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Crystallinity and crystal structure greatly influence the photocatalytic behavior of photocatalysts. Pristine g-C3N4 produced by traditional thermal-induced polycondensation reaction bears low crystallinity and thus poor photoactivity, which originates from the incomplete polymerization of the precursor containing amine groups, abundant hydrogen bonds, and unreacted amino, as well as cyanide functional groups in the skeleton. During photocatalytic process, these residual functional groups often work as electron trap sites, which may hinder the transfer of electrons on the plane, resulting in low photoactivity. Fortunately, crystalline carbon nitride (CCN) was reported as a promising photocatalyst because its increased crystallinity not only reduces the number of carriers recombination centers, but also increases charge conductivity and improves light utilization due to extended π-conjugated systems and delocalized π-electrons. As such, we summarize the recent studies on CCN-based photocatalysts for the photoactivity enhancement. Firstly, the unique structure and properties of CCN materials are presented. Next, the preparation methods and modification strategies are well outlined. We also sum up the applications of CCN-based materials in the environmental purification and energy fields. Finally, this review concerning CNN materials ends with prospects and challenges in the obtainment of high crystallinity by effective techniques, and the deep understanding of photocatalytic mechanism. [ABSTRACT FROM AUTHOR]

Enhancement of the light-absorption response and utilization of the photogenerated carriers represent a robust strategy for the design of high-performance photocatalyst. In this work, grafting CoxP nanoclusters onto S-scheme heterojunction of W18O49/ZnIn2S4 (WO/ZIS-CoxP) with strong response to the ultraviolet–visible–near infrared ray (UV–vis–NIR) region has been achieved, which possesses efficient electron-transfer-channel, and boosts charge-separation and transport kinetics. The as-prepared WO/ZIS-CoxP yields an impressive solar-driven hydrogen production rate of 45 mmol·g−1·h−1. The increased photocatalytic performance is attributed to the synergistic effect of the composite catalyst: (1) The local surface plasmon resonance-induced "hot electron" injection of W18O49 significantly increases the electron density; (2) the engineered S-scheme directional electron transfer promotes charge separation and enhances the reducing capability of photoexcited electrons; and (3) CoxP as electron-trap site for accelerating surface proton reduction reaction. This work provides a platform to impart nonprecious co-catalyst for engineering S-scheme heterojunction, serving a class of efficient solar-driven photocatalyst towards hydrogen production. [ABSTRACT FROM AUTHOR]

Semiconducting transition metal dichalcogenides (MX2) occur in 2H and rhombohedral (3R) polytypes, respectively distinguished by anti-parallel and parallel orientation of consecutive monolayer lattices. In its bulk form, 3R-MX2 is ferroelectric, hosting an out-of-plane electric polarisation, the direction of which is dictated by stacking. Here, we predict that twin boundaries, separating adjacent polarisation domains with reversed built-in electric fields, are able to host two-dimensional electrons and holes with an areal density reaching ~ 1013cm−2. Our modelling suggests that n-doped twin boundaries have a more promising binding energy than p-doped ones, whereas hole accumulation is stable at external surfaces of a twinned film. We also propose that assembling pairs of mono-twin films with a 'magic' twist angle θ* that provides commensurability between the moiré pattern at the interface and the accumulated carrier density, should promote a regime of strongly correlated states of electrons, such as Wigner crystals, and we specify the values of θ* for homo- and heterostructures of various TMDs. The authors investigate the twin boundaries in ferroelectric transition metal dichalcogenides, predicting their trap electrons with low densities, enhancing electron-electron interactions and potentially promoting Wigner crystallisation. [ABSTRACT FROM AUTHOR]

Doping transition metals in ZnO nanoparticles play a vital role in enhancing its photocatalytic activity. (Co,Ni) co-doped ZnO nanoparticles have been synthesized via sol–gel combustion method and explored the impact of co-doping on the structural, optical, morphological and photocatalytic properties of ZnO nanoparticles. The XRD pattern elucidated hexagonal wurtzite structure. The incorporation of co-dopants led to red-shift in the energy band gap. Photoluminescence spectral analysis showed the existence of different defects in the lattice on variation of energization. The assessment for photocatalytic activity was carried out by evaluating the degradation of methylene blue (MB) and rhodamine B (RhB) dyes under sunlight irradiation. Among the photocatalysts, 3%Co–3%Ni showed excellent photocatalytic activity within 75 min. This is in accordance with the decrement in crystallite size, red-shift of band gap, introduction of electron trap levels by the dopants and presence of defects such as oxygen vacancies. Additionally, the calculated CIE co-ordinates of the sample lies in the white region (0.32, 0.32) of CIE diagram and computed CCT were above 5000 K establishing its application in cold white light. [ABSTRACT FROM AUTHOR]

In this study, a novel Z-scheme heterojunction based on g-C3N4/TiO2/NiCo2O4 nanocomposite was synthesized using a combination of hydrothermal and ultrasonic methods and investigated the photocatalytic degradation of Rhodamine B (RhB) dye. The synthesized nanocomposite was characterized XRD, FT-IR, FE-SEM, TEM, EDS, PL, UV–Vis DRS techniques. Subsequently, various parameters such as the effect of NiCo2O4 amount in the composite structure, pH, initial pollutant concentration, photocatalyst dosage, and different scavengers were investigated to determine the exact mechanism of the photocatalytic process. In different concentrations of NiCo2O4, the base value (X: 1) was determined as the optimal value in photocatalytic degradation. g-C3N4/TiO2/NiCo2O4 composite had the highest percentage of 99.5% Rh.B dye degradation in 60 min. In addition, by examining the pH, it was found that its optimal value is 7, and the rate of dye degradation in this condition is more than other materials, and the rate constant value is 0.069 min–1. In addition, the g-C3N4/TiO2/NiCo2O4 catalyst showed good performance for each reuse and retained about 82% of its initial photocatalytic activity after 5 cycles. The results indicate that photoinducd (RhB) holes play a crucial role in the photocatalytic degradation of RhB in the presence of the g-C3N4/TiO2/NiCo2O4 nanocomposite via pair Z-scheme system. In the Z-scheme system, the rapid recombination between the hole-electron pair is not observed due to the electron trapping effect of the needle-shaped NiCo2O4 structure, resulting in high photocatalytic efficiency and dye degradation. Therefore, Z-scheme systems are efficient and effective for the removal of water pollutants. [ABSTRACT FROM AUTHOR]

Highly sensitive, low-power, and chip-scale H2 gas sensors are of great interest to both academia and industry. Field-effect transistors (FETs) functionalized with Pd nanoparticles (PdNPs) have recently emerged as promising candidates for such H2 sensors. However, their sensitivity is limited by weak capacitive coupling between PdNPs and the FET channel. Herein we report a nanoscale FET gas sensor, where electrons can tunnel between the channel and PdNPs and thus equilibrate them. Gas reaction with PdNPs perturbs the equilibrium, and therefore triggers electron transfer between the channel and PdNPs via trapping or de-trapping with the PdNPs to form a new balance. This direct communication between the gas reaction and the channel enables the most efficient signal transduction. Record-high responses to 1–1000 ppm H2 at room temperature with detection limit in the low ppb regime and ultra-low power consumption of ~ 300 nW are demonstrated. The same mechanism could potentially be used for ultrasensitive detection of other gases. Our results present a supersensitive FET gas sensor based on electron trapping effect in nanoparticles. Highly sensitive, low-power, and chip-scale gas sensors are of great interest to both academia and industry. The authors developed a nanotransistor-based gas sensor with high sensitivity enabled by electron trapping effect in nanoparticles. [ABSTRACT FROM AUTHOR]

