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Over the recent past, lead-based halide perovskite materials have drawn significant attention due to their excellent optical and electrical properties for solar cells and optoelectronics applications. However, the toxicity of lead elements and instability under ambient conditions leads to develop alternative compositions. Herein, we report a novel mechanochemical synthesis of tin iodide-based double perovskites (A2SnI6; A = Rb+, Cs+, methylammonium, and formamidinium), and their structural, optical, and electrical properties are investigated. Importantly, we found that the hydrogen iodide (HI) addition during the ball-milling process minimizes secondary phase formation in the synthesized A2SnI6 powders. The effects of HI addition and the A-site substitution are investigated with respect to the lattice parameters, optical bandgaps, and electrical properties of the synthesized perovskite materials. Our results demonstrate essential information to improve the understanding of halide perovskite materials and develop efficient lead-free perovskite photoelectric devices.

In this study, a corrosion-stable silica membrane was developed to be used in H2 purification during the hydrogen iodide decomposition (2HI → H2 + I2), which is a new application of the silica membranes. From a practical perspective, the membrane separation length was enlarged up to 400 mm and one end of the membrane tubes was closed to avoid any thermal variation along the membrane length and sealing issues. The silica membranes consisted of a three-layer structure comprising a porous α-Al2O3 ceramic support, an intermediate layer, and a top silica layer. The intermediate layer was composed of γ-Al2O3 or silica, and the top silica layer that is H2 selective was prepared via counter-diffusion chemical vapor deposition of a hexyltrimethoxysilane. To the best of our knowledge, this is the first report of 400-mm-long closed-end silica membranes supported on Si-formed α-Al2O3 tubes produced via chemical vapor deposition method. A 400-mm-long closed-end membrane using a Si-formed α-Al2O3 tube exhibited a higher H2/SF6 selectivity of 1240 but lower H2 permeance of 1.4 × 10−7 mol Pa−1 m−2 s−1 with compared with the membrane using a γ-Al2O3-formed α-Al2O3 tube (907 and 5.6 × 10−7 mol Pa−1 m−2 s−1, respectively). The membrane using the Si-formed α-Al2O3 tube was more stable in corrosive HI gas than a membrane with a γ-Al2O3-formed α-Al2O3 tube after 300 h of stability tests. In conclusion, the developed silica membranes using the Si-formed α-Al2O3 tubes seem suitable for membrane reactors that produce H2 on large scale using HI decomposition in the thermochemical iodine–sulfur process.

CsPbI3 triggers strong interest in the photovoltaic community for their promising photoelectric property and nonvolatility. However, CsPbI3 layers with a-phase crystal structure are difficult for preparation, and these layers easily degrade to non-photoactive δ-phase at room temperature. Tuning the composition of precursor solutions is an important method for improving the properties of CsPbI3 layers. Herein, we prepare inorganic a-CsPbI3 perovskite solar cells using lead acetate as the lead source, which is different from conventional precursors with lead iodide as the lead source. The lead acetate precursor needs neither incorporating hydrogen iodide nor preparing PbI2 complex, and it is shown to enlarge the grain size, improve the crystallinity and reduce the trap density of CsPbI3 layers. By cooperating the lead acetate precursor with EDAI2 additive, the power conversion efficiency (PCE) of devices increases from 9.2% to 12.9% and the photo-stability of these devices is improved simultaneously.

A thermochemical water-splitting iodine–sulfur process offers the potential for mass-producing hydrogen at high-efficiency levels, and it uses high-temperature heat sources, including high-temperature gas-cooled reactors, solar heat, and waste heat of industries. The raw material (H2O) is split into H2 and O2 by combining three chemical reactions using sulfur and iodine. Currently, R&D tasks are essential to confirm the integrity of the components that are made of practical structural materials and the stability of hydrogen production in harsh working conditions. A test facility for producing hydrogen was constructed from corrosion-resistant components that are developed using industrial materials. In addition, for stable hydrogen production, technical issues for instrumental improvements (i.e., stable pumping of the hydrogen iodide (HI)–I2–H2O solution without locking the shaft seal, prevention of leakage by improving the quality control of glass-lined steel, prevention of I2 precipitation using a water removal technique in a Bunsen reactor) were solved. The entire process was successfully operated for 150 h at the rate of ca. 30 L/h. The integrity of components made of practical structural materials and the operational stability of the hydrogen production facility in harsh working conditions were demonstrated.

Using simple and efficient methods to synthesize biological activated carbon catalysts (ACCs) with the decomposition of hydrogen iodide (HI) in the sulfur-iodine cycle as a typical reaction is urgently needed for the commercialization of hydrogen energy production and development. In this study, a series of ACCs with different specific surface areas (SSAs) and pore structures are prepared by comparing and controlling the changes in carbonization and activation methods of activated carbon (AC) preparation process. Hierarchical porous AC with larger SSA has higher HI decomposition efficiency. The representative samples H240H1h and H240C4h are hierarchical porous ACCs with 48.96% and 46.88% micropores, respectively, and have the highest catalytic activity in the entire series. The nitrogen adsorption and desorption curve is combined with pore size distribution data and analyzed using the capillary aggregation (Kelvin) and monolayer adsorption (Langmuir) theories. And ACC pore grading coefficient—which can improve data visualization—is introduced.

