] These reports are seemingly in conflict with the measured, significantly long, charge-carrier diffusion lengths in MAPbI3 films,[11] as these inhomogeneities should act as traps and sources of nonradiative recombination channels. Very interestingly, the e–h diffusion lengths in iodide-based perovskites can be further enhanced by incorporating a small amount of chlorine anions.[12,13] While it has been claimed that chlorine dopants yield polycrystalline film morphologies with improved charge transport properties,[14,15] possibly by smoothing out structural and energetic discontinuities at grain boundaries[16] or seeding crystallization of higher quality grains,[17,18] recent state-of-the-art studies point to the presence of residual Cl dopants remaining in thin films of MAPbI3. The enhanced PL intensity inside the grains with higher Cl concentration[10] may be explained by reduced trap-assisted nonradiative recombination, thereby increasing the lifetime and diffusion length of photoexcited electrons and holes.[14,15,21,22] However, a model relating charge-carrier decay dynamics to atomistic details of the excited-state electronic structure of Cldoped perovskites is severely lacking.[23] Here, we address these questions by means of a many-body description of the electronic excitations of pristine and defective perovskites that fully accounts for groundand excited-state Lead tri-iodide methylammonium (MAPbI3) perovskite polycrystalline materials show complex optoelectronic behavior, largely because their 3D semiconducting inorganic framework is strongly perturbed by the organic cations and ubiquitous structural or chemical inhomogeneities. Here, a newly developed time-dependent density functional theory-based theoretical formalism is taken advantage of. It treats electron–hole and electron–nuclei interactions on the same footing to assess the many-body excited states of MAPbI3 perovskites in their pristine state and in the presence of point chemical defects. It is shown that lead and iodine vacancies yield deep trap states that can be healed by dynamic effects, namely rotation of the methylammonium cations in response to point charges, or through slight changes in chemical composition, namely by introducing a tiny amount of chlorine dopants in the defective MAPbI3. The theoretical results are supported by photoluminescence experiments on MAPbI3−mClm and pave the way toward the design of defectfree perovskite materials with optoelectronic performance approaching the theoretical limits. Solar Cells

Journal ArticleDOI
TL;DR: This study identifies the presence of mixed crystalline aggregates composed of perovskite and lead iodide during intercalation and structural reorganization and finds that the Avrami models best represent them.
Abstract: Sequential deposition has been extensively used for the fabrication of perovskite solar cells. Nevertheless, fundamental aspects of the kinetics of methylammonium lead iodide perovskite formation remain obscure. We scrutinize the individual stages of the reaction and investigate the crystallization of the lead iodide film, which occurs before the intercalation of methylammonium iodide commences. Our study identifies the presence of mixed crystalline aggregates composed of perovskite and lead iodide during intercalation and structural reorganization. Furthermore, Ostwald ripening occurs in the film for reaction times beyond the point of conversion to perovskite. Using cross-sectional confocal laser scanning microscopy for the first time, we reveal that lead iodide in the over-layer and at the bottom of the mesoporous layer converts first. We identify unreacted lead iodide trapped in the mesoporous layer for samples of complete conversion. We acquire kinetic data by varying different parameters and find that the Avrami models best represent them. The model facilitates the rapid estimation of the reaction time for complete conversion for a variety of reaction conditions, thereby ascertaining a major factor previously determined by extensive experimentation. This comprehensive picture of the sequential deposition is essential for control over the perovskite film quality, which determines solar cell efficiency. Our results provide key insights to realize high-quality perovskite films for optoelectronic applications.

