Absorption In Visible Region Research Articles

Construction of S-scheme Cs3PMo12O40/MnIn2S4 heterojunction for efficient photocatalytic removal of antibiotics: Degradation pathways, toxicity evaluation and mechanism insight

Developing highly efficient photocatalysts for the removal of antibiotics and heavy metals is of vital importance but remains a great challenge. In this investigation, a novel S-scheme Cs3PMo12O40/MnIn2S4 (CPM/MIS) heterojunction with core-shell structure was fabricated successfully via hydrothermal synthesis/dissolution-precipitation approaches, which was labelled as x CPM/MIS (x = 5, 7, 9 and 11, respectively). In the composites, these 2D MIS nanoflakes were securely and uniformly affixed on the exterior of 3D CPM nanospheres, which was verified through SEM and TEM. These as-produced materials manifested enhanced photocatalytic activity towards antibiotics (tetracycline (TC) and ciprofloxacin (CIP)) degradation and Cr(VI) reduction with visible light, and the removal rates of the optimal 9 CPM/MIS for TC, CIP and Cr(VI) could reach 97.81%, 61.78% and 67.07%, respectively. Of note, these resulting CPM/MIS composites possessed excellent stability and reusability. The outstanding photocatalytic property was attributed to the synergistic effect arising from the advantageous core-shell structure and S-scheme heterostructure. This configuration strengthened robustly interfacial interaction between the constituents, which effectively enhanced light absorption in visible region, promoted the separation and transfer efficiency of photoinduced carriers, and preserved the charge carriers with heightened redox abilities. The ESR spectra and trapping tests confirmed the dominating role of holes and superoxide radical in contaminants removal. Additionally, the high-performance liquid chromatography-mass spectrometry (HPLC-MS) technique was employed to identify the photodegradation pathways of TC. And the product toxicity was evaluated using QSAR prediction. Conclusively, combining the in situ XPS data and analysis of energy band structure, a S-scheme catalytic mechanism was elucidated. This study opens new avenues for systematically designing and fabricating S-scheme heterojunction photocatalysts with outstanding catalytic property for contaminants removal.

First-principles calculations to investigate structural and electronic properties of novel halides ZrIX (X = Cl, Br) for photovoltaic application

In order to meet the increasing need for proficient photovoltaic materials, the electronic, structural, optical, and photovoltaic performance of ZrX2 (X = Cl, Br, I) and ZrIX (X = Cl, Br) monolayers have been examined by extensive Density Functional Theory (DFT) based calculation. The energetic, dynamic, and thermal stability of ZrIX (X = Cl, Br) monolayers have been verified by cohesive energy, phonon spectra, and molecular dynamics calculations respectively. Under the equilibrium state, the electronic properties show that ZrICl and ZrIBr monolayers exhibit semiconductor behavior with an indirect bandgap of 1.46 eV and 1.32 eV, respectively with HSE06 functional. The impact of strain on electronic and optical properties is also calculated. To check the optical performance of the ZrIX (X = Cl, Br) monolayer, its dielectric function, absorption coefficient, reflectivity, Transmittance, conductivity, and refractive index have been obtained. The absorption coefficient indicates that ZrIX (X = Cl, Br) monolayers have starting absorption in the visible region and utmost absorption in the UV region. This indicates that ZrIX (X = Cl, Br) monolayers have potential for optoelectronic and photovoltaic applications. The solar parameters have been computed using Shockley-Queisser's method. In addition, the calculated solar power conversion efficiency of 15.91 % for ZrICl and 14.13 % for ZrIBr monolayer indicates its light absorber capacity in the solar energy harvesting domain.