Iodine evaporated from lead–bismuth eutectic (LBE) has been examined with respect to its adsorption behavior on stainless steel in various gases to establish a base for safety evaluations on LBE based nuclear reactors. In inert conditions the iodine forms a single species with an adsorption enthalpy between − 97 and − 106 kJ/mol. The adsorbed species is tentatively identified as bismuth monoiodide, BiI. Addition of moisture to the inert gas has no substantial influence on the adsorption behaviour. For the reducing hydrogen carrier gas depositions with adsorption enthalpies ranging from − 87 to − 134 kJ/mol were observed in dry and water saturated conditions. The larger variation of adsorption enthalpies compared to analogous experiments in helium likely result from surface effects induced by the reactive gas. Formation of highly volatile species such as hydrogen iodide HI was not observed. In oxidizing conditions multiple iodine species with adsorption enthalpies ranging from − 67 to − 83 kJ/mol were observed, with the exception of one experiment where only a lower limit of –ΔHads

The selective reduction of α,β-unsaturated carbonyl compounds was achieved to produce saturated carbonyl compounds with aqueous HI solution. The introduction of an aryl group at an α or β position ...

The first example of a palladium-catalyzed oxidative carbonylative S-cyclization process carried out under aerobic conditions is reported. The method is based on the use of the PdI2/KI catalytic system and an acetylenic substrate bearing a sulfurated group in suitable position for attacking the coordinated triple bond. To avoid the possible oxidation of a free thiol group, a methylthio group was used as sulfur nucleophile, since the methyl group on sulfur could be removed under the reaction conditions by reaction with the iodide anion to give methyl iodide. In particular, we have employed as substrates 1-(methylthio)-3-yn-2-ols, which, upon S-cyclization, demethylation, and alkoxycarbonylation, led to thiophene-3-carboxylic esters in one step, in alcohols as external nucleophile and solvents, and under 40 atm of a 4:1 mixture of CO-air (air being the source of oxygen, used as external oxidant). The Pd(0) species deriving from the alkoxycarbonylation process was reoxidized back to catalytically active PdI2 by the action of oxygen in combination with the hydrogen iodide ensuing from the alkoxycarbonylation step and from water attack to methyl iodide. This new synthetic transformation could be successfully applied to a variety of differently substituted 1-(methylthio)-3-yn-2-ols, including substrates bearing geminal dialkyl substituents.

L-2-[18 F]fluoro-alpha-methylphenylalanine (2-[18 F]FAMP) is a promising amino acid tracer for positron emission tomography (PET) imaging, yet the low production yield of direct electrophilic radiofluorination with [18 F]F2 necessitates further optimization of the radiolabeling process. This paper describes a two-step preparation method for L-2-[18 F]fluoro-alpha-methylphenylalanine (2-[18 F]FAMP) starting from [18 F]fluoride. The (Mesityl)(L-alpha-methylphenylalanine)-2-iodonium tetrafluoroborate precursors with various protecting groups were prepared. The copper-mediated 18 F-fluorination of the iodonium salt precursors successfully produced 2-[18 F]FAMP. The highest radio chemical conversion of 57.6% was noted with N-Piv-protected (mesityl)(aryl)iodonium salt in the presence of 5 equivalent of Cu (OTf)2 . Subsequent deprotection with 57% hydrogen iodide produced 2-[18 F]FAMP within 120 min in 21.4 ± 11.7% overall radiochemical yield with >95% radiochemical purity and an enantiomeric excess >99%. The obtained 2-[18 F]FAMP showed comparable biodistribution profiles in normal mice with that of the carrier-added 2-[18 F]FAMP. These results indicate that usefulness of copper mediated 18 F-fluorination for the production of 2-[18 F]FAMP, which would facilitate clinical translation of the promising tumor specific amino acid tracer. Individual facilities could adopt either production method based on radioactivity demand and equipment availability.

A transition metal-free and efficient TBHP/TBAI-mediated protocol has been developed for the synthesis of 4H-chromen-4-ones from chroman-4-ones via oxidative C–C bond formation. It proceeds in the presence of a catalytic amount of tetrabutylammonium iodide and oxidant tert-butyl hydroperoxide (TBHP, 5–6 M in decane) to afford the corresponding products in good to excellent yields. Furthermore, it has been observed that an increase in the concentration of TBHP to 30 mol % drastically increases the yield of 4H-chromen-4-ones, any further increase will lead to a decrease in percent yield. The mechanism of this reaction involves the generation of tertiary butoxide radical initially which by oxidative single-electron transformation is converted to iodochroman-4-one. Later the hydrogen iodide is removed from iodochroman-4-one to give the desired product, i.e. 4H-chromen-4-ones. Moreover, this is a rare example of the n-Bu4NI/TBHP-mediated C–C bond through dehydrogenative reaction.

As an important biomass-derived chemical, d-sorbitol can be converted to a variety of useful chemicals and fuels. Because of the strong nucleophilicity of I– and reducibility of hydrogen iodide (HI...