Journal ArticleDOI
TL;DR: The mechanism of the aryl iodide-catalyzed asymmetric migratory geminal difluorination of β-substituted styrenes has been explored with density functional theory computations and multiple attractive non-covalent interactions are found to underlie the high asymmetric induction.
Abstract: The mechanism of the aryl iodide-catalyzed asymmetric migratory geminal difluorination of β-substituted styrenes (Banik et al. Science 2016, 353, 51) has been explored with density functional theory computations. The computed mechanism consists of (a) activation of iodoarene difluoride (ArIF2), (b) enantiodetermining 1,2-fluoroiodination, (c) bridging phenonium ion formation via SN2 reductive displacement, and (d) regioselective fluoride addition. According to the computational model, the ArIF2 intermediate is stabilized through halogen−π interactions between the electron-deficient iodine(III) center and the benzylic substituents at the catalyst stereogenic centers. Interactions with the catalyst ester carbonyl groups (I(III)+···O) are not observed in the unactivated complex, but do occur upon activation of ArIF2 through hydrogen-bonding interactions with external Bronsted acid (HF). The 1,2-fluoroiodination occurs via alkene complexation to the electrophilic, cationic I(III) center followed by C–F bond f...

Journal ArticleDOI
TL;DR: In this paper, the authors performed time resolved mass spectrometry of the gas species evolved during the photoinduced degradation of organic-inorganic lead trihalide perovskites made with commonly used monovalent cations, including methylammonium (MA), formamidinium (FA), and Cs.
Abstract: Operational and long-term stability of perovskite solar cells are critical for their commercialization on a large scale. To mitigate stability issues, a fundamental understanding of the physicochemical processes associated with the degradation of perovskite materials is needed. Here, we perform time resolved mass spectrometry of the gas species evolved during the photoinduced degradation of organic–inorganic lead trihalide perovskites made with commonly used monovalent cations, including methylammonium (MA), formamidinium (FA), and Cs. Our results indicate that the hot-carrier-induced deprotonation of MA+ cations is the fundamental origin of the photodegradation, which inevitably leads to the release of volatile species such as ammonia (NH3), aminocarbyne fragments (CNH2), hydrogen (H2), and iodine/hydrogen iodide (I/HI) from methylammonium lead iodide (MAPbI3) at different rates under simulated one sun solar illumination. Photodegradation processes can be mitigated by applying ultra-violet (UV) filters with suitable cutoff wavelengths to the light source. Additionally, we demonstrate that the incorporation of FA reduces the release of organic species but does not prevent the formation of I/HI. However, the addition of Cs effectively suppresses the release of all volatile gases. The best photostability is obtained with the FA/Cs mixed perovskites, showing that the complete removal of MA from mixed-cation perovskites is preferred for more photostable perovskites.

Journal ArticleDOI
TL;DR: Overall, due to a rapid oxidation of I- to IO3- with short-lifetimes of HOI, ferrate(VI) oxidation appears to be a promising option for I-DBP mitigation during treatment of I--containing waters.
Abstract: Oxidative treatment of iodide-containing waters can form toxic iodinated disinfection byproducts (I-DBPs). To better understand the fate of iodine, kinetics, products, and stoichiometries for the reactions of ferrate(VI) with iodide (I–) and hypoiodous acid (HOI) were determined. Ferrate(VI) showed considerable reactivities to both I– and HOI with higher reactivities at lower pH. Interestingly, the reaction of ferrate(VI) with HOI (k = 6.0 × 103 M–1 s–1 at pH 9) was much faster than with I– (k = 5.6 × 102 M–1 s–1 at pH 9). The main reaction pathway during treatment of I–-containing waters was the oxidation of I– to HOI and its further oxidation to IO3– by ferrate(VI). However, for pH > 9, the HOI disproportionation catalyzed by ferrate(VI) became an additional transformation pathway forming I– and IO3–. The reduction of HOI by hydrogen peroxide, the latter being produced from ferrate(VI) decomposition, also contributes to the I– regeneration in the pH range 9–11. A kinetic model was developed that could w...

