Photoinduced Species Research Articles

Fe(III)-incorporated UiO-66(Zr)–NH2 frameworks: Microwave-assisted scalable production and their enhanced photo-Fenton degradation catalytic activities

In this work, the photocatalytic feasibility of UiO-66(Zr)–NH2 was tuned by combining a scalable producing approach and incorporating Fe3+. Different contents of Fe3+ were effectively incorporated into the UiO-66(Zr)–NH2 frameworks utilizing a microwave-assisted continuous flow tubular reactor within 10 min. It was observed that with increasing the Fe3+ content from 0.5 to 1.0, 2.0 and 3.0 M %, the production rate diminished from ∼ 1.72 to 1.65, 1.55, and 1.46 g/h, respectively. The hybrid Fe@UiO-66-NH2 (Fe@UON) showed enhanced light absorption and charge carrier separation efficiency owing to the newly formed heterostructures, Zr-O-Fe linkages, and –H2N:→ Fe3+ chelating. The optimal Fe@UON catalyst achieved the highest photo-Fenton degradation efficiency of ∼ 96 % towards tetracycline (TC) under energy-saving visible LED light (VLEL) conditions. The photodegradation was predominantly governed by the photo-induced species of ·O2–, h+, and •OH and facilitated by the Fe3+/Fe2+ cycles. At the same time, LC/MS analyses detailedly revealed the reaction pathways for the degradation. After several consecutive tests, the constructed hybrid Fe@UiO-66-NH2 catalysts maintained good catalytic durability, and there was an insignificant Fe leak to the environment. The findings showed that hybrid Fe3+@UiO-66(Zr)–NH2 derived from energy-effective, environmental and scalable methods could be a good material for treating antibiotic-polluted effluents.

Exploring three-dimensional photoinhibition to enhance vat photopolymerization: A preliminary study

Vat photopolymerization (VPP) based additive manufacturing (AM) technologies print 3D components by using light to selectively cure photosensitive resins. In VPP-based AM, one outstanding challenge remains in controlling the over-curing, which is mainly caused by the diffusive and/or excessive photo-induced species such as free radicals and can severely affect the geometric properties of as-printed parts. Common practices rely on formulating proper resins or optimizing exposure parameters to address the vertical over-curing but often ignore the lateral over-curing. In this work, we develop a new VPP process of photoinhibition aided photopolymer AM (PinPAM) to comprehensively address over-curing issues in both vertical and lateral dimensions for enhancing the properties of as-printed geometry. The PinPAM method incorporates an adaptive photoinhibition zone, generated both surrounding and underneath the curing zone on a layer basis. This differs from current literature approaches that utilize photoinhibition to create a higher deadzone to increase print speed or constrain vertical profiles for achieving volumetric VPP AM. We present several preliminary experimental study cases involving pillar array sample printing. By comparing part dimensions and shapes resulting from traditional VPP and PinPAM, our experiments prove the concept of PinPAM and demonstrate its potential to address over-curing in VPP. Furthermore, we present an initial case study on optimizing the PinPAM process for printing cylinder samples with targeted dimensions, illustrating the planning and implementation of PinPAM. A discussion on future research directions to establish PinPAM is included. The developed PinPAM opens up a new avenue for improving VPP printed parts’ geometrical properties and facilitating its adoption in precision fabrications that demand dimensional accuracy and resolution.

Interior Exciton Extraction by Spatial-Controlled Iodine Doping in BiOBr Photocatalysts.

Extracting interior photoinduced species to the surface before their recombination is of great importance in pursuing high-efficiency semiconductor-based photocatalysis. Traditional strategies toward charge-carrier extraction, mostly relying on the construction of an electric field gradient, would be invalid toward the neutral-exciton counterpart in low-dimensional systems. In this work, by taking bismuth oxybromide (BiOBr) as an example, we manipulate interior exciton extraction to the surface by implementing iodine doping at the edges of BiOBr plates. Spatial- and time-resolved spectroscopic analyses verified the accumulation of excitons and charge carriers at the edges of iodine-doped BiOBr (BiOBr-I) plates. This phenomenon could be associated with interior exciton extraction, driven by an energy-level gradient between interior and edge exciton states, and the following exciton dissociation processes. As such, BiOBr-I shows remarkable performance in photocatalytic C-H fluorination, mediated by both energy- and charge-transfer processes. This work uncovers the importance of spatial regulation of excitonic properties in low-dimensional semiconductor-based photocatalysis.