Highly efficient interconversion of different types of energy plays a crucial role in both science and technology. Among them, electrochemiluminescence, an emission of light excited by electrochemical reactions, has drawn attention as a powerful tool for bioassays. Nonetheless, the large differences in timescale among diverse charge-transfer pathways from picoseconds to seconds significantly limit the electrochemiluminescence efficiency and hamper their broad applications. Here, we report a timescale coordination strategy to improve the electrochemiluminescence efficiency of carbon nitrides by engineering shallow electron trap states via Au-N bond functionalization. Quantitative electrochemiluminescence kinetics measurements and theoretic calculations jointly disclose that Au-N bonds endow shallow electron trap states, which coordinate the timescale of the fast electron transfer in the bulk emitter and the slow redox reaction of co-reagent at diffusion layers. The shallow electron trap states ultimately accelerate the rate and kinetics of emissive electron-hole recombination, setting a new cathodic electrochemiluminescence efficiency record of carbon nitrides, and empowering a visual electrochemiluminescence sensor for nitrite ion, a typical environmental contaminant, with superior detection range and limit. Differences in timescales of electron transfer reactions limit the efficiency of electrochemiluminescence. Here, the authors coordinate the timescales using shallow trap states in carbon nitride to achieve high efficiencies applied in nitrite sensing. [ABSTRACT FROM AUTHOR]

The prediction of porosity is a crucial task for metal based additive manufacturing techniques such as laser powder bed fusion. Short wave infrared thermography as an in-situ monitoring tool enables the measurement of the surface radiosity during the laser exposure. Based on the thermogram data, the thermal history of the component can be reconstructed which is closely related to the resulting mechanical properties and to the formation of porosity in the part. In this study, we present a novel framework for the local prediction of porosity based on extracted features from thermogram data. The framework consists of a data pre-processing workflow and a supervised deep learning classifier architecture. The data pre-processing workflow generates samples from thermogram feature data by including feature information from multiple subsequent layers. Thereby, the prediction of the occurrence of complex process phenomena such as keyhole pores is enabled. A custom convolutional neural network model is used for classification. The model is trained and tested on a dataset from thermographic in-situ monitoring of the manufacturing of an AISI 316L stainless steel test component. The impact of the pre-processing parameters and the local void distribution on the classification performance is studied in detail. The presented model achieves an accuracy of 0.96 and an f1-Score of 0.86 for predicting keyhole porosity in small sub-volumes with a dimension of (700 × 700 × 50) µm3. Furthermore, we show that pre-processing parameters such as the porosity threshold for sample labeling and the number of included subsequent layers are influential for the model performance. Moreover, the model prediction is shown to be sensitive to local porosity changes although it is trained on binary labeled data that disregards the actual sample porosity. [ABSTRACT FROM AUTHOR]

Herein, a vertical T-shaped heterojunction tunnel field-effect transistor (TFET) structure is proposed. This paper explores the effect of the traps and noise on the electrical characteristics. TFET devices work on the principle of band-to-band tunneling (BTBT). In order to increase the BTBT rate, the proposed structure uses an InP/In0.47Ga0.53 as the heterojunction at the source. In addition, this structure has dual metal gates: gate 1 with a 4.3 eV work function and gate 2 with a 4.1 eV work function. The effect of noise on device performance is investigated in terms of the voltage noise spectral density (Svg) and current noise spectral density (Sid), and the noise spectral densities are compared in the presence of interface trap concentrations. Finally, the variation in noise density with frequency is examined. [ABSTRACT FROM AUTHOR]

The phenomenon of current–voltage hysteresis observed in perovskite-based optoelectronic devices is a critical issue that complicates the accurate assessment of device parameters, thereby impacting performance and applicability. Despite extensive research efforts aimed at deciphering the origins of hysteresis, its underlying causes remain a subject of considerable debate. By employing nanoscale investigations to elucidate the relationship between hysteresis and morphological characteristics, this study offers a detailed exploration of photocurrent–voltage hysteresis at the nanoscale within perovskite optoelectronic devices. Through the meticulous analysis of localized I–V curve arrays, our research identifies two principal hysteresis descriptors, uncovering a predominantly inverted hysteresis pattern in 87% of the locations examined. This pattern is primarily attributed to the energetic barrier encountered at the interface between the probe and the perovskite material. Our findings underscore the pronounced heterogeneity and grain-dependent variability inherent in hysteresis behavior, evidenced by an average Hysteresis Index value of 0.24. The investigation suggests that the localized hysteresis phenomena cannot be exclusively attributed to either photocharge collection processes or organic cation migration at grain boundaries. Instead, it appears significantly influenced by localized surface trap states, which play a pivotal role in modulating electron and hole current dynamics. By identifying the key factors contributing to hysteresis, such as localized surface trap states and their influence on electron and hole current dynamics, our findings pave the way for targeted strategies to mitigate these effects. This includes the development of novel materials and device architectures designed to minimize energy barriers and enhance charge carrier mobility, thereby improving device performance and longevity. This breakthrough in understanding the microscale mechanisms of hysteresis underscores the critical importance of surface/interface defect trap passivation in mitigating hysteretic effects, offering new pathways for enhancing the performance of perovskite solar cells. [ABSTRACT FROM AUTHOR]

In the high friction limit, the initial works of the diffusion–reaction system utilising the one-dimensional Smoluchowski equation have been largely explored by a perfect trap term and a relevant system potential. The fast electronic relaxation process in a polar solvent can best be understood using the perfect sink model. The exact dynamics, however, are only available when the trap is placed in the harmonic potential centre. To solve the model equation for the arbitrary placement of the trap, here we have proposed a fresh, slightly uncommon approach. Additionally, we gave exact results to a recently investigated linear confined-type potential for the perfect trap placed arbitrarily. When the trap is positioned at an uphill location relative to the initial distribution, notable non-monotonic effects of the decay properties have been identified for the variation of potential strength. [ABSTRACT FROM AUTHOR]

In this study, electron beam evaporated tungsten oxide (WO3) thin film (TF) has been investigated for both capacitive and resistive switching memory devices. The fabricated samples underwent annealing at a temperature of 500 °C. Capacitance–voltage (C–V) and conductance–voltage were found to decrease with the increase in frequency for both the as-depo and annealed Au/WO3 TF/Si devices. The decrease in the interface trap density (Dit) from 1.27 × 1011 eV−1 cm−2 (as-depo WO3 TF) to 1.81 × 1010 eV−1 cm−2 (annealed WO3 TF) was attributed to the reduced number of defects. A large memory window of 9.76 V at ± 10 V was exhibited for annealed WO3 TF in the C–V hysteresis loop. A stable high resistance state and low resistance state were obtained for the annealed device up to 105 s without any distinct deterioration. The effects of crystallization are comprehensively explored to explicate the alteration in the resistive switching characteristics and its fundamental mechanism. The observed alterations in resistive switching behavior have been attributed to the processes of charge-trapping de-trapping and the migration of oxygen vacancies within the film. Our work offers insights into the charge-trapping mechanisms in WO3 TF-based nonvolatile memory devices, highlighting the impact of annealing on their performance. [ABSTRACT FROM AUTHOR]

