Cs2 AgBiCl6 : a Novel, High-Efficient and Stable Visible-Light Photocatalyst for Degradation of Organic Dyes.

In the past decades, great efforts have been made to develop novel visible-light photocatalysts to achieve high photocatalytic efficiency by utilizing visible light, the largest proportion of solar energy. As a new type of photocatalyst materials, all-inorganic lead-free halide double perovskites have begun to attract widespread interest. Herein, double perovskite Cs2 AgBiCl6 was developed into a visible-light photocatalyst for degrading organic dyes. Cs2 AgBiCl6 was prepared by the hydrochloric acid precipitation and anti-solvent recrystallization methods, respectively, and was used to degrade organic dyes under visible light. Samples prepared by the anti-solvent recrystallization method are smaller than those prepared by the hydrochloric acid precipitation method, which can degrade 95.7 % of Sudan III in 10 min and show excellent photocatalytic activity. The cyclic experiments demonstrate that Cs2 AgBiCl6 has a good cycle stability. Moreover, Cs2 AgBiCl6 -AS also exhibits good photocatalytic degradation ability for Methyl red and Malachite green. These distinctive results indicate that Cs2 AgBiCl6 may be a promising material for developing novel, high-efficient and stable visible-light photocatalysts.

Polycrystalline Few-Layer Graphene as a Durable Anticorrosion Film for Copper.

Corrosion of metals in atmospheric environments is a worldwide problem in industry and daily life. Traditional anticorrosion methods including sacrificial anodes or protective coatings have performance limitations. Here, we report atomically thin, polycrystalline few-layer graphene (FLG) grown by chemical vapor deposition as a long-term protective coating film for copper (Cu). A six-year old, FLG-protected Cu is visually shiny and detailed material characterizations capture no sign of oxidation. The success of the durable anticorrosion film depends on the misalignment of grain boundaries between adjacent graphene layers. Theoretical calculations further found that corrosive molecules always encounter extremely high energy barrier when diffusing through the FLG layers. Therefore, the FLG is able to prevent the corrosive molecules from reaching the underlying Cu surface. This work highlights the interesting structures of polycrystalline FLG and sheds insight into the atomically thin coatings for various applications.

Mixed-dimensional Te/CdS van der Waals heterojunction for self-powered broadband photodetector.

The 2D layered crystals can physically integrate with other non-2D components through van der Waals (vdW) interaction, forming mixed-dimensional heterostructures. As a new elemental 2D material, tellurium (Te) has attracted intense recent interest for high room-temperature mobility, excellent air-stability, and the easiness of scalable synthesis. To date, the Te is still in its research infancy, and optoelectronics with low-power consumption are less reported. Motivated by this, we report the fabrication of a mixed-dimensional vdW photodiode using 2D Te and 1D CdS nanobelt in this study. The heterojunction exhibits excellent self-powered photosensing performance and a broad response spectrum up to short-wave infrared. Under 520 nm wavelength, a high responsivity of 98 mA W-1is obtained at zero bias with an external quantum efficiency of 23%. Accordingly, the photo-to-dark current ratio and specific detectivity reach 9.2 × 103and 1.9 × 1011Jones due to the suppressed dark current. This study demonstrates the promising applications of Te/CdS vdW heterostructure in high-performance photodetectors. Besides, such a mixed-dimensional integration strategy paves a new way for device design, thus expanding the research scope for 2D Te-based optoelectronics.

High-performance MoS2/Si heterojunction broadband photodetectors from deep ultraviolet to near infrared.

Polycrystalline 2D layered molybdenum disulfide (MoS2) films were synthesized via a thermal decomposition method. The MoS2/Si heterostructures were constructed in situ by synthesis MoS2 on plane Si substrates. Such MoS2/Si heterostructures exhibited high sensitivity to light illumination with wavelengths ranging from the deep ultraviolet to the near infrared. Photoresponse analysis reveals that a high responsivity of 23.1 A/W, a specific detectivity of 1.63×1012 Jones, and a fast response speed of 21.6/65.5 µs were achieved. Notably, the MoS2/Si heterojunction photodetector could operate with excellent stability and repeatability over a wide frequency range up to 150 kHz. The high performance could be attributed to the high-quality heterojunction between MoS2 and Si obtained by the in situ fabrication process. Such high performance with broadband response suggests that MoS2/Si heterostructures could have great potential in optoelectronic applications.