Near-IR Capturing N-Methylbenzene Sulfonamide-Phenothiazine Incorporating Strong Electron Acceptor Push-Pull Systems: Photochemical Ultrafast Carrier Dynamics.

Unraveling the intriguing aspects of the intramolecular charge transfer (ICT) phenomenon of multi-modular donor-acceptor-based push-pull systems are of paramount importance considering their promising applications, particularly in solar energy harvesting and light-emitting devices. Herein, a series of symmetrical and unsymmetrical donor-acceptor chromophores 1-6, are designed and synthesized by the Corey-Fuchs reaction via Evano's condition followed by [2+2] cycloaddition retroelectrocyclic ring-opening reaction with strong electron acceptors TCNE and TCNQ in good yields (~60-85 %). The photophysical, electrochemical, and computational studies are investigated to explore the effect of incorporation of strong electron acceptors 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) and dicyanoquinodimethane (DCNQ) with phenothiazine (PTZ) donor. An additional low-lying broad absorption band extended towards the near-infrared (NIR) region suggests charge polarization after the introduction of the electron acceptors in both symmetrical and asymmetrical systems, leading to such strong ICT bands. The electrochemical properties reveal that reduction potentials of 3 and 6 are lower than those of 2 and 5, suggesting DCNQ imparts more on the electronic properties and hence largely contributes to the stabilization of LUMO energy levels than TCBD, in line with theoretical observations. Relative positions of the frontier orbitals on geometry-optimized structures further support accessing donor-acceptor sites responsible for the ICT transitions. Eventually, ultrafast carrier dynamics of the photoinduced species are investigated by femtosecond transient absorption studies to identify their spectral characteristics and target analysis further provides information about different excited states photophysical events including ICT and their associated time profiles. The key findings obtained here related to excited state dynamical processes of these newly synthesized systems are believed to be significant in advancing their prospect of utilization in solar energy conversion and related photonic applications.

Fabrication and characterization of ternary composite MgFe2O4/MoO3@CNTs for the enhanced photocatalytic activity to degrade organic pollutants

The recent industrial revolution and population growth have escalated the threat to the environment. Industries themselves discharge millions of tons of different harmful solvents, chemicals, and organic/metal ions into the water system each year. For the degradation of these organic wastes, photocatalysis has been extensively studied. The most researched classes of nanoparticles used as photocatalysts in environmental remediation are metal oxide and metal ferrite nanostructures. In this context, we have fabricated magnesium ferrite (MgFe2O4) nanoparticles and molybdenum trioxide (MoO3) nanorods by coprecipitation and hydrothermal processes, respectively. Moreover, their binary composite (MgFe2O4/ MoO3) was fabricated to improve the absorption of light in the visible region. Further, its ternary composite was fabricated with CNTs (MgFe2O4/MoO3 @CNT) to enhance photocatalytic activity by reducing the recombination rate via trapping photoinduced species. X-rays diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic analysis were carried out for structural confirmation. From XRD data, the crystallite size and other crystallographic parameters of the fabricated samples were determined. The calculated crystallite sizes of MgFe2O4 and MoO3were 12.74 nm and 31.36 nm, respectively. Band gap calculation and optical studies were done by UV–visible spectroscopy. The decrease in band gap value of MgFe2O4/MoO3 leads to remarkable photocatalytic activity than bare photocatalysts. The photocatalytic performance of all photocatalysts was examined by degrading methyl orange (MO) dye, pendimethalin (PDM), and benzoic acid (BA). Comparative studies revealed that MgFe2O4/MoO3 @CNT exhibited brilliant photocatalytic activity among the aforementioned photocatalysts. It degraded 96%, 82%, and 67% methyl orange (MO), pendimethalin (PDM), and benzoic acid (BA), respectively. This outstanding increase in photodegradation process was due to the movement of photoexcited species from the conduction band to CNTs, where it traps the photoexcited species and limits their chances of recombination. Overall, this research offers a fresh understanding of the effective utilization of the MgFe2O4/MoO3 @CNT ternary composite as a high-performance photocatalyst to address environmental protection concerns when exposed to visible light.

