High Efficiency Visible Light Research Articles

Unraveling the mystery of sandwich structure: Emerging photocatalytic hydrogen production by g-C3N5 coupled Nb2C MXene forming Schottky heterojunction

The development of new photocatalysts and photocatalytic systems is the essence of the development of photocatalytic hydrogen production engineering. Nitrogen-rich graphite carbon nitride (g-C3N5) has gradually replaced conventional graphite phase carbon nitride (g-C3N4) with a smaller bandgap and high-efficiency visible light utilization. In this study, g-C3N5 and Nb2C MXene coupled composition with sandwich structure were manufactured by a simple ultrasonic magnetic stirring method and used for photocatalytic hydrogen production. By adjusting the ratios of single components in the system, the hydrogen production rate of the optimal sample 4:1g-C3N5/Nb2C under visible light irradiation is 2529.5 μmol·g−1·h−1, which is 21 times higher than that of g-C3N5. The high apparent quantum yield (AQY) value of 17.3 % also proves a high light utilization rate. The atomic force microscopy (AFM) technique reveals variations in the thickness of the samples, while strongly demonstrating the formation of sandwich structure. In addition, X-ray photoelectron spectroscopy (XPS) analysis further reveals the electron transfer paths within the system, preliminarily verifying the formation of Schottky heterojunctions. Kelvin probe force microscopy (KPFM) tests not only re-validate the correctness of the electron transfer path but also demonstrate the accuracy of the energy bands. The density-functional theory (DFT) calculations corroborate that Nb2C MXene plays the role of a photoco-catalyst to form Schottky heterojunctions with g-C3N5 for efficient carrier separation and migration. This work highlights the key role of sandwich structure photocatalytic systems on photocatalytic performance.

Synthesis of novel g-C3N4/CaTiO3/CQDs heterojunction photocatalyst with enhanced visible light photocatalytic performance

In this paper, a high-efficient visible light responsive g-C3N4/CaTiO3/CQDs Z-type heterojunction photocatalyst was successfully prepared by a two-step method for the photodegradation of organic pollutants in water. The combination of g-C3N4, CaTiO3 and CQDs could produce synergistic effect, which facilitated the separation of carriers, thereby enhancing photocatalytic activity. The photocatalytic kinetic removal rate of g-C3N4/CaTiO3/CQDs for methylene blue could reach about 8 times of g-C3N4 and 5.5 times higher than that of CaTiO3. The effects of co-existing ions, initial pH, water source, and humic acid on meloxicam degradation were examined. Repeatability experiments indicated that the composite had good reusability and stability with 81.1 % removal for meloxicam after four cycles. The main active substances of g-C3N4/CaTiO3/CQDs in free radical capture experiment was ⋅O2−. Possible degradation pathways of meloxicam were also analyzed. The results highlight the g-C3N4/CaTiO3/CQDs Z-type heterojunction is a desirable photocatalyst for removing organic pollutants in water.

Investigations of Charge Transfer Processes on Plasmonic Cathode Electrodes

The establishment of efficient light energy conversion system is an important issue in the field of photoelectrochemical region. For the realization of it, the wide-band semiconductor electrode could be the good candidate. However, semiconductor electrodes often have the limitation to the ultraviolet region because of their band gap energy. Because the sunlight energy mainly consists of visible light, the visible-light induced photoenergy conversion is a challenging issue. As the breakthrough for it, recently, the combination of the plasmonic metal nanostructures with wide semiconductor electrodes has been received much attention because of the addition of visible light response characters. Up to now, the various systems of the anodic reaction controls have been established. Recently, the cathode system which can control the reduction reactions at metal semiconductor interfaces have been reported via the introduction of plasmonic metal nanostructures into the p-type semiconductor electrodes. In our previous study, we have established the plasmonic photocathode by using the Ag nanostructures with the p-type GaP electrode [1]. In this system, it can be considered as the holes excited in the metal structures injected into the valence band of the p-type semiconductor and the remained electron are consumed in the hydrogen evolution reaction. In addition, we have observed the unique pH dependence on the hydrogen evolution which could not be observed on conventional metal electrodes. For understanding the unique reaction selectivity on the plasmonic cathode electrode, the detail understanding about both the charge transfer process and absolute electrochemical potential of generated electrons. In this study, we have attempted to obtain such information through the various chemical reactions using the various types of plasmonic structures. Through the various photoelectrochemical measurements, we have confirmed the changes in the electrochemical potential of excited electrons depending on the optical characters of plasmonic structures. The unique molecular selectivity was also observed. Our current research would provide the novel insight for the accurate design of the high efficient visible light conversion device.[1] H. Minamimoto et al., Chem. Lett., 2020, 49, 806.

