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Nature Materials Jun 2024For halide perovskites that are susceptible to photolysis and ion migration, iodide-related defects, such as iodine (I) and iodine vacancies, are inevitable. Even a...
For halide perovskites that are susceptible to photolysis and ion migration, iodide-related defects, such as iodine (I) and iodine vacancies, are inevitable. Even a small number of these defects can trigger self-accelerating chemical reactions, posing serious challenges to the durability of perovskite solar cells. Fortunately, before I can damage the perovskites under illumination, they generally diffuse over a long distance. Therefore, detrimental I can be captured by interfacial materials with strong iodide/polyiodide (I) affinities, such as fullerenes and perfluorodecyl iodide. However, fullerenes in direct contact with perovskites fail to confine I ions within the perovskite layer but cause detrimental iodine vacancies. Perfluorodecyl iodide, with its directional I affinity through halogen bonding, can both capture and confine I. Therefore, inverted perovskite solar cells with over 10 times improved ultraviolet irradiation and thermal-light stabilities (under 85 °C and 1 sun illumination), and 1,000 times improved reverse-bias stability (under ISOS-V ageing tests) have been developed.
PubMed: 38684883
DOI: 10.1038/s41563-024-01876-2 -
Environmental Science & Technology Apr 2024Hydrated electron () treatment processes show great potential in remediating recalcitrant water contaminants, including perfluoroalkyl and polyfluoroalkyl substances...
Hydrated electron () treatment processes show great potential in remediating recalcitrant water contaminants, including perfluoroalkyl and polyfluoroalkyl substances (PFAS). However, treatment efficacy depends upon many factors relating to source water composition, UV light source characteristics, and contaminant reactivity. Here, we provide critical insights into the complex roles of solution parameters on contaminant abatement through application of a UV-sulfite kinetic model that incorporates first-principles information on photogeneration and reactivity. The model accurately predicts decay profiles of short-chain perfluoroalkyl acids (PFAAs) during UV-sulfite treatment and facilitates quantitative interpretation of the effects of changing solution composition on PFAS degradation rates. Model results also confirm that the enhanced degradation of PFAAs observed under highly alkaline pH conditions results from changes in speciation of nontarget scavengers. Reverse application of the model to UV-sulfite data collected for longer chain PFAAs enabled estimation of bimolecular rate constants (, M s), providing an alternative to laser flash photolysis (LFP) measurements that are not feasible due to the water solubility limitations of these compounds. The proposed model links the disparate means of investigating processes, namely, UV photolysis and LFP, and provides a framework to estimate UV-sulfite treatment efficacy of PFAS in diverse water sources.
Topics: Ultraviolet Rays; Water Pollutants, Chemical; Sulfites; Water; Fluorocarbons
PubMed: 38554136
DOI: 10.1021/acs.est.3c10584 -
The Science of the Total Environment Jan 2024Zn(II) is a necessary additive during antibiotic production and aquaculture, leading to the coexistence of Zn(II) and antibiotics in aquatic environment, especially in...
Zn(II) is a necessary additive during antibiotic production and aquaculture, leading to the coexistence of Zn(II) and antibiotics in aquatic environment, especially in receiving waters of pharmaceutical and aquaculture wastewater. However, the roles of Zn(II) in the photochemical behavior of antibiotics are still not clear, which limits the understanding of the fate of antibiotic in nature. In this study, tetracycline (TC) was selected as typical antibiotic to evaluate the effect of Zn(II) on antibiotic photolysis. The removal of TC was accelerated by 22.75 % with TC:Zn(II) molar ratio at 1:5. The mechanism of Zn(II)-induced TC photolysis was explored via reactive oxygen species (ROS) analysis and density functional theory (DFT) calculation for the first time. Zn(II) could enhance the formation of TC excited states and further produce more singlet oxygen (12.54 % higher than control group) to promote indirect photolysis. Besides, Zn(II) could react with TC via complexation, and the complex was more vulnerable to attack by reactive oxygen species due to more active sites. Furthermore, the structure and toxicity of intermediates were identified with mass spectrometer, T.E.S.T. and ECOSAR software. Zn(II) hardly changed the degradation path of TC, and TC was mainly degraded via ring opening, demethylation, deamidation, and hydrogen abstraction with more toxic intermediates than the parent molecule. This work is significant to better understand the environmental fate of antibiotics, and also provides new insight into wastewater treatment in the pharmaceutical and aquaculture industry.
