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The verifications of current-state opacity (CSO) and initial-state opacity (ISO) in discrete event systems (DESs) both suffer from the curse of dimensionality, as these issues were proved to be PSPACE-complete. Hence, how to reduce the state space is crucial. In this paper, we investigate CSO and ISO in modular DESs, which consist of several individual components. Necessary and sufficient conditions of CSO and ISO for modular DESs are derived under the assumption that all synchronous events are observable by each components of modular DESs. Moreover, we prove that the initial state estimator of modular system is isomorphic to the synchronous composition of initial state estimators for individual components. These results offer us the opportunity to reduce the complexity in verifying the opacity of modular DESs.

Opacity is an important security notion for discrete event systems (DESs) to measure the secret behaviors leaked to an intruder. The intruder is usually modeled as a malicious observer who always attempts to infer secret behaviors based on his dynamical observations of the system. In our earlier paper, we proposed several opacity measures for DESs from the perspective of fuzzy logic, in which the intruder is assumed to only infer the current secret behaviors. Considering that modern computers usually have a powerful computation ability and rich memory resources, this paper presents a new opacity measure of DESs, called as fuzzy infinite-step opacity (FIO) measure, where the intruder is assumed to have the ability of inferring all the secret behaviors that occurred in the past. In addition, the properties and the calculation of FIO measure are also investigated. FIO measure can be used to assess the secret-leakage situations of fuzzy DESs attacked by powerful intruders. For the purpose of illustration, we present a practical application of FIO measure in evaluating the privacy protection mechanisms in location-based services.

In our previous paper, we have considered the supervisory control of the probabilistic discrete event systems (PDESs) under the centralized framework. In this paper, we continue to investigate the decentralized probabilistic supervisory control issue of PDESs. The intersection-based control architecture is adopted, and the notion of the probabilistic intersection-based co-observability and its verification algorithm are presented. It is shown that this observability and the probabilistic controllability act as the necessary and sufficient conditions for the existence of the intersection-based decentralized probabilistic supervisors. Moreover, a working example is provided to illustrate the proposed concepts, the obtained results, and the potential application of the proposed control approaches.

Opacity, as an important security property, has been well investigated in crisp discrete event systems. However, in some practical systems, the general behaviors, secret and nonsecret behaviors obtained by the intruder need to be expressed as fuzzy sets rather than crisp sets. Under this situation, the intruder makes inferences by fuzzy logic rather than classic logic, thus the notions of the fuzzy opacity measures are desired to be established. First, by means of the basic laws of fuzzy logic, a general fuzzy opacity measure, as a template, is presented, in this article, for the given generalized characterizations of secret and nonsecret behaviors. Moreover, a specific measure, called as fuzzy initial-final opacity (FIFO) measure, is investigated under the assumption that the secrets and nonsecrets can be coded into the initial-final state-pairs. In addition, two variants of FIFO measure are also proposed under the assumptions that the secrets and nonsecrets are only related to the initial-states or final-states. With these fuzzy opacity measures, the system designers can evaluate the opacity degree of the systems to be designed. To show the applicability of the fuzzy opacity measures to practical systems, we finally present an illustrative example of evaluating the location privacy protection systems in location-based services by means of the fuzzy opacity measures.

Few-mode fiber is a significant component of free-space optical communication at the receiver to obtain achievable high coupling efficiency. A theoretical coupling model from the free-space optical communication link to a few-mode fiber is proposed based on a scale-adapted set of Laguerre-Gaussian modes. It is found that the coupling efficiency of various modes behaves differently in the presence of atmospheric turbulence or random jitter. Based on this model, the optimal coupling geometry parameter is obtained to maximize the coupling efficiency of the selected mode of few-mode fiber. The communication performance with random jitter is investigated. It is shown that the few-mode fiber has better bit-error rate performance than single-mode fiber, especially in high signal-to-noise ratio regimes., 8 pages, 8 figures