A series of N-doped activated carbon (NAC) with varying N contents were prepared to study the effect of N-doping on hydrogen iodide (HI) decomposition over activated carbon in sulfur-iodine (SI) cycle for hydrogen production. Element analysis, XPS and N2 adsorption were performed for samples’ characterization. The HI conversion was proportional to the N content and the sample with 6.006% N content gave the highest HI conversion of 22.84%. Density functional theory (DFT) calculations confirmed the experimental results and elucidated the influence mechanism. The increase of N contents was favor to the decomposition of HI by enhancing the chemisorption of HI molecule on carbon structure. The role of N-doping was to remodel the local electronic density and charge distribution on the carbon surface. In addition, the effect of types of N-containing functional groups on HI decomposition was calculated. Results showed that the N-6 structure was conducive to the chemisorption of HI but N-5 and N-Q structures had a reverse effect. However, when the three N-containing functional groups exist simultaneously, the overall chemisorption of HI was enhanced, which, in turn, enhanced the decomposition of HI. This study can provide underlying guidance for preparing highly efficient NAC for HI decomposition.

In this study, the catalytic decomposition of hydrogen iodide was theoretically and experimentally investigated in a silica-based ceramic membrane reactor to assess the reactor's suitability for thermochemical hydrogen production. The silica membranes were fabricated by depositing a thin silica layer onto the surface of porous alumina ceramic support tubes via counter-diffusion chemical vapor deposition of hexyltrimethoxysilane. The performance of the silica-based ceramic membrane reactor was evaluated by exploring important operating parameters such as the flow rates of the hydrogen iodide feed and the nitrogen sweep gas. The influence of the flow rates on the hydrogen iodide decomposition conversion was investigated in the lower range of the investigated feed flow rates and in the higher range of the sweep-gas flow rates. The experimental data agreed with the simulation results reasonably well, and both highlighted the possibility of achieving a conversion greater than 0.70 at decomposition temperature of 400 °C. Therefore, the developed silica-based ceramic membrane reactor could enhance the total thermal efficiency of the thermochemical process.

Solar-driven photoelectrochemical (PEC) hydrogen production offers a promising solution to simultaneously tackle the global energy crisis and the environmental pollution. Herein, we report a PEC cell of organic-inorganic hybrid perovskite (methylammonium lead iodide, MAPbI3)-TiO2 nanorod array (TNAs) for efficient and stable hydrogen evolution in aqueous hydrogen iodide (HI) solution. The built-in electric field created across the MAPbI3-TiO2 junction is able to efficiently separate the electron-hole pairs photogenerated in MAPbI3 with electrons quickly injected from MAPbI3 to TiO2, which are then transported along the one-dimensional TiO2 nanorod channels to the counter electrode to reduce proton to evolve hydrogen. The optimized MAPbI3-TNA PEC cell exhibits a high photocurrent density of 1.75 mA cm−2 at 0.14 V (vs. Ag/AgCl) under AM 1.5G illumination, which is able to stably produce molecular hydrogen at a rate of 33.3 μmol cm−2 h−1 for more than 8 h.

A convenient method for the synthesis of methyl 8-oxo-3H,8H-2a,5a,7-triazaacenaphthylene-2-carboxylate by iodination of 7-allyl-4-methoxypyrrolo[2,3-d]pyrimidine-6-carboxylic acid methyl ester followed by elimination of hydrogen iodide has been developed. The use of 4-methoxypyrrolo[2,3-d]pyrimidine-6-carboxylic acid as the starting compound led to the formation of iodomethylpyrimido[5',4':4,5]-pyrrolo[2,1-c][1,4]oxazine, a promising precursor for the synthesis of a new tricyclic system based on pyrrolo[2,3-d]pyrimidine.

The potential of the silica membrane reactors for use in the decomposition of hydrogen iodide (HI) was investigated by simulation with the aim of producing CO2-free hydrogen via the thermochemical water-splitting iodine-sulfur process. Simulation model validation was done using the data derived from an experimental membrane reactor. The simulated results showed good agreement with the experimental findings. The important process parameters determining the performance of the membrane reactor used for HI decomposition, namely, reaction temperature, total pressures on both the feed side and the permeate side, and HI feed flow rate were investigated theoritically by means of a simulation. It was found that the conversion of HI decomposition can be improved by up to four times (80%) or greater than the equilibrium conversion (20%) at 400 °C by employing a membrane reactor equipped with a tubular silica membrane. The features to design the membrane reactor module for HI decomposition of the thermochemical iodine-sulfur process were discussed under a wide range of operation conditions by evaluating the relationship between HI conversion and number of membrane tubes.

The sulfur–iodine (SI) cycle is deemed to be one of the most promising alternative methods for large-scale hydrogen production by water splitting, free of CO2 emissions. Decomposition of hydrogen iodide is a pivotal reaction that produces hydrogen. The homogeneous conversion of hydrogen iodide is only 2.2% even at 773 K [1]. A suitable catalyst should be selected to reduce the decomposition temperature of HI and attain reaction yields approaching to the thermodynamic equilibrium conversion. However, residual H2SO4 could not be avoided in the SI cycle because of incomplete purification. The H2SO4 present in the HI feeding stream may lead to the poisoning of HI decomposition catalysts. In this study, the activity and sulfur poisoning of Ru and Ni catalysts loaded on carbon and alumina, respectively, were investigated at 773 K. HI conversion efficiency markedly decreased from 21% to 10% with H2SO4 (3000 ppm) present, which was reversible when H2SO4 was withdrawn in the case of Ru/C. In the case of Ru/C and Ni/Al2O3, catalyst deactivation depends on the concentration of H2SO4; the higher the concentration of H2SO4, the greater the severity of deactivation. Catalysts before and after sulfur poisoning were characterized by transmission electron microscopy (TEM), energy-dispersive X-Ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Experimental results and characterization of poisoned and fresh catalysts indicate that the catalyst deactivation could be ascribed to the competitive adsorption of sulfur species and change in its surface properties.

