Energy Levels Research Articles

Molecular-level regulating intersystem crossing of polyphenols: Engineering high-efficiency phytochemical photosensitizer for MRSA elimination

Natural polyphenols-mediated green photosterilization is promising but remains challenging in practical applications due to their unsatisfactory performance with insufficient intrinsic energy level and ROS generation. In this work, the molecular-level engineering strategy of natural polyphenols (quercetin, QC) by p-Methoxybezaldehyde (MB)-induced nucleophilic substitution is constructed for enhanced photodynamic MRSA therapy. Both the experimental and theoretical results disclose that the unprecedented H-aggregates of QC-MB supramolecular realized accelerated ISC with minimizing the energy level difference (ΔEst), achieving enhanced photodynamic performance with 2.2-fold enhancement on 1O2 quantum yield (75 %) compared to free quercetin (33 %). The well-designed photosensitizer realizes efficient MRSA elimination: with enhanced killing efficacy from 30.44 % to 99.95 % in vitro and effective eradication of mature biofilms. Mechanism study and gene transcription analysis reveal that the combined therapy of optical stimuli with QC-MB achieves the dual mechanism of ROS attack and virulence regulation against MRSA infection during the whole infection process. Moreover, the excellent biocompatibility and anti-infectious in vivo demonstrate the engineered QC-MB as a promising strategy for MRSA therapy.

Crystal growth and the enhanced 1.55 μm fluorescence emission in Ce3+, Yb3+, Er3+ Co-doped KBaCaY(MoO4)3 laser crystal

1.55 μm laser technology has been widely applied in many fields such as military, information and communications, and biomedical. With the continuous progress in these fields, the demand for new 1.55 μm laser gain media has become stronger. However, the small non-radiative transition probability and long fluorescence lifetime between the 4I11/2 and 4I13/2 energy levels of Er3+ ions lead to up-conversion loss, which in turn reduces the luminescence efficiency in the 1.55 μm band. To address this problem, this paper introduces a novel Yb3+, Er3+ and Ce3+ co-doped KBa0.94Ca0.06Y(MoO4)3 crystal and explores the relationship between its structure and spectral properties. By doping Ce3+ ions, the non-radiative transition probability between the 4I11/2 and 4I13/2 energy levels of Er3+ ions is effectively increased, which significantly enhances the emission intensity of Er3+ ions in the 1.55 μm band. Meanwhile, the near-infrared luminescence mechanism of Er3+ ions and its complex competition with up-conversion and mid-infrared luminescence are elaborated in detail. In addition, the doping of Ce3+ ions also significantly enhances the energy transfer efficiency between Yb and Er, from 39.6 % to 94 %. At a Ce3+ ion concentration of 4 mol%, the crystals exhibit optimal emission intensities, indicating their great potential as laser gain media. The research presented here not only provides a comprehensive analysis of the spectral properties of the new laser gain material but also contributes to the advancement of all-solid-state laser gain media suitable for the 1.5 μm spectral range.

Analysis of luminescent properties of 40PbO–35Bi2O3–25Ga2O3 glasses doped with Er2O3

The Er3+ doped lead–bismuth–gallium oxide glasses were prepared by melt quenching technique. The spectral and luminescent properties were analyzed based on experimental and theoretical calculations. Analysis of Er3+ concentration dependences of density and electronic optical polarizability was carried out. The radiative lifetime values for 4S3/2 and 4F9/2 energy states were calculated using Judd-Ofelt theory. In the glassy system under study, the concentration quenching of state 4S3/2 was discovered at content of erbium ions above 0.869 × 1020 cm−3. It was also shown that 4F9/2 energy state was isolated from concentration effects and showed an increase in luminescence intensity with increasing concentration of activator ions. The luminescence quantum efficiency for transition 4S3/2 → 4I15/2 was about 40%, which allows us to consider this system as a glassy matrix effective for activation by rare-earth ions.