A BiVO4/2D g‐C3N4 direct dual semiconductor photocatalytic system has been fabricated via electrostatic self‐assembly method of BiVO4 microparticle and g‐C3N4 nanosheet. According to experimental measurements and first‐principle calculations, the formation of built‐in electric field and the opposite band bending around the interface region in BiVO4/2D g‐C3N4 as well as the intimate contact between BiVO4 and 2D g‐C3N4 will lead to high separation efficiency of charge carriers. More importantly, the intensity of bulid‐in electric field is greatly enhanced due to the ultrathin nanosheet structure of 2D g‐C3N4. As a result, BiVO4/2D g‐C3N4 exhibits excellent photocatalytic performance with the 93.0% Rhodamine B (RhB) removal after 40 min visible light irradiation, and the photocatalytic reaction rate is about 22.7 and 10.3 times as high as that of BiVO4 and 2D g‐C3N4, respectively. In addition, BiVO4/2D g‐C3N4 also displays enhanced photocatalytic performance in the degradation of tetracycline (TC). It is expected that this work may provide insights into the understanding the significant role of built‐in electric field in heterostructure and fabricating highly efficient direct dual semiconductor systems.

Opacity is an important information-flow property, which is used to characterize whether or not the secrets of system have been leaked to the intruders. Over the past ten years, opacity of discrete event systems (DESs) modeled as automata and Petri nets have been well investigated under the assumption that the communication channels between systems and intruders are perfect. However, in networked discrete event systems (NDESs), the DESs run in a shared network, and the communication delays and losses are inevitable usually. In this paper, we investigate the problems of opacity in the framework of NDESs. We formulate four kinds of opacity for NDESs, including current-state opacity, initial-state opacity, initial-final-state opacity, and K-step opacity. We also present the verification algorithms for these notions. We extend the notions of opacity in classical DESs, that is, if the communication delays and losses disappear, then these new notions would reduce to their classical counterparts. A number of examples are provided to illustrate the results obtained.

With the persistence of the COVID-19 pandemic caused primarily by constant viral mutations, rapid identification of different lineages of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by large-scale screening at the point-of-care could be key to monitoring and assessing viral evolutions. Herein, we developed a Fluorescence Enhanced Microarray for Multiplex Analysis of Nucleic acids (FEMMAN) for detecting 8 SARS-CoV-2 variants simultaneously in ~ 3 hours without the need of RNA extraction, opening the possibility of point-of-care testing of multiple SARS-CoV-2 variants while reducing the cost significantly to ~ $ 7 per sample from ~ $100 by Next-Generation Sequencing (NGS). Combined with isothermal amplification, the multiplexed RNA assay achieved single-copy detection sensitivity and single nucleotide variant (SNV) distinction owing to the nanotechnology based plasmonic gold (pGOLD) near-infrared fluorescence enhancing platform. Probing 10 targets of three mutational hotspots in S gene, we differentiated 8 viral lineages (Wild type, Alpha, Beta, Gamma, Delta, Lambda, Mu, and Omicron) of SARS-CoV-2, validated using nasopharyngeal swabs obtained from 127 individuals, achieving a 100% sensitivity and 100% specificity in SARS-CoV-2 detection, and a 91.1% concordance with NGS in variant identification. The scalable, multiplexed FEMMAN assay could shift the paradigm of COVID-19 diagnostic and surveillance from positive/negative assessments to simultaneous lineage identification in large-scale screening, greatly facilitating the global monitoring of SARS-CoV-2 variants.

Constructing Z-scheme photocatalyst is an effective strategy to achieve efficient photogenerated electron-holes separation and retain its outstanding redox ability simultaneously. In this work, a novel ternary BiVO4/protonated g-C3N4/AgI photocatalyst with a double Z-scheme mechanism is successfully constructed by electrostatic self-assembly method loading of BiVO4 onto protonated g-C3N4 and subsequently via an in situ precipitation route. Using Rhodamine B (RhB) as the target of elimination, BiVO4/protonated g-C3N4/AgI displays excellent photocatalytic performance with the 94.67% removal after 60-min visible light irradiation. The photodegradation rate constant of RhB is 0.04963 min−1, which faster than pristine BiVO4 (0.0004 min−1), BiVO4/protonated g-C3N4 (0.0209 min−1) and BiVO4/AgI (0.0317 min−1), respectively. Such enhancement in photocatalytic activity is correlated to improved light absorption, faster charge carrier separation and transportation as well as more powerful redox ability originating from the formation of double Z-scheme heterostructure. Also, the as-prepared ternary sample exhibits high stability after four cycles of the photodegradation reaction. Furthermore, the possible photocatalytic mechanism of BiVO4/protonated g-C3N4/AgI is also proposed. Therefore, we believe that this work can provide insights into the understanding the significant role of design and synthesis the double Z-scheme in semiconductor heterostructure system for environmental remediation.