Direct and indirect photodegradation of bisphenol A in the presence of natural water components.

The impacts and mechanisms of natural water constituents, such as humic acid (HA), nitrates, iron and chloride ions, to the photodegradation of bisphenol A (BPA) were investigated in aqueous media under UV light irradiation. Due to the contributions of ·OH, 1O2, O2- and BPA* to BPA photodegradation in pure water in 13.4, 7.7, 22.9 and 47.9%, respectively, BPA was attenuated through the reaction pathway of direct photodegradation more than self-sensitized photodegradation. About indirect photodegradation, BPA photolysis through inhibitory effect from HA was mainly by light screening effect and quenching effect was insignificant. NO- 3 and NO- 2 both showed inhibitory effect but due to different reactive oxidization species (ROS). The photodegradation of BPA was significantly enhanced by the addition of iron from the formation of ·OH and H2O2, due to iron-assisted indirect photolysis for the degradation process. A dual effect of chloride depending on the different concentration levels involved quenching and promotion effect on reactive photo-induced species (RPS). A simple linear model revealed that BPA photodegradation was significantly impacted by the interaction of the above factors. In natural water, the decreased photolytic rate of BPA was mainly attributed to triple-excited dissolved organic matter (3DOM*), indicating that indirect photolysis was the primary transformation pathway of BPA. The detected photolysis products, such as nitrate and chlorinated products, suggest that there might be potential ecological risk of BPA photodegradation.

Innovative approach to synthesize Mo-Doped CuO Nanostructures: Uncovering structural and photocatalytic insights

The synthesis of molybdenum-doped copper oxide was carried out using a sol–gel technique, with sodium hydroxide as a pH regulator. Structural, morphological, and compositional analysis of both pure and molybdenum-doped copper oxide was observed through X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). For the monoclinic CuO nanostructure, key structural parameters like crystallite size, lattice parameters, micro strain, and dislocation density from XRD data was determined. Several methods, were employed to assess the crystallite size, micro strain, and dislocation density of synthesized nanostructures. The photocatalytic activity of Mo-doped CuO nano photocatalyst was evaluated using PL spectroscopy. Notably, the results demonstrated that 3% molybdenum-doped copper oxide removed 91% of the MB dye, outperforming the pure CuO sample, which only achieved 59% removal. This enhanced performance can be attributed to the increased surface area and optimized band gap of the Mo-doped CuO. The tuned band gap and unique nano architecture of the doped CuO not only facilitated the excitation process but also facilitated in transporting photo-induced species to the photo catalyst’s surface. These findings highlight the exceptional photocatalytic efficacy of the 3% molybdenum-doped CuO photo catalyst, showcasing its potential for treating toxic industrial effluents even through multiple cycles.

Developing boron carbon nitride/boron carbon nitride-citric acid quantum dot metal-free photocatalyst and evaluating the degradation performance difference of photo-induced species for tetracycline via theoretical and experimental study

For opening a way to synthesize novel metal-free catalysts and clarifying the photodegradation performance difference of photoactive species (such as ·O2−, h+), a series of metal-free photocatalysts have been synthesized by using different existing forms of the same materials (boron carbon nitride (BCN) and boron carbon nitride-citric acid quantum dot (BCQD)) as precursors via calcinating their mixture at 350 °C. BCQD has good fluorescence and up-conversion fluorescence performance. BCN/BCQD-350 has the highest removal efficiency (90%, including adsorption 60% and photodegradation 30%) for tetracycline (TC) among all samples under visible light irradiation. TC adsorption by BCN/BCQD-350 conforms to pseudo-second-order kinetic and Langmuir isotherm models. TC photodegradation by BCN/BCQD-350 conforms to type II heterojunction mechanism. Photoactive species capture experiments suggest that·O2− makes a higher contribution for TC photodegradation, followed by h+, ·OH, 1O2 and e−. From LC-MS results, TC photodegradation is initiated by the dehydration step. TC dehydration activated by ·O2− has the lowest barrier (43.4 kcal/mol) than that (50.1 kcal/mol) activated by h+, that (64.8 kcal/mol) without the activation by photoactive species. TC removal rate of BCN/BCQD-350 (0.01563 min−1) is higher than that of g-C3N4, P25 (TiO2), BNPA, BCNPA, etc. Furthermore, BCN/BCQD-350 can also photodegrade TC under infrared light irradiation (λ > 800 nm).

