Halides Research Articles

Machine learning-driven determination of key absorber layer parameters in perovskite solar cells

Perovskite (PVK) materials have revolutionized solar cell research, achieving remarkable efficiency gains of over 26% in a short time span. A major factor behind this progress is the extensive research focused on absorber layer (AL) materials. The cell efficiency is largely influenced by the important physical properties of the AL, such as the bandgap (BG) and the energy levels of the valence band maximum (VBM) and conduction band minimum (CBM), which provide insights into the light absorption and the band offset with the charge transport layers. In this study, we implemented machine learning (ML) models to predict these three important parameters for AL. Using well-cleaned 551 experimental data from the perovskite database, we trained various ML algorithms, selecting CatBoost as the best performer for BG prediction with a test RMSE of an impressive 0.054 eV. The BG model showed very high accuracy when validated with 13 unseen experimentally reported data. This algorithm was further used to enhance the sets of ML models for CBM and VBM prediction, achieving RMSEs of 0.103 eV and 0.120 eV, respectively. For the refinement of the model’s performance, we have used Optuna for parameter tuning. Additionally, SHAP analysis provided valuable insights into the relative feature importance, aligning well with established theoretical principles for BG tuning through metal and halide ion mixing. These models represent the best-performing ML approach to date for predicting these parameters. This framework can dramatically enhance the search for optimal PVK compositions, reducing the need for resource-intensive experimentation.

Universal Approach for Managing Iodine Migration in Inverted Single‐Junction and Tandem Perovskite Solar Cells

AbstractDespite significant progress in the power‐conversion efficiency (PCE) of perovskite solar cells (PSCs), the instability of devices remains a considerable obstacle for commercial applications. This instability primarily originates from the migration of halide ions—particularly iodide ions (I−). Under light exposure and thermal stress, I− migrates and transforms into I2, leading to irreversible degradation and performance loss. To address this issue, we introduced the additive 2,1,3‐benzothiadiazole,5,6‐difluoro‐4,7‐bis(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl) (BT2F‐2B) into the perovskite. The strong coordination between the unhybridized p orbital and lone‐pair electrons from I− inhibits the deprotonation of MAI/FAI and the subsequent conversion of I− to I₂. The highly electronegative fluorine enhances its electrostatic interaction with I−. Consequently, the synergistic effect of BT2F‐2B effectively suppresses the decomposition of perovskite and the defect density of the iodide vacancies. This approach delivers a PCE over 26% for inverted single‐junction PSCs, with exceptional operational stability. According to the ISOS‐L‐3 testing protocol (maximum power point tracking at 85 °C and 50% relative humidity), treated PSCs retain 85% of their original PCE after 1000 h of aging. When the BT2F‐2B is applied to a wide‐bandgap (1.77 eV) perovskite system, the PCE of all‐perovskite tandem solar cells reaches 27.8%, confirming the universality of the proposed strategy.

Heterogenous Chemistry of I2O3 as a Critical Step in Iodine Cycling.

Global iodine emissions have been increasing rapidly in recent decades, further influencing the Earth's climate and human health. However, our incomplete understanding of the iodine chemical cycle, especially the fate of higher iodine oxides, introduces substantial uncertainties into atmospheric modeling. I2O3 was previously deemed a "dead end" in iodine chemistry; however, we provide atomic-level evidence that I2O3 can undergo rapid air-water or air-ice interfacial reactions within several picoseconds; these reactions are facilitated by prevalent chemicals on seawater such as amines and halide ions, to produce photolabile reactive iodine species such as HOI and IX (X = I, Br, and Cl). The heterogeneous chemistry of I2O3 leads to the rapid formation of iodate ions (IO3-), which is the predominant soluble iodine and its concentration cannot be well explained by current chemistry. These new loss pathways for atmospheric I2O3 can further explain its absence in field observations and its presence in laboratory experiments; furthermore, these pathways represent a heterogeneous recycling mechanism that can activate the release of reactive iodine from oceans, polar ice/snowpack, or aerosols. Rapid reactive adsorption of I2O3 can also promote the growth of marine aerosols. These findings provide novel insights into iodine geochemical cycling.

