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•Hollow tubular g-C3N4 isotype heterojunction (SCN-CN) was synthesized.•SCN-CN performed a high visible-light photodegradation efficiency for TCH and RHB.•This work provides a ...theoretical basis for CN isotype heterojunction.•Electronic, optical, and work function properties were calculated based on DFT.
A highly reactive hollow tubular g-C3N4 isotype heterojunction (SCN-CN) was designed to enhance visible light absorption and manipulate the directed transfer of electrons and holes. The results of UV–vis DRS, XPS valence band and DFT theoretical calculations indicated S doping increases the visible-light absorption capacity and changed the ba nd gap structure of g-C3N4 (CN), resulting in the transfer of electrons from the CN to the SCN and holes from the SCN to the CN under visible light. In addition, the tubular structure of the SCN-CN facilitated the transfer of electrons in the longitudinal direction, which reduced charge carrier recombination. Furthermore, the optical properties, electronic structure, and electron transfer of SCN-CN were also studied by experiments and theoretical calculations. The antibiotic tetracycline hydrochloride (TCH) and dye Rhodamine B (RHB) were subjected to evaluate the photocatalytic performance of SCN-CN. The scavenger tests and ESR data showed that the h+, ·O2− and ·OH worked together in the photocatalytic process. Moreover, the photocatalytic degradation pathway was analyzed by LC-MS. This study synthesized a hollow tubular CN isotype heterojunction with high visible-light photocatalytic performance and provided a theoretical basis for CN isotype heterojunction.
Abstract
Constructing photocatalytically active and stable covalent organic frameworks containing both oxidative and reductive reaction centers remain a challenge. In this study, ...benzotrithiophene-based covalent organic frameworks with spatially separated redox centers are rationally designed for the photocatalytic production of hydrogen peroxide from water and oxygen without sacrificial agents. The triazine-containing framework demonstrates high selectivity for H
2
O
2
photogeneration, with a yield rate of 2111 μM h
−1
(21.11 μmol h
−1
and 1407 μmol g
−1
h
−1
) and a solar-to-chemical conversion efficiency of 0.296%. Codirectional charge transfer and large energetic differences between linkages and linkers are verified in the double donor-acceptor structures of periodic frameworks. The active sites are mainly concentrated on the electron-acceptor fragments near the imine bond, which regulate the electron distribution of adjacent carbon atoms to optimally reduce the Gibbs free energy of O
2
* and OOH* intermediates during the formation of H
2
O
2
.
Quantum-sized cerium dioxide (CeO2) show high catalytic capability as well as strong light absorption ability owing to its redox couple Ce4+/Ce3+ and abundant oxygen vacancies, which making it a ...potential material for designing superior photoelectrochemical (PEC) sensors. However, it has scarcely been applied in the field of PEC sensing, because its wide band gap and aggregation effect can restrict the photoelectric conversion efficiency. Herein, we address these two obstacles by coupling CeO2 quantum dots (QDs) with graphitic carbon nitride (g-CN) and Au nanoparticles (NPs). The electron transfer path in this proposed heterojunction was proved by density functional theory (DFT) calculation for the first time, which provided theoretical support for the detection of MC-LR. The as-obtained PEC aptasensor exhibited excellent analytical performance with a wide liner response of 0.05–105 pM, and the detection limit was 0.01 pM. By designing appropriate sensing system and specific recognition mechanism, this work may pave a unique avenue for constructing ultrasensitive and selective analysis of MC-LR in complex environment without any external electric source.
•CeO2 was first applied in PEC sensing by designing an ACG heterostructure.•The electron transfer process in ACG heterostructure was proved by DFT calculation.•The specific recognition mechanism of aptamers makes this sensor more selective.•The accurate measurement of MC-LR in water samples by this sensor was obtained.