Structural dynamics of a thermally silent triiron(II) spin crossover defect grid complex.

The structural evolution of spin crossover (SCO) complexes during their spin transition at equilibrium and out-of-equilibrium conditions needs to be understood to enable their successful utilisation in displays, actuators and memory components. In this study, diffraction techniques were employed to study the structural changes accompanying the temperature increase and the light irradiation of a defect [2 × 2] triiron(II) metallogrid of the form [FeII3LH2(HLH)2](BF4)4·4MeCN (FE3), LH = 3,5-bis{6-(2,2'-bipyridyl)}pyrazole. Although a multi-temperature crystallographic investigation on single crystals evidenced that the compound does not exhibit a thermal spin transition, the structural analysis of the defect grid suggests that the flexibility of the grid, provided by a metal-devoid vertex, leads to interesting characteristics that can be used for intermolecular cooperativity in related thermally responsive systems. Time-resolved photocrystallography results reveal that upon excitation with a ps laser pulse, the defect grid shows the first two steps of the out-of-equilibrium process, namely the photoinduced and elastic steps, occurring at the ps and ns time scales, respectively. Similar to a previously reported [2 × 2] tetrairon(II) metallogrid, FE3 exhibits a local distortion of the entire grid during the photoinduced step and a long-range distortion of the lattice during the elastic step. Although the lifetime of the pure photoinduced high spin (HS) state is longer in the tetranuclear grid than in the defect grid, suggesting that the global nuclearity plays a crucial role for the lifetime of the photoinduced species, the influence of the co-crystalising solvent on the lifetime of the photoinduced HS state remains unknown. This study sheds light on the out-of-equilibrium dynamics of a thermally silent defect triiron SCO metallogrid.

Type-II heterojunction of Bi5O7I/WO3 anchored on Ni foam towards efficient photocatalytic degradation of VOCs

A photocatalytic membrane of Bi 5 O 7 I/WO 3 /Ni foam was first prepared by electrophoretic deposition of WO 3 and Bi 5 O 7 I on Ni foam. The Bi 5 O 7 I and WO 3 with mass ratio of 6:7 loaded on Ni foam (BWN-6/7) represented excellent photocatalytic performances. Approximately 95.2% of gaseous toluene (2000 mg m -3 ) was degraded over BWN-6/7 after the adsorption for 30 min and the light irradiation for 180 min. The BWN-6/7 could still degrade 81.6% of gaseous toluene after it was used for 4 rounds. Type-Ⅱ transfer pathway of charge between Bi 5 O 7 I and WO 3 promotes carrier separation efficiency of Bi 5 O 7 I/WO 3 , which is further boosted by Ni foam due to its excellent electricity conductivity. The photo-induced species such as h + and ∙OH play curial roles in the degradation of gaseous toluene. • An efficient photocatalytic film of Bi 5 O 7 I/WO 3 /Ni foam for toluene degradation is fabricated. • Type-Ⅱ transfer pathway of carriers between Bi 5 O 7 I and WO 3 is determined by self-designed experimental device. • DFT calculations predict the electrons flow direction between Bi 5 O 7 I/WO 3 and Ni foam. • Photocatalytic degradation mechanism of toluene over Bi 5 O 7 I/WO 3 /Ni foam is proposed.

