Density Functional Theoretical Research Articles

Investigating the Antiproliferative Activity of Novel 4-Chloro-8-Nitro-1,2-Dihydro-3-Quinoline Acylhydrazones on Human Cervical Cancer Cell Lines.

A new series of acyl hydrazones have been synthesized from 4-chloro-8-nitro-1,2-dihydroquinoline-3-carbaldehyde. These compounds were characterized using various spectroscopic techniques. Density functional theoretical (DFT) studies were conducted to understand the correlation between electronic parameters and biological activity. The biological activity of the compounds was theoretically examined through molecular docking and ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) analysis. The compounds demonstrated high absorption rates and were found to be non-hepatotoxic. Preliminary cytotoxicity screenings against HeLa cell lines identified compound 7 as the most potent, with an IC50 value of 18.8 μM. This compound was further selected for bioimaging studies. The results indicate that compound 7 induces apoptosis at its IC50 concentration, suggesting its potential as an anticancer agent.

Adsorption of As nano-clusters on different graphene environments

We investigate the adsorption of As nano-clusters on graphene sheets in various environments, including vacancies and anchors with Fe and/or O impurities. To achieve this, we conducted Density-Functional Theoretical (DFT) calculations using the freely distributed SIESTA code. Our findings reveal a direct correlation between the number of vacancies and the adsorption energy, indicating that a higher number of vacancies result in higher adsorption of As-clusters. Additionally, as the Asn-cluster size increases, the adsorption energy decreases. Furthermore, our results suggest that transition metal impurities (such as Fe) serve as effective elements for functionalizing graphene facilitating the adsorption of metallic clusters in this way, making it suitable for applications in wastewater filtration or the purification of toxic elements in water. Finally, we address finite size effects on the adsorption of graphene sheets by perform calculations on graphene flakes of different sizes saturated in different ways.

Hardness, VSM, cyclic voltammetric and DFT studies of Cesium Sulphate-doped TGS crystals

The creation of capacitors, transducers, sensors, and infrared detectors utilise the nonlinear, ferroelectric triglycine sulphate (TGS) crystal. Cesium sulphate is incorporated into the lattice of TGS crystal to change its characteristics. Cesium sulfate-doped triglycine sulphate (CSTGS) single crystals were produced using a solution approach and a slow evaporation process. The title crystal was studied by single crystal XRD, FTIR, hardness, VSM, cyclic voltammetric and density functional theoretical (DFT) studies and the results are discussed in this paper.

Efficient mineralization of cadmium and arsenic by poorly crystalline CaFe-layered double hydroxide in soil: Performance and mechanism

The co-contamination of arsenic (As) and cadmium (Cd) in the environment is of most concern. In this work, poorly crystalline CaFe-layered double hydroxide (CaFe-LDH) was synthesized with a Ca-to-Fe molar ratio of 4 to ensure effective immobilization of Cd and As in soil. The application of Ca4Fe-LDH in soil remediation demonstrated that the targeted heavy metals gradually mineralized into a relatively stable oxidizable and residual state. At a soil remediation dosage of 1.6%, the availability levels of Cd and As decreased significantly, achieving stabilization efficiencies of 99% and 85.2% respectively. Cd is trapped through isomorphic substitution and dissolution-reprecipitation of calcium (Ca) laminate, resulting in the formation of CdCaFe-LDH mineralization products. As is immobilized through ion exchange with interlayer anions, redox with Fe(III), and Fe-Cd-As complexation. Moreover, the results of the characterization and density functional theoretical (DFT) calculations demonstrate that the CdCaFe-LDH formed by isomeric substitution of Ca for Cd enhanced the adsorption of As on the (110) plane of LDH, indicating that the trap mechanism of Cd and As by Ca4Fe-LDH is synergistically promoted. Overall, the above results prove that mineralization using Ca4Fe-LDH is a promising method to remediate soils combined contaminated by both Cd and As.