In the actual implementation of autonomous vehicle controller and related applications, it is difficult to obtain all the actual parameters of the vehicle. Considering factors such as uneven pavement ...and different pavement conditions, it is difficult to accurately establish the vehicle dynamic system model. Based on the non-singular terminal sliding mode and adaptive control theory, this paper establishes a trajectory tracking control strategy for an autonomous vehicle with unknown parameters and unknown disturbances. Firstly, the complex trajectory tracking problem is decoupled from the position and heading angle tracking problem, and the preview error equation is established. Secondly, a non-singular terminal sliding mode (NTSM) controller is established to stabilize the trajectory tracking error to the origin in a finite time, and adaptive laws are proposed to estimate the unknown vehicle parameters to adapt to environmental changes. Through the CarSim–Matlab platform, typical working conditions are implemented to verify the proposed controller. Our experimental outcomes affirm that the NTSM controller effectively guarantees the autonomous vehicle’s accurate following of the reference path, ensuring smooth control inputs throughout the entire process.
Two major forms of human carboxylesterase (CES), CES1A and CES2, dominate the pharmacokinetics of most prodrugs such as imidapril and irinotecan (CPT-11). Excipients, largely used as insert vehicles ...in formulation, have been recently reported to affect drug enzyme activity. The influence of excipients on the activity of CES remains undefined. In this study, the inhibitory effects of 25 excipients on the activities of CES1A1 and CES2 were evaluated. Imidapril and CPT-11 were used as substrates and cultured with liver microsomes in vitro. Imidapril hydrolase activities of recombinant CES1A1 and human liver microsomes (HLM) were strongly inhibited by sodium lauryl sulphate (SLS) and polyoxyl 40 hydrogenated castor oil (RH40) Inhibition constant (Ki) = 0.04 ± 0.01 μg/ml and 0.20 ± 0.09 μg/ml for CES1A1, and 0.12 ± 0.03 μg/ml and 0.76 ± 0.33 μg/ml, respectively, for HLM. The enzyme hydrolase activity of recombinant CES2 was substantially inhibited by Tween 20 and polyoxyl 35 castor oil (EL35) (K(i) = 0.93 ± 0.36 μg/ml and 4.4 ± 1.24 μg/ml, respectively). Thus, these results demonstrate that surfactants such as SLS, RH40, Tween 20 and EL35 may attenuate the CES activity; such inhibition should be taken into consideration during drug administration.
The abuse of pesticides and antibiotics and their harm to the environment are the disadvantages of modern agriculture and breeding industry. g-C3N4 has shown great potential in photocatalytic water ...pollution purification under visible light irradiation, however, the conventional g-C3N4 suffers from the disadvantage of limited optical absorption and serious charge recombination, resulting in inefficient light energy conversion and pollutant degradation. This study provides a strategy of combining defect engineering with a built-in electric field to prepare homojunction a photocatalyst with high optical absorption rate and charge separation efficiency. Experiments and DFT simulation revealed the mechanism of significant improvement in the photocatalytic performance of the prepared catalyst, and proposed the pollutant degradation pathway. In addition, the photocatalytic effects of the prepared catalysts on different natural water bodies, natural light, and various water conditions were investigated, revealing the applicability of the catalysts in the purification of pollutants in various water environments.
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•Defect engineering was applied to the design of homojunction photocatalysts.•The efficient charge transfer over the homojunction interface is determined by experiments and DFT calculation.•The photocatalytic mechanism and degradation pathway of atrazine and tetracycline were proposed.•Photocatalytic performances under nature sunlight and in actual water samples were evaluated.
Photocatalytic H2O2 evolution through two‐electron oxygen reduction has attracted wide attention as an environmentally friendly strategy compared with the traditional anthraquinone or ...electrocatalytic method. Herein, a biomimetic leaf‐vein‐like g‐C3N4 as an efficient photocatalyst for H2O2 evolution is reported, which owns tenable band structure, optimized charge transfer, and selective two‐electron O2 reduction. The mechanism for the regulation of band structure and charge transfer is well studied by combining experiments and theoretical calculations. The H2O2 yield of CN4 (287 µmol h−1) is about 3.3 times higher than that of pristine CN (87 µmol h−1), and the apparent quantum yield for H2O2 evolution over CN4 reaches 27.8% at 420 nm, which is much higher than that for many other current photocatalysts. This work not only provides a novel strategy for the design of photocatalyst with excellent H2O2 evolution efficiency, but also promotes deep understanding for the role of defect and doping sites on photocatalytic activity.
Leaf‐vein‐like g‐C3N4 synthesized via a KBH4‐assisted thermal polycondensation strategy exhibits enhanced optical absorption, efficient charge carrier separation, and ample active sites, accordingly enabling excellent photocatalytic H2O2 evolution. The synergistic effect of B doping and defect sites on the improvement of catalyst performance is fully discussed by experiments and density functional theory calculations.