Neuromorphic engineering in GaN HEMTs exploiting dendritic dislocations for neuromodulation behaviors and adaptive intelligent power forecasting systems

Gallium nitride (GaN), a prominent III-V semiconductor, plays a pivotal role in the advancement of sophisticated power systems. This study presents an innovative neuromorphic engineering approach utilizing the unique dendritic dislocations extending from bulk to channel within GaN High Electron Mobility Transistors (HEMTs) for three-dimensional charge modulation. This approach dynamically alters charge states and channel potentials in response to multiple parametric stimuli, effectively mimicking neural processing and transmission functions, as well as emulating direct and indirect neuromodulation behaviors observed in human nervous system. The advanced neuromodulation emulation enhances biomimetic diversity, laying a solid foundation for the design of intelligent systems. Comprehensive material and electrical analyses reveal the charging and discharging behaviors of the defect energy levels, underlying the neuromorphic working mechanisms. Additionally, by incorporating artificial neural network algorithms, an intelligent power forecasting system that leverages the device’s diverse neuromorphic traits is developed for real-time and adaptive power management, optimizing efficiency and accuracy in balancing supply and demand, thereby enhancing the cost-effectiveness and sustainability of power systems. The findings highlight the neuromorphic capabilities of GaN devices and open avenues for further exploration into the intelligent power management.

Novel multi-layer field shaper in electromagnetic manufacturing process technology of tube joining for uniform deformation

Electromagnetic joining technology is widely utilized in assembling tubular components due to its ability to exert uniform magnetic pressure. To augment this pressure, a field shaper structure has been introduced. However, the conventional design may impair the uniformity of deformation, particularly at the seam. This study presents a novel multi-layer field shaper (MLFS) to enhance deformation uniformity. The performance of the MLFS was evaluated and optimized through experimental trials and simulation analysis. The results showed that MLFS achieved a 300 % increase in minimum deformation with a 56 % reduction in the aspect ratio, demonstrating that our design effectively balances efficiency with deformation uniformity. The magnetic cubic decay formula could fit the simulation data well with R2 higher than 0.999. MLFS was found to enhance uniformity by creating a more even magnetic field that decreased the curvature near the plastic hinge. Compared to altering the interlayer thickness, adjusting the interlayer angle can further enhance uniformity. When the rotation angle is 60°, the radius range can be further reduced by 32.5 %, 39.0 %, and 12.2 % at energy levels of 27 kJ, 30 kJ, and 33 kJ, respectively. The above results indicate that by designing and optimizing MLFS, sufficiently large and uniform electromagnetic forces were obtained.

Polymers Containing Phenothiazine, Either as a Dopant or as Part of Their Structure, for Dye-Sensitized and Bulk Heterojunction Solar Cells.

Potential photovoltaic technology includes the newly developed dye-sensitized solar cells (DSSCs) and bulk heterojunction (BHJ) solar cells. Owing to their diverse qualities, polymers can be employed in third-generation photovoltaic cells to specifically alter their device elements and frameworks. Polymers containing phenothiazine, either as a part of their structure or as a dopant, are easy and economical to synthesize, are soluble in common organic solvents, and have the potential to acquire desired electrochemical and photophysical properties by mere tuning of their chemical structures. Such polymers have therefore been used either as photosensitizers in dye-sensitized solar cells, where they have produced power conversion efficiency (PCE) values as high as 5.30%, or as donor or acceptor materials in bulk heterojunction solar cells. Furthermore, they have been employed to prepare liquid-free polymer electrolytes for dye-sensitized and bulk heterojunction solar cells, producing a PCE of 8.5% in the case of DSSCs. This paper reviews and analyzes almost all research works published to date on phenothiazine-based polymers and their uses in dye-sensitized and bulk heterojunction solar cells. The impacts of their structure and molecular weight and the amount when used as a dopant in other polymers on the absorption, photoluminescence, energy levels of frontier orbitals, and, finally, photovoltaic parameters are reviewed. The advantages of phenothiazine polymers for solar cells, the difficulties in their actual implementation and potential remedies are also evaluated.