Investigations on growth, XRD, strain, FTIR, UV–Vis NIR, photoluminescence, SHG, and Z-scan analyses of L-cysteine picrate single crystal for NLO and optical limiting applications

Organic single crystal of L-cysteine picrate (LCP), an efficient NLO material for frequency conversion, optoelectronic, and optical limiting applications has been grown within 20 days by Slow Evaporation Solution Technique (SEST). PXRD analysis shows that the LCP is subjected to the noncentrosymmetric space group of P21 with a monoclinic crystal system. The very low strain value depicts that the level and dislocations of the defect in the lattice of LCP crystal are very low. The various functional group assignments were investigated by using Fourier-Transform Infrared (FTIR) spectrum analysis with the range of 4000–400 cm−1. The optical analysis (UV–Visible) confirmed that the crystal has a lower cut-off wavelength of 250 nm and very low absorption in the entire visible region. Photoluminescence (PL) spectrum analysis confirmed that the material exhibits blue emission and is suitable for LED device fabrication. The SHG efficiency for LCP crystal is established to be 1.7 times higher than KDP material. Z-scan measurement determined the LCP exhibits two-photon absorption-induced optical limiting action with a nonlinear absorption coefficient of 0.70 × 10−10 m/W and onset limiting threshold of 2.36 × 1012 W/m2 which indicates that it can be used in making laser protection gadgets.

White Light Emission and Judd-Ofelt Analysis of Dy3+ Doped Mixed Alkali Borate Glass for W-LEDs Material

The Dy3+ doped lithium sodium potassium borate glasses with white light-emitting were prepared by the melt quenching technique. In this work, optical, photoluminescence properties and Judd-Ofelt analysis of borate glasses have been investigated. For optical properties, Dy3+ doped glasses showed the absorption in visible and near-infrared region, which originate from 6H15/2 ground state to higher state. While the luminescence properties of Dy3+ doped glasses, the emission spectra were presented more intense at 484 nm (blue light) and 574 nm (yellow light) which are essential for white light emitting materials, whilst decay time decrease with an increase of Dy2O3 contents. The emission intensity of Dy3+ doped glasses were enhanced by adding Dy2O3 concentrations until 0.5 mol%, after that the emission intensities were decreased due to the concentration quenching effect. Judd-Ofelt is analyzed by using the absorption and photoluminescence results, The stimulated emission cross-section has been investigated in this work. The CIE 1931 chromaticity investigation shows that Dy3+ doped glass emitted light with white color. Hence, these glasses may be suitable candidates for use in W-LEDs material.

Synthesis, spectral, structural and biological evaluation of 2-amino-2-ethylpyridinium picrate crystal

Single crystal of 2-amino-2-ethylpyridinium picrate (AEPP) was synthesized by employing slow evaporation technique. FT-IR spectroscopic results showed the formation of N+H group at 3163 cm−1 which confirms the proton transfer in AEPP crystal. Transparency of the crystal was studied using UV–Vis-NIR spectral data and revealed AEPP has no absorption in the entire visible region. The blue light emission capacity of the crystal was confirmed using photoluminescence studies. The TG/DTA analysis shows that the crystal is withstanding up to 180 °C. The molecular structure of the AEPP crystal ascertained through single crystal XRD. The crystal belongs to triclinic system with space group P-1. The inhibition activity against microbes was evaluated using disc diffusion method and showed better antimicrobial activity with increase in concentration.

Carbon Dots Modification Surface of Titanium Dioxide and Their Photocatalytic Activity

This work, we develop the efficient visible-light-responsive titanium dioxide photocatalyst using carbon dots as a sensitizer (C-dots/TiO2). C-dots was synthesized via a simple one-pot reaction by microwave-assisted pyrolysis method using orange juice as carbon precursors. C-dots/TiO2 samples were prepared by a facile route. Moreover, the micro-structure and optical properties of as-prepared C-dots/TiO2 have been evaluated using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible diffuse reflection spectroscopy (DRS). The modification surface of TiO2 with carbon dots enhanced the light absorption in visible region. The photocatalytic properties of as-prepared pure TiO2 and C-dots/TiO2 were also explored indigo carmine decolorization under visible light. The photocatalytic results revealed that the C-dots/TiO2 exhibited higher catalytic performance than the pure TiO2 under visible light.