Organic-inorganic lead halide perovskites are a new class of semiconductor materials with great potential in photocatalytic hydrogen production, however, their development is greatly plagued by their low photocatalytic activity, instability of organic component and lead toxicity in particular. Herein, we report an anti-dissolution environmentally friendly Cs2SnI6 perovskite anchored with a new class of atomically dispersed Pt-I3 species (PtSA/Cs2SnI6) for achieving the highly efficient photocatalytic hydrogen production in HI aqueous solution at room temperature. Particularly, we discover that Cs2SnI6 in PtSA/Cs2SnI6 has a greatly enhanced tolerance towards HI aqueous solution, which is very important for achieving excellent photocatalytic stability in perovskite-based HI splitting system. Remarkably, the PtSA/Cs2SnI6 catalyst shows a superb photocatalytic activity for hydrogen production with a record turnover frequency of 70.6 h−1per Pt, about 176.5 times greater than that of Pt nanoparticles supported Cs2SnI6 perovskite, along with superior cycling durability. Charge-carrier dynamics studies in combination with theory calculations reveal that the dramatically boosted photocatalytic performance on PtSA/Cs2SnI6 originates from both unique coordination structure and electronic property of Pt-I3 sites, and strong metal-support interaction effect that can not only greatly promote the charge separation and transfer, but also substantially reduce the energy barrier for hydrogen production. This work opens a new way for stimulating more research on perovskite composite materials for efficient hydrogen production.

Carbon as a catalyst and catalyst support have wide range of applications. Noble metal like platinum when supported on carbon becomes a popular catalyst, where structure and properties of the carbon also play an important role in the overall performance of the catalyst. In this article, we report the preparation of carbon from rice and its use as a support for platinum catalyst. Two different catalysts were prepared using this carbon support. These catalysts were characterized by X-ray diffraction, Raman and X-ray photoelectron spectroscopy. The catalysts were used for hydrogen iodide (HI) decomposition reaction of the sulphur–iodine cycle, one of the most efficient thermochemical cycles for hydrogen production from water. The catalysts were also evaluated for the stability in the reaction conditions.

Despite intriguing optoelectronic attributes in solar cells, light-emitting diodes, and photocatalysis, the instability of organic-inorganic perovskites poises a grand challenge for long-term applications. Herein, we report a simple yet robust strategy via light-and-solution treatment to create an organic membrane that effectively passivates CH3NH3PbI3 (MAPbI3). Specifically, the restructuring of MA+ is observed on MAPbI3 in aqueous hydrogen iodide. HIO3 molecules are generated via the reaction between water and I2 induced by photocatalysis when MAPbI3 is illuminated. The hydrogen bonding between HIO3 molecules at different perovskite particles not only directs the creeplike growth of perovskite particles but also in situ forms a passivating layer firmly anchoring on the perovskite surface with hydrophilic -NH3+ groups tethering to perovskites and hydrophobic -CH3 moieties exposed to air. Intriguingly, such MA+ film greatly improves the stability of perovskites against moisture as well as their crystal quality, considerably enhancing the photocatalytic hydrogen evolution rate.

This chapter presents a brief review on the radiolysis effect on chemical forms of iodine under the condition of nuclear reactor accidents especially in containments. Radioactive iodine is one of the most important fission products in relation to their release to environment in nuclear reactor accidents. The iodine species released from fuels will get into aqueous phase in containments according to accident scenario. Cesium iodide and hydrogen iodide are very soluble in water and dissociate almost completely in the aqueous phase, giving iodide ions. There have been some thermodynamical and kinetic approaches to understanding of chemical behavior of iodine in relation to nuclear reactor accidents. On the other hand, when iodine species are subject to radiation in the aqueous phase, the radiolysis has a possibility to give a large effect on the chemical form of the iodine species. This radiolytic effect is currently one of the great concerns in the source term problems of nuclear reactor accidents.

The thermochemical sulfur-iodine cycle is a potential method for hydrogen production, and the hydrogen iodide (HI) decomposition is the key step to determine the efficiency of hydrogen production in the cycle. To further reduce the irreversibility of various transmission processes in the HI decomposition reaction, a one-dimensional plug flow model of HI decomposition tubular reactor is established, and performance optimization with entropy generate rate minimization (EGRM) in the decomposition reaction system as an optimization goal based on finite-time thermodynamics is carried out. The reference reactor is heated counter-currently by high-temperature helium gas, the optimal reactor and the modified reactor are designed based on the reference reactor design parameters. With the EGRM as the optimization goal, the optimal control method is used to solve the optimal configuration of the reactor under the condition that both the reactant inlet state and hydrogen production rate are fixed, and the optimal value of total EGR in the reactor is reduced by 13.3% compared with the reference value. The reference reactor is improved on the basis of the total EGR in the optimal reactor, two modified reactors with increased length are designed under the condition of changing the helium inlet state. The total EGR of the two modified reactors are the same as that of the optimal reactor, which are realized by decreasing the helium inlet temperature and helium inlet flow rate, respectively. The results show that the EGR of heat transfer accounts for a large proportion, and the decrease of total EGR is mainly caused by reducing heat transfer irreversibility. The local total EGR of the optimal reactor distribution is more uniform, which approximately confirms the principle of equipartition of entropy production. The EGR distributions of the modified reactors are similar to that of the reference reactor, but the reactor length increases significantly, bringing a relatively large pressure drop. The research results have certain guiding significance to the optimum design of HI decomposition reactors.