Construction of MoS2/Si nanowire array heterojunction for ultrahigh-sensitivity gas sensor.

Few-layer MoS2 thin films were synthesized by a two-step thermal decomposition process. In addition, MoS2/Si nanowire array (SiNWA) heterojunctions exhibiting excellent gas sensing properties were constructed and investigated. Further analysis reveals that such MoS2/SiNWA heterojunction devices are highly sensitive to nitric oxide (NO) gas under reverse voltages at room temperature (RT). The gas sensor demonstrated a minimum detection limit of 10 ppb, which represents the lowest value obtained for MoS2-based sensors, as well as an ultrahigh response of 3518% (50 ppm NO, ∼50% RH), with good repeatability and selectivity of the MoS2/SiNWA heterojunction. The sensing mechanisms were also discussed. The performance of the MoS2/SiNWA heterojunction gas sensors is superior to previous results, revealing that they have great potential in applications relating to highly sensitive gas sensors.

Clinical characteristics and analysis of vestibular-evoked myogenic potentials in patients with sudden sensorineural hearing loss in different ages.

BACKGROUND: Numerous studies have found that patients experiencing sudden sensorineural hearing loss (SSHL), with or without accompanying vertigo, often show impaired vestibular function. However, there is a dearth of studies analyzing vestibular-evoked myogenic potentials (VEMPs) in SSHL patients across various age groups. AIM: To investigate vestibular condition in SSHL patients across various age demographics. METHODS: Clinical data of 84 SSHL patients were investigated retrospectively. Audiometry, cervical vestibular evoked myogenic potentials (c-VEMPs), and ocular vestibular evoked myogenic potentials (o-VEMPs) were conducted on these patients. Parameters assessed included the latencies of P1 and N1 waves, as well as the amplitudes of P1-N1 waves. Moreover, the study evaluated the influence of factors such as sex, affected side, configuration of hearing loss, and presence of accompanying vertigo. RESULTS: Among the 84 SSHL patients, no significant differences were observed among the three groups in terms of gender, affected side, and the presence or absence of vertigo. Group II (aged 41-60 years) had the highest number of SSHL cases. The rates of absent o-VEMPs in the affected ears were 20.83%, 31.58%, and 22.72% for the three age groups, respectively, with no statistically significant difference among them. The rates of absent c-VEMPs in the affected ears were 8.3%, 34.21%, and 18.18% for the three age groups, respectively, with significant differences. In the unaffected ears, there were differences observed in the extraction rates of o-VEMPs in the unaffected ears among the age groups. In the three age groups, no significant differences were noted in the three age groups in the latencies of P1 and N1 waves or in the amplitude of N1-P1 waves for c-VEMPs and o-VEMPs, either on the affected side or on the unaffected side, across the three age groups. CONCLUSION: The extraction rate of VEMPs is more valuable than parameters. Regardless of the presence of vertigo, vestibular organs are involved in SSHL. Notably, SSHL patients aged 41-60 appear more susceptible to damage to the inferior vestibular nerve and saccule.

Deep-blue narrow-band emissive cesium europium bromide perovskite nanocrystals with record high emission efficiency for wide-color-gamut backlight displays.

Lead halide perovskite nanocrystals (NCs) are highly promising for backlighting display applications due to their high photoluminescence quantum yields (PLQYs) and wide color gamut values. However, the practical applications of blue emitters are limited due to the toxicity of lead, unstable structure, and unsatisfactory PLQY. Herein, we report the successful synthesis of divalent europium-based perovskite CsEuBr3 NCs using a modified hot injection method. By optimizing the reaction conditions, the CsEuBr3 NCs display a deep-blue emission at 443 nm with a full width at half maximum (FWHM) of 28.5 nm, a color purity of 99.61%, and a record high PLQY of 93.51% for deep-blue narrow-band emissive lead-free perovskite NCs as far as we know. The emission mechanism of CsEuBr3 NCs is proved through first-principles calculations and spectral analysis. Notably, the CsEuBr3 NCs exhibit remarkable stability when exposed to high temperature, UV irradiation, and long-term sealed storage. The incorporation of CsEuBr3 NCs into polydimethylsiloxane (PDMS) serving as a converter is utilized for white light-emitting devices (WLEDs). WLEDs for backlight displays achieves a wide color gamut of 127.1% of the National Television System Committee standard (NTSC), 94.9% coverage of the ITU-R Recommendation BT.2020 (Rec.2020), and their half-lifetime is up to 1677 h, providing a promising pathway for highly efficient, environment-friendly and practical liquid crystal display backlights.