Chemical Synergic Stabilization of High Br‐Content Mixed‐Halide Wide‐Bandgap Perovskites for Durable Multi‐Terminal Tandem Solar Cells with Minimized Pb Leakage

AbstractHigh Br‐content lead mixed‐halide perovskites with wide‐bandgap (WBG) of 1.6–2.0 eV have showcased vast potential to be used in tandem solar cells. However, WBG perovskites often suffer from severe halide segregation, phase separation and ion migration under the stress of light, heat, moisture and electric bias, which would accelerate the decomposition of perovskite films and thus deteriorate the photovoltaic performance and even aggravate the lead leakage from damaged devices. Here, we report a novel chemical synergic interaction strategy to mitigate the abovementioned issues in WBG perovskites. To achieve that, a small amount of cationic β‐cyclodextrin, composed of multiple ammonium cations, chlorine ions and abundant hydroxyl functional groups, was introduced into WBG perovskites, which effectively stabilized the halide ions and homogenized the phase distribution, comprehensively passivated the crystallographic defects, as well as efficiently immobilized the Pb2+ ions. Encouragingly, the cationic β‐cyclodextrin was universal and useful for different WBG perovskite compositions (i.e. 1.68 eV, 1.79 eV and 1.99 eV), which favorably boosted the efficiencies by 10 %–36 % and extended the operational stability of resultant devices to 2680 h. The four‐terminal all‐perovskite tandem and six‐terminal all‐perovskite tandem solar cells integrated with different WBG perovskite sub‐cells exhibited efficiencies up to 24.39 % and 22.42 %, respectively. More importantly, we demonstrated the cationic β‐cyclodextrin‐assisted internal chemical encapsulation effectively prevented the Pb leakage when the devices were severely damaged and immersed in water. Surprisingly, there was only 5.63 ppb Pb leaching out for the single‐junction devices, far below than the U.S. standard for safe drinking water (<15 ppb). The target tandem solar cells with cationic β‐cyclodextrin modification also realized a Pb sequestration efficiency of 93.4 % under the most adverse environment.

Chemical Synergic Stabilization of High Br-Content Mixed-Halide Wide-Bandgap Perovskites for Durable Multi-Terminal Tandem Solar Cells with Minimized Pb Leakage.

High Br-content lead mixed-halide perovskites with wide-bandgap (WBG) of 1.6-2.0 eV have showcased vast potential to be used in tandem solar cells. However, WBG perovskites often suffer from severe halide segregation, phase separation and ion migration under the stress of light, heat, moisture and electric bias, which would accelerate the decomposition of perovskite films and thus deteriorate the photovoltaic performance and even aggravate the lead leakage from damaged devices. Here, we report a novel chemical synergic interaction strategy to mitigate the abovementioned issues in WBG perovskites. To achieve that, a small amount of cationic β-cyclodextrin, composed of multiple ammonium cations, chlorine ions and abundant hydroxyl functional groups, was introduced into WBG perovskites, which effectively stabilized the halide ions and homogenized the phase distribution, comprehensively passivated the crystallographic defects, as well as efficiently immobilized the Pb2+ ions. Encouragingly, the cationic β-cyclodextrin was universal and useful for different WBG perovskite compositions (i.e. 1.68 eV, 1.79 eV and 1.99 eV), which favorably boosted the efficiencies by 10 %-36 % and extended the operational stability of resultant devices to 2680 h. The four-terminal all-perovskite tandem and six-terminal all-perovskite tandem solar cells integrated with different WBG perovskite sub-cells exhibited efficiencies up to 24.39 % and 22.42 %, respectively. More importantly, we demonstrated the cationic β-cyclodextrin-assisted internal chemical encapsulation effectively prevented the Pb leakage when the devices were severely damaged and immersed in water. Surprisingly, there was only 5.63 ppb Pb leaching out for the single-junction devices, far below than the U.S. standard for safe drinking water (<15 ppb). The target tandem solar cells with cationic β-cyclodextrin modification also realized a Pb sequestration efficiency of 93.4 % under the most adverse environment.