Crystal structure and electronic properties of SnO2 doped with non-metal elements (F, S, C, B, and N) were studied using first-principles calculations. The theoretical results show that doping of non-metal elements cannot change the structure of SnO2 but result in a slight expansion of the lattice volume. The most obvious finding from the analysis is that F-doped SnO2 has the lowest defect binding energy. The doping with B and S introduced additional defect energy levels within the forbidden bandgap, which improved the crystal conductivity. The Fermi level shifts up due to the doping with B, F, and S, while the Fermi level of SnO2 doped with C or N has crossed the impurity level. The Fermi level of F-doped SnO2 is inside the conduction band, and the doped crystal possesses metallicity. The optical properties of SnO2 crystals doped with non-metal elements were analyzed and calculated. The SnO2 crystal doped with F had the highest reflectivity in the infrared region, and the reflectance of the crystals doped with N, C, S, and B decreased sequentially. Based on this theoretical calculations, F-doped SnO2 is found to be the best photoelectric material for preparing low-emissivity coatings.

Structural, electronic and optical properties of Nb and F co-doped SnO2 were mainly investigated using density functional theory (DFT). Hybrid density functional theory was employed to obtain band structure, density of states (DOS) and optical properties. The calculated lattice parameters of pure SnO2 by PBEsol functional (a = 4.774 A and c = 3.218 A) are in good agreement with experimental date (a = 4.742 A and c = 3.206 A). When co-doping with Nb&F, the length of octahedron (4.136 A) closely matches with pure SnO2 (4.112 A) in direction of perpendicular to the c-axis. The direct band gaps of 3.80 eV, 3.38 eV 3.63 eV, 3.23 eV, 3.06 eV have been obtained for pure, F, Nb, Nb&F and Nb&2F doped SnO2 respectively, and the dispersed conduction band after doping does not significantly affect the electron effective mass of the conduction band minimum (CBM). A study of band alignment shows the clearly increasing valence band maximum (VBM) and the slightly decreasing CBM occur after doping. Analyses of the charge density difference and Bader charge suggest that Sn–O bond shows covalent characteristic, but the degree of ionization decreases in following order: Nb > Nb&F > Nb&2F > SnO2 > F. In terms of optical properties after doping, the optical absorption side slightly red or blue shift, and the reflectivity in the visible spectrum is greatly low.

Efficient electrolysis of water is vital to realize the sustainable development of energy, but it is still a challenge. Herein, we propose a common approach to prepare amorphous noble metal alloy nanosheets as advanced bifunctional catalysts to drive the efficient electrochemical water splitting by rapidly annealing metal acetylacetonate (metal = Ru,Co,Fe) and alkali salts, which allows to optimize their catalytic properties by tuning the introduction of transition metals. In particular, as-prepared amorphous RuCoFe nanosheets achieve not only an extremely low overpotential of 2.04 mV at 10 mA cm−2 for hydrogen evolution reaction under alkaline media, but also a high-performance and stable overall water electrolysis with a potential of mere 1.56 V at 10 mA cm−2. Considering the advantages of polymetallic amorphous nanosheets electrocatalysts, our proposed synthetic strategy could be versatile and applicable toward further developing other functional polycompounds for energy generation, storage and conversion.