Manganese oxides and carbon materials are both desirable catalysts for persulfate (PS) advanced oxidation processes in environmental remediation. Nevertheless, manganese oxides suffer from low ...reusability while carbon materials face the problem of limited catalytic efficiency. For the purpose of making full use of the advantages of the two materials as well as avoiding their shortcomings, carbon-coated Mn3O4 composites (Mn3O4/C) with a regular nanocube structure were designed to activate PS for the removal of organics, and the catalytic processes were deeply investigated. The catalyst prepared at 400 °C with a precursor ratio (glucose/KMnO4) of 0.5 exhibited the best catalytic performance along with satisfactory reusability owing to the protection of the outer carbon layer. According to experimental results and density functional theory calculation, there were van der Waals interaction and a part of the strong attraction between the interface of PS and Mn3O4/C, which could be enhanced by inner Mn3O4 and thus promoted the electron transfer between PS and carbon shell, and the defective edges of the carbon layer with hydroxyl (C–OH) groups could act as active sites for PS activation. Radical (SO4 •–, •OH) and nonradical (1O2) oxidation processes both participated in the degradation of 2,4-dichlorophenol, in which •OH was dominating. This study not only proposed a promising catalyst for the degradation of pollutants but also expanded research ideas for future PS activation mechanism studies by integrating the experiment and simulation.
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•Floating porous g-C3N4 composite (FPCN) was successfully fabricated by a facile one-pot method.•FPCN exhibited a good photocatalytic performance under visible light without any ...stirring.•FPCN showed a good stability and reusability.•Possible degradation pathway of tetracycline and mechanism of the photocatalytic process were proposed.
Powder catalysts are difficult to recycle, which may induce secondary pollution and may limit their practical application. Herein, we successfully synthesized floating porous g-C3N4 (FPCN) using a melamine sponge and urea via a facile one-pot method, which can solve the recycling problem of powder catalysts. The highest elimination efficiency of 5 mg/L tetracycline (TC) reached 70% by 2 g/L FPCN without any stirring under visible light after 4 h. However, the elimination efficiency of 5 mg/L TC by 2 g/L powder g-C3N4 was only 36.9% under the same conditions. The good photocatalytic performance of FPCN is attributed to its 3D interconnected network and enhanced light absorption. The effects of inorganic ions and organic matters on the photocatalytic performance of FPCN were studied. Finally, we proposed a possible mechanism and pathway for degradation of TC.
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•Novel Ag@PCNS/BiVO4 nanocomposite was synthesized via an impregnated process combined with photo-reduction method.•Synergistic effects results in enhanced visible-near-infrared ...response ability.•Boosted photocatalytic removal efficiency of ciprofloxacin.•The effect of surface plasmonic resonance caused by metallic Ag contributed to the dual Z-scheme reaction mechanism.
To realize the full utilization of solar energy, the design of highly efficient photocatalyst with improved visible-near-infrared photocatalysis performance has attracted great attentions for environment pollutant removal. In this work, we rationally employed the surface plasmon resonance effect of metallic Ag in the phosphorus doped ultrathin g-C3N4 nanosheets (PCNS) and BiVO4 composites to construct a ternary Ag@PCNS/BiVO4 photocatalyst. It was applied for the photodegradation of ciprofloxacin (CIP), exhibiting 92.6% removal efficiency under visible light irradiation (λ>420nm) for 10mg/L CIP, and presenting enhanced photocatalytic ability than that of single component or binary nanocomposites under near-infrared light irradiation (λ>760nm). The improved photocatalytic activity of the prepared Ag@PCNS/BiVO4 nanocomposite can be attributed to the synergistic effect among the PCNS, BiVO4 and Ag, which not only improves the visible light response ability and hinders the recombination efficiency of the photogenerated electrons and holes, but also retains the strong the redox ability of the photogenerated charges. According to the trapping experiment and ESR measurements results, OH, h+ and O2− all participated in the photocatalytic degradation process. Considering the SPR effect of metallic Ag and the established local electric field around the interfaces, a dual Z-scheme electrons transfer mechanism was proposed.
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