Breaking dielectric dilemma via polymer functionalized perovskite piezocomposite with large current density output

Organometal halide perovskite (OHP) composites are flexible and easy to synthesize, making them ideal for ambient mechanical energy harvesting. Yet, the output current density from the piezoelectric nanogenerators (PENGs) remains orders of magnitude lower than their ceramic counterparts. In prior composites, high permittivity nanoparticles enhance the dielectric constant (ϵr) but reduce the dielectric strength (Eb). This guides our design: increase the dielectric constant by the high ϵr nanoparticle while enhancing the Eb by optimizing the perovskite structure. Therefore, we chemically functionalize the nanoparticles to suppress their electrically triggered ion migration for an improved piezoelectric response. The polystyrene functionalizes with FAPbBr2I enlarges the grains, homogenizes the halide ions, and maintains their structural integrity inside a polymer. Consequently, the PENG produces a current density of 2.6 µAcm−2N−1. The intercalated electrodes boost the current density to 25 µAcm−2N−1, an order of magnitude enhancement for OHP composites, and higher than ceramic composites.

White Light Emission in Europium‐Doped Inorganic Perovskite Single Matrix

AbstractThe realization of stable single‐component white light emission in metal halide perovskites is still challenging due to the fast halide ion migration and narrow luminescence bands. In this work, all‐inorganic single CsPbClxBr3−x perovskite microplates with stable red‐blue‐green triple color light emission are prepared by introducing europium ions Eu3+ as dopants. Eu doping effectively suppresses ion migration and enables two spatially separated halide phases with stable dual‐wavelength emissions. Furthermore, the incorporation of Eu3+ compensates for the absence of red‐light emission, thereby yielding a superior white emission with exceptional quality. The color rendering index of triple‐color‐emitting perovskites can be tuned successfully by controlling the halogen ratios, and the optimal microplate achieved a Commissions Internationale de l’Eclairage (CIE) coordinates of (0.32, 0.32). The results present a new enlightenment for the preparation of low‐cost single‐component white light materials.

The fluid/melt partitioning of chlorine, bromine and iodine in felsic magmas and the utility of halogen ratios to track the devolatilization and fluid fluxing of magma reservoirs

The release of fluids from magmas at crustal depths is an essential process for the formation of magmatic-hydrothermal ore deposits. However, assessing the extent of volatile loss by magma degassing or volatile gain by fluid fluxing from deeper magmas remains challenging. To develop a new tool to quantitatively track these processes, we experimentally determined the partition coefficients of Cl, Br, and I between aqueous fluids and haplogranitic melts (Dif/m) as a function of fluid salinity and the aluminum saturation index [ASI = Al2O3/(Na2O + K2O)] of the silicate melt. The experiments were conducted in externally heated rapid-quench René 41 cold-seal pressure vessel apparatus at 200 MPa and 790 ± 10 °C. The Br and I concentrations in the run product glasses were determined by laser ablation inductively coupled plasma mass spectrometry and secondary ion mass spectrometry, whereas the concentration of Cl was determined by electron probe microanalysis. The results show that the partition coefficients of the three halogens in a system with chloride-dominated fluids increase with fluid salinity increasing from 1.49 to 60.6 wt% total NaCl equivalent. Specifically, DClf/m increases from 23 ± 5 to 168 ± 7 (1σ), DBrf/m increases from 57 ± 13 to 271 ± 14, and DIf/m increases from 198 ± 61 to 736 ± 159. As for the influence of melt composition, DClf/m and DBrf/m attain maximum values at ASI = 1, whereas DIf/m appears to be independent of ASI within error. Bromine and iodine partition into the fluid more strongly in the presence of significant Cl, indicating that these halogens compete for the same structural sites in the silicate melt. Empirical equations were derived to predict the Df/m of Cl, Br, and I in felsic magmatic systems as a function of fluid salinity and silicate melt ASI. These equations were in turn implemented in numerical models simulating the degassing of granitic magma reservoirs emplaced in the Earth’s upper crust. The results of these calculations show that the Br/Cl and I/Cl ratios in the silicate melt and the released fluid rapidly decrease during progressive magma degassing at depth due to the significantly increasing fluid/melt partition coefficients with increasing halide ion radius. On the other hand, a sudden increase of Br/Cl and I/Cl in the silicate melt indicates fluid fluxing of the magma. Therefore, halogen ratios may become particularly useful tools to track crystallization-driven degassing if the record of the variation of the silicate melt composition can be recovered from silicate melt inclusions in minerals. In addition, the evolving Br/Cl and I/Cl ratios of magmatic fluids feeding magmatic-hydrothermal ore forming systems, as recorded by fluid inclusions in minerals, may inform about the evolution of the underlying magma reservoir.