The present work reports fabrication of polyaniline (PANI)-porous silicon (PS) heterostructure obtained by PANI coating on PS using vacuum coating deposition technique. Electrical properties are studied through the measurement of current (I)–voltage (V) characteristics. Some parameters (viz. ideality factor, barrier height, series resistance) are calculated from the I-V plots. Fitting of these curves is done with the thermionic emission (TE) and Cheung's method. It is found that Cheung's method provides better knowledge about the heterostructure in terms of series resistance. The heterostructure comes out as an electrically active material with minimal series resistance of 23.53 kΩ resulting high-driven electric current. The I–V of the heterostructure follows space charge limited conduction (SCLC) mechanism due to the presence of traps or imperfection in the heterostructure. Prior to electrical measurement the device is characterized through field emission scanning electron microscope (FESEM), UV–vis–NIR reflectance, photoluminescence (PL) and Raman spectra for morphological and optical properties. FESEM shows the modified PS structure after PANI deposition revealing short-chained PANI molecules due to thermal treatment. UV–vis-NIR shows lower reflectance of the heterostructure due to impregnation of PANI to the pores of PS resulting change in refractive index. PANI-PS shows quenched PL peak. Raman spectra complement the FESEM results. [ABSTRACT FROM AUTHOR]

Organic solar cell (OSC) devices suffer from low power conversion efficiency (PCE) due to deep trap states that absorb photogenerated charges, act as recombination centers, and reduce charge collection. To further improve the PCE, an optimized hole transport layer (HTL) must be engineered for efficient hole transport and reduced deep trap states. A hybrid HTL consisting of organic and inorganic materials was formed using a combination of CuO nanoparticles (NPs) having an average size of 50 nm and poly(3-hexylthiophene) (P3HT). The hybrid HTL was used in the fabrication and characterization of an inverted OSC device structure. In consequence, the incorporation of CuO-NPs into the P3HT resulted in an increase of 8.66% in photocurrent density. Additionally, the PCE increased from 3.77 to 4.22% while the open circuit voltage (Voc) was maintained. The higher hole mobility obtained for the optimum device using the charge extraction by increasing voltage (CELIV) measurement was 8.47 × 10− 4 cm2 V− 1 s− 1. This highlights the potential of designing novel organic solar cells with inorganic nanoparticles, offering enhanced performance and efficiency. [ABSTRACT FROM AUTHOR]

Since the launch of the Fermi mission in 2008, it has become possible to study high-energy solar γ -rays with an unprecedented imaging capability. In particular, the position of the > 100 MeV γ -ray source can shed light on the origin of high-energy protons that is still controversial. However, the imaging of solar γ -ray sources with the Fermi Large Area Telescope (LAT) is a complex multi-stage process influenced by a number of factors and instrumental effects, which is difficult to fully comprehend a priori. The SOL2014-09-01 behind-the-limb event was significant, for which the γ -ray source position was not firmly established at once. Following the methodology outlined by the Fermi/LAT team, we estimated the proton power-law indices and γ -ray centroid positions at two temporal intervals of this event, separated by one hour. Our estimates for the first interval are comparable to estimates recently updated by the Fermi/LAT team, thereby confirming the consistency of the analysis applied. Although, in the second interval, corresponding to the decay phase of the flare, the proton power-law index clearly hardened, the presumable position of the fading γ -ray source remained unchanged. Its constancy in both temporal intervals and its proximity to the bases of long coronal loops connected to the flare site support the flare origin of high-energy protons injected into these loops along with electrons and trapped there for a long time. Our experience analyzing Fermi/LAT data clarifies their complex handling and will hopefully benefit the solar community in their wider use. [ABSTRACT FROM AUTHOR]

In this work, the concentric structure of MIS tunnel diodes with coupling effect was explored for memory application. The thickness of the charge storage layer (Al2O3/SiO2) and annealing temperature were controlled to result in an efficient charge trapping with electrons from the substrate. This led to a significant reduction in operation time. In addition, it was found that the signal of non-uniform charge trapping at the device edge could be amplified (about three times) in the tunneling current of nearby MIS TD through the coupling effect. This phenomenon was initially observed and subsequently validated through TCAD simulation. Utilizing the coupling effect and the non-uniform charge storage, the proposed device's operating window is 1 V, with an on/off ratio of approximately 100. Furthermore, it exhibits small cycle-to-cycle variation (3%) and low power consumption. [ABSTRACT FROM AUTHOR]

The physical unclonable functions (PUFs) are novel cryptographic primitives in modern hardware security systems. Compared with traditional alternatives based on digital keys and non-volatile memory (NVM), the PUF system shows great unclonability, high efficiency, and physical attack resilience. However, the conventional PUF design suffers from weak machine learning immunity, high storage overhead, and unreliability, making it difficult to implement in the Internet of Things (IoT) and edge computing applications. This paper presents a new PUF design that could solve the proposed obstacles. By utilizing the emission probability of traps commonly found in nano-scaled transistors, a model-based PUF system with strong machine learning resistance could be achieved. This PUF design, called Prob-PUF, needs fewer challenge-response pairs (CRPs) space and reveals superior resistance to modeling attacks due to the mixture of stable/random bits in its output response. Moreover, the Prob-PUF system could reach a high level of uniqueness and robustness, making it a potential candidate for future cryptographically secured protocols within the IoT. [ABSTRACT FROM AUTHOR]

Silicon oxide based and aluminum gated MOS structures fabricated on n-type silicon are investigated after irradiation with low energy electrons in scanning electron microscope. The thermally stimulated current (TSC) technique in the temperature range from 80 K to 320 K revealed a number of the electron beam induced charge traps. With the help of the capacitance-voltage method, the traps revealed by the TSC were identified by their location (within dielectric, semiconductor or at the interface) and by their nature (trap for electrons or for holes). [ABSTRACT FROM AUTHOR]

The features of hydrogen trapping under the irradiation of zirconium alloys E110 and E635 with an electron beam (400 eV, 0.8 mA/cm2) in various gaseous ambient containing oxygen and hydrogen (Ar + O2 + H2; Ar + H2O) are studied. The effect of surface temperature on the hydrogenation of zirconium alloys under electron irradiation is studied. It is shown that neither exposure nor electron irradiation in a gaseous ambient containing a mixture of H2 and O2 at 700 K for 20 h leads to a change in the hydrogen level in the E110 alloy, while hydrogen partially escapes from the E635 alloy during the experiment. The amount of hydrogen in zirconium alloys after exposure in a gaseous ambient containing H2O in a similar temperature–time regime also changes insignificantly; however, if the alloys are irradiated with electrons under these conditions, then they contain 1.5–2 times more hydrogen. When temperature of the samples is raised to 900 K, electron irradiation in the presence of water vapor, on the contrary, reduces the trapping of hydrogen in the E110 and E635 alloys, compared with exposure in the same gaseous ambient without irradiation. It is concluded that electron irradiation affects the balance of surface reactions of formation of hydroxyl groups from adsorbed water molecules and reverse reactions of formation of water molecules from surface hydroxyls. The direction of shifting the balance of these reactions depends on the surface temperature. [ABSTRACT FROM AUTHOR]