Selective hydrogenation of acetylene over Pd/β-Mo2C catalyst: Experimental and theoretical studies

Molybdenum carbide is a promising support to tune the metal reactivity, which originates from the interaction between metal and support. In this work, Pd/β-Mo2C was prepared using a deposition-precipitation method for selective hydrogenation of acetylene. The high temperature calcination is employed to modulate the interaction between Pd and β-Mo2C. The Pd/β-Mo2C catalyst calcined at 600 °C exhibits significant promotion in selective hydrogenation, which shows 100 % acetylene conversion and 81.4 % ethylene selectivity at 160 °C. The activity promotion originates from the enhanced electronic metal-support interaction, which induces a shift of Pd 3d to higher binding energy. Besides, the Pd species become atomically dispersed after calcination. The changes in geometric and electronic structure suppress the formation of Pd hydrides, which consequently inhibits the excessive hydrogenation capacity of Pd. The structure variation also affects the adsorption of ethylene. No strong adsorbed ethylene (di-σ bonded ethylene) can be identified, which is conducive to the improvement of ethylene selectivity. Density functional theoretical (DFT) calculations confirm that Pd on β-Mo2C is positively charged. The desorption energy of C2H4* (0.78 eV) is significantly lower than that of further hydrogenation (1.45 eV), which explains the improved ethylene selectivity of the calcinated catalyst. The present study indicates calcination is an effective method to tune the activity of Pd/β-Mo2C for reactions beyond selective hydrogenation of acetylene.

Substituent Controlled Tunable Fluorescence from Green to Red and pH Stimuli‐Induced Reversible Fluorescence Switching in Triphenylamine–Quinoxaline Derivatives

A series of triphenylamine‐quinoxaline donor‐acceptor (bipolar) compounds (TPA‐QH, TPA‐QMe, TPA‐QCOOH and TPA‐QNO2) with different substituents were synthesized and investigated their fluorescence properties, including stimuli‐induced fluorescence responses in solution and the solid‐state. Single crystal structural analysis revealed non‐planar molecular conformation, substituent controlled intermolecular interactions and molecular packing in the crystal lattice. TPA‐QH, TPA‐QMe, TPA‐QCOOH and TPA‐QNO2 showed tunable solid‐state emission from green to red. TPA‐QH showed strong fluorescence at 487 nm (quantum yield (Φf) = 28.3%) whereas NO2 substituted TPA‐QNO2 exhibited relatively weak fluorescence at 610 nm (Φf = 4.3%). Density functional theoretical (DFT) calculations also indicated reduction of optical bandgap with substituting electron withdrawing group. The donor‐acceptor structure with intramolecular charge transfer (ICT) resulted solvent polarity dependent fluorescence tuning. The presence of acid responsive quinoxaline group was utilized to demonstrate pH‐responsive fluorescence switching and dual state fluorescence was utilized for fabricating rewritable fluorescent platform. Thus, the present study provides a structural insight to develop dual state emissive triphenylamine–quinoxaline based bipolar materials for optoelectronic applications.

Thermodynamic and kinetic models for the photolytic and hydrolytic degradation of picaridin: A computational and theoretical study

The popularity of insect repellents presents the opportunity for continuous human and environmental exposure to such chemical mixtures. Consequently, the effects of their chemical components on human health and environmental safety is significantly reliant on their stability and hence, residence times under typical environmental conditions. Hence, for the first time, a thorough density functional theoretical (DFT) study on some possible hydrolytic and photolytic degradation pathways is presented and applied in the derivation of a comprehensive kinetic model, allowing evaluation of the residence time of picaridin; a very popular insect repellent. These results show that picaridin undergoes very slow hydrolysis via two pathways which present activation free energy barriers (ΔG‡) of ca. 225 and ca. 247 kJ mol−1 due to the asynchronous formation of four-membered cyclic activated complexes in both cases. Similarly, their photolytic transformations occur via two pathways, both of which are limited by the formation of the initial radical cation.

In Situ Growth of Amorphous MnO2 on Graphite Felt via Mild Etching Engineering as a Powerful Catalyst for Advanced Vanadium Redox Flow Batteries.

Owing to the advantages of low cost, high safety, and a desirable cycling lifetime, vanadium redox flow batteries (VRFBs) have attracted great attention in the large-scale energy storage field. However, graphite felts (GFs), widely used as electrode materials, usually possess an inferior catalytic activity for the redox reaction of vanadium ions, largely limiting the energy efficiency and rate performance of VRFBs. Here, an in situ growth of amorphous MnO2 on graphite felt (AMO@GF) was designed for application in VRFBs via mild and rapid etching engineering (5 min). After the etching process, the graphite felt fibers showed a porous and defective surface, contributing to abundant active sites toward the redox reaction. In addition, formed amorphous MnO2 can also serve as a powerful catalyst to facilitate the redox couples of VO2+/VO2+ based on density functional theoretical (DFT) calculations. As a result, the VRFB using AMO@GF displayed an elevated energy efficiency and superior stability after 2400 cycles at 200 mA cm-2, and the maximum current density can reach 300 mA cm-2. Such a high-efficiency and convenient design strategy for the electrode material will drive the further development and industrial application of VRFBs and other flow battery systems.