Wafer-Scale Patterning Synthesis of Two-Dimensional WSe2 Layers by Direct Selenization for Highly Sensitive van der Waals Heterojunction Broadband Photodetectors.

Two-dimensional (2D) transition-metal dichalcogenides (TMDs) exhibit promising potential in fabricating highly sensitive photodetectors due to their unique electrical and optoelectrical characteristics. However, micron-sized 2D materials produced by conventional chemical vapor deposition (CVD) and mechanical exfoliation methods fail to satisfy the demands for applications in integrated optoelectronics and systems given their poor controllability and repeatability. Here, we propose a simple selenization approach to grow wafer-scale (2 in.) 2D p-WSe2 layers with high uniformity and customized patterns. Furthermore, a self-driven broadband photodetector with a p-WSe2/n-Si van der Waals heterojunction has been in situ fabricated with a satisfactory responsivity of 689.8 mA/W and a large specific detectivity of 1.59 × 1013 Jones covering from ultraviolet to short-wave infrared. In addition, a remarkable nanosecond response speed has been recorded under 0.5% duty cycle of the input light. The proposed selenization approach on the growth of 2D WSe2 layers demonstrates an effective route to fabricate highly sensitive broadband photodetectors used for integrated optoelectronic systems.

Polarity-Reversible Te/WSe2 van der Waals Heterodiode for a Logic Rectifier and Polarized Short-Wave Infrared Photodetector.

As a p-type elemental material with high carrier mobility, superior ambient stability, and anisotropic crystal structure, emerging two-dimensional (2D) tellurium (Te) has been considered a successor to black phosphorus for developing infrared-related optoelectronics. Nevertheless, the lack of a scalable thickness engineering strategy remains an obstacle to unleashing its full potential. Te-based electronics with logic functions are also less explored. Herein, we propose a novel wet-chemical thinning method for 2D Te, with the merits of scalability and site-specific thickness patterning capability. A polarity-switchable van der Waals (vdW) heterodiode with a high rectification ratio of 2.4 × 103 is realized on the basis of Te/WSe2. The electronic application of this unique characteristic is demonstrated by fabricating a logic half-wave rectifier, in which the rectifying states are switchable via electrostatic gating control. Besides, the narrow band gap of Te endows the device with a broad spectral response from visible to short-wave infrared. The room-temperature responsivity reaches 5.2 A W-1 at the telecom wavelength of 1.55 µm, with an external quantum efficiency of 420% and detectivity of 6.8 × 109 Jones. In particular, owing to the intrinsic in-plane anisotropy of Te, the device exhibits a favorable photocurrent anisotropic ratio of ∼3. Our study demonstrates the enormous potential of Te for novel electronics, promoting the development of elemental 2D materials.

Interface engineering of nickel Hydroxide-Molybdenum diselenide nanosheet heterostructure arrays for efficient alkaline hydrogen production.

The stacking of Molybdenum Diselenide (MoSe2) nanomaterials as well as its poor intrinsic conductivity lead to sluggish water dissociation kinetics, which limit the performance of the alkaline hydrogen evolution reaction (HER). Herein, we constructed Nickel Hydroxide Ni(OH)2-MoSe2 heterostructures directly on 3D self-supporting carbon cloth (CC) substrate via a simple hydrothermal and the subsequent chemical bath deposition process, then systemically studied the effect of the Ni(OH)2 deposition time on the HER performance. The synergistic effect between Ni(OH)2 and MoSe2 in the Ni(OH)2-MoSe2 heterostructures optimizes the poor conductivity and Gibbs free energy for water adsorption, thus improving the water dissociation kinetics and giving rise to fast electron transfer in the HER process. The Ni(OH)2-MoSe2/CC constructed in this way with a Ni(OH)2 deposition times of 30 min performs good catalytic activities with a low overpotential of 130 mV at -10 mA cm-2, a low Tafel slope of 78.2 mV dec-1 and good stability. Our results suggest that interface engineering combining with conductive substrate are conducive to enhance alkaline HER activity of MoSe2 and other similar transition metal dichalcogenides.