The relativistic self-trapping of a laser pulse is an efficient mechanism for the acceleration of electrons, which allows one to achieve an extreme charge of a high-energy particle beam and the corresponding conversion coefficient of laser energy. It has been shown that the compression of the femtosecond laser pulse in this regime using the innovative compression after compressor approach (CafCA) [E.A. Khazanov, S.Yu. Mironov, and G. Mourou, Phys. Usp. 62, 1096 (2019)] to extremely short durations keeping the energy of the laser beam significantly increases the efficiency of particle acceleration. This effect has been illustrated on the example of the Multitera laser facility for the project implemented at the Russian National Center for Physics and Mathematics. [ABSTRACT FROM AUTHOR]

Conventional spectroscopies are not sufficiently selective to comprehensively understand the behaviour of trapped carriers in perovskite solar cells, particularly under their working conditions. Here we use infrared optical activation spectroscopy (i.e., pump-push-photocurrent), to observe the properties and real-time dynamics of trapped carriers within operando perovskite solar cells. We compare behaviour differences of trapped holes in pristine and surface-passivated FA0.99Cs0.01PbI3 devices using a combination of quasi-steady-state and nanosecond time-resolved pump-push-photocurrent, as well as kinetic and drift-diffusion models. We find a two-step trap-filling process: the rapid filling (~10 ns) of low-density traps in the bulk of perovskite, followed by the slower filling (~100 ns) of high-density traps at the perovskite/hole transport material interface. Surface passivation by n-octylammonium iodide dramatically reduces the number of trap states (~50 times), improving the device performance substantially. Moreover, the activation energy (~280 meV) of the dominant hole traps remains similar with and without surface passivation. Conventional spectroscopic techniques are not sufficiently selective to follow the dynamics of trapped carriers in working perovskite solar cells. Here, authors use infrared optical activation spectroscopy to observe real time evolution of trapped carriers and compare the behaviour of trapped holes. [ABSTRACT FROM AUTHOR]

In this research, we investigate the integrability properties of the Schamel–Korteweg–de Vries (S-KdV) equation, which is important for understanding the effect of electron trapping in the nonlinear interaction of ion-acoustic waves. Using the optimal system, we come over reduced ordinary differential equations (ODEs). To deal with reduced ODEs for this problem, Lie symmetry analysis is combined with the modified auxiliary equation (MAE) procedure and the generalized Jacobi elliptic function expansion (JEF) method. The analytical solutions reported here are novel and have a wide range of applications in mathematical physics. [ABSTRACT FROM AUTHOR]

Photonic synaptic transistors are being investigated for their potential applications in neuromorphic computing and artificial vision systems. Recently, a method for establishing a synaptic effect by preventing the recombination of electron–hole pairs by forming an energy barrier with a double-layer consisting of a channel and a light absorption layer has shown effective results. We report a triple-layer device created by coating a novel electron-trapping layer between the light-absorption layer and the gate-insulating layer. Compared to the conventional double-layer photonic synaptic structure, our triple-layer device significantly reduces the recombination rate, resulting in improved performance in terms of the output photocurrent and memory characteristics. Furthermore, our photonic synaptic transistor possesses excellent synaptic properties, such as paired-pulse facilitation (PPF), short-term potentiation (STP), and long-term potentiation (LTP), and demonstrates a good response to a low operating voltage of − 0.1 mV. The low power consumption experiment shows a very low energy consumption of 0.01375 fJ per spike. These findings suggest a way to improve the performance of future neuromorphic devices and artificial vision systems. [ABSTRACT FROM AUTHOR]

Confinement time of electron plasmas trapped using a purely toroidal magnetic field has been found to exceed 100 s in a small aspect ratio ( R o / a ∼ 1.59 , R o and a are device major and minor radius, respectively), partial torus. It improves upon the previously reported confinement time by nearly two orders of magnitude. Lifetime is estimated from the frequency scaling of the linear diocotron mode launched from sections of the wall, that are also used for mode diagnostics. Confinement improves as neutral pressures are reduced to < 5 × 10 - 10 mbar in the presence of a steady state magnetic field of 200 Gauss ( ∼ 60 s with droop < 0.1 % ) at 100 V electron injection energies. With reduced pressures the role of (ion driven) instability diminishes and loss mechanisms resulting from elastic electron–neutral (e–n) and the ubiquitous electron–electron (e–e) scattering seem to play an important role which suggests low electron temperatures. The contribution to electron population resulting from the ionization of background neutral gas at these temperatures and pressures are expected to be insignificant and is corroborated in our experiments. [ABSTRACT FROM AUTHOR]

The fabrication of a cadmium sulfide (CdS) thin film has been carried out by the chemical bath deposition method under two different conditions, namely, without UV light (nonexposed) and with UV light (exposed). The thin films were found to be uniform, smooth, and homogenous under both growth conditions. Structural and microstructural studies were carried out to understand the mechanism of thin-film growth. Under both conditions, the CdS thin film was found to be face-centered cubic structured. The UV light-exposed CdS thin film acquired acicular or flower-like over structures embedded in the continuous thin film of CdS. The optical band gap increased for the UV light-exposed CdS thin film. In addition, the dark and light currents also increased around 6 times for the UV light-exposed thin film compared to the nonexposed UV light thin films. The highest photosensitivity for the nonexposed and exposed UV light CdS thin film device was ~ 200% and 230%, respectively. A decrease in the photocurrent was detected and probed as a result of traps and the recombination of electrons and holes. Our findings suggest that photoexcitation during chemical reactions could be used as an effective tool to modulate the growth process and, in turn, to tune the optoelectrical properties. [ABSTRACT FROM AUTHOR]

Conjugated polymers offer flexible and lightweight solar cells devices which are fabricated via cost-effective solution processing techniques; however, these devices suffer from lower efficiency and short-term lifespan. To improve the efficiency and stability of device, the knowledge of the mechanism of the sun light absorption, dissociation of excitons into the free electron-hole pair and their transport to the collecting electrodes are essential. Herein, the impact of PCBM concentrations on photophysical and optical and properties of PTB7 were investigated by spectroscopic ellipsometer and fluorescence spectroscopy. It was noticed that with increase of PCBM concentrations, the dielectric constant (εr) and refractive index (n) of PTB7 thin films decreases which ascribed to the reduction of electric polarization and increase of the surface roughness. The emission intensity was noted to be dropped and charge carrier lifetime decreases for PTB7:PCBM bulkhetrojucntion as compared to pristine PTB7, confirms the charge transfer between donor and acceptor. The charge transport mechanism in PTB7 thin film was investigated in hole only device architecture by recording the temperature-dependent current-density vs. voltage (J–V) curves. The charge transport for the temperatures above 220 K was governed by the trap-free space charge limited (SCL) conduction described by Mott-Gurney square law and switched to the trap-filling SCL conduction for T ≤ 220 K. For the temperature 220 K, the trap density Hb, hole mobility µ and characteristics trap depth Et were evaluated to be 2.98 × 1017 cm−3, µ = 6.08 × 10−5 cm2 V−1 s−1and 25 meV, respectively. [ABSTRACT FROM AUTHOR]