Rare-earth (R) nickelates (such as perovskite RNiO3, trilayer R4Ni3O10, and infinite layer RNiO2) have attracted tremendous interest very recently. However, unlike widely studied RNiO3 and RNiO2 films, the synthesis of trilayer nickelate R4Ni3O10 films is rarely reported. Here, single-crystalline (Nd0.8Sr0.2)4Ni3O10 epitaxial films were coherently grown on SrTiO3 substrates by high-pressure magnetron sputtering. The crystal and electronic structures of (Nd0.8Sr0.2)4Ni3O10 films were characterized by high-resolution X-ray diffraction and X-ray photoemission spectroscopy, respectively. The electrical transport measurements reveal a metal-insulator transition near 82 K and negative magnetoresistance in (Nd0.8Sr0.2)4Ni3O10 films. Our work provides a novel route to synthesize high-quality trilayer nickelate R4Ni3O10 films., 9 pages, 4 figures

Mesoporous Fluorine doped SnO2 (FTO) nanoparticles (NPs) have been successfully synthesized by hydrothermal process. Subsequent annealing process at 350 °C, 500 °C, 650 °C and 800 °C has been carried out to synthesize FTO photocatalysts with different specific surface areas and oxygen vacancy contents. X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy characterization, Raman measurement, X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance and Photoluminescence (PL) spectra have been used to investigate the effects of specific surface areas and oxygen vacancy contents on the photocatalytic properties of mesoporous FTO photocatalysts. The results show that the mesoporous FTO NPs consist of spherical nanoparticles of 3–6 nm in diameters with a tetragonal crystal structure. The as–synthesized mesoporous FTO NPs with the band gap of 3.91 eV, the largest number of oxygen vacancies and the largest surface area of 145.55 m2 g−1 exhibit an excellent photocatalytic activity when degrading methyl orange (MO) under UV light irradiation, and the degradation of dye methyl orange (MO) can reach 97% within 80 min. Moreover, the superoxide oxide (•O2−) is the major active specie, which has played a key role in MO degradation system. The photocatalytic mechanism of FTO photocatalysts has been also proposed.

Titanium dioxide (TiO2)/fluorine-doped tin dioxide (FTO) bilayer films were deposited on glass substrates by spray pyrolysis. The effects of hydrogen plasma exposure on structure, morphology and optical properties of the films were studied. The distribution of elements in the double layer film was investigated by glow discharge spectrometer. The results indicate that the TiO2 film provides effective protection of the underlying FTO film from the bombardment with hydrogen ions and radicals. Without the TiO2 protective layer, SnO2 will be reduced to sub-oxidized SnO and metallic Sn by hydrogen ions and radicals with increasing the exposure time. In addition, the TiO2/FTO film presents a nano-flower shaped appearance due to the small particles (TiO2) agglomerated on the surface of large particles (SnO2), the novel textured morphology is preferred for improving light scattering and haze of the film. A high haze value of 36.7% was obtained when the approximate thickness of the prepared TiO2 layer is 213 nm. This work may provide an alternative for improving performance of a-Si based solar cells.

Limited by the narrow photoresponse range and high electron-hole recombination rate, the photocatalytic efficiency of TiO2 is still far below what is expected. Herein, the Mo-C donor-acceptor passivated co-doping TiO2 ((Mo,C)-TiO2) was synthesized via a hydrothermal synthetic strategy, then it is coupled with FTO. The donor-acceptor co-doped TiO2 exhibit band gap reduction of ∼1.0 eV, and enable the nanoparticles to be photoactive in the visible light range. The band structure investigated by Mott-Schottky plots and valence band spectra reveal that doping induces an extended-tail-states near the valence band edges, which is responsible for the photoresponse in the visible light region. Density-functional theory (DFT) calculations manifest that donor-acceptor co-doping TiO2 exhibit both the advantages of the Mo, C mono-doped cases, and results in higher charge density in (Mo,C)-TiO2. The photoluminescence (PL) spectra and time-resolved PL spectra show that co-doping induced deep electron trap state in (Mo,C)-TiO2, confirmed by the surface photovoltage (SPV) spectroscopy, which enables accumulate long-lived photoinduced electrons and effectively suppresses the radiative electron-hole recombination. Meanwhile, FTO as the electronic receiver is beneficial for the charge carrier separation. As expected, the (Mo,C)-TiO2/FTO photocatalysts show a remarkably enhanced photocatalytic activity in the visible-light irradiation degradation of methylene blue (MB) and tetracycline (TC), up to ∼4 times higher than that of TiO2.