Highly-efficient and stable photocatalytic activity of lead-free Cs2AgInCl6 double perovskite for organic pollutant degradation.

Photocatalytic applications of halide perovskites have attracted increasing attention. However, lack of stability and lead toxicity of lead halide perovskites have hindered their applications. Metal halide double perovskite (DP) Cs2AgInCl6 is a stable, environment-friendly semiconductor with direct band gap, and then the best promising alternative to lead halide perovskites. Here, the applications of Cs2AgInCl6 DP to photocatalytic degradation of organic pollutants have been developed, in which the octahedral Cs2AgInCl6 DP particles (~3.33 eV) were prepared by precipitation from acid solutions. The as-prepared samples exhibit high photocatalytic activity, which can degrade about 98.5% of water-insoluble carcinogen Sudan Red III in only 16 min, and have a good stability for 5 cycle operations. Furthermore, the Cs2AgInCl6 DP also can degrade Rhodamine B, Methyl orange and Methyl red efficiently, demonstrating a highly-efficient and stable ethanol solvent-based photocatalytic system for organic pollutants degradation. The high photocatalytic activity could be attributed to direct band gap and long carrier lifetime of Cs2AgInCl6 DP. These unique features of Cs2AgInCl6 DP indicate that it could have a good application prospect for photocatalytic degradation of organic pollutants.

Fabrication of 2D PdSe2/3D CdTe Mixed-Dimensional van der Waals Heterojunction for Broadband Infrared Detection.

Room-temperature infrared photodetectors are in great demand because of their vitally important applications in the military and civilian fields, which has inspired intensive studies in recent decades. Here, we present the fabrication of a large-size PdSe2/CdTe mixed-dimensional van der Waals (vdW) heterojunction for room-temperature infrared detection. Taking advantage of the wide light absorption of the multilayer PdSe2, high-quality vdW interface, and unique mixed-dimensional device geometry, the present device is capable of detecting an ultrawide light up to long-wave infrared (LWIR) of 10.6 µm at room temperature. In addition, our photodetector exhibits a good capability to follow short pulse infrared signals with a quick response rate of 70 ns, a large responsivity of 324.7 mA/W, and a reasonable specific detectivity of 3.3 × 1012 Jones. Significantly, the assembled photodetector is highly sensitive to a polarized infrared light signal with a decent polarization sensitivity of 4.4. More importantly, an outstanding LWIR imaging capability based on the PdSe2/CdTe vdW heterojunction at nonrefrigeration condition is demonstrated. Our work paves a novel route for the design of highly polarization-sensitive, room-temperature infrared photodetectors.

Two-dimensional Ti3C2 MXene-based nanostructures for emerging optoelectronic applications.

Since the first discovery of Ti3C2 in 2011, two-dimensional (2D) transition-metal carbides, carbonitrides and nitrides, known as MXenes, have attracted significant attention. Due to their outstanding electronic, optical, mechanical, and thermal properties, versatile structures and surface chemistries, Ti3C2 MXenes have emerged as new candidates with great potential for applications in optoelectronic devices, such as photovoltaics, photodetectors and photoelectrochemical devices. The excellent metallic conductivity, high anisotropic carrier mobility, good structural and chemical stabilities, high optical transmittance, excellent mechanical strength, tunable work functions, and wide range of optical absorption properties of Ti3C2 MXene nanostructures are the key to their success in a number of electronic and photonic device applications. Herein, we summarize the fundamental properties and preparation of pure Ti3C2 MXenes, functionalized Ti3C2 MXenes and their hybrid nanocomposites, as well as their optoelectronic applications. In the end, the perspective and current challenges of Ti3C2 MXenes toward the development of advanced MXene-based nanostructures are briefly discussed for future optoelectronic applications.

Antisolvent-Processed One-Dimensional Ternary Rubidium Copper Bromine Microwires for Sensitive and Flexible Ultraviolet Photodetectors.