International audience; Solar‐to‐fuel conversion with organic–inorganic hybrid halide perovskites has attracted growing attention as a result of their excellent optoelectronic properties as well as the low temperature of the solution based fabrication process. However, the most comprehensively developed hybrid perovskite materials are comprised of the toxic metal lead, raising concerns about environmental health threats. Herein, a lead‐free bismuth (Bi)‐based hybrid perovskite showing in situ growth of heterojunctions is successfully developed at the interface of methylammonium bismuth iodide (MA3Bi2I9) and tri(dimethylammonium) hexa‐iodobismuthate (DMA3BiI6) by a facile solvent engineering technique. The air‐stable MA3Bi2I9/DMA3BiI6 perovskite heterostructure with enhanced photoinduced charge separation exhibit outstanding visible‐light‐induced photocatalytic activity for H2 evolution in aqueous hydrogen iodide solution. The powdered MA3Bi2I9/DMA3BiI6 heterostructured composite (BBP‐5) shows a H2 evolution rate of 198.2 µmol h−1 g−1 without the addition of Pt co‐catalysts under 100 mW cm−2 of visible‐light (λ ≥ 420 nm) illumination.

A first-principles density functional theory calculation was carried out to study the adsorption of acetic acid, methyl amine, methanethiol, and hydrogen iodide on the (100) surface of PbS. All four ligands are common capping agents used in colloidal PbS quantum dot-based photovoltaics. Interestingly, among the considered adsorbates, dissociative adsorption was energetically preferred for hydrogen iodide, while associative adsorption was favorable for the rest. Associative adsorption was driven by strong interactions between the electronegative elements (Y) in the respective ligands and the Pb surface atoms via Pb 6

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).

Photocatalytic hydrogen production from aqueous hydrogen iodide (HI) over alkali metal tantalates loaded with Pt (Pt/ATaO3, A = Li, Na, or K) was demonstrated. Of the photocatalysts examined, Pt/KTaO3 showed the highest photocatalytic activity for HI decomposition. KTaO3, having the lowest excitation energy, absorbs the largest number of photons for use in photocatalytic reactions, and its corresponding catalyst has the highest number of reaction sites owing to the excellent dispersion of the Pt cocatalyst. These results demonstrate the possibility of developing a new solar-energy-based water splitting process that can convert both light and thermal energy in sunlight to hydrogen energy.

A photoinitiating system for controlled cationic polymerization of isopropyl vinyl ether (IPVE) was developed using diaryliodonium salts as the photoinitiator. UV irradiation triggered the degradation of diphenyliodonium iodide, which was followed by the controlled polymerization of IPVE mediated by long-lived propagating species. Polymerization was most likely initiated via the generation of hydrogen iodide through photodegradation of the initiator. The propagation reactions then proceeded via the spontaneous cleavage of carbon–iodine bonds in the initiating and propagating chain ends. In addition, other photoinitiators that do not possess an iodide anion as a counteranion induced long-lived-species-mediated cationic polymerization of IPVE when combined with a tetraalkylammonium iodide.

2-Iodomethyl-2,3-dihydro[1,3]oxazolo[3,2-a]pyridinium triiodide was synthesized by the reaction of 1-allylpyridin-2(1H)-one with hydrogen iodide in the presence of hydrogen peroxide or with iodine in acetone. The title compound reacted with palladium(II) iodide in DMSO to give crystalline bis(2-iodomethyl-2,3-dihydro[1,3]oxazolo[3,2-a]pyridinium) di-μ2-iodido-tetraiodidodipalladate(II) whose structure was proved by X-ray analysis. The reaction of 2-iodomethyl-2,3-dihydro[1,3]oxazolo[3,2-a]pyridinium triiodide with sodium iodide in acetone afforded 2-iodomethyl-2,3-dihydro[1,3]oxazolo[3,2-a]pyridinium iodide which decomposed into initial 1-allylpyridin-2(1H)-one and iodine on heating in methanol.

The current work presents the synthesis of carbon nanotubes supported palladium catalyst for hydrogen production from hydrogen-iodide decomposition in thermochemical water-splitting sulfur-iodine (SI) cycle. XRD results showed that the Pd nanoparticles were highly dispersed on the CNT support. Raman results showed that Pd(3%) possessed the highest quantity of defects than other loaded Pd samples and CNT support. The order of catalytic activity for hydrogen-iodide decomposition is: Pd(3%)/CNT > Pd(5%)/CNT > Pd(1%)/CNT > CNT. This is due to high degree of defects present in Pd(3%)/CNT as compared to others. Pd(3%)/CNT also showed an excellent stability of 100 h for the reaction. The post-characterizations (BET, ICP-AES, XRD and TEM) of spent-Pd(3%)/CNT after 100 h were carried out in order to find out the changes in the specific surface area, elemental analysis, structure and particle size. No changes were observed in the specific surface area, elemental analysis, particle size, and structure of the spent catalyst as compared to the fresh one. This shows the Pd/CNT has a lot of potential of generating hydrogen in the thermochemical SI cycle.