In this study, a large high-quality tetragonal KTa0.53Nb0.47O3 (KTN) single crystal of 18 × 18 × 35 mm3 was grown by the top-seeded solution growth method. The complete sets of elastic, dielectric, and piezoelectric constants for the [001]C-poled KTN single crystal with a macroscopic 4-mm system were confirmed via the combined resonance and pulse-echo ultrasonic methods. The values of the electromechanical coupling factors k33 and kt were 0.690 and 0.618, respectively, similar to those of PZT5A. In addition, the orientation dependence of those properties was calculated via the tensor transformation method, and it was found that the maximum d33 = 132 pC/N, s 33 E = 9.5 × 10−12 m2/N, and k33 = 0.69 occurred with the new z-axis oriented along [001]C.

An efficient photocatalyst has an important role in the photocatalytic water splitting using solar energy to produce hydrogen and oxygen. In this paper, MoSSe/BiVO4(010) heterostructure photocatalyst was constructed to solve the problem of low efficiency of individual photocatalysts. The results of first-principles calculations show that this composite structure has the photocatalytic mechanism of Z-scheme heterostructure, which is helpful for improving the photocatalytic efficiency. Calculations of Gibbs free energy changes confirm the thermodynamic feasibility of hydrogen evolution reaction and oxygen evolution reaction in MoSSe/BiVO4(010) heterostructures. These results indicate that the MoSSe/BiVO4(010) heterostructure has great application potential for visible-light-driven water splitting.

As an emerging biomarker, cell-free DNA (cfDNA) carries crucial genetic information for the diagnosis of hereditary disease and cancer. However, test accuracy was severely compromised by the low abundance of cell-free DNA in peripheral blood, frequently diluted by genomic DNA released from white blood cells, resulting in sample rejection, test inaccuracy, and restricted clinical utility. Herein we report a novel strategy for the efficient recovery of cfDNA with significant removal of genomic DNA contamination during the cfDNA extraction process, based on a nano-magnetic size selective cfDNA extraction platform. With this platform, over 90% cfDNA recovery rate was achieved with minimal genomic DNA contamination. For non-invasive prenatal testing, an increase of fetal fraction from 10.10% to 29.94% medially was observed in 11 maternal plasma samples, with two false-negative samples identified by the proposed workflow. Enrichment of cfDNA in plasma sample of cancer patient demonstrated ∼ 100% increase of circulating tumor DNA (ctDNA) percentage by panel sequencing of specific mutation sites. The approach is simple, automatable and cost-efficient, can improve liquid biopsy precision and reduce sequencing depth through significant enrichment of target abundance. The nano-magnetic platform demonstrated its potential application in liquid biopsy, since it exhibited numerous advantages in avoiding false negative results, reducing sequencing cost, improving data quality, and rescuing contaminated samples.

In this paper, the secrecy outage probability of a partially coherent beam free-space optical communication system considering the combined effect of anisotropic non-Kolmogorov strong turbulent atmosphere and the eavesdropper’s position is investigated. The Fisher–Snedecor distribution is chosen to model the atmospheric turbulence because it is not only suitable for weak to strong turbulence conditions but is also mathematically simple. Based on the fading channel model and the generalized pointing error model, we derive analytical expressions for the lower bounded secrecy outage probability. Also, we obtain asymptotic closed-form expression at a high signal-to-noise regime. The obtained expressions are corroborated by Monte Carlo simulations. The calculation results based on the analytical expressions show that increasing the source coherence parameter makes the secrecy interruption probability performance first better and then worse for a given condition, and an optimal value is observed. The anisotropic coefficient and power law have a positive effect on the secrecy outage probability of the free-space optical communication system. Under the given conditions, the performance of the secrecy outage probability is significantly improved by the divergent beam, although the increased spot size at the receiver makes it easier for eavesdroppers to tap the link. The secrecy outage probability performance deteriorates as the vertical component of Bob, the jitter variance, and the refractive index structure constant increase.