Effects of Dietary Energy Levels on Growth Performance, Serum Metabolites, and Meat Quality of Jersey Cattle-Yaks.

Energy feed can provide animals with balanced nutrition, thereby enhancing their growth performance. This study aimed to evaluate the effects of dietary energy levels on the growth performance, serum metabolites, and meat quality of Jersey cattle-yaks. A total of 24 male Jersey cattle-yaks were randomly divided into three groups. Each group was fed diets with metabolizable energy levels of 8.21 MJ/kg (LE), 9.50 MJ/kg (ME), and 10.65 MJ/kg (HE), respectively. The HE and ME groups showed significantly higher final body weight, average daily gain (ADG), and feed efficiency compared to the LE group (p < 0.05). The glucose (GLU) and total cholesterol (TC) concentrations were significantly increased in the serum of the ME and HE groups (p < 0.05). The low-density lipoprotein cholesterol (LDL-C) and alanine aminotransferase (ALT) levels were significantly higher in the serum of the HE group than in the ME group (p < 0.05). Blood urea nitrogen (BUN) levels exhibited a significant decrease with increasing metabolizable energy levels in the diet (p < 0.05). Increasing dietary energy levels enhances the eye muscle area and intramuscular fat content of Jersey cattle-yaks (p < 0.05), with no effect on pH45 min, pH24 h, and shear force. In the HE group, the levels of heneicosanoic acid (C21:0), palmitoleic acid (C16:1), elaidic acid (C18:1n9t), and eicosadienoic acid (C20:2n6) were notably elevated (p < 0.05) when compared to the LE group. We concluded that a higher dietary energy level enhanced the growth performance and meat quality traits of male Jersey cattle-yaks.

Determining the thickness of a thin aluminum sheet using the transmission measurement of X-rays with varying energies: A comparative analysis between calibration curve fitting and artificial neural network approaches

This study proposes an innovative configuration for thickness measurement based on X-ray transmission, intending to improve the precision of measuring thin aluminum sheets. In this configuration, an activation sample containing Zr, Sb, and Ba elements is irradiated by 59.54 keV gamma rays emitted from three 241Am radioactive sources with a total activity of 1.78 GBq. Subsequently, the activation sample emits fluorescent X-rays at energy levels of 15.78 keV (Zr-Kα1,2), 17.67 keV (Zr-Kβ1), 26.36 keV (Sb-Kα1,2), 29.73 keV (Sb-Kβ1), 32.2 keV (Ba-Kα1,2), and 36.38 keV (Ba-Kβ1). These X-rays are collimated into a narrow beam, which then penetrates through an absorbing sample, and is ultimately recorded by a Si(Li) detector. Two different approaches are investigated to determine the thickness of absorbing samples including Calibration Curve Fitting (CCF) and Artificial Neural Network (ANN). The CCF approach requires constructing linear calibration curves for establishing the relationship between lnR (R is the ratio of the peak areas in measurements with and without absorbing sample) and the thickness of the absorbing sample at each X-ray energy level. The sample thickness is then determined by calculating a weighted average of the measured thicknesses associated with all analyzed energy levels. This approach requires in-depth understanding of radiation physics and proficiency in X-ray spectrum analysis. Meanwhile, the ANN approach uses raw spectra obtained by the Si(Li) detector to predict the thickness of aluminum sheets, facilitating analysis without requiring human intervention. The reliability of these approaches is evaluated through experimental measurements on aluminum sheets with thicknesses ranging from 0.064 cm to 1.074 cm. The results indicate that using X-rays with many different energies leads to superior accuracy in thickness measurements compared to using X-rays with a single energy. Besides, both the CCF and ANN approaches yield relative deviations of less than 3% between the predicted and reference thicknesses. It is important to emphasize that the ANN approach represents a promising solution for automated analysis without the intervention of experts.