Photovoltaic devices require p-type layers with high optical transparency and electrical conductivity. One promising material is cuprous iodide, CuI, thin films of which have hole mobilities in the 1–12 cm2/V·s range. However, despite adequate electrical properties in many CuI thin films, most deposition processes afford only rough films that have poor continuity and low optical transparency, hampering the final device performance. We now report an all-vapor method, amenable to large-scale processing, for preparation of CuI thin films with near record optical and electrical properties. In this process, thin films of Cu(2–x)S (x = 0–0.1) or Cu2O grown by chemical vapor deposition from bis(N,N′-di-sec-butylacetamidinato)dicopper(I) in combination with hydrogen sulfide or water, respectively, were converted to γ-CuI upon exposure to dilute hydrogen iodide vapor. The rate of this iodide-for-chalcogenide anion exchange reaction is controlled by the concentration and delivery rate of HI. The nucleation rate of ...

The preparation of anhydrous hydrogen iodide directly from molecular hydrogen and iodine using a rhodium catalyst is reported for the first time. The anhydrous hydrogen iodide generated was proven to be highly active in the transformations of alkenes, phenyl aldehydes, alcohols, and cyclic ethers to the corresponding iodoalkanes. Therefore, the present methodology not only has provided convenient access to anhydrous hydrogen iodide but also offers a practical preparation method for various iodoalkanes in excellent atom economy.

Sulfur-iodine thermochemical water splitting cycle is a promising and carbon dioxide-free method for hydrogen production. Among the reactions in this cycle, hydrogen iodide catalytic decomposition is the rate-determining step. In this study, catalytic reactivity test combined with characterizations of nitrogen physisorption, X-Ray diffraction, and Raman spectroscopy provide evidences that hydrofluoric acid modified semi-coke is a promising catalyst candidate for hydrogen iodide decomposition because of its high active and low cost. The raw semi-coke enhanced the hydrogen iodide conversion rate. After modification of hydrofluoric acid, the catalytic activity of semi-coke increased largely. Semi-coke modified by 40 wt% hydrofluoric acid showed better performance than commercial activated carbon catalyst. Combine the characterization results and catalytic reactivity, the graphitic edge carbon atoms in semi-coke are the active sites for hydrogen iodide decomposition. This finding pointed out the direction of carbon material catalyst design for hydrogen iodide decomposition.

Ceria (CeO2) and Ir-doped CeO2 nanoparticles are tested for catalytic hydrogen-iodide decomposition in a thermochemical sulfur-iodine (SI) cycle. Ir-doped CeO2 strongly increases the hydrogen-iodid...

Reaction of 2-sulfanylbenzoxazole with 1-iodopropan-2-one, 2-iodo-1-phenylethanone, and 2-iodo-1-(thiophen-2-yl)ethanone without solvent and bases afforded bis(benzoxazol-2-yl)disulfonium derivatives in a single preparative stage. The reaction proceeds as a domino-process and includes the alkylation of a sulfanyl group of benzoxazole, the reduction of iodoketone with hydrogen iodide, the oxidation of 2-sulfanylbenzoxazole to disulfide, the alkylation of disulfide atoms of sulfur, and the formation of triiodideanions. The yield of disulfonium derivatives increases twice in the presence of equimolar amount of iodine.

We report the H I bond activation on free and confined silver tetramer clusters using the first principles approach. The objective of this study is to underscore the effect of confinement on the chemical reactivity of Ag4. All calculations were carried out under the density functional theory formalism using both atomic and plane wave basis sets. We have used armchair carbon nanotube as a model system for confinement. The results show that the interaction energy is increased inside nanotube, leading to enhanced bond stretching. The origin of such effect has been demonstrated using molecular orbital theory and electronic density of state analysis.

With the goal of eventually developing a replacement for the Claus process that also produces H 2 , we have explored the possibility of decomposing hydrogen sulfide through a thermochemical cycle involving iodine. The thermochemical cycle under investigation leverages differences in temperature and reaction conditions to accomplish the unfavorable hydrogen sulfide decomposition to H 2 and elemental sulfur over two reaction steps, creating and then decomposing hydroiodic acid. This proposed process is similar to ideas put forth in the 1980s and 1990s by Kalina, Chakma, and Oosawa, but makes use of thermochemical hydrogen iodide decomposition methods and catalysts rather than electrochemical or photoelectrochemical methods. Process models describing a potential implementation of this thermochemical cycle were created. Motivated by the process model results, experimentation showed the possibility of using alternative solvents to dramatically decrease the energy requirements for the process. Further process modeling incorporated these alternative solvents and suggests that this theoretical hydrogen sulfide processing unit has favorable economic and environmental properties.

The present work applies the density functional theory (DFT) to study the interactions between armchair (n,n) single walled carbon nanotubes (SWCNTs) and hydrogen halides confined along the nanotube axis and perpendicular to it. Calculations are performed using the CAM-B3LYP functional. According to the hydrogen halides orientation and the internal diameter of CNTs hollow space, HF, HCl, HBr and HI behave differently. The nanoconfinement alters the charge distribution and the dipolar moment. The encapsulated hydrogen fluoride (HF) molecule is stable along and perpendicular to the nanotubes (5,5) and (6,6) axis. The hydrogen chloride (HCl), hydrogen bromide (HBr) and hydrogen iodide (HI) form stable systems inside the nanotube (6,6) only at the perpendicular orientation. In addition, other phenomena are observed such as leaving the nanotube or decreasing the bond length of the molecule and even the creation of covalent bind between the guest molecule and the host nanotube.

