Fukui Index Research Articles

Constructing oxygen absorption and activation sites in Ce-doped g-C3N4 photocatalyst for effective removal of amoxicillin: Performance, mechanism and degradation pathways

Accelerating oxygen absorption and activation to generate O2− efficiently is challenging toward photocatalytic removal of antibiotic pollutions for water treatment. Herein, the Ce-doped g-C3N4 photocatalysts with active sites for adsorbing and activating oxygen were prepared by a pyrolysis method. It was found that CeCN-1 exhibits excellent performance toward the photocatalytic degradation of amoxicillin (AMX), which was about 3.4 times more than that of pure g-C3N4. Both experimental and theoretical studies elucidated that the Ce-g-C3N4-x have excellent oxygen absorption and activation capacity attributed to the doping of Ce ions destroys the original sp2 hybrid mode of nitrogen and carbon in the triazine ring, and the increase of solitary electrons forms the activated site. Meanwhile, the generation of N vacancies sites not only accelerate the conversion of excitons to photogenerated carriers but also generate more O2− acting as the main active species for the AMX degradation. Additionally, the photocatalytic degradation pathway of AMX was revealed through HPLC-MS and Fukui index based theorical calculation, proving that the intermediate products degraded by AMX are non-toxic and harmless. This study disclose the superiority of constructing the O2 adsorption and activation sites for photocatalytic removal of antibiotic pollutants.

Ceftriaxone sodium degradation by carbon quantum dots (CQDs)-decorated C-doped α-Bi2O3 nanorods

A novel carbon quantum dots decorated C-doped α-Bi2O3 photocatalyst (CBO/CQDs) was synthesized by solvothermal method. The synergistic effect of adsorption and photocatalysis highly improved contaminants removal efficiencies. The ceftriaxone sodium degradation rate constant (k) of CBO/CQDs was 11.4 and 3.2 times that of pure α-Bi2O3 and C-doped α-Bi2O3, respectively. The interstitial carbon doping generated localized states above the valence band, which enhanced the utilization of visible light and facilitated the separation of photogenerated electrons and holes; the loading of CQDs improved the charge carrier separation and extended the visible light response; the reduced particle size of CBO/CQDs accelerated the migration of photogenerated carriers. The •O2− and h+ were identified as the dominant reactive species in ceftriaxone sodium degradation, and the key role of •O2− was further investigated by NBT transformation experiments. The Fukui index was applied to ascertain the molecular bonds of ceftriaxone sodium susceptible to radical attack, and intermediates analysis was conducted to explore the possible degradation pathways. The toxicity evaluation revealed that some degradation intermediates possessed high toxicity, thus the contaminants require sufficient mineralization to ensure safe discharge. The present study makes new insights into synchronous carbon dopping and CQDs decoration on modification of α-Bi2O3, which provides references for future studies.

Visible photocatalytic degradation of tetrabromobisphenol A by CuO-modified Ce2O3: Mechanisms and DFT studies

The widespread use of brominated flame retardants poses serious hazards to environment and health. In this study, CuO/Ce2O3 nanocomposites were synthesized by a coprecipitation method. Various characterization methods and density functional theory (DFT) calculations were used to analyze the composition and surface structure of material. Under visible light, the prototypical pollutant, namely, tetrabromobisphenol A (TBBPA) exhibited the highest degradation efficiency of 80.46% after 120 min with a CuO/Ce2O3 ratio of 1:20. The photocatalytic degradation mechanism of TBBPA in the CuO/Ce2O3 system was comprehensively investigated. Radical scavenging experiments showed that h+ is the primary active substance in TBBPA photodegradation, and·OH and·O2− are secondary contributors. Moreover, the Fukui index was used to predict the active site, and DFT methods were used to calculate the degradation mechanism of TBBPA. Combined gas chromatography/mass spectrometry and high-performance liquid chromatography-mass spectrometry showed that the possible degradation pathways of TBBPA were determined to be debromination, C–C bond breaking, and ring-opening. Ecotoxicity evaluation showed that degradation products have significantly lower acute toxicity than TBBPA. The excellent reusability and stability of CuO/Ce2O3 indicate that this system can be successfully applied in water treatment, which is of great significance for the environmentally-friendly removal of TBBPA.