Topics: Photolysis; Reactive Oxygen Species; Tetracycline; Anti-Bacterial Agents; Pharmaceutical Preparations; Zinc; Water Pollutants, Chemical
PubMed: 37972777
DOI: 10.1016/j.scitotenv.2023.168484 -
The Journal of Physical Chemistry. A Nov 2023We investigated the photodissociation dynamics of CpCo(CO) (cyclopentadienylcobalt dicarbonyl) in metal-to-ligand charge transfer (MLCT) bands. By employing DFT...
We investigated the photodissociation dynamics of CpCo(CO) (cyclopentadienylcobalt dicarbonyl) in metal-to-ligand charge transfer (MLCT) bands. By employing DFT calculations, the absorption band (210-240 nm) was characterized as a charge transfer from the Co center to the Cp (cyclopentadienyl, CH) ligand. Ion imaging was utilized to analyze the CO fragments and coordinatively unsaturated complexes (CpCoCO, CpCo, and CoCH) across the entire MLCT band. Measuring the production yields of individual unsaturated complexes as a function of photolysis wavelength by considering wavelength dependence indicated the involvement of several photochemical pathways: the first photodissociation and sequential dissociation of CpCo(CO), and the second photodissociation of unsaturated intermediates within the pulse duration of the photolysis laser. The recoil velocity shifts of CpCo and CoCH were attributed to the onset of the sequential dissociation of CpCoCO. Evidence for the second photodissociation of CpCoCO was obtained through the matching of linear momenta between the CO( = 0, 1) and CpCo fragments. The DFT calculations performed to determine the electronic structures and potential energy curves for photoinduced CO loss in CpCo(CO) and CpCoCO supported our interpretation of the experimental results. This study presents a practical approach to selectively detecting specific processes among the mixture of products and intermediates when photolyzing transition-metal carbonyls, as their concurrent generation is unavoidable in laser-based experiments.
PubMed: 37972309
DOI: 10.1021/acs.jpca.3c04455 -
Water Research Nov 2023Dissolved organic matter (DOM) is an ubiquitous component of environmental snow and ice, which can absorb light and produce reactive species (RS) and thus is of...
Dissolved organic matter (DOM) is an ubiquitous component of environmental snow and ice, which can absorb light and produce reactive species (RS) and thus is of importance in ice photochemistry. The photodegradation of sulfachloropyridazine (SCP) without and with DOM present in liquid water and ice were investigated in this study. The photodegradation rate constants for SCP without DOM present was enhanced by 52.5 % in ice relative to liquid water, likely due to the enhanced role of SCP self-sensitized RS in ice. DOM significantly promoted SCP photolysis in both liquid water and ice, which was mainly attributed to roles of singlet oxygen (O) and triplet excited-state DOM (DOM*) generated from DOM. O production from DOM was significantly enhanced in ice relative to liquid water. Hydroxyl radical (OH) production from DOM in ice was similar to those in liquid water. Enhancement in DOM* production in ice was observed at low DOM concentrations. Suwannee River Fulvic Acid (SRFA) and Elliott Soil Humic Acid (ESHA) exhibited differences in RS production in liquid water and ice, as well as in enhancement of O and DOM* produced in ice relative to liquid water. DOM induced reaction pathways of SCP different from those without DOM present, and therefore affected toxicity of SCP photoproducts. There were differences in photodegradation pathways of SCP as well as in toxicity of SCP photoproducts between liquid water and ice.
Topics: Water; Photolysis; Ice; Dissolved Organic Matter; Sulfachlorpyridazine; Water Pollutants, Chemical
PubMed: 37837902
DOI: 10.1016/j.watres.2023.120714 -
Environmental Science & Technology Jun 2024Hydrogen-tuned 185 nm vacuum ultraviolet (VUV/H) photolysis is an emerging technology to destroy per- and polyfluoroalkyl substance (PFAS) in brine. This study...