HI decomposition in Iodine-Sulfur (IS) thermochemical process for hydrogen production is one of the critical steps, which suffers from low equilibrium conversion as well as highly corrosive environment. Corrosion-resistant metal membrane reactor is proposed to be a process intensification tool, which can enable efficient HI decomposition by enhancing the equilibrium conversion value. Here we report corrosion resistance studies on tantalum, niobium and palladium membranes, along with their comparative evaluation. Thin layer each of tantalum, palladium and niobium was coated on tubular alumina support of length 250 mm and 10 mm OD using DC sputter deposition technique. Small pieces of the coated tubes were subject to immersion coupon tests in HI-water environment (57 wt% HI in water) at a temperature of 125–130 °C under reflux environment, and simulated HI decomposition environment at 450 °C. The unexposed and exposed cut pieces were analyzed using scanning electron microscope (SEM), energy dispersive X-ray (EDX) and secondary ion mass spectrometer (SIMS). The extent of leaching of metal into liquid HI was quantified using inductively coupled plasma-mass spectrometer (ICP-MS). Findings confirmed that tantalum is the most resistant membrane material in HI environment (liquid and gas) followed by niobium and palladium.

One of the most important factors governing the photovoltaic efficiency and environmental stability of Perovskite Solar Cells (PSCs) is the quality of their perovskite films. However, the present study demonstrates that CH3NH3PbI3 perovskite films after anti-solvent washing are far from perfect on the surface, where the crystallization degree is quite low with complex multi-phases associated with numerous defects and notable chemical inhomogeneity. Herein, we report a novel anti-solvent washing treatment simply using Hydrogen Iodide (HI) additive in chlorobenzene (CB) which can enormously improve CH3NH3PbI3 films surface with high crystallization phase purity and chemical homogeneity, leading to excellent structural stability under humidity, heat and even tensile force. Based on such high quality films with defect-less surface, fabricated planar PSCs with an architecture of ITO/TiO2/CH3NH3PbI3/Spiro-OMeTAD/MoOx/Au present a champion PCE of 19.94% and improved stability under humidity. Moreover, fabricated flexible planar PSCs on PET/ITO substrates with a champion PCE of 17.32% are shown to be more robust under tensile force than their control devices. The present study thus not only provides more insight into the facile defects passivation process on the surface achieved via balancing halide ions, but also provides a practical but efficient treatment which can be widely used to fabricate high quality CH3NH3PbI3 films for environmentally stable high performance device applications.

In this work, TiO2 nanoparticles have been prepared by the sol–gel (at different calcination temperatures) and solution-combustion method for hydrogen-iodide decomposition in thermo-chemical water-splitting sulfur-iodine (SI) cycle for hydrogen production. The sol-gel method derived TiO2 (TiO2-SGM-300 and TiO2-SGM-500) provide smaller nanoparticles as compared to the solution-combustion (TiO2-SCM). TEM revealed a particle size of around 4–5 nm of TiO2-SGM-300. XRD and Raman confirmed that TiO2-SGM-300 and TiO2-SGM-500 exhibited pure anatase phase, whereas a small amount of rutile phase was observed in TiO2-SGM-700 and TiO2-SCM samples. It is found that with increase in calcination temperatures during sol-gel method, the average particle size of TiO2 increases and specific surface area decreases. Commercial TiO2 (Degussa P-25) was used for the comparison purpose. As far as the author knows, TiO2 has been used here for the first time for hydrogen-iodide decomposition. The hydrogen-iodide decomposition experiments were carried out in a vertical-fixed bed quartz reactor at a WHSV of 12.9 h−1 under atmospheric pressure. The order of catalytic activity was as follows: TiO2-SGM-300 > TiO2-SCM > TiO2-COMM (commercial). Also, it was observed that the hydrogen-iodide conversion decreases with increase in calcination temperatures of TiO2 during sol–gel method. Their activity was as follows: TiO2-SGM-300 > TiO2-SGM-500 > TiO2-SGM-700. TiO2-SGM-300 catalyst also showed a reasonable time-on-stream stability of 6 h for hydrogen-iodide decomposition. The apparent activation energy of TiO2-SGM-300 is found to be 72.29 kJ mol−1. This shows that the TiO2 has a potential of generating hydrogen from hydrogen iodide in SI cycle. This can further be explored as a catalyst support using some non-precious and precious metal catalysts for hydrogen-iodide decomposition.

A new protocol for the synthesis of 2-substituted quinolines from 2-aminostyryl ketones has been developed using iodide as a nucleophilic catalyst. Conjugate addition of iodide to 2-aminostyryl ketones yielded the corresponding β-iodoketones, which could have a conformation where the amino and carbonyl groups are proximal through free rotation about the Cα–Cβ single bond. Subsequent condensation between the amino and carbonyl groups followed by elimination of hydrogen iodide provided the corresponding quinolines, with regeneration of the iodide catalyst.

The need to produce Hydrogen in an environmentally friendly manner has increased as the transportation industry has started to employ cleaner sources of energy. One of the cleaner ways to produce H2, is to use the Bunsen S-I cycle. This includes the separation of the H2 from an ionic mixture of Hydrogen Iodide and water using distillation. In this work, the Pitzer’s model for electrolyte solutions has been employed to represent the vapour-liquid equilibrium (VLE) of the binary system of HI and H2O. The activity coefficient (γ) is calculated from the equation which indicated the non-ideal nature of the system and aided the calculation of the vapour phase mole fraction. The experimental VLE data was obtained from a recirculating still at 101.3 kPa pressure for the binary system. This experimental data and data from literature was used to estimate the parameters of the Pitzer’s model to represent the activity coefficient of HI in this mixture. These optimized parameters could explain all the variations in the data with more that 90% accuracy for most of the data, with an average standard deviation of about 0.04. Furthermore, the temperature dependent form of the Pitzer’s equation was used to predict the VLE data at higher pressures of 3 and 5.7 bars and higher temperature conditions.