The role of water vapour on CO2 mobility on calcite surface during carbonation process for calcium looping: A DFT study

The presence of water vapour has been proven to stimulate carbonation for the calcium looping process, while its effect mechanism during the slow reaction stage still lacks insight understanding at the atomic level, where H2O molecules may interact with the product layer to affect the transportation of CO2. This study tried to reveal the role of water vapour on CO2 mobility on the calcite surface through density functional theoretical (DFT) calculation. H2O molecule has higher adherence to calcite surface than CO2, and it can react with CO3 to generate HCO3− and OH− ions. Then, the formed OH− ion above the surface layer can adsorb CO2. Moreover, H2O can also react with O2− defect to form OH− ions, and the OH ion at the deeper position can still adsorb CO2 through a two-step process with remarkable energy barriers. However, the formation of HCO3− can degrade the energy barriers to CO2 release from the calcite surface, owning to the weaker CO bond. Two directions of CO2 movement between anions were involved in this investigation, including crossing through the surface layer to the second layer and the movement inside the surface layer, where the higher mobility of CO2 from HCO3− to O2− ion occurs in both movement directions. For the case inside the surface layer, the movement from O2− ion to HCO3− has a higher energy barrier, indicating that the stimulation by H2O is a one-way effect, and the enhancement by H2O for CO2 mobility is caused by the reaction with CO32− other than O2− ion.

Engineering Heterostructured Fe-Co-P Arrays for Robust Sodium Storage.

Transition metal phosphides attract extensive concerns thanks to their high theoretical capacity in sodium ion batteries (SIBs). Nevertheless, the substantial volume fluctuation of metal phosphides during cycling leads to severe capacity decay, which largely hinders their large-scale deployment. In this regard, heterostructured Fe-Co-P (FeP/Co2P) arrays are firstly constructed in this work for SIBs. The novel self-supported construction without insulated binders favors fast charge migration and Na+ ion diffusion. In addition, the special heterostructure with abundant heterointerfaces could considerably mitigate the volume change during (de)sodiation and provide increased active sites for Na+ ions. Density functional theoretical (DFT) calculations confirm the built-in electric field in the heterointerfaces, which greatly hastens charge transfer and Na+ ion transportation, thereafter bringing about enhanced electrochemical performance. Most importantly, the FeP/Co2P heterostructure discloses higher electrical conductivity than that of bare FeP and Co2P based on the theoretical calculations. As anticipated, the heterostructured Fe-Co-P arrays demonstrate superior performance to that of Fe-P or Co-P anode, delivering high reversible capacities of 634 mAh g-1 at 0.2 A g-1 and 239 mAh g-1 at 1 A g-1 after 300 cycles.

Oxygen vacancy regulating transition mode of MIL-125 to facilitate singlet oxygen generation for photocatalytic degradation of antibiotics

Efficient yield of 1O2 determines the photocatalytic degradation rate of antibiotics, but the regulatory mechanism for 1O2 selective generation in O2 activation is still lacking exploration. Herein, oxygen vacancy (OV) modification strategy of MIL-125 was successfully practiced to promote the selective generation of 1O2. Multiple characterizations including extended X-ray absorption fine structure (EXAFS) and electron paramagnetic resonance spectra (EPR) confirmed the formation of oxygen vacancy in OV-MIL-125. The synthesized OV-MIL-125 exhibited greatly enhanced 1O2 selective (∼90 %) and antibiotics removal rate in water with high mineralization rate. Dynamics analysis of excitons by transient-steady state fluorescence and phosphorescence, transient absorption spectra (TAS) revealed that oxygen vacancy greatly enhanced the intersystem crossing (ISC) of singlet exciton, promoting triplet exciton generation. Density functional theoretical (DFT) calculation also proved the reduced gap of intersystem (ΔEST) and the modulated highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) population which was conducive to intersystem crossing process. Calculation of transition state further confirmed the lower energy barrier for π* orbital spin flip of O2 adsorbed on OV-MIL-125. The Dexter energy transfer involving triplet annihilation dominated the O2 activation mechanism to generate 1O2 instead of the charge transfer to generate O2•− which happened in MIL-125. This study provides new thinking for photocatalytic activation of molecular oxygen and is expected to guide the design of MOF-based catalysts for water treatment.