Promotive Effects of Chloride and Sulfate on the Near-Complete Destruction of Perfluorocarboxylates (PFCAs) in Brine via Hydrogen-tuned 185-nm UV Photolysis: Mechanisms and Kinetics.
Hydrogen-tuned 185 nm vacuum ultraviolet (VUV/H) photolysis is an emerging technology to destroy per- and polyfluoroalkyl substance (PFAS) in brine. This study discovered the promotive effects of two major brine anions, i.e., chloride and sulfate in VUV/H photolysis on the hydrated electron (e) generation and perfluorocarboxylates (PFCAs) destruction and established a kinetics model to elucidate the promotive effects on the steady-state concentration of e ([e]). Results showed that VUV/H achieved near-complete defluorination of perfluorooctanoic acid (PFOA) in the presence of up to 1000 mM chloride or sulfate at pH 12. The defluorination rate constant () of PFOA peaked with a chloride concentration at 100 mM and with a sulfate concentration at 500 mM. The promotive effects of chloride and sulfate were attributed to an enhanced generation of e via their direct VUV photolysis and conversion of additionally generated hydroxyl radical to e by H, which was supported by a linear correlation between the predicted [e] and experimentally observed . The value increased from pH 9 to 12, which was attributed to the speciation of the H/e pair. Furthermore, the VUV system achieved >95% defluorination and ≥99% parent compound degradation of a concentrated PFCAs mixture in a synthetic brine, without generating any toxic perchlorate or chlorate.
Topics: Kinetics; Photolysis; Ultraviolet Rays; Fluorocarbons; Sulfates; Hydrogen; Chlorides; Salts; Water Pollutants, Chemical; Caprylates
PubMed: 38808621
DOI: 10.1021/acs.est.3c10552 -
Journal of Hazardous Materials Mar 2024Cyano liquid crystal monomers (LCMs) are proposed as emerging chemical pollutants with persistent, bioaccumulative, and toxic properties. Herein, five cyano LCMs,...
Cyano liquid crystal monomers (LCMs) are proposed as emerging chemical pollutants with persistent, bioaccumulative, and toxic properties. Herein, five cyano LCMs, including 4-cyano-4'-ethylbiphenyl (2CB), 4-Butyl-4'-cyanobiphenyl (4CB), 4-cyano-4'-ethoxybiphenyl (2OCB), 4-(trans-4-Ethylcyclohexyl)benzonitrile (2CHB) and 4-(trans-4-Vinylcyclohexyl)benzonitrile (2eCHB), were selected to investigate the reaction kinetics and excited state characteristic variations with their molecular structures by ultraviolet (UV) photolysis. Theoretical calculations reveal that the benzene ring, ethoxy and double bond can deeply alter the electron distribution of cyano LCMs. This will affect the exciton separation ability, excitation properties and active sites to electrophilic attack, causing the distinction in photolysis efficiency. Due to the effective charge separation during local excitation (LE) process and the property of being most susceptible to electrophilic attack by O and O, 2eCHB with double bond exhibits the largest degradation rate. Conversely, the weakest exciton separation of 2OCB with ethoxy during charge transfer (CT) process limits its subsequent sensitized photolysis process. The molecular orbital and fragment contributions to holes and electrons further deepen the understanding of the excited states charge transfer. This study confirmed that the intrinsic molecular structure, chemical nature and existing sites directly defined the excitation and decomposition activity in the UV photolysis of cyano LCMs.
PubMed: 38006861
DOI: 10.1016/j.jhazmat.2023.133033 -
Environmental Monitoring and Assessment Aug 2023Keeping in view the toxicity of the Rhodamine B, the present study is designed to remediate the water loaded with toxic dyes using gallium oxide and gallium hybrids as...