Recently, newly emerging halide perovskites have aroused intensive attention in photoelectric fields in virtue of their good properties, such as well-balanced carrier transport, large light absorption coefficient, tunable band gap, and low-temperature solution processing technique. Nevertheless, their future commercial development is severely hampered by lead toxicity and instability of such materials. In this work, one-dimensional Rb2CuBr3 single-crystal microwires (MWs) were prepared by antisolvent engineering, and they were further employed as absorbers to prepare sensitive ultraviolet (UV) photodetectors. The optical band gap of Rb2CuBr3 MWs is measured to be 3.83 eV, exhibiting an excellent UV absorption. The fabricated device demonstrates a remarkable UV light detection ability with a specific detectivity of 1.23 × 1011 Jones, responsivity of 113.64 mA W-1, and response speed of 69.31/87.55 ms under light illumination of 265 nm. Meanwhile, the proposed photodetector without any encapsulation shows outstanding stability and repeatability. After storing in ambient air for 2 weeks, the light detection ability remains basically unchanged. Further, a flexible photodetector was fabricated with the same structure, which demonstrates a remarkable bending endurance. These results confirm the great potential of Rb2CuBr3 for high-performance UV photodetectors, increasing the possibility for assembly of optoelectronic systems.

A defect-induced broadband photodetector based on WS2/pyramid Si 2D/3D mixed-dimensional heterojunction with a light confinement effect.

Broadband photodetection is of vital importance for both civil and technological applications. The widespread use of commercial photodiodes based on traditional semiconductors (e.g. GaN, Si, and InGaAs) is limited to the relatively narrow response range. In this work, we have demonstrated a self-driven and broadband photodetector based on WS2/pyramid Si 2D/3D mixed-dimensional van der Waals (vdW) heterojunction, which is assembled by directly transferring 2D WS2 film on 3D pyramid Si. Thanks to the enhanced light absorption with the pyramid Si structure, the defect-induced narrowed bandgap of the WS2 film, and high-quality vdW heterojunction, impressive device performances in terms of a large responsivity of 290 mA W-1, a high specific detectivity of up to 2.6 × 1014 Jones and an ultrabroad response spectrum ranging from 265 nm to 3.0 µm are achieved at zero bias. Importantly, the photodetector can function as an infrared imaging cell with a high spatial resolution. The totality of these excellent features confirms that the demonstrated WS2/pyramid Si 2D/3D mixed-dimensional vdW heterojunction device may hold great promise for applications in high-performance broadband infrared photodetection and imaging.

Recent advances toward environment-friendly photodetectors based on lead-free metal halide perovskites and perovskite derivatives.

Recently, metal-halide perovskites have emerged as promising materials for photodetector (PD) applications owing to their superior optoelectronic properties, such as ambipolar charge transport characteristics, high carrier mobility, and so on. In the past few years, rapid progress in lead-based perovskite PDs has been witnessed. However, the critical environmental instability and lead-toxicity seriously hinder their further applications and commercialization. Therefore, searching for environmentally stable and lead-free halide perovskites (LFHPs) to address the above hurdles is certainly a worthwhile subject. In this review, we present a comprehensive overview of currently explored LFHPs with an emphasis on their crystal structures, optoelectronic properties, synthesis and modification methods, as well as the PD applications. LFHPs are classified into four categories according to the replacement strategies of Pb2+, including AB(ii)X3, A3B(iii)2X9, A2B(i)B(iii)'X6, and newly-emerging perovskite derivatives. Then, we give a demonstration of the preliminary achievements and limitations in environment-friendly PDs based on such LFHPs and perovskite derivatives, and also discuss their applications in biological synapses, imaging, and X-ray detection. With the perspective of their properties and current challenges, we provide an outlook for future directions in this rapidly evolving field to achieve high-quality LFHPs and perovskite derivatives for a broader range of fundamental research and practical applications.

Highly Sensitive and Selective NiO/WO3 Composite Nanoparticles in Detecting H2S Biomarker of Halitosis.

