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•A day-night photocatalyst WO3-FePc with dual reaction centers was synthesized.•The catalyst has enhanced visible light response and effective charge separation.•The synergistic ...effect of dual reaction centers improves photocatalytic activity.•WO3-FePc can degrade pollutants under day-night cycle with recyclability.
In this article, we presented a novel WO3-FePc day-night dual reaction centers photocatalyst covalently modified by iron-tetra (N-carbonylacrylic) aminephthalocyanine (FePc), in which WO3 as an electron-storage reservoir and FePc as a photosensitizer and Fenton reaction center, which synergistically improve photocatalytic activity. The photocatalytic performance of WO3-FePc was evaluated using Rhodamine B (RhB) as a model pollutant, and it exhibited remarkable efficiency, with degradation of 93.0% RhB achieved under visible light irradiation for 60 min, and 40.4% RhB degraded in the dark, corresponding to approximately 12.4 times the performance of WO3 and 7.8 times that of FePc. In addition, the removal rates of methylene blue (MB), tetracycline hydrochloride (TC•HCl) and K2Cr2O7 (Cr (VI)) by WO3-FePc under visible light were 99.9%, 99.9% and 81.5% in 20 min, respectively. The rapid charge separation and the synergistic effect between the photocatalytic center and the Fenton center lead to excellent photocatalytic performance. This study prepared a highly efficient photocatalyst WO3-FePc that can act continuously during both day and night, and its distinctive day-night dual reaction center provides a new way to overcome the limitations of traditional photocatalytic technology.
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•Functionalized abrasives were designed for photochemical mechanical polishing (PCMP).•The binary composites contain elastic meso-silica cores and active nano-ceria shells.•The ...abrasive helps to simultaneously improve the surface quality and removal rate.•UV irradiation and Er3+-doping treatments contributed to superior polishing behavior.•Synergistic role and action mechanism of the novel abrasives in PCMP were proposed.
We report the design and synthesis of meso-silica/ceria binary composite particles and their usage as functionalized abrasives for photochemical mechanical polishing (PCMP). Meso-silica nanospheres were uniformly coated with (Er3+-doped) ceria nanoparticles via an environmentally friendly precipitation approach. The resulting products were characterized by XRD, FESEM, HRTEM, HADDF-STEM, EDX mapping, UV–vis, Raman, XPS, PL, and nitrogen adsorption–desorption measurements. High-resolution AFM analyses revealed that the binary abrasives contributed to mechanical damage and scratch eliminations, and finally achieved ultra-smooth surfaces with an average root-mean-square roughness of less than 0.2 nm. Owing to the increased oxygen vacancy and Ce3+ ion contents, the Er3+-doped abrasives in oxide-PCMP exhibited superior removal rates derived from the improved photocatalytic and tribochemical activities, thus leading to a 160% increment of removal rates compared to the undoped ones in oxide-CMP. The topographical variations of the surfaces after PCMP with Er3+-doped composites significantly reduced from ±3.1 nm to ±0.39 nm. High-quality and high-efficiency polishing can be achieved by the dynamical balance between the photocatalytic surface modification and the tribochemical material removal of the chemically soft layers. Furthermore, the synergistic roles of elastic meso-silica supports and active ceria components of the binary abrasives in material removal processes were also discussed.
Self-assembly of two Zn-MOFs, Zn
L(DMF)
H
O·5DMF (1) and Zn
L(H
O)
4H
O·3DMF (2), was achieved with an amide-functionalized tetracarboxylate ligand under similar conditions. Incorporated amide ...groups make the tetratopic linkers exhibit different configurations, tetrahedron and square, and subsequently combine tetrahedral Zn
(CO
)
clusters or square paddle-well Zn
(CO
)
clusters to afford a
net for 1 and a
net for 2. Remarkably, 2 demonstrated high porosity and amide group decorated cages, and thereby proved to be a good capturing agent for a fluorescent dye molecule (DMASM). Consequently, a dual-emitting DMASM@2 sensor was successfully fabricated based on effective energy transfer from the host framework to DMASM with the variable luminescent color being visible to the naked eye. DMASM@2 could be used for the detection of metronidazole (MDZ) and dimetridazole (DTZ) with high sensitivity and remarkable recyclability.