Environmental Persistence of the Antidepressant Fluoxetine and Its Pharmaceutical Alternative: Kinetics of Oxidation and Mathematical Simulations

To investigate the impact of antidepressants (ANT) in water, estimates of the direct and indirect photolysis of standard fluoxetine hydrochloride (FLX) and a pharmaceutical alternative, fluoxetine sulfate (FLXSO4), were evaluated. The second-order kinetic constants of the ANT and reactive photoinduced species (RPS) (singlet oxygen, 1O2; hydroxyl radicals, HO•; and triplet excited states of chromophoric dissolved organic matter, 3CDOM*) were obtained by competition kinetics under simulated solar radiation. These parameters were used in combination with water characteristics to assess the environmental persistence of the ANT based on mathematical kinetic simulations. The results indicated that the reactions with HO• (kFLX,HO• = (2.54 ± 0.06) × 109 L mol−1 s−1; kFLXSO4,HO• = (3.07 ± 0.03) × 109 L mol−1 s−1) and 3CDOM* (kFLX,3CDOM* = (2.67 ± 0.05) × 109 L mol−1 s−1; kFLXSO4,3CDOM* = (1.48 ± 0.03) × 109 L mol−1 s−1) play a more important role in the degradation of ANT compared to the reactions with 1O2 (kFLX,1O2 = (1.37 ± 0.07) × 107 L mol−1 s−1; kFLXSO4,1O2 = (1.63 ± 0.33) × 107 L mol−1 s−1). The main removal pathways were biodegradation and direct photolysis with persistence in the following order FLX > FLXSO4. Therefore, the presence of sulfate anions can contribute to the degradation of fluoxetine in sunlit environmental waters.

Photochemical environmental persistence of venlafaxine in an urban water reservoir: A combined experimental and computational investigation

The photochemical behavior of venlafaxine (VNX) in surface water was investigated using a hybrid theoretical-experimental-kinetic modeling approach. In addition to the direct photolysis quantum yield, the rate constants of the reactions between VNX and reactive photo-induced species (hydroxyl radicals, HO·; singlet oxygen, 1O2; and triplet excited states of chromophoric dissolved organic matter, 3CDOM*) in sunlit water were measured under simulated solar radiation using competition kinetics. To elucidate possible degradation products, first-principles calculations were applied, followed by toxicity estimation by quantitative structure-activity relationship (QSAR) calculations. Furthermore, kinetic simulations of VNX persistence in an urban water reservoir of the São Paulo Metropolitan Region, Brazil, were performed. The results indicate low direct photolysis of VNX, with ΦVNX = (1.06 ± 0.18) × 10−2 mol Einstein−1. The measured values of the second-order reaction rate constants are kVNX,3CDOM* = (3.98 ± 0.28) × 109 L mol−1 s−1 and kVNX,1O2 = (2.09 ± 0.17) × 107 L mol−1 s−1, which are lower than kVNX, HO·obs = (6.92 ± 0.37) × 109 L mol−1 s−1 and kVNX, HO·theo = 4.98 × 109 L mol−1 s−1. O-desmethylvenlafaxine, the most thermodynamically stable metabolite predicted by theoretical calculations, revealed potentially greater toxicity and, therefore, higher environmental risk to aquatic ecosystems. The estimated half-lives for VNX range from 9 to 62 days, depending on the season, local weather conditions and water quality parameters, the effects of which can be satisfactorily simulated with the aid of the modified photochemical fate model proposed in this work.

Dynamics of broadband photoinduced species and enabled photodetection in MXenes

Abstract Dynamics of photoinduced species, as a key parameter for nanomaterials plays a significantly role in the performance of optoelectronic devices. In this work, the origin of broadband optical response for the emerging Ti3C2T x MXene is revealed by transient spectroscopic analysis. From ultraviolet to infrared, the steady-state and transient optical responses present wavelength-related features. The carrier lifetime is found to change from femtosecond to nanosecond time scale dominated by various photoinduced species, i.e., carrier and surface plasmon. The unique optoelectronic character enables photodetection. This fundamental study on carrier, plasmon dynamics, and application in photodetection is helpful for exploring MXene-based optoelectronic devices.