Carbon Quantum Dot-Decorated BiOBr/Bi2WO6 Photocatalytic Micromotor for Environmental Remediation and DFT Calculation

Efficient photocatalysts are crucial for degrading antibiotic pollutants in water and vital for environmental remediation. In this study, an efficient carbon quantum dot (CQD)-modified BiOBr/Bi2WO6 hybrid material was prepared by a mild hydrothermal method. Meanwhile, a visible-light-driven micromotor based on the photocatalyst was developed. The micromotor can achieve self-propelled motion powered by the photocatalytic degradation reaction. It exhibited remarkable photocatalytic activity toward common pollutants in water, such as sulfonamide, quinolone, and tetracycline antibiotics. Among them, 10CQD/BiOBr/Bi2WO6-4 (10CBBr-4) exhibited the highest photocatalytic activity, which was 2.8 and 5 times higher than those of BiOBr and Bi2WO6, respectively. The high activity is attributed to the decoration of CQDs, which promoted visible-light absorption. Additional contributions may be due to the specific Z-type electron transport mode and flower-like BiOBr inserted by two-dimensional (2D) Bi2WO6 nanosheets, which enriched the active reaction sites, facilitated the adsorption of antibiotic molecules, and promoted the final radical attack. Based on the theoretical calculation of molecular orbitals and the Fukui index, the possible intermediate products, degradation pathways, and photocatalytic mechanism were elucidated. This study suggests that structural engineering based on CQD modification effectively allows the design of self-propelled microrobots for antibiotic degradation.

Photo-Induced Holes Initiating Peroxymonosulfate Oxidation for Carbamazepine Degradation via Singlet Oxygen

Peroxymonosulfate (PMS) has been intensively used to enhance the photocatalytic activity of catalysts, which is adopted as an electron acceptor to inhibit the recombination of electrons and holes. However, the effect of holes generated by visible light (VL) on PMS activation is always overlooked. Herein, the VL/Bi2WO6/PMS process was constructed for the efficient removal of organics, in which the degradation rate of carbamazepine (CBZ) increased by over 33.0 times by the introduction of PMS into Bi2WO6 under visible light. The radical quenching and determination experiments confirmed that the photogenerated holes could firstly oxidize PMS to form SO5•− and react with HSO5− to produce 1O2, then inducing the formation of other reactive species to greatly enhance the performance of pollutant removal by the VL/Bi2WO6/PMS process. Density functional theory (DFT) predicted that sites with high Fukui index (f0) on CBZ were more susceptible to being attacked, resulting in hydroxylation, ring closure, and C=C bond cleavage of CBZ. Toxicity estimation indicated that photocatalysis degradation products from CBZ were less toxic compared to the parent compound. This study provides a potential avenue for improving photocatalytic efficiency and widening the application of photocatalytic technology in wastewater purification.

Upcycling contaminated biomass into metal-supported heterogeneous catalyst for electro-Fenton degradation of thiamethoxam: Preparation, mechanisms, and implications

The safe disposal and resource utilization of heavy metal contaminated biomass has long posed a huge challenge. The direct preparation of heavy metal-contaminated straw into a biomass-derived multi-metal loading heterogeneous Fenton catalyst (BHFC) through pyrolysis for thiamethoxam (THX) degradation is a win–win strategy to address this problem. In this method, Fe, Mn, Cu, and Zn in contaminated biomass collected from mineral areas are released as active metals and loaded in the form of metal oxides on biomass pyrolysis biochar with a mesoporous structure. The presence of multiple metals accelerated the mutual redox, increased oxygen mobility, synergistically promoted the generation of hydroxyl radicals, and reached 100% THX degradation rate and 90% total organic carbon removal within 20 min using the optimum BHFC-600. The BHFC derived from biomass contaminated with different heavy metal contents showed differences in catalytic performance. The THX degradation rate of BHFC prepared from higher metal level biomass increased by 1.2-fold compared to the low level. Possible pathways and mechanisms of THX degradation was investigated using different methods, including density functional theory calculations. The degradation of THX can be mainly attributed to h+, OH, and O2– attacking the region with a high Fukui index. This study presents a promising strategy for preparing sustainable environmentally functional materials and provides new feasible ideas for the safe treatment of contaminated biomass.