In-situ construction of direct Z-scheme NiO/Bi2MoO6 heterostructure arrays with enhanced room temperature ether sensing properties under visible light irradiation

Light irradiation has emerged as a promising strategy to promote room temperature sensing of resistive-type semiconductor gas sensors recently. However, high recombination rate of photo-generated carriers and poor visible light response of conventional semiconductor sensing materials have greatly limited the further performance improvement. It is urgent to develop gas sensing materials with high photo-generated carrier separation efficiency and excellent visible light response. Herein, a novel direct Z-scheme NiO/Bi2MoO6 heterostructure arrays were designed and in-situ constructed on alumina flat substrate to form thin film sensors, which realized excellent room temperature gas response towards ether under irradiation of visible light for the first time, together with excellent stability and selectivity. Based on density functional theory calculation and experimental characterization, it was demonstrated that the construction of Z-scheme heterostructure could greatly promote the separation of photo-generated carriers and adsorption of ether. Moreover, the excellent visible light response characteristics of NiO/Bi2MoO6 could improve the utilization of visible light. In addition, the in-situ construction of array structure could avoid a series of problems caused by the conventional thick film devices. The work not only provides a promising guideline for Z-scheme heterostructure arrays in promoting the room temperature sensing performance of semiconductors gas sensors under visible light irradiation, but also clarifies the gas sensing mechanism of Z-scheme heterostructure at the atomic and electronic level.

Perovskite‐Organic Coupling WLED: Progress and Perspective

AbstractPerovskite shows great potential in lighting and display owing to its advantages of low cost, high efficiency, and whole visible light tunability. However, how to realize high‐efficiency white perovskite light‐emitting diodes (WPeLEDs) still faces challenges such as the stability of devices and the energy regulation between different emission centers. In recent years, some organic molecules are introduced into the perovskite system because of their role in stabilizing perovskite crystals and enhancing photoelectric properties. In this review, the strategy of perovskite‐organic combination and coupling emission are emphasized, hoping to promote the development of high‐efficiency WPeLEDs. First, the research status of perovskite‐organic coupling WLEDs (POC‐WLEDs) is summarized in detail. Then, the development direction and possibility of POC‐WLEDs are proposed by combining them with some recent reports on POC methods. Finally, an outlook on POC‐WLEDs is proposed. It is a considerable strategy to introduce organic luminescent molecules into perovskite systems as ligands or A‐site organic cations for coupling emission with perovskite. In addition, the technologies of the organic polymer matrix, interfacial exciplex, and organic crosslinking are noteworthy exploration directions. They will promote the development of POC‐WLEDs in improving the stability of perovskite electroluminescence and regulating the energy transfer efficiency between perovskite/organic‐molecule emitting centers.