The crystal structure, electronic properties of F, S, C, B and N doped SnO2 were studied with the First-Principle Method. The theoretical results show that doping of non-metal elements did not change the structure of SnO2 but result in slight lattice volume expansion. The dope of the non-metal elements of B, F, and S cause the Fermi level to shift upThe most obvious finding to emerge from the analysis is that F-doped SnO2 has the lowest defect binding energy, stable crystal structure, and the easiest doping. The B, F, and S element doped SnO2 can modulate the fermi level. The doping of the B and S elements introduced additional defect energy levels to appear within the forbidden band-gap，which improved the crystal conductivity. Analysis of the energy band structure of SnO2 crystals doped with C and N elements shows that the Fermi level has crossed the impurity level. The Fermi level of F doped SnO2 is inside the conduction band, and the doped crystal has metallicity. The optical properties of SnO2 crystals doped with non-metallic elements were analyzed and calculated. The SnO2 crystal doped with F element had the highest reflectivity in the infrared region, and the reflectance of the crystals doped with N, C, S, and B elements decreased sequentially. Based on this theoretical calculations, F doped SnO2 is found to be the best photoelectric material for for preparing low-e thin film.

SnO2-based photocatalysts with excellent photocatalytic activity and promising prospects have widespread applications in the field of environmental science and energy. However, the photocatalytic efficiency of traditional SnO2 semiconductor with its inherent drawbacks is far from the actual requirements. Considerable works have been carried out to structural design, control morphology and construct composite systems to improve the photocatalytic performance. In this review, the latest developments and achievements of adjustment methods have been discussed in detail including doping, solid solution, stoichiometry alteration, ultrafine particles, fibers, thin structures, hierarchical and porous structures, crystal facet engineering, heterojunctions, SnO2/carbon materials, noble metal modified and dye sensitized SnO2. The photocatalytic applications of SnO2-based photocatalysts in organic pollutants degradation, water splitting, Cr(VI) reduction, CO2 reduction, air purification, and photocatalytic sterilization are summarized. Finally, the development prospects and challenges of SnO2-based photocatalysts are also proposed.

A novel composite material composed of inorganic semiconductor antimony sulphide (Sb2S3) and organic semiconductor copper tetra-β-(4-carboxyphenoxy) phthalocyanine (CuTβPc) was prepared by a simple...

Opacity is an important information-flow property, which is used to characterize whether or not the secrets of system have been leaked to the intruders. Over the past ten years, opacity of discrete event systems (DESs) modeled as automata and Petri nets have been well investigated under the assumption that the communication channels between systems and intruders are perfect. However, in a shared network, the communication delays and losses are inevitable usually. In this paper, we investigate the problem of opacity of networked discrete event systems (NDESs). We propose the notions of current-state opacity, initial-state opacity, initial-final-state opacity, and infinite-step opacity for NDESs. We also present the verification algorithms for these notions. Some examples are provided to illustrate the results obtained.

Limited by the narrowed photoresponse range and unsatisfactory recombination of photoinduced electron-hole pairs, the photocatalytic efficiency of TiO2 is still far below what is expected. Here, we initially doped TiO2 nanotubes (TNTS) by transition metal ion Nb, then it is coupled with reduced graphene oxide (rGO) to construct a heterostructure photocatalyst. The defect state presented in TiO2 leading to the formation of localized midgap states (MS) in the bandgap, which regulating the band structure of TiO2 and extending the optical absorption to visible light region. The internal charge transport and transfer behavior analyzed by electrochemical impedance spectroscopy (EIS) reveal that the coupling of rGO with TNTS results in the formation of electron transport channel in the heterostructure, which makes a great contribution to the photoinduced charge separation. As expected, the Nb-TNTS/rGO exhibits a stable and remarkably enhanced photocatalytic activity in the visible-light irradiation degradation of methylene blue (MB), up to ∼5 times with respect to TNTS, which is attributed to the effective inhibition of charge recombination, the reduction of bandgap and higher redox potential, as well as the great adsorptivity.

Antimony sulfide (Sb2S3) films on indium tin oxide (ITO) glass substrates were prepared by electrodeposition method followed with heat-treatment process using a thiol–amine as solvent mixture under ambient conditions. The structure and properties of the Sb2S3 films were characterized by XRD, SEM, TEM and electrochemical workstation. The results show Sb2S3 films mainly consist of orthorhombic phase with micro-nanorods morphology. Sb2S3 films exhibit good electrocatalytic activity towards hydrazine oxidation with a low detection limit of 0.4 μM. The facile synthesis method and excellent sensing properties make the Sb2S3 films as a promising candidate for potential application in the field of catalysis and environmental.