A metal-free photoactive nitrogen-doped carbon nanosolenoid with broad absorption in visible region for efficient photocatalysis

Riemann surfaces inspired chemists to design and synthesize such multidimensional curved carbon architectures. It has been predicted that carbon nanosolenoid materials with Riemann surfaces have unique structures and novel physical properties. Here we report the first synthesis of a nitrogen-doped carbon nanosolenoid (N-CNS) using bottom-up approach with a well-defined structure. N-CNS was obtained by a rational Suzuki polymerization, followed by oxidative cyclodehydrogenation. The successful synthesis of N-CNS was fully characterized by GPC, FTIR, solid-state 13C NMR and Raman techniques. The intrinsic single-strand molecular structures of N-CNS helices can be clearly resolved using low-dose integrated differential phase contrast scanning transmission electron microscopy (iDPC-STEM) technique. Possessing unique structural and physical properties, this long π-extended polymer N-CNS can provide new insight towards bottom-up syntheses of curved nanoribbons and potential applications as a metal-free photocatalyst for visible-light-driven H2 evolution and highly efficient photocatalyst for photoredox organic transformations.

Au nanoparticles and reduced graphene oxide based plasmonic photodetector with enhanced performance in visible spectral region

This work reports on a photodetector (PD) based on SiO2 substrate, Au nanoparticles (NPs) and reduced graphene oxide (rGO) thin layer with plasmonic enhancement of light absorption in visible spectral region. Finite difference time domain (FDTD) methodology is used for simulation. The results show that a surrounding medium with higher refractive index (RI) leads to greater absorption with plasmonic enhancement resulting in higher magnitudes of quantum efficiency (η) and responsivity (ρ). The proposed PD design operating at 654.52 nm provides the values of η and ρ as large as 0.527 and 0.278 A/W, respectively. Further, a possible practical implementation of the proposed PD design is reported while analyzing it with Au electrodes and rGO acting as a conducting layer. This analysis comprises of dark current (Idark) estimation followed by the evaluation of detectivity (D) and detectable power (Pd). SiO2-rGO (6 nm)-Au NPs (6 nm radius) structure (with surrounding medium RI = 1.33) further achieves the values of Idark, D, and Pd as 6.33 × 10−14 A, 1.36 × 1011 Jones, and 2.28 × 10−13 W, respectively. Further, the proposed PD design is able to provide superior performance (i.e., small Idark along with large values of D and ρ) compared to recently-reported (2020-23) PD designs in visible range.

Fluorescent pH sensors based on BODIPY structure sensitive in acidic media

Two BODIPY phenolic esters 1 and 2 were synthesized and their acid-catalyzed hydrolytic and esterase enzymatic stability was demonstrated. Their photophysical properties were investigated in solvents of different polarity. Their spectral properties are the typical of BODIPY dyes with narrow absorption and emission spectra in the visible spectral region and large molar absorption coefficients (≈500 nm, ε = 40000-50000 M−1cm−1). The derivative with methyl substituted BODIPY core 2 shows quantum yields of fluorescence one magnitude higher (Φf = 0.30–0.55) compared to the BODIPY without methyl groups. Solvents affect very weakly spectral properties, with more pronounced effect of the solvent polarizability than the solvent polarity. Both BODIPY dyes show pH responsive fluorescence in aqueous solution (pKa = 2.72 ± 0.08 and 4.18 ± 0.05), with quenching of fluorescence by protonation due to PET from the BODIPY to phenol, rendering them applicable for intracellular pH measurements. The feasibility of the PET in the protonated form of 1 was corroborated by electrochemical measurements and calculation of ΔETGo for PET, and (time-dependent) density functional theory computations. This less frequently encountered quenching mechanism where the BODIPY is an electron donor provides new opportunities in the rational design of new generations of fluorescent sensors. The applicability for intracellular measurements was demonstrated by confocal fluorescence microscopy on H460 human cancer cell line.