Mechanistic insights into UV photolysis of carbamazepine and caffeine: Active species, reaction sites, and toxicity evolution

The pseudo-persistence of pharmaceutical and personal care products (PPCPs)in the aqueous environment may pose potential risks to human health and ecosystems. The UV disinfection in wastewater treatment plants is one of the essential processes before PPCPs enter the water environment, so it is crucial to elucidate the photolytic behavior and mechanism of PPCPs under UV radiation. In this work, carbamazepine (CBZ) and caffeine (CAF) were selected as typical pollutants to investigate the effect of water matrixes, humic acid, inorganic ions, and pH on the UV radiation performance. Hydroxyl radical (•OH) and singlet oxygen (1O2) were identified by quenching experiments and electron paramagnetic resonance (EPR) spectra as playing a dominant role in the degradation process. UPLC-TOF/MS was conducted to identify 13 and 14 possible intermediates of CBZ and CAF, respectively. Moreover, combining density functional theory (DFT) calculations (Frontier Molecular Orbital and Fukui index), hydroxylation, oxidation, and ring cleavage were proposed as the main degradation pathways of the contaminants, which occurred first at the C(7C), N(17 N) and O(18O) sites of CBZ and at the C(9C) site of CAF. The bio-acute toxicity experiment and the Ecological Structure-Activity Relationships (ECOSAR) program were performed to analyze and predict the toxicity of the intermediates of CBZ and CAF under UV radiation, respectively. The results showed that the acute toxicity of both solutions increased after UV radiation and followed with the combined toxicity. This work has great scientific value and practical environmental significance for evaluating the UV disinfection process and managing PPCPs in the aqueous environment.

Visible light-Fenton degradation of tetracycline hydrochloride over oxygen-vacancy-rich LaFeO3/polystyrene: Mechanism and degradation pathways

In this study, the oxygen–vacancy–rich (OV) lanthanum ferrite (LaFeO3) perovskite (also called LFO) was successfully prepared by an ultrasound–assisted sol–gel method and hydrothermally loaded onto polystyrene (PS) to obtain LaFeO3/polystyrene–oxygen–vacancies (LFO/PS–OVs). The structure and properties of LFO/PS–OVs were investigated using scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS), X–ray photo–electron spectroscopy (XPS), photoluminescence spectra (PL) and other characterization methods. The authors also investigated the effects of hydrogen peroxide (H2O2) concentration, catalyst dosage, solution concentration, pH and inorganic anions on the tetracycline hydrochloride (TC) removal efficiency. According to the results, the ultrasonic cavitation treatment and the composite reaction significantly increased the specific surface area of LFO as well as the content of oxygen vacancies and broadened the forbidden band width of LFO. The significant improvement in catalytic activity can be attributed to solving the agglomeration problem of powdered LFO and the introduction of a large amount of OVs. The degradation mechanism was proposed according to the free radical capture experiments and the electron spin resonance (ESR) tests. Based on the DFT calculations and identification of intermediates by LC/MS, the main degradation pathways of TC were proposed. The results showed that reactive oxygen species (ROS) may preferentially attack atoms with the high f0 values of Fukui index. This study gives an insight into the promising application of oxygen–vacancy–rich perovskite/polystyrene composites in environmental remediation.