Overview of Available Functioning Data in Switzerland: Supporting the Use of Functioning as a Health Indicator Alongside Mortality and Morbidity.

To identify official sources that routinely collect data on functioning in Switzerland, to provide an overview of the existing data and its comparability, and to assess the extent to which the data is suitable for developing a functioning metric and indicator. Data sources were identified through an iterative search. Standardized rules were applied to map the functioning information assessed by the sources using a current WHO functioning and disability survey as a reference framework for the content comparison. Four sources were identified: the Swiss Survey of Health, Ageing and Retirement in Europe (SHARE), the Swiss Health Survey (SHS), the Lausanne cohort 65+ (Lc65+), and the Swiss Household Panel (SHP). All tools addressed sleep functions, energy level, emotional functions, and sensation of pain. Additionally, nine functioning categories were common across three sources. Population data sources in Switzerland routinely collect comparable functioning data, which can serve as the basis for creating a functioning indicator. Among others, this indicator is relevant to complement mortality and morbidity data and to support both the estimation of rehabilitation and long-term care needs.

The influence of AuNs on the optical properties of GaAs/AlGaAs tunnel-coupled quantum well

Using a numerical approach, we investigated a GaAs/AlGaAs tunnel-coupled quantum well (TCQW) to examine the interplay between electromagnetic waves and gold nanospheres (AuNs) in the presence of an extra SiO2 layer and surface roughness. Our findings demonstrated that the optical efficiency of the response of AuNs was increased in the presence of the SiO2 layer. The extinction cross-section also increased in the presence of surface roughness. Furthermore, we discovered that the orientation of AuNs on the rough surface of TCQW can give rise to a new mode of resonant frequency in the near infrared range. This new mode is advantageous for the TCQW as it is usually seen in AuNs only in the visible range. Lastly, the energy level and wave function of electrons in the TCQW intersubband could be adjusted by an electric field produced by the presence of AuNs. Therefore, this theoretical study could be applied to improve output efficiency and the tuning of performances of optical devices such as solar cells and tunable wavelength photoemitters.

Scalable polyolefin-based all-organic dielectrics with superior high-temperature capacitive energy storage performance

Polymer dielectrics capable of efficient and stable operation at elevated temperatures (>150 °C) are urgently needed to meet the stringent requirements of capacitive energy storage in harsh environments. However, the current leading commercially available polymer dielectric, biaxially oriented polypropylene (BOPP), can only sustain continuous operation at temperatures below 85 °C due to its limited thermal stability and significant increase in electrical conduction at high temperatures. Here, we present an all-organic polymer composite comprising nonpolar polyolefin and organic semiconductor that demonstrates superior dielectric and capacitive energy storage performance at 150 °C. Notably, the dielectric properties of the polymer composite remain stable across a broad temperature range, exhibiting an ultralow dissipation factor at elevated temperatures. Benefiting from the deep trap energy levels introduced by the organic semiconductor, the composite film achieves one order of magnitude reduction in electrical conductivity. As a result, the composite film attains discharged energy densities of 7.1 J/cm3 and 5.5 J/cm3 with a charge-discharge efficiency of 90 % at 25 °C and 150 °C, respectively. Furthermore, the composite film maintains stable capacitive performance over extended charge-discharge cycles (50,000 cycles) in harsh environments (500 MV/m and 150 °C), along with excellent breakdown self-healing capability. These remarkable performances, coupled with the potential for large-scale production using commercially available raw materials, highlight the practically viability of the composite film for high-temperature capacitive energy storage applications.