Synthesis, antioxidant, DNA interaction, electrochemical, and spectroscopic properties of chromene-based Schiff bases: Experimental and theoretical approach

Two chromene-based Schiff base ligands were synthesized by the condensation of 5-hydroxy-2,2-dimethyl-2H-chromene-6-carbaldehyde with 2-aminodiphenylamine and 1,8-diaminonaphthalene: (E)-2,2-dimethyl-6-(((2-(phenylamino)phenyl)imino)methyl)-2H-chromen-5-ol (2) and (E)-6-(((8-aminonaphthalen-1-yl)imino)methyl)-2,2-dimethyl-2H-chromen-5-ol (3). The compounds were characterized by Fourier transform infrared (FT-IR), absorption (UV-Vis) and nuclear magnetic resonance (NMR) spectroscopies, in addition to mass spectrometry (MS) analyses; the results of which were rationalized using density functional theoretical (DFT) calculations. Antioxidant activity of the Schiff bases was determined using the DPPH free radical scavenging and CUPric Ion Reducing Antioxidant Capacity (CUPRAC) assays. Compound 3 (IC50 = 14 μM) showed greater free radical scavenging ability than compound 2 (35 μM), and was also more effective than ascorbic acid and Trolox. DFT studies indicate that the HAT mechanism is favored over SET for DPPH scavenging. Both compounds exhibited stronger Cu(II) ion reducing capacity than Trolox and ascorbic acid with Trolox equivalent activity coefficient (TEAC) values of 2.0 and 1.6 for compounds 2 and 3, respectively. Furthermore, DNA cleavage and binding properties were determined using gel electrophoresis, UV-Vis spectroscopy, and cyclic voltammetry. The compounds showed copper-mediated cleavage of plasmid DNA and strong binding to DNA, with binding constants on the order of 104 M−1. The strength of DNA binding was verified by molecular docking analysis using two DNA models: a B-DNA dodecamer (-8.4 to -9.3 kcal/mol) and a hexamer (-7.8 to -7.9 kcal/mol). Overall, the chromene Schiff bases show promise as antioxidant and DNA binding agents.

Hollow AMn2O4-δ (A = Co, Zn, Ni) nanotube for direct photo-oxidation of methane to C1 and C2 alcohols at atmospheric pressure and room temperature

Methane (CH4) conversion is brought into research hotspot in the field of environment, and direct photo-oxidation of methane into C1 and C2 alcohols under moderate conditions remains a huge challenge. Herein, we report a series of hollow AMn2O4-δ (A = Co, Zn, Ni) spinel nanotubes (HNTs) for the direct photo-oxidation of methane (DPOM) reaction. The results of catalytic performance demonstrated that the CH4 conversion and the yields of high value-added liquid products arrange in order of ZnMn2O4-δ HNTs > CoMn2O4-δ HNTs > NiMn2O4-δ HNTs. The ZnMn2O4-δ HNTs exhibited a superior CH4 conversion of 53.9 %, a liquid product yield of 241.7 μmol g−1h−1 (CH3OH 40.1 μmol g−1h−1, CH3CH2OH 200.9 μmol g−1h−1) and a selectivity of 100 % under light irradiation at atmospheric pressure and room temperature conditions. Xray photoelectron spectroscopy (XPS) and low-temperature electron paramagnetic resonance (EPR) analysis showed that the substitution of Zn ion at the A-site of manganate spinel significantly improved surface chemisorbed oxygen (Oα) and oxygen vacancy activity, which were beneficial to the formation of •CH3. Multi-technology photocatalytic activity characterizations results showed that ZnMn2O4-δ HNTs possessed a narrower band gap and greatly favored the separation of photogenerated carriers. Moreover, the DPOM reaction mechanism involving the formation and dehydrogenation of alkyl and alkoxy intermediates was proposed over AMn2O4-δ (A = Zn, Co, Ni) HNTs, which was investigated through temperature-programmed desorption of CH4 (CH4-TPD), in situ EPR, in situ Fourier transform infrared spectroscopy (FT-IR) and density functional theoretical (DFT) calculations. It emphasized that CH3OH was formed via the combination of •CH3 and •OH. And it was more inclined to generate CH3CH2OH through the intermediates *CH2CH3/*CH3O. This study could broaden the avenue toward the application of manganese-based spinel in the direct photo-oxidation of methane into alcohols and offer a disparate perspective on the role of the substitution of metal ion at the A-site in enhancing the photocatalytic performance.