Fighting poison with poison: Enhancing the performance of oxygen reduction reaction on Pt(111) via trace halide ion addition

The sluggish kinetics of the cathodic oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs) and phosphoric acid fuel cells (PAFCs) remains a primary obstacle to their large-scale application. Anionic adsorbates, such as OH, sulfonate, and phosphate, are widely recognized as detrimental species that diminish ORR activity. In this study, we present a novel approach aimed at mitigating the poisoning effect of such adsorbates and enhancing ORR performance by modifying either the electrolyte or the electrode with trace amounts of stronger adsorbates—a concept termed “fighting poison with poison.” Our results demonstrate that the addition of minute quantities of halide ions (e.g., Cl− or Br−) to commonly used electrolytes (0.05 M H2SO4, 0.05 M H3PO4, and 0.10 M HClO4) or to the Pt(111) electrode surface significantly boosts ORR activity. The inhibitory effect of stronger adsorbates on the shielding effect of those commonly adsorbed weaker adsorbates is probably the origin of such enhancement. The insights gained and strategies developed for optimizing the ORR activity of Pt(111) in this study offer valuable guidance for the future development of efficient catalysts and the optimization of electrolytes for PEMFCs and PAFCs.

Biobased Polymers Enabling the Synthesis of Ultralong Silver Nanowires and Other Nanostructures.

Conventional polyol synthesis of silver nanowires has exclusively relied on polyvinylpyrrolidone (PVP), a nonbiodegradable polymer with no viable alternatives. The underlying reaction mechanism remains unclear. Herein, we discovered a new sustainable solution by employing biobased cellulose derivatives, including hydroxyethyl cellulose (HEC), as effective substitutes for PVP. Under mild reaction conditions (125 °C, ambient pressure), HEC facilitates the growth of ultralong silver nanowires (>100 μm) from penta-twinned silver seeds through a four-stage kinetic process. Theoretical calculations further reveal that HEC is physiosorbed onto the silver surfaces, while the presence of bromide ions (Br-) facilitates the evolution of seeds into nanowires. By varying halide ion concentrations and substitution in different cellulose derivatives, we successfully synthesized silver nanostructures with additional intriguing morphologies, including quasi-spherical nanoparticles, bipyramids, and nanocubes. Furthermore, transparent conductive films fabricated from ultralong silver nanowires synthesized with HEC demonstrated superior performance compared to those made with PVP-synthesized nanowires.

Study on the sorption and desorption behavior of La3+ and Bi3+ by bis(2-ethylhexyl)phosphate modified activated carbon.