Keeping in view the toxicity of the Rhodamine B, the present study is designed to remediate the water loaded with toxic dyes using gallium oxide and gallium hybrids as photocatalyst. Precipitation coupled with sonochemical method is adopted for the synthesis of gallium oxide while the post grafting method is adopted for the synthesis of gallium hybrids with the indole and its derivatives. FTIR spectra showed the characteristic absorption bands of gallium oxide and gallium hybrids at 400-700 cm and 1400-1600 cm. SEM and XRD showed the micro-sized rectangular rod-shaped gallium oxide with rhombohedral geometry. The average crystallite size of gallium hybrids was 26-32 nm calculated using the Debye Scherrer and Williamson-Hal models. The BET isotherm of gallium hybrids revealed the adsorption type-IV and hysteresis loop (H3) proposing multilayer and mesoporous structures with increase in surface area from 26 m/g of gallium oxide to 31 m/g of gallium-indole, 35 m/g of gallium-methyl indole, and 37 m/g of gallium-carboxylic indole. XPS showed the presence of gallium (3-14%), oxygen (28-32%), nitrogen (23-46%), and carbon (9-46%). The gallium oxide and gallium hybrids showed 47-72% optimum degradation of Rhodamine B under 2 h of illumination at pH 7 and 0.03 mg/L. The degradation rate followed a Langmuir-Hinshelwood model with R > 0.9.
Topics: Photolysis; Environmental Monitoring; Gallium; Indoles
PubMed: 37642762
DOI: 10.1007/s10661-023-11683-y -
Molecules (Basel, Switzerland) Oct 2023Photochemical properties of symmetrical pyromellitic diimide containing two cymantrenyl fragments at two nitrogen atoms were studied with IR, NMR, UV-vis, ESI-MS, and...
Photochemical properties of symmetrical pyromellitic diimide containing two cymantrenyl fragments at two nitrogen atoms were studied with IR, NMR, UV-vis, ESI-MS, and cyclic voltammetry. It was found that new unstable chelates are formed during photolysis. At the same time, the CO ligand dissociates from two Mn(CO) fragments during photoexcitation, which dramatically changes the electronic and redox properties of the molecule compared to the cymantrene derivative containing one imide fragment. Photolysis leads to a color change from light yellow to green. DFT calculations confirmed the possibility of the formation of complexes due to the loss of one or two CO ligands from manganese atoms. The results obtained with variation of photolysis conditions demonstrated the hemilabile character of the Mn-O=C(imide) bond. On addition of external ligands, the color and electrochemical properties changed, which is promising for the use of this complex as a sensor for small molecules.
PubMed: 37894576
DOI: 10.3390/molecules28207098 -
Environmental Science & Technology Jul 2023Photolysis of free chlorine is an increasingly recognized approach for effectively inactivating microorganisms and eliminating trace organic contaminants. However, the...
Photolysis of free chlorine is an increasingly recognized approach for effectively inactivating microorganisms and eliminating trace organic contaminants. However, the impact of dissolved organic matter (DOM), which is ubiquitous in engineered water systems, on free chlorine photolysis is not yet well understood. In this study, triplet state DOM (DOM*) was found to cause the decay of free chlorine for the first time. By using laser flash photolysis, the scavenging rate constants of triplet state model photosensitizers by free chlorine at pH 7.0 were determined to be in the range of (0.26-3.33) × 10 M s. DOM*, acting as a reductant, reacted with free chlorine at an estimated reaction rate constant of 1.22(±0.22) × 10 M s at pH 7.0. This study revealed an overlooked pathway of free chlorine decay during UV irradiation in the presence of DOM. Besides the DOM's light screening ability and scavenging of radicals or free chlorine, DOM* played an important role in the decay of free chlorine. This reaction pathway accounted for a significant proportion of the decay of free chlorine, ranging from 23 to 45%, even when DOM concentrations were below 3 mg L and a free chlorine dose of 70 μM was present during UV irradiation at 254 nm. The generation of HO and Cl from the oxidation of DOM* by free chlorine was confirmed by electron paramagnetic resonance and quantified by chemical probes. By inputting the newly observed pathway in the kinetics model, the decay of free chlorine in UV-irradiated DOM solution can be well predicted.
Topics: Chlorine; Dissolved Organic Matter; Ultraviolet Rays; Oxidation-Reduction; Water Pollutants, Chemical; Photolysis
PubMed: 37428984
DOI: 10.1021/acs.est.3c02458