Ultrasonic radiation assisted synthesis of (CH3NH3)2CuCl4, CH3NH3PbCl3, and CH3NH3SnCl3 perovskites for energy application

The present research provides an outline for the synthesis of organic-inorganic hybrid perovskites such as (CH3NH3)2CuCl4, CH3NH3PbCl3, and CH3NH3SnCl3 by using Ultrasonic radiation assisted method. An X-ray diffraction study reveals the presence of crystalline phase in the Cu, Pb and Sn based perovskites. The optical and electrical properties were carefully examined using UV–Vis diffuse reflectance spectroscopy. The optical band gaps of the synthesized sample were estimated using Tauc's plot. The current-voltage characteristics of all the samples demonstrate increase in photocurrent under UV light compared to darkness. The findings indicated that the addressed samples are improved in the visible absorption region and were in good agreement with earlier research. The photo-induced mechanisms that result in the remarkable charge separation efficiency of these materials are fundamental properties that provide insight into the special features of such a material which has driven this to the forefront of photovoltaic research.

Theoretical investigation of the optical and electronic properties of surface engineered V 2 N MXene

In this work, density functional theory is utilized to explore the impact of surface adsorption of (O, S, Se and Te) on the structural, electronic and optical properties of two-dimensional vanadium nitride (V 2 N) MXene and the results are compared with pristine V 2 N MXene. Our calculations show that V 2 NSe 2 MXene has the most stable structure among all the studied structures. Adsorption energy computations reveal that all terminal groups on the surface of the pristine V 2 N tightly attach to the V atoms. A metallic to semiconductor transition is observed in all the considered V 2 NT 2 (T=O, S, Se and Te) MXene structures. Among them, oxygen, selenium and tellurium adsorbed V 2 N shows a direct bandgap of 0.45, 0.86 and 0.53 eV, respectively. However, in case of sulphur adsorbed V 2 N MXene, an indirect bandgap of 1.19 eV is observed. This study also reports the effect of surface adsorption on the optical properties and dielectric constant of V 2 NT 2 (T=O, S, Se and Te). The results reveal a larger absorption in visible region as well as in ultraviolet region for all the computed structures except oxygen adsorbed V 2 N MXene as compared to pristine V 2 N MXene monolayer, which indicates the significance of surface adsorption on the optical properties of the studied MXene. Additionally, a very low reflectivity has been seen in all the V 2 NT 2 MXene structures as compared to pristine V 2 N. Our findings demonstrate the potential of these surface adsorbed V 2 N MXene materials in novel light-electron conversion devices.

Ultra-narrow band absorber in visible region based on the couple of Fabry-Pérot and guide mode resonance

Metasurface based near perfect absorbers show great potential in the regulation of ultra-narrow visible light absorption with their advantages of ultra-high light absorption, high integration and wide wavelength adjustable range. However, there is a bottleneck in achieving narrower light absorption through a single resonant absorption mechanism. In this work, we proposed a low-cost absorber based on Ag/Al2O3/Ag sandwich structure. The proposed absorber successfully realizes the ultra-narrow visible light absorption regulation through the coupling effect of Fabry-Pérot (FP) resonance and guide mode resonance (GMR). When the absorption peak is 435 nm (blue light), 546 nm (green light) and 699 nm (red light), the full width at half maxima (FWHM) is 5.34 nm, 2.14 nm and 2.88 nm respectively. Further, based on this kind of absorber unit, we designed an encryption structure that can display the two-dimensional code image only under the irradiation of a specific wavelength, showing its potential application value in the field of image encryption and anti-counterfeiting recognition.