In recent years, the combination of perovskite with other materials to improve the optoelectronic performance and detection range has received widespread attention. In this paper, ZnO/perovskite ...heterostructure photodetectors were prepared by sputtering and sol-gel spin-coating method. ZnO/perovskite photodetector exhibits superior photoelectric performance over a wide detection range from UV to visible compared to ZnO and perovskite photodetector. Under 360 nm illumination, the detection performance is higher than ZnO and perovskite photodetector, with responsivity of 2.73 A/W, light-to-dark current ratio of 5.88 × 104, a detectability of 1.09 × 1012 Jones, and an external quantum efficiency of 940.86 %. Meanwhile, perovskite combined with ZnO, the device has higher light-to-dark ratio, responsivity and detectivity than perovskite photodetector in the visible region of 550 and 750 nm. The heterojunction formed by ZnO and perovskite, which has a built-in electric field, thus reducing the dark current, reducing carrier recombination and enhancing the photovoltaic performance. The responsivity of the device slightly decreases after being placed in the atmosphere for 10 days. This study provides a basis for the preparation of heterojunction photodetectors with high optoelectronic performance.
•ZnO/perovskite PD exhibits superior photoelectric performance over a wide detection range from UV to visible.•Compared with ZnO PD and perovskite PD, ZnO/perovskite PD improve its optoelectronic performance.•Under 360 nm, R is 2.73 A/W, / is 5.88 × 104, D* is 1.09 × 1012 Jones, and EQE is 940.86 % of ZnO/perovskite PD.•ZnO/perovskite PD also has higher /, R and D* than perovskite PD in the visible region of 550 and 750 nm.
Molybdenum disulfide (MoS2) is a nonlinear optical material with graphene-like structure. In order to further improve the nonlinear optical performance of MoS2 and expand the application fields of ...MoS2, we report a simple in-situ self-growth method to functionalize MoS2 nanosheets with metal-organic framework (MOF) for the first time to pursuit excellent reverse saturable absorption performance and optical limiting performance. Firstly, defective MoS2 nanosheets was obtained by chemical etching with H2O2 and cysteamine was inserted into the sulfur vacancies under ultrasound to obtain MoS2–NH2. Then 5,10,15,20-Tetra (4-carbomethoxyphenyl) porphyrin (TCPP) as MOF active growth sites were grafted on MoS2–NH2 by amido linkage to obtain MoS2-TCPP in mild conditions. Finally, flower-like porphyrin-based CuMOF was grown on MoS2-TCPP by solvothermal method to obtain MoS2-CuMOF with stable structure. The third order nonlinear optical performance of MoS2-CuMOF were studied by Z-scan technique. It was found that the third order nonlinear absorption coefficient of MoS2-CuMOF was significantly improved compared with MoS2. Under the same energy of laser irradiation, the third order nonlinear absorption coefficient of MoS2-CuMOF nanocomposite in solution was 6 × 10−10 m/W about 2.3 times of the pristine MoS2 (2.6 × 10−10 m/W). After blending the above materials with polymethyl methacrylate (PMMA) to prepare a solid device, the third order nonlinear absorption coefficient of MoS2-CuMOF/PMMA was 18 × 10−10 m/W about 3.6 times of the MoS2/PMMA (5 × 10−10 m/W). And MoS2-CuMOF/PMMA had better optical limiting ability than MoS2/PMMA. The significant improvement in the performance of the composites can be attributed to the energy transfer between MoS2 and CuMOF, and porphyrin aggregation was inhibited by PMMA after the preparation of devices. Energy transfer can be proved by fluorescence spectroscopy. This work not only provided an example for the covalent functionalization of MoS2, but also offered a new method for designing materials with excellent nonlinear optical performance.