Promoting charge migration of Co(OH)2/g-C3N4 by hydroxylation for improved PMS activation: Catalyst design, DFT calculation and mechanism analysis

Cobalt-based materials were considered as promising catalysts for peroxymonosulfate (PMS) activation, while few reactive sites and ion leaching limit its environmental application. Herein, Co(OH)2 nanosheets in-situ anchored hydroxylated hollow tubular g-C3N4 (Co/CNH) was successfully fabricated by a facile impregnation method, and used to activate PMS for enrofloxacin hydrochloride (ERF) degradation. Compared with neat Co(OH)2 and CNH, the optimum catalyst (10 %Co/CNH) exhibited higher ERF degradation efficiency for 95.6 % within 30 min. The enhanced performance was attributed to the synergistic effect between Co(OH)2 and CNH. CNH can not only provide numerous nucleation sites for Co(OH)2 to inhibit its agglomeration, but also provide abundant OH− for formation of the key PMS activation species CoOH+. Furthermore, DFT-based electron density difference elucidated that the sp3 hybridization introduced by OH− greatly facilitated charge transfer from 10 %Co/CNH to PMS. A series of characterization verified that 1O2 dominated the degradation of ERF (nonradical pathway), SO4•− and •OH (radical pathway) as well as electron transfer also contributed to this process. Fukui index (f−) and bond degree (BD) indicated that reactive oxygen species tend to attack atoms with higher f− and scavenge covalent bonds with larger BD in the process of ERF degradation.

Highly efficient electro-cocatalytic Fenton-like reactions for the degradation of recalcitrant naphthenic acids: Exploring reaction mechanisms and environmental implications

In this study, an electrochemical/peroxymonosulfate/Fe(III) (EC/PMS/Fe(III)) system was established for efficient degradation of four naphthenic acids (NAs) compounds including cyclohexanecarboxylic (CHA), heptanoic (HPA), benzoic (BA) and 2-methylhexanoic acids (2-MHA). The introduction of electric field enhances the redox cycle of Fe(III)/Fe(II) to activate PMS for degredation of NAs. Complete degradation of NAs compounds (5 mg/L) has been achieved within 30 min in the EC/PMS/Fe(III) system. The results of electron paramagnetic resonance (EPR) analysis, scavenging experiment, and chemical probe experiments indicated hydroxyl radical (•OH), sulfate radical (SO4•−) and singlet oxygen (1O2) are primary reactive oxygen species (ROS) in the EC/PMS/Fe(III) system. NAs compounds with different structures exhibit inconsistent degradation efficiency in current system (kCHA > kBA > kHPA > k2-MHA), depending on the selectivity of the different ROS and stability of respective intermediate organic radicals. Besides, multiple degradation pathways of CHA, mainly including hydroxylation and carbonylation, were proposed by combining the results of mass spectrometry analysis with the calculated Fukui index based on density functional theory (DFT) calculation. In addition, the EC/PMS/Fe(III) system exhibited robust performance with the addition of co-existing ions. This work provides a novel strategy for efficient degradation of NAs for future remediation of petroleum wastewater.

Blue TiO2 nanotube electrocatalytic membrane electrode for efficient electrochemical degradation of organic pollutants

In this study, a Ti3+-doped TiO2 porous membrane (Blue TiO2/Ti) was fabricated and employed for electrochemical degradation of organic pollutants in the single-pass flow-through mode. Characterizations including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microcopy (SEM) and energy dispersive spectroscopy (EDS) verified that Ti3+-doped anatase TiO2 with nanotube structures was successfully prepared. Electrochemical analysis including linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and electrochemical active surface area (ESA) revealed higher oxygen evolution potential (OEP, 2.23 V vs. Ag/AgCl), larger redox peak current, lower impedance and larger ESA (69 cm2/cm2) of Blue TiO2/Ti compared to the Ti and TiO2/Ti membranes. The effects of current density, flow rate and solution environment on the removal of methylene blue (MB) were investigated. The removal rates of various organic pollutants including sulfamethoxazole (SMX), methyl orange (MO), bisphenol A (BPA) and MB could reach 92.2%–99.5%. The quenching experiment proved that hydroxyl radicals (•OH) played the major role in the Blue TiO2/Ti based electrochemical system. Furthermore, the degradation pathways of two typical pollutants (SMX and MB) were proposed by analyzing the oxidation products with liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS), with the assistance of orbital-weighted Fukui index (fw0 and fw−) obtained through Density Functional Theory (DFT) calculations. Moreover, toxicity indexes of the oxidation products were obtained and compared to the parent SMX and MB using Toxicity Estimation Software Tool (TEST) software. Finally, the long-term operation performance of the Blue TiO2/Ti membrane was evaluated.