Pivotal role of water molecules in the photodegradation of pymetrozine: New insights for developing green pesticides

Photodegradation of the insecticide pymetrozine (PYM) was studied on surface of wax films, and in aqueous and nonaqueous phase. The half-life of PYM on the wax surface was approximately 250 times longer than in water. Scavenging experiments, laser flash photolysis, and spectra analysis indicated the first singlet excited state of PYM (S1 *PYM) to be the most important photoinduced species initiating the photodegradation. Quantum chemistry calculations identified significant molecular torsion and changes in the structure C–CN–N of S1 *PYM, and the absolute charges of the CN atoms increased and the bond strength weakened. Free energy surface analysis, and O18 labeling experiments further confirmed that the mechanism was two-step photoinduced hydrolysis. The first step is the hydrolysis of S1 *PYM at CN upon reaction with 2–3 water molecules (one H2O molecule as the catalyst). The second step is an intramolecular hydrogen transfer coupled with the cleavage of C–N bond and formation of two cyclic products. During the interactions, water molecules experience catalytic activation by transferring protons, while there is a negligible solvent effect. Clarifying the detailed photodegradation mechanisms of PYM is beneficial for the development of green pesticides that are photostable and effective on leaf surfaces, and photolabile and detoxified in the aquatic environment.

Excitonic effects on photophysical processes of polymeric carbon nitride

Recently, polymeric carbon nitride (nominally, g-C3N4) has attracted extensive attention due to its photoresponsive applications such as photocatalysis, photoluminescence, and photoelectrochemistry. Due to unique compositions and structures, strong excitonic effects of g-C3N4 network derived from low dielectric property have led to complicated photophysical processes. Studying exciton-related photophysical processes in g-C3N4 is of great significance for gaining in-depth understandings of the relationship between excitonic effects and photoresponsive behaviors. In this Perspective, we highlight the impacts of excitonic effects on photophysical processes of g-C3N4, in which excitonic behaviors like excitation, recombination, nonradiative relaxation, and annihilation are summed up. In addition, the key role of excitonic regulation in optimizing photoresponsive properties of g-C3N4 is also summarized, where the relevance between different photoinduced species and structural factors is emphasized. This Perspective will present a comprehensive understanding of excitonic effects-dominated photophysical processes of g-C3N4 and pave a new way for the design of novel photoresponsive polymeric semiconductors with strong excitonic effects.

A Metastable Photoinduced Protein-Flavin Adduct in Choline Oxidase, an Enzyme Not Involved in Light-Dependent Processes.

Photoinduced formation of protein-flavin adducts is crucial in photoresponsive proteins containing light-oxygen-voltage (LOV) domains. LOV proteins typically share an N-terminal sensor domain with FMN and a C-terminal effector domain such as a kinase, a phosphodiesterase, or a DNA-binding protein. Light absorption by FMN results in a covalent flavin-cysteine adduct, which allosterically translates to the linked effector domain. Photoinduced protein-flavin adducts have not been reported in enzymes not involved in light-dependent processes. Here, we have used fluorescence, pH effects, and mutagenesis to follow up a serendipitous observation of an unusual fluorescence excitation spectrum in choline oxidase at alkaline pH (M. Ghanem and G. Gadda, unpublished observations). Physiologically, choline oxidase oxidizes choline to betaine through two FAD-associated reactions and is not a photoenzyme. The enzyme-bound flavin showed a progressive shift of the fluorescence excitation maximum (λex) from 468 to 399 nm with increasing pH values between pH 6.0 and 10.0, consistent with a metastable photoinduced protein-flavin adduct. In contrast, the maximal λem was independent of pH, with values of ∼526 nm. For comparison, fluorescence spectra of FAD in bulk solution had maximal values differing by ≤2 nm at different pH values, with λex at 453 nm and λem at 527 nm. The unusual behavior of the enzyme persisted in the mutated S101A enzyme variant but was eliminated in the H466Q variant, suggesting that the photoinduced species is likely a C4a-N-histidyl-FAD. The results provide evidence that metastable photoinduced formation of a flavin-protein adduct can occur in an enzyme that is not a photoreceptor or a photoenzyme.

Photoinduced Terminal Hydride of [FeFe]-Hydrogenase Biomimetic Complexes.