F and Nb co-doped tin oxide films were deposited from monobutyltin trichloride (C 4 H 9 SnCl 3 ) on glass substrates at 470 °C by spray pyrolysis. The evolution of the film structure and morphology was investigated by X-ray diffraction and scanning electron microscopy, respectively. All the films were a single phase with polycrystalline, exhibiting a tetragonal cassiterite structure with (200) orientation. The introduction of F and Nb contributed to the growth of the films towards (200) crystal orientation and the formation of pyramidal shape particles with (101) twin planes. Resistivity, carrier concentration, and Hall mobility values of 3.62 × 10 −4 Ω cm, 7.463 × 10 20 cm −3 , and 27.8 cm 2 V −1 s −1 , respectively, were achieved in the films for a dopant concentration of 20 at.% F and 1 at.% Nb in the precursor solution. Also, the transmittance of all the films in the visible range reached about 80% and the infrared reflectivity was oscillated between 92 and 96%.

Aluminium-doped zinc oxide (AZO)/fluorine-doped tin dioxide (FTO) double-layered transparent conducting films were manufactured on quartz glass substrates by spray pyrolysis. Like top films, AZO ha...

A novel 0D SnO2 nanoparticles/2D g-C3N4 nanosheets heterojunction has been successfully constructed by electrostatic self-assembly. The 2D g-C3N4 nanosheets (CNNSs) are prepared by multiple thermal exfoliation at 500 °C, and 0D SnO2 nanoparticles (NPs) with the average diameter of about 30 nm are prepared by hydrothermal method. The experiment and calculation results have revealed that a built-in electric field (BIEF) has been established at the contact interface of SnO2/CNNSs type II heterojunction, and this BIEF can specify charge transfer direction and promote charge separation. Furthermore, the raised conduction band (CB) of CNNSs provides a greater driving force for the charge transfer from CNNSs to SnO2. SnO2/CNNSs heterojunction exhibits the highest degradation of 96.9% for Rhodamine B (RhB) within 50 min under simulated visible light, which is 32.3 and 1.5 times than that of SnO2 and CNNSs, respectively. The superoxide radical (•O2−）is confirmed as the most important active substance in photocatalytic activity and a possible photocatalytic mechanism of SnO2/CNNSs has been proposed for the improved photocatalytic performance.

The Sb2S3 film on indium-tin oxide (ITO) substrate has been used as an efficient electron transfer mediator for the fabrication of novel chemical sensor towards hydrazine, which is a diamine known as neurotoxin and carcinogen. Sb2S3 film is deposited on ITO substrate by drop-casting process using Sb2S3 solution as precursor and possesses reticular structure with the morphology of uniform hollow hemispheres. The fabricated chemical sensor for selective detection of hydrazine displays a high sensitivity of 106.25 μA/(mM cm2) with a low detection limit of 0.5 μM and it also exhibits excellent reproducibility and stability in hydrazine detection.

The TiO 2 nanotube (TONT) based heterojunction photocatalyst was developed via the coupling of reduced graphene oxide (rGO) and SnO 2 :F film (FTO). Based on the characterization of Raman analysis, XRD, SEM, TEM, XPS and ESR, the crystal phase, morphology, heterojunction interfacial interaction and the photoinduced electron chemical environment of the samples are studied. In the photodegradation of methylene blue (MB) solution under UV irradiation, the rGO-TONT/FTO heterojunction photocatalyst exhibits the improved photocatalytic reaction rate, 3 times greater than that of pure TONT. The enhanced photocatalytic mechanism was discussed by PL. The effectively separate charge in heterojunction structure of rGO-TONT/FTO is responsible for the enhanced photocatalytic activity. Wherein, the abundant oxygen vacancies at TiO 2 surface and the chemically bonded interface in rGO-TONT heterojunction also contributes to the interfacial electron transfer. Besides, the introduction of rGO enhanced its optical absorption capacity.