Computational Structure Characterization of 1,2,3-Selendiazole Isomers, Investigation of Some Molecular Properties and Biological Activities

Four different selendiazole compounds were handled by computational chemistry methods. Compounds 1,2,3-selendiazole, 1,2,5-selendiazole, 1,2,4-selendiazole and 1,3,4-selendiazole were optimized at the B3LYP/6-31G(d) level. Structural parameters were examined. In the structural determination, IR and NMR techniques, which are spectroscopic methods, were applied. Quantum chemical parameters giving global properties such as the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy, hardness (η), softness (σ), chemical potential (µ), electronegativity (χ), electrophilicity index (ω), nucleophilicity index (ε), the electron accepting power (ω+), electron donating power (ω-) and polarizability were investigated for biological activities of selendiazoles. Local electrophilic and nucleophilic regions were determined using Fukui index functionals. Docking studies of the studied selendiazoles were performed with proteins representing the cervical cancer cell line and the MCF-7 breast cancer cell line.

Quantitative structure-activity relationship (QSAR) guides the development of dye removal by coagulation

QSAR modeling could be a promising tool for guiding the development of novel and cost-effective environmental technologies. As an example, it could be widely used to analyze the degradation rules of organic pollutants in various decomposition methods. However, a lack of systematic research on a particular removal method is significant in revealing the decomposition rule of pollutants more accurately and guiding industrial applications. In this study, six coagulation systems (MnO2/Fe(OH)3/AlCl3/FeCl3/CaCl2/MgCl2) were used as examples to remove 38 dyes under three pH conditions, and the characteristics and differences of these systems were explored by QSAR modeling. The results showed that the removal effect by MnO2 under acidic and neutral conditions and Fe(OH)3 under acidic conditions were quantitatively described mainly by bond order (BO) and Fukui index (f (+) and f (0)), which reflected that oxidative degradation dominated. In contrast, most of the critical parameters of other systems were molecular descriptors represented by ∑q(O) (the total charge of all the oxygen atoms in the molecule) and SAA (surface area of a molecule), which reflected that electrostatic adsorption and hydrogen-bond adsorption processes dominated.

Sulfadiazine degradation by combination of hydrodynamic cavitation and Fenton-persulfate: parametric optimization and deduction of chemical mechanism.

This paper reports the degradation of the sulfadiazine (SDZ) drug with a hybrid advanced oxidation process (AOP) of heterogeneous α-Fe2O3/persulfate coupled with hydrodynamic cavitation. The major objectives of the study are parametric optimization of the process and elucidation of the chemical mechanism of degradation. The optimum conditions for maximum SDZ degradation of 93.07 ± 1.67% were as follows: initial SDZ concentration = 20ppm, pH = 4, α-Fe2O3 = 181.82mg/L, Na2S2O8 = 348.49mg/L, H2O2 = 0.95mL/L, inlet pressure = 0.81MPa (8atm), orifice plate configuration: hole dia. = 2mm and number of holes = 4. Density functional theory (DFT) calculations revealed that the atoms of SDZ with a high Fukui index (f 0) were potentially active sites for the attack of •OH and [Formula: see text] radicals. Fukui index calculation revealed that atom 11N has a higher value of f 0 (0.1026) for oxidation at the α-amine group of the sulfadiazine molecule. Degradation intermediates detected through LC-MS/MS analysis corroborated the results of DFT simulations. Using these results, a chemical pathway has been proposed for SDZ degradation.