Insights into adsorption and high photocatalytic oxidation of ciprofloxacin under visible light by intra-molecular Donor-Acceptor like p-n isotype heterojunction: Performance and mechanism

Antibiotics, e.g. ciprofloxacin (CIP) are frequently detected in natural waters and sewage, however, the conventional sewage treatment techniques presents a great challenge for efficient removal them due to the inhibition of bacterial proliferation. Herein, the intra-molecular Donor-Acceptor like p-n isotype heterojunction of phosphorus and boron co-doped hollow tubular g-C3N4 (xB-PCN) was synthesized for high-efficiency visible light photocatalytic degradation of CIP. The Mott-Schottky curves showed that the xB-PCN exhibited both p and n-type conductivities, which probably because the doped boron has electron acceptor effect and the NH/NH2 groups could act as electron donors. This unique property enables xB-PCN to have excellent charge generation, separation and transfer ability for the highly efficient photodegradation of CIP, reaching 87.56% of decomposition efficiency within 1 h with the apparent rate constant (0.01151 min−1) of 6.85 times that of PCN. Furthermore, the 3B-PCN maintained high degradation percentage in tap water (84.63%) and aquaculture wastewater (78.41%). The results of LC-MS and TOC showed that CIP was gradually mineralized and the degradation pathways were proposed. Based on the radical trapping experiments and ESR characterization, the reactive oxygen species involved in the degradation of CIP were checked. This work offers a promising approach for treating antibiotics polluted water based on a metal-free conjugated polymeric g-C3N4.

High-efficient visible light photocatalytic degradation by nano-Ag-doped NH2-MIL-125(Ti) composites

A series of stable nano-Ag-doped NH2-MIL-125(Ti) composites (A/M125) were prepared by two facile successive steps: hydrothermal and photo reduction method. The photocatalytic composites were characterized by powder X-ray diffraction (PXRD), scanning and transmission electron microscopy (SEM, TEM), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), BET method and UV–visible diffuse reflectance spectroscopy. The results showed that Ag nanoparticles have been evenly distributed on the surface of NH2-MIL-125(Ti) (M125), which as a whole displays good visible-light absorption ability. Further photocatalytic degradation for Rhodamine B (RhB) in the visible light indicated that the photocatalytic rate of the optimal A/M125−20 composite is 2.7 times that of pure M125, and the final degradation rate reaches 97.4 % within 120 min. The subsequent free radical capture experiment showed ·O2¯ and h+ acted as the main reactive species. Moreover, the photocatalytic degradation mechanism was also investigated via electrochemical tests.

S-scheme heterojunction of polyfluorene derivatives coupled with ZnxCd1-xS nanoparticles for efficient and stable photocatalytic hydrogen evolution

In studying photocatalytic splitting of water, the efficiency and stability of catalysts for hydrogen evolution is a thorny problem. Conjugated polymer is a novel photocatalyst that can harness solar energy and have the advantages of high efficiency, non-toxicity and long-lasting visible light tolerance, making them a popular photocatalyst material. In this paper, the organic polyfluorene derivatives PF-((g-N3)-alt-(g-OH))/inorganic semiconductor ZnxCd1-xS composite catalyst PF-((g-N3)-alt-(g-OH))/ZnxCd1-xS (ZPF-OH) was synthesized, and the S-scheme heterojunction was successfully constructed to achieve efficient and stable hydrogen evolution. The hydrogen evolution activity of the composite photocatalytic material ZPF-OH-5 remained stable in 0.35/0.25 M Na2S/Na2SO3 solution for 60 h without replacing the sacrificial reagent. The 8.41 mmol g−1 h−1 hydrogen evolution performance of ZPF-OH-5 is 50 times higher than the case of pure ZnxCd1-xS but also 11 times higher than that of PF-((g-N3)-alt-(g-OH)) in 0.35/0.25 M Na2S/Na2SO3 solution. The apparent quantum efficiency at 400 nm has corresponded to 7.9% in 10% of lactic acid solution. In addition, the in-situ X-ray photoelectron spectroscopy irradiation and fluorescence analysis has used to explore the electron transfer path after the coupling of the two pure catalysts and to confirm the formation of S-scheme heterojunction in the composite catalysts. The optimized energy band structure and high electron transfer rate of organic-inorganic S-scheme heterojunction composite catalyst promote the H2 evolution, which shows excellent potential in stable and efficient photocatalytic hydrogen evolution.