A miniature temperature sensor based on upconversion luminescence for real-time GPU temperature monitoring

This paper introduces a miniaturized optical fiber temperature sensor based on Fluorescence Intensity Ratio (FIR) technology for real-time monitoring of graphics processing unit (GPU) temperature. Utilizing a femtosecond micromachining system, miniature rectangular holes are etched on a standard multimode fiber. These holes are then filled with a mixture of Er3+/Yb3+ co-doped TeO2-Na2CO3-ZnO powder and polydimethylsiloxane (PDMS) through capillary action, forming a sandwich structure. When illuminated by a 980 nm light source, upconversion (UC) fluorescence is generated, and a mathematical model correlating the fluorescence intensity ratio of two adjacent energy levels with temperature is established. The fundamental temperature sensing characteristics of the sensor are tested in a temperature-controlled chamber, with a maximum error of ± 1 K. The sensor is also applied to a GPU with real-time temperature variations, demonstrating a maximum error of 0.9 K and a response time of 1.96 s. The sensor not only possesses the advantages of a simple structure, micro size, and convenient fabrication but also exhibits immunity to electromagnetic interference, rapid response, good stability, and excellent repeatability in real-time monitoring of GPU temperature, showing potential for large-scale application.

Misalignment Assembly Effect on the Impact Mechanical Response of Tandem Nomex Honeycomb-Core Sandwich Structures.

To optimize the assembly methods of honeycomb structures and enhance their design flexibility, this study investigated the impact mechanical responses of tandem honeycomb-core sandwich structures with varying misalignment assembly lengths. Impact tests were conducted across different energy levels on single-layer and tandem honeycomb-core sandwiches to observe their impact processes and failure behaviors. Our findings indicate that tandem honeycomb cores significantly enhance the impact resistance compared with single-layer configurations, even though a misaligned assembly can deteriorate this property. A finite element model was developed and validated experimentally; the model showed good agreement with the experiments, thereby allowing the simulation and evaluation of the impact responses. Herein, we reveal that specific misalignment lengths can either increase or decrease the impact resistance, providing insights into improving the resilience of tandem honeycomb-core structures. Our results not only contribute to enhancing the impact resistance of honeycomb-core sandwich structures but also offer a valuable basis for their practical applications in engineering.

HII galaxies as standard candles: Evolutionary corrections

Over the past decade, the relation between the Balmer-line luminosity of HII galaxies and the velocity width of the emission lines, the relation, has been painstakingly calibrated as a cosmological distance indicator with seemingly spectacular results: the Hubble constant and the energy density of dark energy obtained using the indicator agree remarkably well with the values from canonical indicators. Since most of the luminosity of these young compact starburst galaxies is emitted by a few narrow emission lines, they can be observed with good precision up to redshifts of $z with JWST, making the indicator a potentially unique cosmological probe. However, the precision of the method remains too low to effectively constrain the relevant cosmological parameters, notably the equation of state of dark energy. The scatter of the relation is significantly larger than the random observational errors, so we do not have a good handle on the systematics of the method. In a previous paper, we posited that since the ionizing radiation of these young galaxies fades rapidly over timescales of only a few million years, age differences could be the main underlying cause of the scatter. In this paper, we explore several different ways of explaining the scatter of the correlation, but without success. We show that the majority of HII galaxies are powered by multiple starbursts of slightly different ages, and therefore that the equivalent widths are not reliable chronometers to correct the luminosities for evolution. Thus, it is not likely that the accuracy of the distance indicator can be improved in the near future. Since we do not fully understand either the systematics or the underlying physics of the relation, using large samples of distant HII galaxies may or may not improve the accuracy of the method.

High-accuracy optical clocks with sensitivity to the fine-structure constant variation based on Sm[formula omitted]

We identify two metastable excited states in Sm10+ highly charged ion as candidates for high accuracy optical clocks. Several atomic properties relevant to optical clock development are calculated using relativistic many-body methods. This includes energy levels, transition amplitudes, lifetimes, scalar polarizabilities, black body radiation shift, and the sensitivity to the fine structure constant variation. We found that the clock transitions are not sensitive to perturbation, e.g., relative black body radiation shifts are ∼10−19. The enhancement factor for the α variation is ∼ 0.8 for one clock transition and ∼ 16 for another.