The separation of 213Bi from its parent radionuclide 225Ac via radionuclide generators has proven to be a challenge due to the limited performance of the current sorbents. This study evaluated the separation performance of La3+ (as a surrogate for 225Ac) and Bi3+ using bis(2-ethylhexyl)phosphate monofunctionalized activated carbon (HDEHP/AC). The potential applications of phosphate groups as active sites and the carbon structure as a sorbent support were confirmed and validated. Various factors, including pH values, salt concentration, halide ions, contact time, solid-to-liquid ratio, initial La3+/Bi3+ concentration, and gamma irradiation were examined through batch sorption experiments in both single and binary systems. HDEHP/AC had a high sorption capacity for La3+ via electrostatic attraction, with the sorption data fitting well to the pseudo-second-order kinetic equation and Langmuir model. The sorption performance of La3+ on HDEHP/AC was minimally affected as the NaCl/NaI concentrations increased at pH = 2, whereas the sorption capacity for Bi3+ decreased significantly. Additionally, selective desorption of La3+ and Bi3+ was achieved using HNO3 and NaI solutions, respectively. These results backed up by a conceptual separation process point toward a potential use of these materials in a direct/inverse 225Ac/213Bi radionuclide generator. Further optimization of the material and separation process will be required to bring this class of promising materials into an actual generator for medical applications.

Air and Water Stable Bicyclic (Alkyl)(Amino)Carbene Stabilized Phosphenium Cation: Reactivity and Selective Fluoride Ion Affinity.

The synthesis and reactivity of an air and water stable Bicyclic (alkyl)(amino)carbene (BICAAC) stabilized phosphenium cation (1) is reported. Air and water stable phosphenium cation are rare in the literature. Compound 1 is obtained by reaction of BICAAC with Ph2PCl in THF followed by anion exchange with LiOTf. The reduction and oxidation of 1 yielded corresponding α-radical phosphine species (2) and BICAAC stabilized phosphenium oxide (3) respectively. All compounds are well characterized by single crystal X-ray diffraction studies. The Lewis acidity of compounds 1 and 3 are determined by conducting fluoride ion affinity experiments using UV-Vis spectrophotometry and multinuclei NMR spectroscopy. Compounds 1 and 3 exhibited selective binding to fluoride anion but did not interact with other halides (Cl- and Br-). Quantum chemical calculations were performed to understand the structure and nature of bonding interactions in these compounds, as well as to comprehend the specific bonding affinity to fluoride over other halide ions.

Post-Synthetic Modification of Porous Organic Cages for Enhanced Iodine Adsorption Performance.

The capture of radioactive iodine species from nuclear waste is crucial for environmental protection and human health. Porous organic cages (POCs), an emerging porous material, have showed potential in iodine adsorption due to the advantages of tunable pores and processibility. However, integrating multiple desirable characteristics into a single POC through bottom-up assembly of pre-designed building blocks remains challenging. Post-synthetic modification (PSM) offers an alternative approach, enabling the introduction of various functions into a single POC. Herein, a viable and highly efficient three-step PSM strategy to modify a representative POC (CC3), is presented. The modified POC, OFT-RCC36+6Br-, features a charged confined space, electron-rich heteroatom, and halide ions, exhibiting significantly enhanced iodine vapor uptake compared to the parental cage. The universality of the PSM strategy has been verified by successfully modifying two other POCs. The iodine adsorption behaviors of three modified cage adsorbents in organic solvent and aqueous solution have also been investigated, all of which exhibited improved performance, especially in comparison to ionic cages modified through direct protonation. This work provides an effective PSM strategy for POCs to facilitate iodine adsorption. More importantly, the introduction of a new PSM strategy enriches the functional diversity of POCs, potentially broadening their future applications.

Customizing Aniline-Derived Molecular Structures to Attain beyond 22 % Efficient Inorganic Perovskite Solar Cells.

The characteristics of the soft component and the ionic-electronic nature in all-inorganic CsPbI3-xBrx perovskite typically lead to a significant number of halide vacancy defects and ions migration, resulting in a reduction in both photovoltaic efficiency and stability. Herein, we present a tailored approach in which both anion-fixation and undercoordinated-Pb passivation are achieved in situ during crystallization by employing a molecule derived from aniline, specifically 2-methoxy-5-trifluoromethylaniline (MFA), to address the above challenges. The incorporation of MFA into the perovskite film results in a pronounced inhibition of ion migration, a significant reduction in trap density, an enhancement in grain size, an extension of charge carrier lifetime, and a more favorable alignment of energy levels. These advantageous characteristics contribute to achieving a champion power conversion efficiency (PCE) of 22.14 % for the MFA-based CsPbI3-xBrx perovskite solar cells (PSCs), representing the highest efficiency reported thus far for this type of inorganic metal halide perovskite solar cells, to the best of our knowledge. Moreover, the resultant PSCs exhibits higher environmental stability and photostability. This strategy is anticipated to offer significant advantages for large-area fabrication, particularly in terms of simplicity.