To solve the problem of water pollution, using environment friendly and cost effective method in short time is the need of hour. In this work, chromium (Cr) and nitrogen (N) co-doped TiO2 nanoparticles were synthesized and were used for the photocatalytic degradation of dyes under visible light. The synergistic effect of metal and non-metal co-dopants added would result in appropriate reduction of band gap {from 3.2 eV of TiO2 to 2.67 eV}, decrease in recombination rate of charge carriers by trapping electrons and holes, and in better light harvesting capacity. Nanoparticles were synthesized by sol–gel method and characterized using ultraviolet–visible (UV–VIS) spectroscopy, fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), zeta potential, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, field emission scanning electron microscopy (FE-SEM), and RAMAN spectroscopy. Eosin yellow (EY) and rose bengal (RB) were subjected to photocatalytic degradation under solar light to check the photocatalytic activity of the synthesized nanoparticles. Effects of dye concentration, the concentration of nanoparticles, time, and pH were investigated to optimize the parameters. The results obtained were remarkable for 20 ppm EY solution took 10 min using 1 gL−1 NPs at pH 3 and 10 ppm RB solution took 5 min using 0.75 gL−1 NPs at pH 5.78 (original pH) for complete degradation. Kinetics studies were also performed and both dyes followed pseudo-second-order kinetics with R2 values 0.99312 and 0.99712 for EY and RB, respectively. The study of degraded products was conducted using high-performance liquid chromatography (HPLC) hyphenated with electron spray ionization mass spectroscopy (ESI–MS) (LC–MS) and possible degradation pathways were made for both dyes. A reusability test was also performed showing the efficiency of the particles was up to 88% after 3 cycles of use. These notable results can be attributed to the efficient removal of organic pollutants using the proposed dopants in this study. [ABSTRACT FROM AUTHOR]

Electron capture into the mode of synchronous gyromagnetic autoresonance in a combined mirror-type magnetic trap with a high-frequency field in a cylindrical resonator is studied. The averaged equations of motion of electrons in such a trap are obtained taking into account the terms of the first order of smallness in the high-frequency field amplitude. An equation for the resonant phase, which has the form of an equation for a nonlinear oscillator with a constant force, is derived to change the magnetic field with time according to a linear law in a weakly relativistic approximation. Based on the analysis of its solutions, a general criterion for the electron capture into the gyromagnetic autoresonance mode is obtained. Using the Bogolyubov method, the change in the energy of particles is studied, taking into account the time dependence of the parameters of the combined trap. It is shown that during autoresonance, the change in the electron energy with time occurs synchronously with the change in the magnetic field. [ABSTRACT FROM AUTHOR]

The initial operation of a light-emitting electrochemical cell (LEC) constitutes the in-situ formation of a p–n junction doping structure in the active material by electrochemical doping. It has been firmly established that the spatial position of the emissive p–n junction in the interelectrode gap has a profound influence on the LEC performance because of exciton quenching and microcavity effects. Hence, practical strategies for a control of the position of the p–n junction in LEC devices are highly desired. Here, we introduce a "chemical pre-doping" approach for the rational shifting of the p–n junction for improved performance. Specifically, we demonstrate, by combined experiments and simulations, that the addition of a strong chemical reductant termed "reduced benzyl viologen" to a common active-material ink during LEC fabrication results in a filling of deep electron traps and an associated shifting of the emissive p–n junction from the center of the active material towards the positive anode. We finally demonstrate that this chemical pre-doping approach can improve the emission efficiency and stability of a common LEC device. [ABSTRACT FROM AUTHOR]

Deep-level transient spectroscopy (DLTS) is a widely used method to analyze the properties of deep defects in semiconductors. However, it has been rarely reported to measure the deep-levels of highly-doped silicon because the large leakage current badly affects the transient capacitance signal of DLTS technique, due to the trap occupancy dominated by thermal emission instead of capture of carriers. Herein, by employing an asymmetric structure to reduce leakage current, we observed two deep-level defect states of highly phosphorus-doped silicon (7 × 1017 cm−3) in the DLTS spectrum, corresponding to the E-center (vacancy-P trap) and doubly negative charged states. Furthermore, the photocurrent spectrum of the sample under 4 K shows two mid-infrared response peaks, arising from the photoexcitation behavior of the above two defects. This finding provides a new route to measure the deep-level defect properties of highly-doped semiconductor materials using DLTS method. It also suggests potential applications of photoexcitation activity of defects in photoelectric detection. [ABSTRACT FROM AUTHOR]

Solid-state perovskite solar cells are increasingly being studied for their relatively low material processing cost, high solar absorption coefficient, and promising power conversion efficiency. However, the major hurdles preventing commercialization of these devices, typically consisting of a perovskite light absorber sandwiched between electron and hole transporting layers, are poor stability and scalability that are intrinsically linked to issues with the solid construction of the cells including ion migration, charge trapping and accumulation, and defect density and energy level mismatch. To potentially resolve the above-mentioned issue and explore an alternative to solid-state perovskite solar cells, in this paper, we studied a liquid-junction perovskite solar cell that employs electrochemically active redox species as both the charge transport materials and efficient energy media to achieve simultaneous energy generation and storage. Specifically, nonaqueous redox couples (i.e., Fc+/Fc and BQ/BQ⋅‒) dissolved in a low-dielectric-constant solvent have been attempted to fully encapsulate and stabilize the perovskite. We explored different perovskite photoelectrode fabrication processes, electrode construction, and cell parameters to further improve the photoelectrochemical performance. We conclude that the prior development in the great wealth of solid-state perovskite solar cell literature can be conveniently adopted to the design and optimization of the photoelectrochemical energy storage cell. [ABSTRACT FROM AUTHOR]

The present work investigates the charge storage behaviors of the silicon nitride charge trapping (CT) films. Herein, the silicon nitride has been synthesized by a new green deep eutectic solvent (DES) for the first time. The nitride films with a new chemical route are deposited on silicon (Si) substrate using a homemade and cost-effective spin coating method (SCM). X-ray diffraction and scanning electron microscopy have been performed to study the crystallographic and surface morphological properties of the fabricated silicon nitride films. The deposited silicon nitride thin films confirm polycrystalline nature. It is revealed that the silicon nitride films using the DES can be developed efficiently on the Si substrate by the SCM at nearly room temperature. In this work, the charge storage properties of the prepared spin-coated silicon nitride-based metal–insulator-semiconductor (MIS) memory device of Ag/silicon nitride/p-silicon/Ag are also explored by quantifying the current–voltage (I–V) and capacitance–voltage (C–V) characteristics. The flat-band potentials of the MIS capacitor having the nitride film with two-layer cycle deposition are estimated to be 0.043 V and 0.22 V for 1st and 2nd scans, respectively. The large flat-band potentials of 0.79 V for 1st scan and 1.60 V for 2nd scan are estimated, respectively, for the MIS capacitor with six-layer deposition. The positive flat-band potential is owing to the trapped electrons by trap centers located in the fabricated silicon nitride CT films. Therefore, it is suggested that the silicon nitride films fabricated by an inexpensive and efficient SCM at low (nearly room) temperature can be employed as a CT layer in the memory cell. [ABSTRACT FROM AUTHOR]