CuFe2O4/CuO magnetic nano-composite activates PMS to remove ciprofloxacin: Ecotoxicity and DFT calculation

In this study, we used the hydrothermal method and high-temperature calcination method to attach CuFe2O4 to CuO for the first time. The (111) plane of CuO and (112) plane of CuFe2O4 formed surface heterojunction, which acts as the interface for adsorbing PMS. Meanwhile, the most stable form of CuFe2O4/CuO, charge transfer and charge density in CuFe2O4/CuO/PMS system are proposed by combining density functional theory (DFT) and transmission electron microscope (TEM). The experimental data from electron spin resonance (ESR) determinations and active species capture demonstrated that both nonradical singlet oxygen (1O2) and active radicals (•OH, •SO4-) participate in CIP degradation. The degradation pathways and the intermediates are proposed by Fukui index and liquid chromatography-mass spectrometry (LC-MS). Based on the T.E.S.T program (Toxicity Calculation Software), the bioaccumulation factor, acute toxicity, mutagenicity, and development toxicity of intermediates are proposed. Also, CuFe2O4/CuO demonstrated good reusability and stability. The findings within this work offered deep insights into the mechanisms of organic pollutants degradation via SR-AOP over Fe-Cu catalyst. Besides, verification of the experimental results indicated that the CIP removal of 86.67% and the mineralization efficiency of 47.17% under optimal conditions. Finally, chemical oxygen demand (COD) and fluorescence spectra in a three-dimensional excitation-emission matrix (3D EEMs) are used to characterize the potential performance of catalyst CuFe2O4/CuO-500 in medical wastewater.

Photocatalytic degradation of persistent organic pollutants by Co-Cl bond reinforced CoAl-LDH/Bi12O17Cl2 photocatalyst: mechanism and application prospect evaluation

The widespread distribution of persistent organic pollutants (POPs) in natural waters has aroused global concern due to their potential threat to the aquatic environment. Photocatalysis represents a promising mean to remediate polluted waters with the simple assistance of solar energy. Herein, we fabricated a Co-Cl bond reinforced CoAl-LDH/Bi12O17Cl2 heterogeneous photocatalyst to investigate the feasibility of photocatalysis to treat POPs-polluted water under environmental conditions. The optimum CoAl-LDH/Bi12O17Cl2 (5-LB) composite photocatalyst exhibited excellent photocatalytic performance, which could degrade 92.47 % of ciprofloxacin (CIP) and 95 % of bisphenol A (BPA) with 2h of actual solar light irradiation in Changsha, China (N 28.12 °, E 112.59 °). In view of the synergistic influence of water constituents, various water matrices greatly affected the degradation rate of CIP (BPA), with the degradation efficiency of 82.17% (84.37%) in tap water, 69.67% (71.63%) in wastewater effluent, and 44.07% (67.7%) in wastewater inflow. The results of electron spin resonance, and chemical trapping experiment, HPLC-MS and density functional theory calculation reflected that the degradation of CIP was mainly attributed to h+ and 1O2 attacking the active atoms of CIP molecule with high Fukui index. Furthermore, the non-toxicity of both 5-LB photocatalyst and treated CIP solution was proved by E.coli and B.subtilis cultivation, which further demonstrated the feasibility of the 5-LB to treat POPs in real water under irradiation of solar light.

A quantitative structure activity relationship (QSAR) model for predicting the rate constant of the reaction between VOCs and NO3 radicals

NO3 radical is one of the important oxidants used for the chemical degradation of Volatile organic compounds (VOCs). Thus, the derivation of rate constant (kNO3) is critical to understand the removal kinetics of VOCs. To better estimate the kNO3, a quantitative structure activity relationship (QSAR) model was established using the kNO3 of 189 VOCs and quantum chemical parameters. The optimal QSAR model can predict the kNO3 with its R2, q2, and Qext2 being 0.880, 0.872, and 0.861, respectively. The QSAR analysis results indicate that the energy of the highest occupied molecular orbital (EHOMO) and the maximum value of electrophilic Fukui index (f(−)x) are two intrinsic factors determining the kNO3. Additionally, the analysis of the correlation between kNO3 values and quantum chemical parameters shows that the gap energy between LUMO and HOMO (EGAP), the minimum value of free radical Fukui index (f (0)n), and the maximum value of bond order (BOx) also significantly affect kNO3. The validations of the optimal QSAR model confirm the high realizability, stability and accuracy, and the wide applicability of the derived model for predicting kNO3.

Assessing Alkene Reactivity toward Cytochrome P450-Mediated Epoxidation through Localized Descriptors and Regression Modeling.