Up/down-conversion luminescence and optical thermometry of Er3+-activated bismuth tellurium borate

Base on up/down-conversion luminescence with thermally coupled energy levels, Er3+-activated phosphors have been significantly promising in non-contact optical thermometry technology. In this study, a new bismuth tellurium borate-based phosphor was synthesized via replacing Bi3+ with Er3+. The structure, morphology, photoluminescence, and concentration quenching are elucidated thoroughly. Particularly, according to the temperature-dependent up/down-conversion luminescence behaviors of Er3+, the fluorescence intensity ratio (FIR, 2H11/2→4I15/2 /4S3/2→4I15/2) of thermally coupled energy levels is investigated. the maximum absolute/relative sensitivities of 0.38 % K−1/0.87 % K−1 (λex = 380 nm), 0.33 % K−1/1.01 % K−1 (λex = 453 nm), and 0.37 % K−1/1.19 % K−1 (λex = 980 nm) is determined. The findings indicate that the resulting phosphor is a promising optical thermometric material.

Cu-doped ZnCdS-based photocatalyst for efficient photocatalytic hydrogen production by photothermal assistance

In solar energy utilization, photocatalytic hydrogen production has been widely researched. To address issues such as low efficiency of photocatalysts, Cu-doped Zn0.5Cd0.5S composite photocatalysts were prepared using a hydrothermal method for photocatalytic hydrogen production. The Cu/Zn0.5Cd0.5S photocatalyst was characterized using XRD, XPS, SEM, TEM, UV–vis-DRS, fluorescence spectrophotometer, and electrochemical workstation. The results indicate that Cu doping alters the crystal and band structures of Zn0.5Cd0.5S. Hydrogen production experiments were conducted under xenon lamp irradiation, and at 45 °C, the highest hydrogen production rate was 2.72 and 1.63 times that of single Zn0.5Cd0.5S and Cu-doped Zn0.5Cd0.5S at room temperature (25 °C), respectively. Cu doping imparted a photothermal effect to the photocatalytic hydrogen production experiment, enhancing its efficiency.Cu doping captured electrons by replacing some Zn, constructing an internal electric field, forming defect energy levels, which hindered electron-hole recombination. Additionally, Cu ions acted as a plasma, inducing a plasma effect during hydrogen production, accelerating the rate of solar energy conversion to thermal energy, thus improving hydrogen production efficiency. This research not only provides a photocatalyst for photocatalytic hydrogen production but also utilizes it for photothermal synergistic catalysis.

Symmetry properties, tunneling splittings of some vibrational energy levels and torsional IR spectra of the trans – and cis – conformers of hydroquinone molecule

Torsional vibrational states of trans − and cis − conformers belonging to point symmetry groups C2H and C2V, respectively, of hydroquinone molecules are classified according to the irreducible representations of the molecular symmetry group D2H(M). A correspondence has been established between the symmetry elements of the D2H(M) group and the symmetry elements on the torsional coordinate plane for two-dimensional surfaces of potential energy, wave functions, kinetic coefficients and dipole moment projections. A correspondence has been established between the symmetry species of the point symmetry groups C2H, C2V and the symmetry species of the molecular symmetry group D2H(M). Conformational states, barriers to internal rotation and the above-mentioned characteristics of the hydroquinone molecule were calculated at the MP2/Aug-cc-pVDZ, MP2/Aug-cc-pVQZ, MP2/Aug-cc-pVTZ, MP2/CBS(aD,aT,aQ), and CCSD(T)/dAug-cc-pVDZ levels of theory. The calculated data sets were approximated using symmetry-adapted sets of basis functions. Using a numerical solution of the vibrational Schrödinger equation of restricted dimensionality, the energies and wave functions of 50 stationary torsional states of the hydroquinone molecule were determined for the first time. The values of tunneling splittings of the ground vibrational and a number of excited torsional states of trans − and cis − conformers were determined. In particular, when calculating at the MP2/CBS(aD,aT,aQ) level of theory, the values of tunneling splittings of the ground vibrational states of trans − and cis − conformers turned were 1.32*10-6 and 1.62*10-6 cm−1, which is consistent with the experimentally established upper limit for this value in the cis − conformer by authors of [W. Caminati, S. Melandri, L. B. Favero, J.Chem.Phys., 100 (1994) 8569 – 8572] (0.2 MHz or 6.67*10-6 cm−1). The calculations of the matrix elements of the dipole moment operator and the partition function made it possible to simulate the torsional IR spectra of the molecule’s conformers at different temperatures. The frequencies of fundamental torsional vibrations in the trans – (267.1 and 269.0 cm−1) and cis – (269.5 and 270.9 cm−1) conformers, calculated at the MP2/CBS(aD,aT,aQ) level of theory, are in good agreement with the experimental value of frequency of this vibration (266 cm−1), established in [W.G. Fateley, G.L. Carlson, F.F. Bentley, J.Phys.Chem., 79 (1975) 199–204.].