Hetero-Nucleation Induced [111]-Oriented Mixed Halide Perovskite for Stable Pure Red Light-Emitting Diodes.

Mixed halide 3D perovskites are promising for bright, efficient, and wide-color gamut light-emitting diodes (LEDs) due to their excellent carrier transport, high luminescence, and easily tunable bandgaps. However, serious halide ion migration inside mixed halide 3D perovskite results in poor operational and spectral stability of the as-fabricated LEDs. Here, a hetero-nucleation crystallization strategy is reported to grow [111]-orientationpreferred mixed halide 3D perovskite CsPbI3-xBrx thin films for stable pure red LEDs. This hetero-nucleation crystallization is enabled by the addition of phosphoric acid (H3PO4) complexation, which promotes the growth of small perovskite grains into large grains with uniform [111]-orientation. The obtained [111]-orientation preferred film exhibits excellent stability under light or electric field stimulus as revealed by model analysis and experimental results compared to that of [001]-orientation preferred film. Thus, based on the [111]-orientationpreferred film, the fabricated LED exhibits an external quantum efficiency of 22.8%, a maximum brightness of 12000cdm-2, and a half-life time of 4080min under 1.5mA cm-2. More importantly, the electroluminescence spectrum of the device remains stable during the continuous operation of 4080min, showcasing the significant spectral stability improvement enabled by the hetero-nucleation induced [111]-orientation strategy.

Two mercury(II) halide coordination polymers with efficient photoluminescence

Two coordination polymers (CPs), [Hg(Bpbp)X2]n (X = Br (1), I (2), Bpbp = 4,4′-bis(4-pyridyl)-biphenyl), were synthesized via solvothermal synthesis methods, and were further fully characterized by single crystal X-ray diffraction, powder X-ray diffraction, elemental analyses, FT-IR spectroscopy, and thermogravimetric analyses. The two CPs exhibit similar one-dimensional zigzag chain structures constructed by Bpbp ligand connecting Hg(II) cations with halide ions as terminal ligands, while the zigzag chains show different configurations, symmetries and packing modes. The results of photoluminescence experiments and DFT calculations indicate that both the halide anions and conjugated Bpbp ligands show important roles in the emission process of CPs, and halide anions may tune the luminescence properties of CPs.

Nanometer-Resolved Mapping of Organic Cation Migration Behavior in Methylammonium Lead Halide Perovskites.

The performance and stability of organic metal halide perovskite (OMHP) optoelectronic devices have been associated with ion migration. Understanding of nanoscale resolved organic cation migration mechanism would facilitate structure engineering and commercialization of OMHP. Here, we report a three-dimensional approach for in situ nanoscale infrared imaging of organic ion migration behavior in OMHPs, enabling to distinguish migrations along grain boundary and in crystal lattice. Our results reveal that organic cation migration along OMHP film surface and grain boundaries (GBs) occurs at lower biases than in crystal lattice. We visualize the transition of organic cation migration channels from GBs to volume upon increasing electric field. The temporal resolved results demonstrate the fast MA+ migration kinetics at GBs, which is comparable to diffusivity of halide ions. Our findings help understand the role of organic cations in the performance of OMHP devices, and the proposed approach holds broad applicability for revealing migration mechanisms of organic ions in OMHPs based optoelectronic devices.