Pyropheophorbide-a/(001) TiO2 Nanocomposites with Enhanced Charge Separation and O2 Adsorption for High-Efficiency Visible-Light Degradation of Ametryn.

It is highly desired to enhance charge separation and O2 adsorption of the pyropheophorbide-a (Ppa) to promote visible-light activity and stability. Herein, Ppa modified 001-facet-exposed TiO2 nanosheets (Ppa/001T) nanocomposites with different weight ratios were fabricated via the self-assembly approach by OH induced. Compared with the bare Ppa, the 8% amount optimized 8Ppa/001T sample displayed 41-fold enhanced activity for degradation of Ametryn (AME) under visible-light irradiation. The promoted photoactivities could be attributed to the accelerated charge carrier’s separation by coupling TiO2 as thermodynamic platform for accepting the photoelectrons with high energy from Ppa and the promoted O2 adsorption because of the residual fluoride on TiO2. As for this, a distinctive two radicals (•O2− and •OH) involved pathway of AME degradation is carried out, which is different from the radical pathway dominated by •O2− for the bare Ppa. This work is of utmost importance since it gives us detailed information regarding the charge carrier’s separation and the impact of the radical pathway that will pave a new approach toward the design of high activity visible-light driven photocatalysts.

Bifunctional metastable LaOCl@hcp-Ni nanocomposite via Mott-Schottky effect for improved photoelectrocatalytic and photocatalytic activities

Fabrication of low-cost, stable and highly efficient catalysts for clean energy and environmental control applications is an urgent task. In this work, we have successfully synthesized a multifunctional two-dimensional rare earth-based LaOCl@hcp-Ni heterostructure via a simple one-pot method. Here, the semiconductor LaOCl nanoparticles were well deposited on the metastable metal hcp-Ni, and the hexagonal close-packed structure of hcp-Ni matched the layered-structure LaOCl to form a highly active LaOCl@hcp-Ni Schottky catalyst. Furthermore, LaOCl@hcp-Ni were tested for Photoelectrochemical (PEC) oxygen evolution reaction (OER) in alkaline media and the photocatalytic (PC) degradation of Rhodamine B (RhB) in aqueous solution. LaOCl@hcp-Ni shows excellent PEC-OER catalytic activity and RhB degradation performance under artificial simulated sunlight. This enhancement of PEC and PC performance is due to the Schottky interface constructed by the coupling of hcp-Ni and LaOCl, which generates an interface electric field to effectively promote the transfer of photogenerated electrons from the semiconductor LaOCl to the metal hcp-Ni through the interface. Thus, energy band gap of LaOCl with oxygen defects is adjusted to the visible light region and their valence state of La is lowered, realizing high-efficiency visible light catalytic activity. Thus, it would be a potential rare earth-based Schottky catalyst, which can be used for the PEC oxygen evolution and the PC degradation of organic pollutants. • We successfully synthesized a bifunctional LaOCl@hcp-Ni nanocomposite as Schottky catalyst for PEC-OER and PC degradation of RhB. • Metal hcp-Ni with a metastable structure has high catalytic performance due to its low symmetry. However, its synthesis is difficult and usually requires high pressure conditions. We successfully synthesized hcp-Ni under mild oleylamine solution conditions at 320 °C. • This enhancement of PEC and PC performance is due to the Schottky interface effect between the semiconducting LaOCl and the metallic hcp-Ni, as well as the synergistic effect of the structural distortion and defects of the LaOCl.