Graphene shows great promise as a high-efficiency electrothermal film for flexible transparent defoggers/defrosters. However, it remains a great challenge to achieve a good balance between the production cost and the properties of graphene films. Here, we proposed a cost-effective self-assembly method to fabricate high-performance, large-area graphene oxide/electrochemically exfoliated graphene hybrid films for heater applications. The self-assembled graphene hybrid films with the area of 20 × 20 cm2 could be transferred onto arbitrary substrates with nonplanar surfaces and simply patterned with the hard mask. After reduction by hydrogen iodide vapor followed by 800 °C thermal treatment, the hybrid films with the transmittance of 76.2% exhibit good heating characteristics and defogging performance, which reach a saturation temperature of up to 127.5 °C when 40 V was applied for 60 s.

The stability of perovskite is a bottleneck for the application of perovskite solar cells. Herein, 4-ethylamine Phenylphosphate disodium salt (EAPP) was explored as a functional surface ligand to passivate perovskite surface. As the addition of 1 mol% of EAPP, the degradation of the film in high humidity condition was effectively reduced. Solar cells based on EAPP doped perovskite film show merely slight decrease of its initial efficiency in high humidity condition, whereas the control device show catastrophic decrease. Apart from as a passivating molecule to protect perovskite from contacting with water, EAPP show function as a reducing reagent to bond with hydrogen iodide formed in perovskite decomposition.

A highly active and stable catalyst for hydrogen-iodide decomposition reaction in sulfur-iodine (SI) cycle has been prepared in the form of Pd CeO 2 nanocatalyst by sol-gel method with different calcination temperatures (300 °C, 500 °C, and 700 °C). XRD and TEM confirmed a size around 6–8 nm for Pd CeO 2 particles calcined at 300 °C. Raman study revealed large number oxygen vacancies in Pd CeO 2 -300 when compared to Pd CeO 2 -500 and Pd CeO 2 -700. With increase in calcination temperature, the average particle size increased whereas the specific surface area and number of oxygen vacancies decreased. Hydrogen-iodide catalytic-decomposition was carried out in the temperature range of 400°C–550 °C in a quartz-tube, vertical, fixed-bed reactor with 55 wt % aqueous hydrogen-iodide feed over Pd CeO 2 catalyst using nitrogen as a carrier gas. Pd CeO 2 -300 showed hydrogen-iodide conversion of 23.3%, which is close to the theoretical equilibrium conversion of 24%, at 550 °C. It also showed a reasonable stability with a time-on-stream of 5 h.

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.

Developing cost-effective and high-performance catalysts in biomass chemistry is motivated by creating sustainable technologies dependent on inexpensive and abundant resources. The existing methods for the direct preparation of 5-methylfurfural (5-MF) from biomass-derived fructose mediated by hydrogen iodide (HI) mainly require precious metal catalysts. This research showed that low-cost tungsten carbide (WC) was capable to produce HI from iodine (I2) via liquid-phase hydrogenation, but a pivotal limitation was the poor stability under the combination effects of water and I2. To solve this problem, the bulk WC and the high dispersion supported WC were modified by hydrophobic organosilicones through simple liquid phase deposition. Both of the two superhydrophobic WC materials had better stability and their catalytic activity were comparable to the expensive palladium-carbon (Pd/C) catalyst in the preparation of 5-MF, especially the superhydrophobic high dispersion supported WC. This work highlights the potential of the low-cost WC with simple superhydrophobic modification in assisting the direct preparation of 5-MF from fructose mediated by HI, which has high significance to the sustainable development of the low-cost biomass chemical engineering.

Hydrogen iodide decomposition is the core hydrogen production step in the sulfur-iodine thermochemical cycle, which determines the hydrogen production rate and thermal efficiency of the device. The conventional decomposition reactor is limited by equilibrium conditions, so the hydrogen iodide conversion rate is low at normal reaction temperature, and membrane reactor technology can break the limit of equilibrium condition and greatly improve the conversion rate. Most of the previous hydrogen iodide membrane reactor models were built under isothermal conditions and did not consider the influence of different sweep modes. In this paper, a one-dimensional non-isothermal hydrogen iodide decomposition membrane reactor mathematical model in co-current and countercurrent sweep modes is established, and the effects of reactor parameter on hydrogen iodide conversion and hydrogen recovery rate are analyzed under the two sweep modes. The results show that the countercurrent mode can obtain higher hydrogen iodide conversion rate than the co-current mode under larger sweep flow rate, inlet pressure of reaction and permeation zone, reactor length; the maximum recovery rate of hydrogen in countercurrent mode is close to 100%. A modified membrane reactor structure combining the traditional reactor and membrane reactor is proposed, which could effectively increase the hydrogen permeation flux per unit membrane surface. In engineering application, the reasonable design of the modified membrane reactor can effectively reduce the investment cost of the membrane reactor on the premise of satisfying the hydrogen production rate.