The prediction of sites of epoxidation by cytochrome P450s during metabolism is particularly important in drug design, as epoxides are capable of alkylating biological macromolecules. Reliable methods are needed to quantitatively predict P450-mediated epoxidation barriers for inclusion in high-throughput screening campaigns alongside protein-ligand docking. Utilizing the fractional occupation number weighted density (FOD) and orbital-weighted Fukui index (fw+) as descriptors of local reactivity and a data set of 36 alkene epoxidation barriers computed with density functional theory (DFT), we developed and validated a multiple linear regression model for the reliable estimation of epoxidation barriers using only substrate structures as input. Using our recommended level of theory (GFN2-xTB//GFN-FF), mean absolute errors in the training and test sets were found to be 0.66 and 0.70 kcal/mol, respectively, with coefficients of determination of ca. 0.80. We demonstrate the utility of this approach on three known substrates of CYP101A1 and further show that this approach is inappropriate for particularly electron-rich alkenes. By employing a modern semiempirical method on force-field-generated geometries, the required descriptors can be calculated on the millisecond timescale per structure, making the approach well suited for incorporation into high-throughput methodologies alongside docking.

Interface Engineering of Co(OH)2 Nanosheets Growing on the KNbO3 Perovskite Based on Electronic Structure Modulation for Enhanced Peroxymonosulfate Activation

Material-enhanced heterogonous peroxymonosulfate (PMS) activation on emerging organic pollutant degradation has attracted intensive attention, and a challenge is the electron transfer efficiency from material to PMS for radical production. Herein, an interface architecture of Co(OH)2 nanosheets growing on the KNbO3 perovskite [Co(OH)2/KNbO3] was developed, which showed high catalytic activity in PMS activation. A high reaction rate constant (k1) of 0.631 min-1 and complete removal of pazufloxacin within 5 min were achieved. X-ray photoelectron spectroscopy, X-ray absorption near edge structure spectra, and density functional theory (DFT) calculations revealed the successful construction of the material interface and modulated electronic structure for Co(OH)2/KNbO3, resulting in the hole accumulation on Co(OH)2 and electron accumulation on KNbO3. Bader topological analysis on charge density distribution further indicates that the occupations of Co-3d and O-2p orbitals in Co(OH)2/KNbO3 are pushed above the Fermi level to form antibonding states (σ*), leading to high chemisorption affinity to PMS. In addition, more reactive Co(II) with the closer d-band center to the Fermi level results in higher electron transfer efficiency and lower decomposition energy of PMS to SO4•-. Moreover, the reactive sites of pazufloxacin for SO4•- attack were precisely identified based on DFT calculation on the Fukui index. The pazufloxacin pathways proceeded as decarboxylation, nitroheterocyclic ring opening reaction, defluorination, and hydroxylation. This work can provide a potential route in developing advanced catalysts based on manipulation of the interface and electronic structure for enhanced Fenton-like reaction such as PMS activation.

Photocatalytic degradation of organic pollutants in water by N-doping ZnS with Zn vacancy: enhancement mechanism of visible light response and electron flow promotion.

In order to improve the visible light response, N-doping ZnS (N-ZnS) nanospheres with Zn vacancy and porous surface were prepared by a simple one-pot hydrothermal method. Characterizations and density functional theory simulations showed excellent visible light response of N-ZnS. N-doping introduced impurity energy levels, which led to orbital hybridization and changed the original dipole moment. The presence of ortho Zn vacancy (O-Znv) can effectively reduce e--h+ recombination and photocorrosion. Furthermore, O-Znv caused lattice distortion (twisted the -S-Zn-N-(O-Znv)-S-Zn-S- chemical bond chain), resulting in "vacancy effect" to accelerate e- flow. Under visible light, the photocatalytic degradation efficiency of tetracycline (TC) and 2,4-dichlorophenol (2,4-DCP) was 90.31% and 60.84%, respectively. TOC degradation efficiency was 31.4% and 25.6%, respectively. Combined with Fukui index and LC-MS methods, it was found that TC and 2,4-DCP were degraded under the constant attack of active substances such as ·OH. This work can provide a reference for the application of catalytic materials in the field of visible light photocatalysis.