High recombination of the photoexcited electron–hole pairs leading to a drop in the photocatalytic performance. The pore of activated carbon (AC) can be act as a trap of the charge of electron/hole (e/h) which can suppress recombination. The objective in this study maximizing function of the pore of AC for create composite combine with TiO2 that can act in visible light. In the pore, the reaction occurs between the charge and the H2O or O2 produces OH* radicals. These radicals entering the chemical site of pollution to break up the bonding with the final product are harmless. The prepared composite TiO2/activated carbon (TAC) by wet impregnation method were characterized by X-ray diffraction, Fourier-transform infrared, and ultraviolet–visible spectroscopy. Composite TAC with ratio 0.5:1.5, 1:1, 1.5:0.5 shows degradation 94.06%, 94.91%, and 88.98%, respectively, for only 45 min irradiation, indicated that the pore successfully suppressing recombination of the charge. We have performed good efficiency for five adsorption–desorption cycles of TAC. The TAC 1:1 ratio shows the best photocatalyst performance which degraded 94.91% for 45 min irradiation. The composite TAC shows high potential in suppressing recombination of charge, means that, effective and efficient ground wastewater treatment materials in future for improvement human access to the clean water. [ABSTRACT FROM AUTHOR]

To alleviate the energy and environmental crisis, in the last decades, energy harvesting by utilizing optical control has emerged as a promising solution. Here we report a polar crystal that exhibits photoenergy conversion and energy storage upon light irradiation. The polar crystal consists of dinuclear [CoGa] molecules, which are oriented in a uniform direction inside the crystal lattice. Irradiation with green light induces a directional intramolecular electron transfer from the ligand to a low-spin CoIII centre, and the resultant light-induced high-spin CoII excited state is trapped at low temperature, realizing energy storage. Additionally, electric current release is observed during relaxation from the trapped light-induced metastable state to the ground state, because the intramolecular electron transfer in the relaxation process is accompanied with macroscopic polarization switching at the single-crystal level. It demonstrates that energy storage and conversion to electrical energy is realized in the [CoGa] crystals, which is different from typical polar pyroelectric compounds that exhibit the conversion of thermal energy into electricity. Energy harvesting by utilizing optical control has emerged as a promising solution to alleviate energy and environmental crisis. However, it is challenging to realise nano-scale energy storage and conversion in the same material. Here the authors report a nonferroelectric molecular [CoGa] crystal that uses light as an external stimulus to exhibit photoenergy conversion and energy storage properties. [ABSTRACT FROM AUTHOR]

In this work, the effects of the substrate material on the electrical properties of self-assembled InAs quantum dots (QDs)-based laser structures have been reported. Two InAs QD laser structures with the same active regions deposited on GaAs and Si substrates utilizing strain reducing layer (SRL) containing GaAs/InGaAs have been investigated using current–voltage (I–V), capacitance–voltage, and Deep-Level Transient Spectroscopy (DLTS) techniques. The I–V measurements illustrated that the rectification ratio (IF/IR) and built-in potential (ϕB) for the sample deposited on Si substrate are higher than that of sample deposited on GaAs substrate. However, the series resistance (Rs) of the InAs QDs deposited on Si substrate is lower than that of the InAs QDs deposited on GaAs substrate. The DLTS and Laplace-DLTS measurements showed that the number of traps in InAs QDs/GaAs devices is lower than that in InAs QDs/Si devices, corroborating with I–V results. [ABSTRACT FROM AUTHOR]

Studies on modeling the charge distribution in semiconductor nanoparticles are analyzed. The charge distribution largely depends on the type of nanoparticles and the concentration of conduction electrons. In the case of nanoparticles with a high content of electrons in the conduction band, the negatively charged layer plays an important role. The conductivity and sensor effect depend on this layer. It is shown that both the distribution of electrons and the sensor effect differ significantly in one- and two-component systems. The reasons for this difference are discussed. [ABSTRACT FROM AUTHOR]

Experimental temperature dependences (77–293 K) of absorption and photoluminescence spectra of CdSe/ZnS semiconductor quantum dots (QDs) were analyzed based on modern models of exciton–phonon coupling. It was proven that the first excitonic transition absorption band formed with participation primarily of optical phonons of the CdSe core while the photoluminescence properties reflected the interaction of the ZnS layer with optical phonons. Photoluminescence quenching for CdSe/ZnS QDs of various diameters upon formation of nanoassemblies with porphyrin molecules was analyzed in the framework of a quantum-mechanical model. It was shown that the quenching rate constant decreased with increasing QD diameter and that the quenching process under quantum confinement conditions was due to the electron of an excited electron–hole pair tunneling onto the QD surface with subsequent localization on surface traps. [ABSTRACT FROM AUTHOR]

Novel cotton-based TiO2/Ag/TiO2 nanocomposites for wastewater treatment were developed by fine chemical synthesis path with the goal of coping with wastewater issues and environmental remediation. The photocatalytic performances of nanocomposites were tested during photodegradation processes of RB, AO7 and MR under simulated solar light. Double- and single-loaded nanocomposites were synthesized by a simple bottom-up approach implying in situ photoreduction of Ag+ ions on the surface of TiO2 NPs previously deposited on cotton fibers from colloids. The spherical-like colloidal TiO2 NPs (4.5 nm) and TiO2/Ag NPs (8 nm) and the formation of uniform TiO2/Ag and TiO2/Ag/TiO2 nano-coatings on cotton fibers were examined by TEM and FESEM. The reduction of Ag+ ions on TiO2 surface was undoubtedly proven by the appearance of SPR band of Ag NPs in UV/Vis spectra. Raman spectroscopy clearly confirmed the presence of anatase TiO2 in nanocomposites. Quantitative determination of TiO2 and Ag in nanocomposites was accomplished using EDX and ICP–OES. The cotton-based TiO2/Ag/TiO2 nanocomposite showed the highest photocatalytic efficiency (> 90%) and maintained its removal efficiency after three reuse cycles, indicated its exceptional photochemical ability. The initial idea of improved photocatalytic performances of a TiO2 NPs double-layer with immobilized Ag NPs was justified as the TiO2/Ag/TiO2 processed sample contributed additional binding sites for dye molecules. Considering that the photocatalytic activity of the cotton-based TiO2 and TiO2/Ag samples was practically imperceptible, it can be assumed that the synthesized Ag NPs act predominantly as electron traps in the double-loaded synthesized system. [ABSTRACT FROM AUTHOR]

Organic field-effect transistors (OFETs) with polymer charge-trapping dielectric, which exhibit many advantages over Si-based memory devices such as low cost, light weight, and flexibility, still suffer challenges in practical application due to the unsatisfied endurance characteristics and even the lack of fundamental of behind mechanism. Here, we revealed that the degradation of endurance characteristics of pentacene OFET with poly(2-vinyl naphthalene) (PVN) as charge-storage layer is dominated by the deep hole-traps in PVN by using the photo-stimulated charge de-trapping technique with the fiber-coupled monochromatic-light probes. The depth distribution of hole-traps in PVN film of pentacene OFET is also provided. [ABSTRACT FROM AUTHOR]