Oxidative Dissolution Mechanisms of Pyrite {100} and {210} Faces: An Atomic Study

ABSTRACT The oxidative dissolution of pyrite discharging into tailing pond as gangue minerals attracts intensive interesting as this forms the main source of acid mine drainage. However, the related dissolution mechanisms on the individual crystal faces of pyrite particles remain unclear. In this study, the oxidative dissolution mechanisms of pyrite {100} and {210} faces under acidic and neutral conditions were investigated. The results indicated that the dissolution rate of pyrite correlates positively to the reactivity of pyrite face. The reactivity of {210} was higher than that of {100}, mainly due to the geometric arrangements of the atoms. In addition, the oxidative dissolution on pyrite faces follows the chemical reaction model. Further density functional theoretical (DFT) calculation indicated that {210} face showed obvious Fe-S breakage and S-S formation while {100} face only showed slight atoms movement during relaxation process. Moreover, a higher conductivity and electron transfer ability of {210} faces than that of {100} face was found base on scanning electrochemical microscopy. This study therefore provides new insights into oxidative dissolution of pyrite crystal faces at an atomic level.

Unsaturated cobalt-nitrogen atomic sites in necklace-like hairy fibers towards highly efficient oxygen electrocatalysis for flexible Zn-Air battery

Exploration of single-atom catalysts (SACs) with high activity and efficient utilization efficiency holds great promise in the field of electrocatalysis. However, it is still a challenge to rationally design the SACs due to their properties are greatly influenced by the local electron environment and the effective substrate. Herein, we synchronously realized the modulation of unsaturated cobalt-nitrogen atomic sites (CoN3) and uniformly archoring them on the carbon-nanotube assembled necklace-like fiber (NLF). The unsaturated cobalt-nitrogen atomic sites with asymmetric structure favor the adsorption/desorption features and promote the electrocatalytic reactions of oxygen. Meanwhile, the hairy NLF fiber with the highly conductive and porous matrix guarantees the active sites accessibility and fast kinetics. In addition, the unique necklace-like configuration endows good mechanical strength and high reliability for the CoN3 NLF fiber. Both density functional theoretical (DFT) calculation and the experimental results reveal its superior catalytic properties and good reliability in the oxygen electrocatalytic reactions. Moreover, the finite element analysis (FEA) and the corresponding tests further certify its high pliability and good robustness. Based on the CoN3 NLF fiber air cathode, the aqueous Zn-air battery (ZAB) delivers a high power density (306 mW cm−2) and outstanding cycling stability over 300 h. Furthermore, all-solid-state ZAB based on the freestanding CoN3 NLF air cathode shows considerable flexibility and superior reliability over a wide range of temperatures (-20∼25 °C). Therefore, this work provides an effective catalyst design for the development of metal-air batteries for diverse applications.

Full-exposed Cu site of Cu2O-(1 0 0) driven high ethylene selectivity of carbon dioxide reduction

Cu2O shows great potential as a catalyst for the electrochemical CO2 reduction reaction (ECO2RR). However, the mechanism behind the formation of different final products from Cu2O nanostructures remains a challenge. In this study, we combine theoretical and experimental approaches to demonstrate that the full-exposed Cu sites in Cu2O (100) microcubes contribute to superior C2H4 selectivity compared to other microstructures such as Cu2O (111), (110), and (311) facets. Density functional theoretical (DFT) calculations reveal that the stronger orbital splitting between Cu 3d and O 2p orbital of Cu2O (100) facet facilitates the formation of neighboring and low valence state Cu active site, thereby enhancing *CO adsorption and C2H4 formation. These DFT results are supported by the synthesis of four kinds of Cu2O microparticles (MPs) with different exposed facets, where cubic-Cu2O with the (100) facet exhibits the highest Faradaic efficiency (61.3 %). This study has significant implications for the structural design and mechanism analysis of innovative catalysts used in ECO2RR.

Rational design of graphdiyne-based single-atom catalysts for electrochemical CO2 reduction reaction.