Conjugated porous polymers regulated by thiophene and polycyclic aromatic hydrocarbons for photocatalytic water splitting toward hydrogen production

Rational design of organic semiconductors with wide visible light absorption and quick charge separation is of great significance for photocatalytic hydrogen production form water. In this work, the chemical structure of a linear conjugated polymer composed of ethynyl-linked benzene (B) and 2,1,3-benzothiadiazole (BT) is regulated by thiophene (TP) and polycyclic aromatic hydrocarbons [naphthalene (N) and anthracene (A)], and series of polymers including B-BT-TP-x, N-BT-TP-x and A-BT-TP-x (x = 0.2, 0.4, 0.6, 0.8) are synthesized. After thiophene and polycyclic aromatic hydrocarbon regulation, the polymers exhibit strong absorption in the whole visible light region of 400->650 nm and quick internal charge separation and transfer. Visible-light-driven photocatalytic hydrogen production rates of the synthesized polymers follow the order of B-BT (170.0 μmol/h) < B-BT-TP-0.6 (735.3 μmol/h) < N-BT-TP-0.4 (841.5 μmol/h) < A-BT-TP-0.6 (969.2 μmol/h) using 30 mg catalyst with 1.0 wt% Pt as cocatalyst. In addition, high apparent quantum yield (AQY) values of 8.04%, 5.58% and 0.95% under 550 nm, 650 nm and 700 nm monochromatic lights are obtained using A-BT-TP-0.6 catalyst. The present work provides new insights into design of advanced organic semiconductors for highly efficient photocatalytic solar energy conversion.

Xenobiotic Bi3+ Coordination by Cysteine-Rich Metallothionein-3 Reveals a Cooperatively Formed Thiolate-Sharing Bi2S5 Cluster.

The field of designing artificial metalloproteins has yet to effectively tackle the incorporation of multimetal clusters, which is a key component of natural metalloproteins, such as metallothioneins (MTs) and calmodulin. MT is a physiological, essential, cysteine-rich metalloprotein that binds to a variety of metals but is only known to form metal-thiolate clusters with Cd2+, Zn2+, and Cu+. Bismuth is a xenobiotic metal and a component of metallodrugs used to treat gastric ulcers and cancer, as well as an emerging metal used in industrial practices. Electrospray ionization mass spectrometry, UV-visible spectroscopy, and extended X-ray absorption fine structure spectroscopy were used to probe the Bi3+ binding site structures in apo-MT3 (brain-located MT) at pH 7.4 and 2 and provide the complete set of binding affinities. We discovered the highly cooperative formation of a novel Bi3+ species, Bi2MT3, under physiological conditions, where each Bi3+ ion is coordinated by three cysteinyl thiolates, with one of the thiolates bridging between the two Bi3+ ions. This cluster structure was associated with a strong visible region absorption band, which was disrupted by the addition of Zn2+ and reversibly disrupted by acidification and increased temperature. This is the first reported presence of bridging cysteines for a xenobiotic metal in MT3 and the Bi2MT structure is the first Bi cluster found in a metalloprotein.

Engineering push–pull structural versatility in highly functional carbazole-based hole transporting materials design for efficient perovskites solar devices

This study proposes a push–pull molecular engineering strategy to design highly functional hole transport materials (HTMs) for perovskite solar cells (PSCs). The strategy involves introducing acceptor-anchor groups via benzene spacer to the versatile carbazole core containing dimethoxytriphenylamine side groups, resulting in a series of nine newly designed HTM moieties (BEN-A1 to BEN-A9). Quantum simulation protocols using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods were employed to investigate the designed HTMs. Our results demonstrate that the designed HTMs exhibit promising charge separation and transport throughout the molecule with lower spatial hole-electron overlap at the carbazole core, resulting in 98% intrinsic charge transfer and small exciton binding energy (0.003–0.108 eV). The HTMs also exhibit stabilized HOMO energy levels (by up to 0.13 eV) approaching the threshold (−5.38 eV) with appropriate HTM/Perovskite energy levels alignment, suggesting excellent charge extraction and higher VOC. Optical analysis shows that our proposed HTMs exhibit large stokes shift values (82–108 nm) and transparent absorption in broader visible region, enabling full utilization of light for perovskite layer for photocurrent generation, efficient energy conversion, reduced thermalization losses, and improved spectral selectivity. The HTMs exhibit smaller hole reorganization energy (0.111–0.137 eV) and higher transfer integral, indicating robust hole mobility owing to enhanced carbazole core functionality. Furthermore, higher negative solvation-free energy values (−16.19 to −20.89 kcal/mol) and elevated dipole moments imply better solubility and surface-wetting properties. Overall, this study broadens our understanding of push–pull molecular engineering for versatile carbazole-based HTMs, which have immense prospects for efficient and functional application in PSCs.