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•MOF was grown on MoS2 by a simple in-situ self-growth method to prepare MoS2-CuMOF.•MoS2-CuMOF had larger third-order nonlinear absorption coefficient.•MoS2-CuMOF had excellent properties through energy transfer between components.•MoS2-CuMOF can be prepared into PMMA-based optical limiter.
The metal–semiconductor–metal (MSM) structure is widely applied in photodetectors (PDs) owing to its simple preparation method and a more effective light collecting area. However, the realization of ...weak light detection remains a daunting challenge, attributed to the low external quantum efficiency (EQE) in MSM‐based PDs. Herein, sandwich structure PD (SSPD), a new structure of PD based on MSM structure, is presented to solve the problem of low gain in MSM PDs. Herein, the high‐EQE MgZnO/Au/ZnO SSPD with avalanche effect is reported for the first time. The avalanche effect is realized by changing the position of electronic transmission through energy band engineering between MgZnO and ZnO in the sandwich structure. The SSPD exhibits high EQE when photogenerated carriers get transported at the interface of ZnO and MgZnO. Under 275 nm illumination, the MgZnO/Au/ZnO SSPD achieves avalanche multiplication at 63 V and shows EQE of up to 502780% at 90 V. These results reveal that a high EQE originates from the special sandwich structure existing in MgZnO/Au/ZnO SSPD. This study presents possible guidance for high‐performance ZnO‐based avalanche PD for applications in telecommunications, sensing, and single‐photon detection.
MgZnO/Au/ZnO sandwich structure photodetector (SSPD) is presented to solve the problem of low gain in metal–semiconductor–metal photodetectors. The MgZnO/Au/ZnO SSPD achieves avalanche effect and high external quantum efficiency. Avalanche effect is realized by changing the position of electronic transmission through energy band engineering between MgZnO and ZnO in the sandwich structure.
Metal phthalocyanines (MPcs) have attracted more and more attention in recent years for the catalytic degradation of pollutants in water driven by visible light. However, they are easy to aggregate ...in the aqueous phase and difficult to recycle, which seriously limits their photocatalytic activity and applicability. Introducing phthalocyanine into polymers may be an effective way to solve the above problems. Herein, three kinds of copolymers PNIPAMx-co-PDUPcZny with different molecular weights and monomer ratios were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, with S-1-dodecyl-S′-(α,α’-dimethyl-α”-acetic acid)trithiocarbonate (DDMAT) as chain transfer agent, 3-undecenamide-9(10),16(17),23(24)-decyloxy‑zinc phthalocyanine (DUPcZn) and N-isopropyl acrylamide (NIPAM) as monomers, 2,2′-azobis(2-methylpropionitrile) (AIBN) as initiator. The polymerization process shows the characteristics of living polymerization, and the polymer dispersity index (PDI) values are <1.1. The three copolymers exhibit obvious thermo-responsive characteristics and the lower critical solution temperatures (LCSTs) are between 32.7 °C and 33.1 °C. The photocatalytic activity of the copolymers was evaluated by using 1,5-dihydroxynaphthalene (DHN) and Cr(VI) as model pollutants. It was found that the three copolymers had photocatalytic oxidation performance for DHN and photocatalytic reduction performance for Cr(VI), and their photocatalytic property was affected by the pH of the model pollutant solution and the catalytic temperature. Among them, PNIPAM57-co-PDUPcZn7 exhibit a photocatalytic oxidation rate of 93.0% for DHN and the photocatalytic reduction rate of 70.0% for Cr(VI), respectively, under the visible light irradiation for 120 min at pH = 5 and 32 °C. More importantly, the homogeneous catalysis and heterogeneous recovery are achieved in the catalytic process through simple temperature regulation. In addition, the copolymers exhibited excellent chemical stability and reusability after three cycles. Finally, O21/e− was determined to be the active species that plays a crucial role in the photocatalytic oxidation/reduction process, upon which a possible photocatalytic mechanism was proposed. This research provides a promising strategy for the synthesis of environmentally friendly visible light catalysts for the sewage (waste) water treatment.