Tetrapyrrolic macrocycles self-organization into floating layers and sensory properties of their Langmuir-Schaefer films

The influence of the chemical structure of the 5,10,15,20-tetraphenylporphyrin (I) and 2-aza-21-carba-5,10,15,20-tetraphenylporphyrin (II) on their supramolecular organization in floating layers at the air/water interface and sensor properties in Langmuir-Schaefer films has been investigated. It was shown that a minor change in the macrocycle structure (namely, the replacement of a single nitrogen atom from the center to the periphery of macrocycle) has a considerable effect on the surface properties and hysteresis processes of the floating layers. Using the Bruster angle microscopy, it was established that both porphyrins aggregate even before the compression of their floating layers begins. The aggregation is more pronounced in porphyrin I. The analysis of hysteresis loops showed that the formation of a floating layer by the modified porphyrin II requires approximately 100 times more energy than for the unmodified porphyrin I. Using the Langmuir-Schaefer (LS) method, the floating layers were transferred onto solid substrates and the resulting thin films were analyzed by atomic force microscopy, scanning electron microscopy, polarization optical microscopy, and spectrophotometry. The combination of these methods revealed a general tendency of the porphyrins to form 3D structures on the surface of LS-films. The study of the basic properties of the porphyrin's LS-films showed that both porphyrins are diprotonated. The protonation process in porphyrin II occurs at a concentration of HClO4 that is 1000 times lower than that observed in porphyrin I. The greater tendency to protonation of porphyrin II is caused by the availability of both nitrogen atoms (the external nitrogen atom located at the macrocycle periphery and the internal nitrogen atom, which becomes more assesible to interactions due to the distortion of the macrocycle). As for the sensor properties of LS-films for iodide ion in aqueous solutions, it was observed that the diprotonated form of porphyrin I exhibited higher sensitivity due to a more developed film surface because of the presence of a greater number of 3D aggregates. The data obtained can be used in the development of efficient pH-controlled thin-film sensor materials for halide ions.

Effect of Halide Ions on the TiO2-mediated Photocatalysis of Carbendazim in Aqueous Medium Under Near-ultraviolet Light Irradiation

The degradation of carbendazim (CBZ) through TiO2 photocatalysis, in the presence of halide ions and under near-UV light irradiation, was investigated. HPLC–MS technique was used to characterize the photoproducts. Spectrophotometric analysis showed that CBZ degraded slowly in TiO2 aqueous dispersions containing no salt (CBZ conversion of 6% after ca. 5 h of irradiation). The photodegradation efficiency increased particularly by addition of bromide salts. Indeed, CBZ reached complete degradation after ca. 30 min at the maximum concentration of NaBr used (0.05 M). Two significant aspects have emerged from the data analysis: the bromide role is to cause inhibition of the electron–hole recombination, a reaction known to be competitive with the reactive process; CBZ photodegradation is especially initiated by direct hole transfer pathway, whereas the OH• role is crucial in the catalyst regeneration process. Degradation attempts under sunlight appeared promising for a more sustainable photocatalytic process.

A Perspective on Electrochemical Point Source Utilization of CO2 and Other Flue Gas Components to Value Added Chemicals.

Electrochemical CO2 reduction reaction (eCO2RR) has been explored extensively for mitigation of noxious CO2 gas generating C1 and C2+ hydrocarbons and oxygenates as value-added fuels and chemicals with remarkable selectivity. The source of CO2 being a pure CO2 feed, it does not fully satisfy the real-time digestion of industrial exhausts. Besides the detrimental effect of noxious gas mixture leading to global warming, there is a huge capital investment in purifying the flue gas mixtures from industries. The presence of other impurity gases affects the eCO2RR mechanism and its activity and selectivity toward C2+ products dwindle drastically. Impurities like NOx, SOx, O2, N2, and halide ions present in flue gas mixture reduce the conversion and selectivity of eCO2RR significantly. Instead of wiping out these impurities via separation processes, new strategies from material chemistry and electrochemistry can open new avenues for turning foes to friends! In this perspective, the co-electroreduction will vividly discussed and supporting role of different heteroatom-containing impurity gases with CO2, generating highly stable C─N, C─S, C─X bonds, and highlight the existing limitations and providing probable solutions for attaining further success in this field and translating this to industrial exhaust streams.