Quantum computing promises exponential speed-up compared to its classical counterpart. While the neutral atom processors are the pioneering platform in terms of scalability, the dipolar Rydberg gates impose the main bottlenecks on the scaling of these devices. This article presents an alternative scheme for neutral atom quantum processing, based on the Fermi scattering of a Rydberg electron from ground-state atoms in spin-dependent lattice geometries. Instead of relying on Rydberg pair-potentials, the interaction is controlled by engineering the electron cloud of a sole Rydberg atom. The present scheme addresses the scaling obstacles in Rydberg processors by exponentially suppressing the population of short-lived states and by operating in ultra-dense atomic lattices. The restoring forces in molecule type Rydberg-Fermi potential preserve the trapping over a long interaction period. Furthermore, the proposed scheme mitigates different competing infidelity criteria, eliminates unwanted cross-talks, and significantly suppresses the operation depth in running complicated quantum algorithms. Current Rydberg quantum processors suffer from limitations in fidelity and scalability. Here, the authors address these limitations by proposing highly controllable multi-qubit operations that utilize the Fermi scattering of Rydberg electrons trapped in an optical lattice. [ABSTRACT FROM AUTHOR]

A new type of poly(methyl methacrylate) nanocomposite containing TiO2/Ag (TiO2–Ag/PMMA) at low dosage of nanoparticles was prepared by microemulsion method for the first time. To investigate effect of Ag nanoparticles on the photodegradation efficiency, the nanocomposites with various TiO2:Ag molar ratios were prepared by direct in situ synthesis of Ag nanoparticles in W/O microemulsion. The fabricated nanocomposites were characterized by DRS, TEM, and XPS techniques. The TEM characterization results indicated that the TiO2/Ag nanoparticles were well dispersed in the polymer framework with an average size of 15 nm. The formation of Ag0 decorated on the surface of TiO2 nanoparticles, acted as both a plasmonic sensitizer and an electron trap, verified with XPS analysis. The visible-light photocatalytic performance of the prepared nanocomposites was studied in degradation of acid blue 92 (AB92) dye, representative pollutant model, and compared with PMMA, TiO2/PMMA, and Ag/PMMA as control samples. Effect of TiO2:Ag molar ratios, pH, and reusability on the photodegradation efficiency of pollutant model has been studied. [ABSTRACT FROM AUTHOR]

The need for high-performance gas sensors is driven by concerns over indoor and outdoor air quality, and industrial gas leaks. Due to their structural diversity, vast surface area, and geometric tunability, metal oxides show significant potential for the development of gas sensing systems. Despite the fact that several previous reports have successfully acquired a suitable response to various types of target gases, it remains difficult to maintain the reliability of metal oxide-based gas sensors. In particular, the degradation of the sensor platform under repetitive operation, such as off-state stress (OSS) causes significant reliability issues. We investigate the impact of OSS on the gas sensing performances, including response, low-frequency noise, and signal-to-noise ratio of horizontal floating-gate field-effect-transistor (FET)-type gas sensors. The 1/f noise is increased after the OSS is applied to the sensor because the gate oxide is damaged by hot holes. Therefore, the SNR of the sensor is degraded by the OSS. We applied a self-curing method based on a PN-junction forward current at the body–drain junction to repair the damaged gate oxide and improve the reliability of the sensor. It has been demonstrated that the SNR degradation caused by the OSS can be successfully recovered by the self-curing method. [ABSTRACT FROM AUTHOR]

The consumption of non-renewable energy resources, such as fossil fuels, coal, etc., has widely increased due to the increase in population; before it goes out of the world, alternating renewable energy resources will replace it. One of the renewable energy resources is thin film I-III-VI2 semiconductor photovoltaic cells. In this work, AgInGaS2 thin films are investigated, and their applications in photovoltaic cells are attempted. On ITO conducting glass substrates, AgInGaS2 films are deposited by pulse electrodeposition technique at various duty cycles. AgIn0.9Ga0.1S2 films deposited at 6, 15, 33, and 50% duty cycles exhibit an X-ray diffraction (XRD) pattern. The strain, crystal size, and dislocation density were estimated from X-ray diffraction patterns. According to EDAX investigations, Ag, In, Ga, and S have peaked. In the XPS spectra, there were peaks for Ag-3d3/2 and 3d5/2, In-3d5/2 and 3d3/2, Ga-2p1/2 and 2p3/2, and S-2p1/2 and 2p3/2. The band gap of the deposited material was determined to be in the range of 1.95 – 2.08 eV. The film's surface roughness was measured using atomic force microscopy and found to be 0.6 nm. The carrier concentration at room temperature is 0.11 × 1017 (cm−3), the mobility is 23.6 cm2V−1 s−1, and the resistivity is 23.7Ω cm. After the 70 s photo etching, the power output characteristics show a Voc of 0.64 V, Jsc of 15.00 mA cm−2, ff of 0.65, and η of 10.40% for 60 mW cm−2 illumination. The nature of the plot and the capacitance–voltage measurements obtained indicated p-type behaviour. [ABSTRACT FROM AUTHOR]

Exploration of low-sulfidation epithermal Au deposits is expected to increase because these deposits are economically competitive and globally occurring as well as produce low environmental load via underground mining. Drilling is the main exploration tool for identifying mineralized zones in three dimensions; however, selecting drill targets is a major technical challenge in exploration work. This challenge can be addressed by effectively employing our conceptual model of a "cold-water trap," an ore-deposition mechanism induced by cold groundwater in shallow aquifer. In two previous case studies on low-sulfidation epithermal deposits, this mechanism was verified via geological modeling and numerical simulations, and potential mineralized zones were three-dimensionally confirmed in undrilled areas. Here, we methodize the utilization of numerical simulations for epithermal Au exploration and prepare the operational guidelines for a new exploration method. In this method, the trapping scenario can be modified to explore deposits generated by incomplete cold-water trapping. Because this method functions effectively from the time at which the necessary data for geological modeling are obtained, it is adapted to operate over the time of drill exploration. Furthermore, the proposed method can be adapted to brownfield explorations, such as around the existing deposits. Sensitivity analysis revealed permeability to be the most important parameter for the numerical simulation. Analyzing drill cores with respect to fracture properties such as width and density as well as the extent of the hydrothermal alteration halo is crucial for the accurate estimation of permeability. [ABSTRACT FROM AUTHOR]

For the first time, NiO and Ag–Cd co-doped NiO CdxAg0.30Ni0.70−xO (X = 0.0, 0.05, 0.10, and 0.15) have been synthesized through a facile sol–gel method to investigate the photocatalytic performance by visible-light-driven degradation of rhodamine B dye for wastewater treatment. All samples were characterized through X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray, Fourier transform infrared, photoluminescence, and ultraviolet–visible spectroscopy for structural, morphological, elemental, functional groups, optical, and bandgap analysis, respectively. Face-centered cubic structure of NiO was confirmed through X-ray diffraction. The formation of NiO and Ag–Cd co-doped NiO nanoparticles was confirmed through elemental and functional groups analysis. Optical properties obtained from photoluminescence spectroscopy revealed visible-light emission spectrum and slower electron/hole pair recombination rate with an increase in doping. Minimum optical bandgap energy of 2.37 eV was found for the Cd0.15Ag0.30Ni0.55O sample. Photocatalytic performance study revealed that degradation followed first-order kinetics. Cd0.15Ag0.30Ni0.55O was the best sample which showed the maximum efficiency of 97%, the reaction rate constant K (min−1) of 0.0496, and the correlation coefficient (R2) of 0.988 after 140-min degradation of rhodamine B dye. The reusability and stability of the best sample were checked for six cycles by obtaining an X-ray diffraction pattern after the photocatalytic process. [ABSTRACT FROM AUTHOR]