Journal ArticleDOI
TL;DR: In this article, a quantitative expression for the vacancy jump rate was obtained by studying iodine tracer diffusion as a function of temperature and iodine-vacancy concentration by means of classical molecular-dynamics simulations.
Abstract: The current picture of ion transport in the solar-cell absorber material CH3NH3PbI3 (MAPbI3) suffers from a disturbing lack of clarity In this study, we demonstrate that, with knowledge of the jump rate of iodine vacancies and with a defect chemical model, various experimental data reported in the literature for the ionic conductivity of MAPbI3 can be reconciled A quantitative expression for the vacancy jump rate was obtained by studying iodine tracer diffusion as a function of temperature and iodine-vacancy concentration by means of classical molecular-dynamics simulations The defect-chemical model yields acceptor concentrations in experimental samples of 1015 cm−3 and lower, and the enthalpy and entropy of anti-Frenkel disorder We also demonstrate that the generation of additional iodine vacancies can explain quantitatively the increase in the ionic conductivity under illumination Finally, the consequences for devices under bias and for grain-boundary transport are discussed

Journal ArticleDOI
TL;DR: An advanced protocol for the intramolecular C–H amination of alkyl groups via amidyl radicals (Hofmann–Loffler reaction) under homogeneous iodine catalysis is reported, which employs common mCPBA as terminal oxidant.
Abstract: An advanced protocol for the intramolecular C–H amination of alkyl groups via amidyl radicals (Hofmann–Loffler reaction) under homogeneous iodine catalysis is reported. This protocol employs common mCPBA as terminal oxidant. It proceeds under mild conditions, with complete chemoselectivity, is compatible with radical intermediates, and allows for the selective intramolecular amination reaction of secondary and tertiary hydrocarbon bonds and is not restricted to benzylic C–H amination. The involvement of an iodine(III) catalyst state in the C–N bond formation derives from selective oxidation at the stage of the corresponding alkyl iodide with mCPBA. Its formation is corroborated by quantum-chemical calculations. This new catalysis thus proceeds within a defined iodine(I/III) catalysis manifold.

Journal ArticleDOI
TL;DR: This study underscores the importance of producing eaq- efficiently and of minimizing the eq- scavenging of intermediates inherently formed and accumulated, and highlights the potential of the sulfite/iodide/UV process to efficiently eliminate recalcitrant contaminants.

Journal ArticleDOI
TL;DR: In this paper, a hybrid perovskite structure was obtained from methylammonium lead triiodide passivated with imidazolium iodide, which can effectively passivate the surface at the perovsite/hole transporting layer (HTM) interface.

Journal ArticleDOI
TL;DR: This direct C(sp2)-H selenation strategy, with reduced environmental impact, provides efficient access to a host of selenyl indoles and some other N-heteroarenes under aerobic and galvanostatic conditions.

Journal ArticleDOI
TL;DR: Time-resolved photoluminescence confirms that melaminium iodide plays a more important role in passivating the rear surface of the perovskite layer contacting the hole transporting spiro-MeOTAD layer, and an aging test under a relative humidity of 65% reveals that melamination iodide improves stability because of the suppression of the defect evolved by moisture.
Abstract: Surface passivation of perovskite grains is one of the promising methods to reduce recombination and improve stability of perovskite solar cells (PSCs). We herein report the effect of a melaminium iodide additive on the photovoltaic performance of PSCs based on (FAPbI3)0.875(CsPbBr3)0.125 perovskite. Cyclic −C═N– and primary amine in melamine are a good hydrogen bond acceptor and Lewis base, which can interact with both the organic cation and Lewis acidic lead iodide in the perovskite film. Melaminium iodide is synthesized and added to the precursor solution, which is directly spin-coated to form the perovskite film. The presence of melaminium iodide additive reduces the trap density from 1.02 × 1016 to 0.645 × 1016 cm–3, which leads to the reduction of nonradiative recombination and thereby improving the mean open-circuit voltage and the fill factor from 1.054 to 1.095 V and from 0.693 to 0.725 V, receptively. In addition, photocurrent–voltage hysteresis is reduced by the melaminium iodide additive, whic...