The active site of the [FeFe]-hydrogenase ([FeFe]-H2ase) has a bridging carbonyl ligand and a terminal hydride in the key H-cluster intermediate Hhyd. However, nearly all of the synthetic mimics reported, so far, prefer a hydride bridging the two irons, and only few mimics with a terminal hydride were achieved by tuning the steric effects of bulky diphosphine ligands. Moreover, although intermediates with either a terminal hydride or a protonated bridging thiolate ligand were proposed to exist during protonation processes or hydrogen exchange in the [FeFe]-H2ase mimic, [Fe2(μ-pdt)(μ-H)(CO)4(PMe3)2]+ (1H+), only bridging hydrides were observed by time-resolved IR spectroscopy. In this report, FTIR spectroscopy of 1H+, under CO with longer irradiation time, revealed several new photoinduced species. In addition to the CO loss species, many of the photoinduced products can be assigned to 1H+ with a terminal hydride by comparison of their CO vibrational frequencies with density functional theory calculations.

Novel mixed metal oxide (ZnO.La2O3.CeO2) synthesized via hydrothermal and solution combustion process – A comparative study and their photocatalytic properties

Designing of novel semiconductor materials or enhance the potential of existing materials for the removal of the environmental pollutants is growing area of scientific interest. In this paper, novel binary ZnO.La2O3 (ZL) and ternary mixed metal oxides ZnO.La2O3.CeO2 (ZLC) are synthesized using hydrothermal and solution combustion approach. The synthesized materials are characterized by the various techniques such as XRD, FESEM, UV-DRS and BET surface analyzer to uncover the structural, morphological and optical properties of the materials. The photocatalytic activity was evaluated by taking Rhodamine B dye as a model pollutant and 125 W mercury vapor lamp was used as light source. Despite the low crystallinity, hydrothermally synthesized samples possess better activity as compared to the solution combustion synthesized samples, which is attributed to their regular morphology and large surface area. The large surface area provide the more active sites and the regular morphology enhance the lifetime of the charge carriers by helping in migration of the photoinduced species. The hydrothermally synthesized sample showed 94.99% degradation of RhB on irradiation for about 160 min in basic medium. Experiments were performed using different scavengers to find the role of the active species in the degradation process.

Characterization of reactive photoinduced species in rainwater.

Rainfall is a highly effective and important carrier that can remove a majority of aerosol mass into land and marine ecosystems. The photochemically formed reactive species in the rainwater are likely dominant oxidants for organic and inorganic substances. Here, we collected rainwater samples from Oct. 2016 to Dec. 2016 in CUG campus (Wuhan, Hubei, China) and measured their formation rates, lifetimes, steady-state concentrations, and apparent quantum yields of reactive photoinduced species, including hydroxyl radical (HO•), H2O2, singlet oxygen (1O2), and chromophoric dissolved organic matter triplet state (3CDOM*) in the laboratory. Results showed that rainwater samples contained photochemical sources, like DOM, nitrate, heavy metals, etc. Quantification of HO• showed that rHO• (the photogeneration rate of HO•) were in the range of 1.05 × 10-10-4.56 × 10-10Ms-1, and [•OH]ss (the steady-state concentrations of OH•) were of 4.06 × 10-18-2.97 × 10-17M for the three samples. Further investigations revealed that 10-24% of r•OH was attributed to nitrate photolysis, suggesting DOM was possibly the prevailing source of HO•. Apparent quantum yields of H2O2 (ΦH2O2) correlated negatively with E2/E3 (the ratio of absorption at 250 and 365nm), while Φ1O2 and Φ3CDOM* increased with elevated E2/E3.

Photocatalysis in Two-Dimensional Black Phosphorus: The Roles of Many-Body Effects.

Two-dimensional (2D) black phosphorus (BP) has drawn tremendous attention in solar-light-driven catalytic processes for its intriguing chemical and physical properties. Benefiting from the highly anisotropic electronic structure induced by its puckered crystal geometry, 2D BP tends to have greater confinement with respect to traditional inorganic nanomaterials, thereby leading to robust many-body effects. Such Coulomb-interaction-mediated effects dominate the electronic and optical properties of 2D BP-based nanosystems, where exotic correlations between photoinduced species give rise to unique photoexcitation processes that are closely associated with the involved photocatalytic behavior. In this Perspective, we highlight the critical role of many-body effects in 2D BP-based photocatalysis and exemplify the relationships between the correlated photoinduced species-dominated photoexcitation processes and photocatalytic behavior involved therein. The relevant challenges and opportunities in pursuing efficient 2D BP-based solar energy utilization are also discussed.