On-site and on-demand photocatalytic methane conversion under ambient conditions is one of the urgent global challenges for the sustainable use of ubiquitous methane resources. However, the lack of microscopic knowledge on its reaction mechanism prevents the development of engineering strategies for methane photocatalysis. Combining real-time mass spectrometry and operando infrared absorption spectroscopy with ab initio molecular dynamics simulations, here we report key molecular-level insights into photocatalytic green utilization of methane. Activation of the robust C–H bond of methane is hardly induced by the direct interaction with photogenerated holes trapped at the surface of photocatalyst; instead, the C–H activation is significantly promoted by the photoactivated interfacial water species. The interfacial water hydrates and properly stabilizes hydrocarbon radical intermediates, thereby suppressing their overstabilization. Owing to these water-assisted effects, the photocatalytic conversion rates of methane under wet conditions are dramatically improved by typically more than 30 times at ambient temperatures (~300 K) and pressures (~1 atm) in comparison to those under dry conditions. This study sheds new light on the role of interfacial water and provides a firm basis for design strategies for non-thermal heterogeneous catalysis of methane under ambient conditions. Photocatalytic methane conversion under ambient conditions holds immense promise for sustainable use of methane resources, but incomplete knowledge of reaction mechanisms hampers the development of engineering strategies for methane photocatalysis. Here, combining real-time mass spectrometry and operando infrared absorption spectroscopy with ab initio molecular dynamics simulations, the authors explore the role of interfacial water in C–H activation during the photocatalytic conversion of methane. [ABSTRACT FROM AUTHOR]

COVID-19-led antibiotic waste generated from hospitals and health centres may cause serious health issues and significantly impact the environment. In the coming decades, antibiotic resistance will be one of the most significant threats to global human health. Photocatalytic water remediation is an effective and promising environmental solution that can be utilized to address this issue, to convert antibiotic waste into non-toxic products by utilizing renewable and abundant solar energy. In the present study, a novel nanocomposite of zeolitic imidazolate frameworks (ZIF-8) and molybdenum diselenide (MoSe2) was efficiently synthesized by the solvothermal method for the complete degradation of the antibiotics and textile waste from water. The morphology, crystallinity and band gap of the samples were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and UV–visible spectroscopy. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) provide the binding information of the sample. The photocatalytic activity was tested for degradation of the antibiotics (tetracycline hydrochloride (TC) and metronidazole (MNZ)) used in COVID-19 treatment and textile dye (malachite green). Time-resolved photoluminescence spectroscopy confirmed the enhanced charge separation in the MoSe2@ZIF-8 nanocomposite with an average lifetime of 4.72 ns as compared to pristine samples. The nanocomposite showed ~ 100% removal efficiency with rate constants of 63 × 10−3, 49 × 10−3 and 42 × 10−3 min−1 for TC, MNZ and malachite green, respectively. The photocatalytic degradation of TC was carried out under different pH conditions (4, 7 and 9), and the degradation mechanism was explained on the basis of zeta potential measurements and active species trapping experiment. The by-products of the photocatalytic treatment of TC antibiotics were tested using liquid chromatography-mass spectroscopy (LC–MS), and they were found to be non-toxic for aquatic and human life. The regeneration property of the nanocomposite was confirmed by FESEM with regeneration efficiency of 88.7% in the 4th cycle. Thus, MoSe2@ZIF-8-based photocatalysts have potential application in water remediation, especially in making the antibiotic waste less toxic. [ABSTRACT FROM AUTHOR]

In this work, a CuxS/GO composite hole transport layer is prepared on the surface of TiO2/CuInS2 photo-electrodes to modulate the charge transfer efficiency of quantum dot-sensitized solar cells. The normalized PL intensity of TiO2/CuInS2 photo-electrodes had been obviously quenched with the as-prepared CuxS/GO composite hole transport layer, which had exhibited excellent charge separation properties of the solar cells. Due to the reduce of charge recombination traps under CuxS/GO composite hole transport layer, the charge transfer efficiency of the solar cells had been effectively improved. As a result, the higher Voc, FF and Jsc value can be obtained for TiO2/CuInS2 quantum dot sensitized solar cells with this CuxS/GO composite hole transport layer, which had exhibited the photovoltaic conversion efficiency enhancement from 4.85% to 6.07%. [ABSTRACT FROM AUTHOR]

The lack of electron donors prevents the effective degradation of azo dyes by bacteria, which severely limits the practical application of conventional biological treatment. Herein, we innovatively designed a bio-photoelectric reduction degradation system composed of CdS and Shewanella decolorationis, which could effectively degrade amaranth in anaerobic conditions driven by light when electron donors were unavailable. Compared with bare S. decolorationis and S. decolorationis (heat-killed)-CdS biohybrid, S. decolorationis-CdS biohybrid had 39.36-fold and 3.82-fold higher first-order kinetic constants, respectively. The morphology, particle size, elemental composition, crystalline type, photovoltaic properties, and band structure of the nanoparticles synthesized by S. decolorationis were carefully examined and analyzed. Light-driven biodegradation experiments showed that amaranth was degraded by the synergy of CdS and S. decolorationis. Reductive degradation of amaranth by electrons was demonstrated by electron and hole trapping. The effect of potential coexisting contaminants, which might serve as hole scavengers, on the degradation of amaranth was evaluated. Membrane protein inhibition experiments also suggested that NADH dehydrogenase, menaquinone, and cytochrome P450 played an important role in electron transfer between CdS and Shewanella decolorationis. The cyclic conversion of NAD+/NADH was probably the most critical rate-limiting step. Electrochemical measurements suggested that faster electron transfer might facilitate the degradation of amaranth. Our findings might contribute to the degradation of azo dyes in wastewater lacking electron donors and deepen our recognition of the microbe-material interface. Key points: • A BPRDS was constructed with Shewanella decolorationis and CdS. • Amaranth was effectively degraded by BPRDS in anaerobic conditions driven by light. • NDH, MQ, and CYP450 were involved in electron transfer. [ABSTRACT FROM AUTHOR]

In this work, an attempt to augment the photocatalytic dye degrading ability of zinc oxide thin films by suitably doping strontium + molybdenum(Sr + Mo). The ZnO:Sr:Mo film were coated onto glass substrates via automatic nebulizer spray pyrolysis method. The photocatalytic studies were done by degrading two dyes viz methyl orange (MO) and methylene blue (MB) and the efficiency of the prepared films was tested at different pH levels. A 97% and 84% decomposition are observed for MB and MO dyes, respectively, in 60 min. The kinetics and reusability of the catalyst were studied. The results indicated that the catalysts exhibit considerable reusability and high photocatalytic efficiency. A possible mechanism for the improved degradation has been elaborated with the support of characterization studies. [ABSTRACT FROM AUTHOR]