Optimizing perovskite solar cell efficiency with Cs0.15FA0.81MA0.04PbBr0.14I2.86 - MAPbBr3 QDs Complex active layer and GuBr interface modified layer

Achieving optimal efficiency in perovskite solar cells (PSCs) necessitates the creation of a light-absorbing layer with superior crystallization, minimal defect concentration, exceptional stability and better energy level alignment. In this context, the active layer of the PSCs comprises (Cs0.15FA0.81MA0.04PbBr0.14I2.86), incorporating MAPbBr3 quantum dots doped with toluene as an anti-solvent to enhance device performance, achieving a Photovoltaic Conversion Efficiency (PCE) of 18.9 %. Furthermore, GuBr is introduced at the interface between NiOx and photovoltaic active layer for effective interface modification. These improvements lead to optimized devices, particularly with GuBr modification at doping amount of 3 mg/ml, showcasing an impressive PCE of 20.6 %. Noteworthy attributes of these devices include a short-circuit current density of 24.7 mA/cm2 and an open-circuit voltage (Voc) value of 1.02 V. Significantly, the altered film retained more than 81 % of its original effectiveness for a prolonged duration surpassing 10 days. The conclusive findings underscore the successful attainment of high efficiency and high stability through the employed design strategy in PSCs.

Fe(Ⅲ)-doped ZnIn2S4-modified graphene oxide in-situ for the degradation of tetracycline hydrochloride in simulated sunlight

To improve the efficiency of photocatalytic reactions, it is important to understand how to achieve fast directional migration and separation of photogenerated carriers at the interface. Here, Fe(III)-doped ZnIn2S4 (ZIS)-coated graphene oxide (GO) composite (GZF) was in-situ prepared via the low-temperature water bath method. Ultrathin Fe(III)-doped ZIS nanosheets were uniformly grown upright on the GO surface. The prepared samples were studied via, such as, X-ray diffraction, scanning electron microscopy combined with energy-dispersive spectroscopy, transmission electron microscopy, ultraviolet spectroscopy, N2 adsorption–desorption measurements, X-ray photoelectron spectroscopy, and electron spin resonance. Compared with ZnIn2S4 (ZIS)-coated graphene oxide (GZ), the GZF exhibit a 2.26-fold increase in the photocatalytic degradation performance of tetracycline hydrochloride (TCH) in simulated sunlight. Through density functional theory calculations, found that Fe(III) doping introduces new energy levels into ZIS, which effectively narrow its bandgap and thus enhance its light absorption efficiency. It was found that h+, ·O2−, and 1O2 were the major reactive oxygen species involved in the photocatalysis, and the effect of pH on the catalytic degradation of TCH was examined. Electron spin resonance and density functional theory results indicate that Fe(III) acts as an electron trap in the ZIS structure to promote the separation of photogenerated electron-hole pairs, which in turn enhances the photocatalytic efficiency of GZF-25.