Journal ArticleDOI
TL;DR: In this article, a tandem particle-suspension (PPS) reactor design for solar water splitting comprising micron-scale photocatalyst particles suspended in an aqueous solution with soluble redox shuttles is investigated.
Abstract: Sunlight-driven water splitting to produce hydrogen and oxygen provides a pathway to store available solar energy in the form of stable, energy-dense chemical bonds. Here we investigate a tandem particle-suspension reactor design for solar water splitting comprising micron-scale photocatalyst particles suspended in an aqueous solution with soluble redox shuttles. A porous separator facilitates redox species transport between the hydrogen and oxygen evolution reaction compartments while averting gas crossover. A two-dimensional, transient model of the reactor is presented to illustrate the coupling between light absorption, interfacial electron-transfer kinetics and species transport, and their combined impacts on overall solar-to-hydrogen conversion efficiency. The volumetric reactivity of the suspended semiconductor particles is dictated by combining the (photo)current–voltage behavior of a photodiode with Butler–Volmer electron-transfer kinetics. For the first time, a quantitative approach to determine the impacts of surface-dependent redox shuttle kinetic parameters on reaction selectivity in a Z-scheme system is established. Model results provide insights on the effects of optical, transport and kinetic properties of the semiconductor particles and the redox shuttles on the overall reactor performance. Solar-to-hydrogen reactor efficiencies predicted with BiVO4 particles for oxygen evolution are at least two times larger than efficiencies achieved with wider band-gap TiO2 particles due to enhanced visible light absorption; hydrogen evolution with SrTiO3:Rh particles was considered for both cases. Superior performance is predicted with proton-coupled electron transfer redox shuttles (para-benzoquinone/hydroquinone and iodide/iodate) that absorb little-to-no visible light, while also facilitating operation at near-neutral pH conditions, as compared to the non-proton-coupled triiodide/iodide and iron(III)/iron(II) redox shuttles. For 1 cm tall reaction compartments, diffusive species transport is fast enough to sustain reactor operation at a 1% solar-to-hydrogen conversion efficiency for both para-benzoquinone/hydroquinone and iodate/iodide redox shuttles with less than 2.2 mg L−1 of each of BiVO4 and SrTiO3:Rh particles in the solution.

Journal ArticleDOI
TL;DR: A brief summary of recently developed methods, in which this arising former waste is used as an additional reagent in cascade transformations to generate multiple substituted products in one step and with high atom efficiency.
Abstract: Hypervalent iodine compounds, in particular aryl-λ3-iodanes, have been used extensively as electrophilic group-transfer reagents. Even though these compounds are superior substrates in terms of reactivity and stability, their utilization is accompanied by stoichiometric amounts of an aryl iodide as waste. This highly nonpolar side product can be tedious to separate from the desired target molecules and significantly reduces the overall atom efficiency of these transformations. In this short review, we want to give a brief summary of recently developed methods, in which this arising former waste is used as an additional reagent in cascade transformations to generate multiple substituted products in one step and with high atom efficiency.

Journal ArticleDOI
TL;DR: TPPS4 behaves as if it has some cationic character in the presence of bacteria, which may be related to its delivery from suppliers in the form of a dihydrochloride salt.
Abstract: We recently reported that addition of the non-toxic salt, potassium iodide can potentiate antimicrobial photodynamic inactivation of a broad-spectrum of microorganisms, producing many extra logs of killing. If the photosensitizer (PS) can bind to the microbial cells, then delivering light in the presence of KI produces short-lived reactive iodine species, while if the cells are added after light the killing is caused by molecular iodine produced as a result of singlet oxygen-mediated oxidation of iodide. In an attempt to show the importance of PS-bacterial binding, we compared two charged porphyrins, TPPS4 (thought to be anionic and not able to bind to Gram-negative bacteria) and TMPyP4 (considered cationic and well able to bind to bacteria). As expected TPPS4 + light did not kill Gram-negative Escherichia coli, but surprisingly when 100 mM KI was added, it was highly effective (eradication at 200 nM + 10 J/cm2 of 415 nm light). TPPS4 was more effective than TMPyP4 in eradicating the Gram-positive bacteria, methicillin-resistant Staphylococcus aureus and the fungal yeast Candida albicans (regardless of KI). TPPS4 was also highly active against E. coli after a centrifugation step when KI was added, suggesting that the supposedly anionic porphyrin bound to bacteria and Candida. This was confirmed by uptake experiments. We compared the phthalocyanine tetrasulfonate derivative (ClAlPCS4), which did not bind to bacteria or allow KI-mediated killing of E. coli after a spin, suggesting it was truly anionic. We conclude that TPPS4 behaves as if it has some cationic character in the presence of bacteria, which may be related to its delivery from suppliers in the form of a dihydrochloride salt.