Yttrium -barium oxide as a robust photocatalyst for photocatalytic degradation of organic dyes under visible light

Based on the structure related to the high-temperature superconductor yttrium-barium-copper oxide, two novel high-efficiency visible light photocatalysts were created in this study. The yttrium-barium oxide (YBO) semiconductors Y2Ba3O6 (YB3O) and Y2Ba4O7 (YB4O) were prepared by a copper-free solid-phase sintering method. They were applied for the effective treatment of dye-containing wastewater by photocatalysis under visible light irradiation. The degradation efficiency of methylene blue (MB) reached more than 95% within 10 min. Stable visible light degradation of methyl orange (MO) was achieved in the presence of YB3O and YB4O. The electron spin resonance technique and active substance capture technique confirmed the presence of superoxide radicals (·O2−), hydroxyl radicals (·OH) and holes (hVB+) under visible light illumination. UV–Vis diffuse reflectance spectroscopy analysis showed that the direct optical band gaps of YB3O and YB4O were 2.550 eV and 2.583 eV, respectively, which resulted in their high visible absorption at 486.27 nm and 480.06 nm. After five cycles, the recoveries of YB3O and YB4O reached 67.15% and 72.98%. Therefore, YB3O and YB4O are considered as powerful semiconductor catalysts for the photocatalytic degradation of organic dyes in wastewater.

K+-Intercalated carbon nitride with electron storage property for high-efficiency visible light driven nitrogen fixation

Photocatalytic nitrogen fixation is one of the most promising sustainable energy conversion technologies and might serve as a cheaper and more energy-efficient alternative to the capital- and energy-intensive Haber-Bosch process. However, the solution to solve the nitrogen fixation kinetic problem induced by high reduction potential of intermediates remains a grand challenge. In this work, the kinetic problem of nitrogen fixation is addressed under ambient conditions using K+-intercalated crystalline carbon nitride (KCCN) with an electron storage property. Combined with vigorous N2 chemisorption and activation properties of nitrogen vacancies (NVs), a photocatalytic nitrogen fixation system is constructed, where the NVs on KCCN chemisorb and activate N2 molecule, and subsequently reduce it to NH3 by multielectron reactions facilitated by the stored electrons of KCCN. The unique structure of KCCN-NVs demonstrates a high NH3 production rate of 3.51 mmol h−1 g−1 under visible light irradiation and an apparent quantum yield of 2.05% at λ = 430 nm. This work offers an intriguing solution toward the development of nitrogen-fixing photocatalysts.

Delta InN-InGaN Quantum Wells With AlGaN Interlayers for Long Wavelength Emission

An active region design based on InGaN / delta-InN quantum well (QW) with AlGaN interlayer (IL) and GaN barriers (delta-structure) is investigated for potential high-efficiency visible light emitters. Numerical simulations demonstrate a large wavelength redshift with a simultaneous increase of the electron-hole wavefunction overlap for the delta-structure as compared to the conventional InGaN QW with AlGaN IL and GaN barriers. Proof of concept experimental growths via the metalorganic chemical vapor deposition demonstrate the effect of the delta-InN insertion into the conventional InGaN-based QW.

In suit constructing S-scheme FeOOH/MgIn2S4 heterojunction with boosted interfacial charge separation and redox activity for efficiently eliminating antibiotic pollutant

Photocatalytic elimination of antibiotic pollutant is an appealing avenue in response to the water contamination, but it still suffers from sluggish charge detachment, limited redox capacity as well as poor visible light utilization. Herein, a particular S-scheme FeOOH/MgIn2S4 heterojunction with wide visible light absorption was triumphantly constructed by in-situ growth of MgIn2S4 nanoparticles onto the surface of FeOOH nanorods, and employed as a high-efficiency visible light driven photocatalyst for removing tetracycline (TC). Conspicuously, the as-obtained FeOOH(15 wt%)/MgIn2S4 elucidated the optimal TC removal rate of 0.01258 min−1 after 100 min of visible light illumination, which was almost 33.1 and 6.6 times larger than those of neat FeOOH and MgIn2S4, separately. The exceptional degradation performance was principally put down to the establishment of S-scheme heterojunction between FeOOH and MgIn2S4, which could not merely accelerate the detachment of photogenerated carriers, but also retain the powerful reducing ability of photoinduced electrons for MgIn2S4 and high oxidizing capacity of photoexcited holes for FeOOH, strongly driving the generation of plentiful active species including holes, superoxide and hydroxyl radicals. Additionally, the possible degradation mechanism and pathways of TC were also speculated. This work offers a valuable perspective for constructing high-efficiency S-scheme heterojunction photocatalysts for eradicating antibiotics.