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•Novel unsymmetrical zinc phthalocyanine with alkenyl group has been synthesized.•A series of thermo-responsive copolymers PNIPAMx-co-PDUPcZny were prepared.•The copolymers were prepared by RAFT polymerization.•The photocatalytic oxidation/reduction activity of the copolymers was evaluated.•The catalysts showed excellent catalytic activity without requiring any cocatalyst.
In this study, TiO2 nanoparticle-encapsulated ZIF-8/polyacrylonitrile (PAN)-derived porous carbon nanofibers (PCNFs) have been synthesized by combining electrospinning and hydrothermal methods, which ...were then sensitized with tetra-carboxyphenylporphyrin copper(Ⅱ) (CuTCPP) to obtain porous carbon nanofibers ternary photocatalyst (PCNFs@TiO2-CuTCPP) for photocatalytic degradation of pollutants. The structure and composition of the samples were characterized by XRD, FT-IR and XPS. The internal pore structure of PCNFs@TiO2-CuTCPP and the uniformity of the outer layer wrapped by TiO2 nanoparticles can be observed by SEM and HRTEM. PCNFs@TiO2-CuTCPP has a high specific surface area (136.68 m2/g), which enables it to have excellent adsorption activity for model dye-Rhodamine B (RhB, 47.2 %, 4.7 × 10−4 mol/g), Methylene Blue (MB, 27.7 %, 2.8 × 10−4 mol/g) and Tetracycline hydrochloride (TC, 38.9 %, 3.1 × 10−4 mol/g) within 30 min. Photocatalytic experiments showed that the degradation rates of RhB and MB by PCNFs@TiO2-CuTCPP as photocatalyst were 95.4 %, 92.8 % and 89.9 %, respectively, after 180 min of visible light irradiation. PCNFs@TiO2-CuTCPP was continuously reused for four cycles without significant photoactivity loss and structural changes. Furthermore, the crucial role of .O2−, 1O2 and .OH were confirmed by active species capture experiments, and the photocatalytic mechanism under visible light was proposed. Above all, this study prepared a recyclable TiO2-based porous carbon nanofibers photocatalyst and provided a new idea for the effective modification of TiO2 in the field of photocatalysis.
•CuTCPP-sensitized TiO2@PCNFs was prepared for visible light photocatalysis.•PCNFs@TiO2-CuTCPP has large specific surface area and porous structure.•PCNFs@TiO2-CuTCPP could effectively adsorb RhB, MB and TC in dark.•PCNFs@TiO2-CuTCPP could efficiently degrade RhB, MB and TC under visible light irradiation with recyclability.
The spontaneous formation of two-dimensional electron gas (2DEG) with a high carrier density (∼1018 cm−3) was achieved at a ZnO/Mg0.2Zn0.8O interface grown using a facile radio-frequency magnetron ...sputtering system on a quartz substrate. Compared with Mg0.2Zn0.8O ultraviolet (UV) photodetectors (PDs) with and without a ZnO buffer layer, the PD based on ZnO/Mg0.2Zn0.8O bilayer films exhibited not only sensitivity to dual wavelength in the UV region, but also significantly enhanced spectral responsivity, photocurrent-to-dark current ratio (107), specific detectivity (1014), and UV/visible rejection ratio of about four orders of magnitude at a low operating voltage bias. Induced by 2DEG, the external quantum efficiency (EQE) of photodetector reached 14858% at 10 V, indicating that a considered high gain was achieved in the device based on this heterojunction architecture. The gain mechanism was further demonstrated by polarization induction and band bending in detail. This application of 2DEG in a practical detector offers a novel and effective approach for the substantial improvement in the high-performance of ZnO/Mg0.2Zn0.8O dual-band UV PDs.
2DEG formed at the ZnO/MgZnO interface greatly enhanced the gain and photoelectric performances of UV photodetector. Display omitted
•The polarization induced 2DEG achieved at a ZnO/Mg0.2Zn0.8O interface using a facile RF magnetron sputtering system.•The 2DEG photodetector exhibited significantly enhanced EQE (14858%) and specific detectivity (1014 Jones).•This feasible fabrication and practical application of 2DEG paved a promising way for performance improvement of UV PDs.