Indirectly monitoring halitosis via the detection of hydrogen sulfide (H2S) biomarkers using gas sensors is a newly emerging technique. However, such H2S sensors are required with critically high selectivity and sensitivity, as well as a ppb-level detection limit, which remains technologically challenging. To address such issues, here, we have developed highly sensitive and selective H2S sensors with NiO/WO3 nanoparticles (NPs), which have been synthesized by firstly hydrolyzing WO3 NPs and subsequently decorating with NiO NPs in a hydrothermal process. Theoretically, the NiO/WO3 NPs assist in forming a thicker electron depletion layer, adsorbing more oxygen species O2- to oxidize H2S and finally release more electrons. Beneficially, 2.1 wt % NiO/WO3 NPs show high sensitivity to H2S (Ra/Rg = 15031 ± 1370 @ 10 ppm, 100 °C), which is 42.6-fold higher than that of the pristine WO3 NPs (Ra/Rg = 353 ± 5.6 @ 10 ppm, 100 °C). Further, the H2S sensor shows ppb-level detection limit (Ra/Rg = 4.95 ± 2.9 @ 0.05 ppm, 100 °C) and high selectivity. Practically, NiO/WO3 NP sensor prototype has been employed to detect the simulated exhaled halitosis compared with that of gas chromatography, revealing a close concentration of H2S. Our investigation offers an experimental base in future intelligent medical applications.

High Color-Rendering Index and Stable White Light-Emitting Diodes by Assembling Two Broadband Emissive Self-Trapped Excitons.

White light-emitting diodes (WLEDs) are promising next-generation solid-state light sources. However, the commercialization route for WLED production suffers from challenges in terms of insufficient color-rendering index (CRI), color instability, and incorporation of rare-earth elements. Herein, a new two-component strategy is developed by assembling two broadband emissive materials with self-trapped excitons (STEs) for high CRI and stable WLEDs. The strategy addresses effectively the challenging issues facing current WLEDs. Based on first-principles thermodynamic calculations, copper-based ternary halides composites, CsCu2 I3 @Cs3 Cu2 I5 , are synthesized by a facile one-step solution approach. The composites exhibit an ideal white-light emission with a cold/warm white-light tuning and a robust stability against heat, ultraviolet light, and environmental oxygen/moisture. A series of cold/warm tunable WLEDs is demonstrated with a maximum luminance of 145 cd m-2 and an external quantum efficiency of 0.15%, and a record high CRI of 91.6 is achieved, which is the highest value for lead-free WLEDs. Importantly, the fabricated device demonstrates an excellent operation stability in a continuous current mode, exhibiting a long half-lifetime of 238.5 min. The results promise the use of the hybrids of STEs-derived broadband emissive materials for high-performance WLEDs.

[Retroauricular teratoma with congenital microtia and ankylotia: a case report].

Teratoma is a germ cell tumor, which is rare behind the ear. We described a rare case of retroauricular teratoma accompanied with congenital malformation of external and middle ear and cholesteatoma of middle ear in a 13-years-old girl. Congenital microtia and ankylotia of right ear was found since childhood, suppuration occurred repeatedly behind the right ear 1 year ago. Temporal bone CT and MRI scan revealed congenital malformation of middle ear and cholesteatoma of middle ear. Cystic mass containing a tooth was found intraoperatively. The pathological results showed that it was benign cystic teratoma. It showed no evidence of recurrence on the patient during 3 months follow-up.

An ultrasensitive self-driven broadband photodetector based on a 2D-WS2/GaAs type-II Zener heterojunction.

High-performance broadband photodetectors have attracted extensive research interest because of their significance in optoelectronic applications. In this study, a highly sensitive room-temperature (RT) broadband photodetector composed of a WS2/GaAs type-II van der Waals heterojunction was demonstrated, which exhibited obvious photoresponse to broadband light illumination from 200 to 1550 nm beyond the limitation of the bandgaps. Impressive device performances were achieved in terms of a low noise current of ∼59.7 pA, a high responsivity up to 527 mA W-1, an ultrahigh Ilight/Idark ratio of 107, a large specific detectivity of 1.03 × 1014 Jones, a minimum detection light intensity of 17 nW cm-2 and an external quantum efficiency (EQE) up to 80%. Transient photoresponse measurements revealed that the present detector is capable of working at a high frequency with a 3 dB cutoff frequency up to 10 kHz and a corresponding rise/fall time of 21.8/49.6 µs. Notably, this heterojunction device demonstrated Zener tunneling behaviors with a threshold voltage of -4 V. The capacitance-voltage (C-V) properties of the heterojunction were investigated to understand the device performances. In addition, the as-fabricated device can function as an image sensor with an outstanding imaging capability. Considering the above superior features, the proposed WS2/GaAs type-II van der Waals heterojunction may find great potential in high-performance broadband photodetection applications.