Journal ArticleDOI
TL;DR: The stability studies confirmed that the addition of small amount of iodide into the CsPbBr3 is necessarily to stabilize the cell performance over time.
Abstract: Perovskite solar cells based on series of inorganic cesium lead bromide and iodide mixture, CsPbBr3-xI x , where x varies between 0, 0.1, 0.2, and 0.3 molar ratio were synthesized by two step-sequential deposition at ambient condition to design the variations of wide band gap light absorbers. A device with high overall photoconversion efficiency of 3.98 % was obtained when small amount of iodide (CsPbBr2.9I0.1) was used as the perovskite and spiro-OMeTAD as the hole transport material (HTM). We investigated the origin of variation in open circuit voltage, Voc which was shown to be mainly dependent on two factors, which are the band gap of the perovskite and the work function of the HTM. An increment in Voc was observed for the device with larger perovskite band gap, while keeping the electron and hole extraction contacts the same. Besides, the usage of bilayer P3HT/MoO3 with deeper HOMO level as HTM instead of spiro-OMeTAD, thus increased the Voc from 1.16 V to 1.3 V for CsPbBr3 solar cell, although the photocurrent is lowered due to charge extraction issues. The stability studies confirmed that the addition of small amount of iodide into the CsPbBr3 is necessarily to stabilize the cell performance over time.

Journal ArticleDOI
TL;DR: In this paper, three environmentally friendly ionic liquids (ILs) namely: 1-Methyl-3-propylimidazolium iodide (MPIMI), 1-butyl-3methylimide-naphosolium ionide (BMIMI) and 1-hexyl 3-methylamidazolate (HMIMI)) were examined as inhibitors for suppressing mild-steel corrosion in 1'M HCl solution.

Journal ArticleDOI
TL;DR: Due to the simple synthetic procedure, the excellent removal performances for iodine and uranium, and the easy separation from water, the Ag2O@Mg(OH)2 nanocomposite has real potential for application in radioactive wastewater treatment, especially during episodic environmental crisis.

Journal ArticleDOI
TL;DR: In this paper, an I− ion was inserted into the interlayer of Bi2WO6, expanding the layer spacing, favoring the efficient charge separation and transfer and prohibiting the recombination of the photogenerated electrons and holes.

Journal ArticleDOI
Juanjuan Song1, Li Zhao1, Yesheng Wang1, Yun Xue1, Yujia Deng1, Xihui Zhao1, Qun Li1 
TL;DR: Water-soluble and reductive carbon quantum dots were fabricated by the hydrothermal carbonization of chitosan and used to synthesize gold nanoparticles (AuNPs) and showed good selectivity toward I− over other anion ions, and was used for the analysis of salt samples.
Abstract: Water-soluble and reductive carbon quantum dots (CQDs) were fabricated by the hydrothermal carbonization of chitosan. Acting as a reducing agent and stabilizer, the as-prepared CQDs were further used to synthesize gold nanoparticles (AuNPs). This synthetic process was carried out in aqueous solution, which was absolutely “green”. Furthermore, the CQDs/AuNPs composite was used to detect iodine ions by the colorimetric method. A color change from pink to colorless was observed with the constant addition of I− ions, accompanied by a decrease in the absorbance of the CQDs/AuNPs composite. According to the absorbance change, a favorable linear relationship was obtained between ΔA and I− concentration in the range of 20–140 μM and 140–400 μM. The detection limit of iodide ions, depending on the 3δ/slope, was estimated to be 2.3 μM, indicating high sensitivity to the determination of iodide. More importantly, it also showed good selectivity toward I− over other anion ions, and was used for the analysis of salt samples. Moreover, TEM results indicated that I− ions induced the aggregation of CQDs/AuNPs, resulting in changes in color and absorbance.