Graphdiyne (GDY) has achieved great success in the application of two-dimensional carbon materials in recent years due to its excellent electrochemical catalytic capacity. Considering the unique electronic structure of GDY, transition metal (TM1) (TM = Fe, Ru, Os, Co, Rh, Ir) single-atom catalysts (SACs) with isolated loading on GDY were designed for electrochemical CO2 reduction reaction (CO2RR) with density functional theoretical (DFT) calculations. The charge density difference and projected densities of states have been systematically calculated. The mechanism of electrochemical catalysis and the reaction pathway of CO2RR over Os1/GDY catalysts have also been investigated and high catalytic activity was found for the generation of methane. The calculated results provide a theoretical basis for the design of efficient GDY-based SACs for electrochemical CO2RR.

Microwave Quasi‐Solid State to Construct Strong Metal‐Support Interactions with Interfacial Electron‐Enriched Ru for Anion Exchange Membrane Electrolysis

AbstractRegulating the metal‐support interaction of the anchored metal nanoclusters is recognized as valid approach to optimize the electrocatalytic performance through tuning the interfacial electronic structure. However, developing novel support and understanding the interfacial electron accumulation on modulating the reaction kinetics are still elusive. Herein, highly‐dispersed Ruthenium (Ru) nanoclusters anchored onto phosphorous doped molybdenum boride (Ru/P‐MoB) is developed through ultrafast microwave‐plasma (60 s) approach. The synthesized Ru/P‐MoB impressively promote the hydrogen evolution with low overpotentials of 34, 45, and 40 mV to drive 10 mA cm−2 in alkaline freshwater, alkaline seawater and acid media. Specially, it presents superior turnover frequency and mass/specific activity relative to Pt/C, Ru/C, and Ru/MoB. Moreover, the anion exchange membrane (AEM) electrolyzer cell based on Ru/P‐MoB can achieve 500 and 1000 mA cm−2 with small voltages of 1.71 and 1.78 V with good durability. Experimental and density functional theoretical (DFT) analysis reveal that the strong metal‐support interactions (Ru─Mo and Ru─P bonds) with generated interfacial electron‐enriched Ru, and then favoring the water‐molecule adsorption/dissociation and optimal H intermediate adsorption free energy. This work provides novel designing avenue to exploit electrocatalysts with outstanding catalytic performance under high current density at practical high‐temperature.

Active Electrochemical Catalysts for Ammonia and Hydrogen Evolution Reaction

An environmentally friendly alternative synthesis process is desired to produce NH3 with no CO2 emissions and low energy demand in a sustainable and ecological way in the future. The electrochemical method assisted by earth-abundant materials has been widely utilized for the chemical energy conversion. We have developed new earth-abundant layered structure metal sulfide based materials as active catalysts for electrochemically nitrogen reduction reaction. From electrochemical analysis, the Faraday efficiency of MoS2 and FeS2 for NRR can be achieve to~27% and 14% with good catalytic stability, respectively. The energy profile of the NRR reaction pathway on the catalysts will be performed by the density functional theoretical (DFT) calculation. Besides, there have been lots of studies on hydrogen evolution reaction (HER) catalytic activity using ultralow loading of Pt catalysts or even Pt single atom catalysts as well. However, Pt single atom deposited on the surface of the carbon or metal oxide material showed some drawbacks, such as high possibility of Pt desorption from the supported material in the electrolyte. Our work demonstrated that gold nanodendrites (Au NDs) with high facet surface was chosen as the supported materials for studying the relation between the low loading amount of Pt atoms and reaction mechanism of HER activity. Overall results provides a feasible approach to morphological control of metal sulfide and atomic deposition of Pt element on the specific substrate as active catalysts for NRR and HER applications, respectively.

Lamellar WO3/AgI S-scheme heterojunction for superior visible light driven photocatalytic degradation of ciprofloxacin

A unique lamellar WO3/AgI S-scheme heterojunction is constructed via integrated hydrothermal and coprecipitation methods. Optimized WO3/AgI composite shows significantly enhanced photocatalytic ciprofloxacin (CIP) degradation under visible light irradiation, achieving a removal rate of 53.4 % within 3 h, which is about 7.63 and 1.56 times superior than those of pristine WO3 and AgI, respectively. The characterizations, experiment results and Density Functional Theoretical (DFT) calculation results confirm the enhanced light absorption, well-aligned straddling band structures and reasonable formation of S-scheme heterojunction with efficient photogenerated carriers transfer between WO3 and AgI. Moreover, O2− and h+ are identified as the main active species, with O2− plays a dominant role in WO3/AgI during the photocatalytic degradation of CIP. This work elucidates a possible approach to develop photocatalysts with a high antibiotic removal efficiency through a higher reducing ability and stronger oxidizing ability of S-scheme heterojunction by reasonable structure configuration.