High-efficient lignin-based polymerizable macromolecular photoinitiator with UV-blocking property for visible light polymerization

Developing high-efficient visible light macromolecular photoinitiator (macro PI) with excellent initiation performance, low migration, high biosafety and multi-function is beneficial to broaden the application of photopolymer. Lignin contains chromophores which could generate free radicals under light irradiation. In this study, a lignin-based polymerizable macro PI (DAL-11ene-amine) was designed and synthesized through covalent grafting 10-undecenoyl chloride (11ene) and hydrogen donor 4-(dimethylaminobenzoic acid) ethyl ester (EDAB) into dealkaline lignin (DAL) skeleton. The structure of DAL-11ene-amine was characterized by UV–vis, FTIR, 1H NMR, GPC, and 31P NMR spectra. Under the irradiation of a 405 nm LED, DAL-11ene-amine can directly produce active species and initiate the polymerization of acrylate monomers or thiol-ene click reaction. The photoinitiation efficiency of DAL-11ene-amine is higher than that of DAL-11ene or the two-component combination of DAL-11ene and EDAB. Using DAL-11ene-amine as PI, the prepared polymer films exhibit excellent UV-blocking property. With only 0.5 wt% addition of DAL-11ene-amine, nearly 100% of UVB + UVC and the most of UVA can be blocked by the films. Moreover, DAL-11ene-amine exhibits higher migration stability and biosafety because it can be covalently linked into polymer cross-linking networks. The results indicate that DAL-11ene-amine has great application potentials in preparing environmentally friendly UV-blocking films and biosafety coatings.

Visible light photocatalytic degradation of sulfanilamide enhanced by Mo doping of BiOBr nanoflowers

Design of high-efficiency visible light photocatalysts is critical in the degradation of antibiotic pollutants in water, a key step towards environmental remediation. In the present study, Mo-doped BiOBr nanocomposites are prepared hydrothermally at different feed ratios, and display remarkable visible light photocatalytic activity towards the degradation of sulfanilamide, a common antibacterial drug. Among the series, the sample with 2% Mo dopants exhibits the best photocatalytic activity, with a performance 2.3 times better that of undoped BiOBr. This is attributed to Mo doping that narrows the band gap of BiOBr and enhances absorption in the visible region. Additional contributions arise from the unique materials morphology, where the highly exposed (102) crystal planes enrich the photocatalytic active sites, and facilitate the adsorption of sulfanilamide molecules and their eventual attack by free radicals. The reaction mechanism and pathways are then unraveled based on theoretical calculations of the Fukui index and liquid chromatography/mass spectrometry measurements of the reaction intermediates and products. Results from this study indicate that deliberate structural engineering based on heteroatom doping and morphological control may serve as an effective strategy in the design of highly active photocatalysts towards antibiotic degradation.

Noble-metal-free Cd0.3Zn0.7S-Ni(OH)2 for high efficiency visible light photocatalytic hydrogen production

Heterogeneously structured materials with supported precious metals, such as Pd, Pt, and Ru, as co-catalysts are important catalysts for efficient photocatalytic water splitting. However, the high costs and low reserves of precious metals have been an obstacle to their application in hydrogen production. In this work, the noble-metal-free Cd0.3Zn0.7S solid solution was designed and synthesized with an optimized molar ratio of Cd/Zn for the best visible light photocatalytic performance. In addition, a heterojunction hybrid material formed between the Cd0.3Zn0.7S and Ni(OH)2 nanosheet was engineered to improve the utilization of light and to inhibit the recombination of holes and electrons. Ni(OH)2 nanosheets assisted the transfer of the photoexcited electrons to participate in the reduction reactions which is critical for efficient and rapid catalytic hydrogen production. The photoelectrochemical property of the hybrid material was investigated with UV–vis absorption, photoluminance (PL) and electrochemical impedance spectroscopy measurements. The mechanism of the high-efficiency and low-cost photocatalytic hydrogen production was established by analyzing the hydrogen evolution kinetics. With the success of replacing precious metal with nickel-based surface heterostructure, this work is expected to provide a new type of photocatalyst for the application of photocatalytic hydrogen production.