Synthesis and numerical simulation of formamidinium-based perovskite solar cells: a predictable device performance at NIS-Egypt

Formamidinium lead triiodide (δ-FAPbI3)-based perovskite solar cells showed remarkable potential as light harvesters for thin-film photovoltaics. Herein, the mechanochemical synthesis of δ-FAPbI3, MAPbI3, and mixed-cation FA1−xMAxPbI3 with (x = 0.3, 0.5, and 0.7) perovskite materials were prepared as a novel green chemistry method for scaling up production. Crystallinity, phase identification, thermal stability, optoelectronic properties, and nanoscale composition are discussed. The results demonstrated that the prepared mixed-cation samples are enhanced in the visible absorption region and are consistent with previous works. The crystal structure of δ-FAPbI3 was altered to a cubic structure due to the change in FA-cation. Moreover, the performance of delta-FA-based perovskites was investigated using the Solar Cell Capacitance Simulator (SCAPS-1D) software. The validity of the device simulation was confirmed by comparing it to real-world devices. The photovoltaic characteristics and impact of absorber thickness on device performance were explained. The delta-FA-based solar cell with a 50% MA-doped molar ratio shows a better performance with an efficiency of 26.22% compared to 8.43% for δ-FAPbI3. The outcome results of this work confirm the beneficial effect of mixed cations on device operation and advance our knowledge of the numerical optimization of perovskite-based solar cells.

Graphitic carbon nitride modified by 5-sulfonic-8-hydroxyquinoline and Fe (III) ions as visible-light photocatalyst to efficiently reduce nitroaromatic compounds

In this study, a new graphitic carbon nitride (CN) catalyst was synthesized by combining 5-sulfonic-8-hydroxyquinoline (SQ) and Fe (III) ions. Photocatalysis reduction of nitroaromatic compounds was employed to evaluate the catalytic performance of the synthesized catalyst. Compared to the pristine CN, the optimized CN-SQ-2-Fe photocatalyst showed enhanced absorption in visible light region, which promoted photogenerated charge transfer and separation. Herein, we also developed a green and efficient photocatalysis route to convert nitrophenols (NPs) into aminophenols (APs) using CN-SQ-2-Fe photocatalyst. The visible light, separation of photogenerated charges and carrier transportation of the optimized sample CN-SQ-2-Fe were significantly improved in comparison with the pristine CN and the modified samples of CN-Fe and CN-SQ-2. Accordingly, the CN-SQ-2-Fe showed a high conversion (96%) of p-nitrophenol (p-NP) to p-aminophenol (p-AP) under visible light irradiation for 2 h and possessed high photocatalytic durability. Different NP compounds were also studied under the condition of photocatalysis reduction and demonstrated high conversion (>97%). Finally, a possible mechanism was proposed for the photocatalytic reduction of p-NP by CN-SQ-2-Fe. This work provides an effective approach to prepare graphitic carbon nitride (CN) modified by 5-sulfonic-8-hydroxyquinoline (SQ) and Fe (III) ions, which is a potential visible light driven photocatalyst for the reduction of nitrobenzene derivatives.