Environmentally benign hybrid nanocomposite beads for azo dye remediation via synchronized dual degradation mechanisms.

Practically, 12% of used dyes are excluded as waste in the mobile aqueous environment. Methyl orange (MO), an industrial azo dye, is known to be carcinogenic. Accordingly, this work was engaged to fabrication of a high-efficiency visible light photocatalysts based on Ag-Alginate/Chitosan-coated MgO nanocomposite beads. MgO and Ag were prepared via precipitation and γ-radiation reduction technique as a green physical one, respectively. The degradation mechanisms depended on catalytic reduction by means of sodium borohydride/Ag and photooxidative degradation. XRD proved the periclase crystalline form of MgO of size 20 nm and the formation of face-centered cubic silver crystals of size 15 nm. The degradation yield varied directly with time, MgO, and dye concentration until certain limit. Five and twenty minutes were enough to get clear solution of MO (30 and 15 ppm, respectively) while 60 min was required to achieve the same target for 60 ppm MO solution. The catalysts showed high efficiency for MO of high concentration. The incorporation of Ag into catalytic beads could support both mechanisms as it could elevate the degradation efficiency up to 50% and save the time to a great extent. Thus, this carrier fruitfully converted wastewater into an effluent that can be repaid to the water cycle with minimal strike on the ecosystem.

Optical management in organic photovoltaic devices

AbstractDue to their potentials in light‐weight, flexible, and semitransparent devices, organic photovoltaics are of great significance in the field of renewable energy. However, the narrow intrinsic absorption spectrum of organic materials hinders the full utilization of solar energy. To fabricate a highly efficient opaque solar cell, it is greatly necessary to modify the optical properties of the device to improve light absorption. In addition, the growing interest in building‐integrated photovoltaics drives the development of semitransparent devices. The preparation of semitransparent solar cells with excellent performance imposes high requirements on the high efficiency and appropriate visible light transmittance of effective optical management. In this review, the recent research progress of optical management in organic photovoltaics is reviewed, including the design of light‐absorbing materials, the modification of different layers, adding a light‐trapping structure, and changing the light absorption capabilities of specific materials, so as to provide strategies of how to improve the performance of organic photovoltaic devices and present the prospect of the area.

A one-pot microwave irradiation route to synthesis of CoFe2O4-g-C3N4 heterojunction catalysts for high visible light photocatalytic activity: Exploration of efficiency and stability

In this investigation, a high efficient visible light induced photocatalyst based CoFe2O4/g-C3N4 heterostructure was prepared through a microwave irradiation approach. Pure and various composition of CoFe2O4/g-C3N4 hybrid catalysts were characterized by Powder X-ray diffraction method (PXRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), UV–visible absorbance, Photoluminescence (PL), Raman and BET surface area analysis to know the physico-chemical properties. The interaction of CoFe2O4 nanoparticles with g-C3N4 nanosheets have reduced the optical band gap of CoFe2O4 to 2.85 eV from 2.35 eV and improve the charge carrier separation process. Photocatalytic activity of the CoFe2O4/g-C3N4 composite was assessed by degrading of methyl orange (MO) and rhodamine B (RhB) in aqueous medium under visible light irradiation. The optimized ratio of CoFe2O4/g-C3N4 (15 wt%. loaded CoFe2O4/g-C3N4) composition show high photocatalytic performance. It could degrade MO up to 93.5% in 60 min under stimulated visible light, which is higher than pure catalysts like CoFe2O4 (45.7%) and g-C3N4 (41.5%). This remarkable improvement can be ascribed to synergistically improved charge carrier separation through spinel type CoFe2O4 support g-C3N4.