Fe-and-N co-doped Fe-ZIF-8-NH2(1/10) prepared by molecular-scale cages effect for highly efficient photocatalytic degradation of organic dyes

The amino and iron modified Metal-organic frameworks was successfully synthesized via a skillfully strategy and used as a photocatalyst to decompose organic dyes under visible light irradiation. Results show that 50 mg catalyst can almost degrade 100% MB within just 25 min at a wide pH (3.4–11.9) range. The kinetics constant (k) on Fe-ZIF-8-NH2(1/10) is estimated to be 0.0896 min−1, significantly higher than control samples. Meanwhile, there is little effect of various water sources on catalytic activities, and the rate reaches 97.1% (in Tap water), 88.5% (in Yangtze River water) and 78.1% (in oilfield brine with ultrahigh mineralization). Besides, the Fe-ZIF-8-NH2(1/10) exhibits high stability after 5 cyclic runs, and the ICP detects a small amount of Fe3+ (0.153 mg/L) leaching. Characterization reveals the catalyst has hierarchical porous structure, a rather homogeneous geometric topology and uniformly dispersed active sites. Based on the N 1 s spectrum of XPS, the nitrogen group is successfully loaded in amino mode. Its band gap drops sharply from 5.11 eV to 2.17 eV and the peak of PL spectra is much smaller, and the Fe-ZIF-8-NH2(1/10) possesses stronger absorption in visible light region and the response wavelength is widened to 700 nm. Further, the possible mechanism of photocatalytic degradation of pollutants is also proposed. The h+ is the most effective active species, meanwhile, •O2−, e− and •OH are both apparently participated in the photodegradation process. This study introduces valuable information for constructing high active catalysts on administration of water pollution.

Enhanced tetracycline photocatalytic degradation of FeOx/Fe-Bi2O2CO3 synthesized by one-step hydrothermal method

As an effective method to reduce the antibiotic contamination in water, photocatalysis has been widely investigated. Here, we report a preparation and tetracycline photodegradation of FeOx/Fe-Bi2O2CO3 system. The system consists of FeOx nanoparticles deposited on Fe-doped Bi2O2CO3. We used a simple one-step hydrothermal technique to successfully dope Fe into the Bi2O2CO3 lattice and simultaneously deposit FeOx. Based on experiments and calculations, it is found that incorporation of Fe in Bi2O2CO3 lattice results in a preferential growth of {001} facets, which are the active facets for photocatalytic reactions, and an increased light absorption in visible region. Additionally, FeOx nanoparticles increase light absorption and carriers’ generation via an interfacial charge transfer. Moreover, FeOx acts as cocatalyst to trap photogenerated electrons and holes, reducing the carriers’ recombination. A combination of positive effects from both Fe doping and FeOx deposition increase tetracycline photodegradation performance by two to three times compared to the pristine Bi2O2CO3. Thus, this work provides an easy-to-prepare and enhanced Bi2O2CO3 – based photocatalysts, which could benefit the future development of other materials in the field.

Electronic structure, mechanical properties and optical properties of three cobalt-based double halide perovskites: A first-principles study

The physical properties of three potential colbat-containing perovskites are studied through first principles calculation. The structural analysis reveals that the Cs2InCoI6 and Cs2AgCoI6 are ductile and potential in flexible devices. The negative formation energies indicate that all these perovskite syntheses are practicable in experiment. However, the results of tolerance factors and phonon spectra are presented against the structural dynamic stability of pure cubic phase of Cs2TlCoI6 and Cs2AgCoI6 and there may be lattice distortion. The band gaps of Cs2InCoI6, Cs2TlCoI6 and Cs2AgCoI6 are 0.833 eV, 1.713 eV and 0.783 eV, respectively, all values are within the ideal range for semiconductors that applied in optoelectronic devices. They all exhibit broad-spectrum light absorption in ultraviolet and visible region, and the absorption coefficient of Cs2InCoI6 even maintains a value above 10000 cm−1 at wavelength of 1400 nm. Among them, Cs2InCoI6 perovskite has direct band structure, smaller carrier effective mass than that of CsPbI3 and broad solar absorption characteristics, which is considered as a promising candidate material for optoelectronic devices.