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Metal nanonetworks fabricated by chemical plating of metals on electrospun polymer nanofiber network templates have come into the spotlight for use as flexible transparent electrodes. However, depositing continuous and smooth metal films on hydrophobic polymer nanofiber templates is difficult because of the Volmer–Weber growth of metals. This work reports a simple argon plasma treatment approach to increase the surface energy of the templates and achieve the formation of dense silver layers. Furthermore, instead of using external treatment methods that either require high energy injection or are incompatible with plastic substrates, a low-temperature Joule heat-assisted self-welding method is used to improve the conductivity of the solution-grown Ag nanofibers. Instantaneous Joule heat generated by a direct current can target the high-resistance interfaces formed between the Ag nanoparticles and at the grain boundaries, thus lowering the junction resistance and decreasing the interface scattering. The resulting Ag nanofiber networks exhibit high visible light transmittance of ∼91%, low sheet resistance of ∼5.4 Ω □−1, and good stretchability. These results offer valuable insight into the abilities of plasma treatment and Joule heating to modulate the metal film formation mode on polymer nanofiber surfaces. These interface engineering methods can be extended to the development of polycrystalline metal nanonetwork-based electronics.

Even though various theranostic agents have been exploited for effective cancer therapy over the years, appropriate design and fabrication of theranostic agents with simple composition, convenient preparation, high theranostic efficiency and minimal side effects on non-cancer cells are still urgently needed. Herein, multifunctional NaYF4:Yb,Er@polyelectrolyte (PE3)@Fe3O4 nanocomposites, with upconversion luminescence, superparamagnetism and photothermal performance, are prepared by a layer-by-layer self-assembly technique. Compared with Fe3O4 nanoparticles (NPs), the nanocomposites exhibited nearly 2-fold strong absorption at 808 nm, and thus resulted in an enhanced near-infrared photothermal effect. With the assistance of an external magnetic field, a high sensitivity of upconversion fluorescence imaging and a low cancer cell viability of 13.9% were achieved under 808 nm laser irradiation. It is expected that multifunctional NaYF4:Yb,Er@PE3@Fe3O4 nanocomposites would pave the way toward promoting the clinical applications of theranostic nanomaterials.

Holography is a feasible route to realize information encryption, which is crucial for the secure processing of massive data. However, the limited number of application channels in a coherent light field hinders advancement in holographic encryption. Herein, we design a serial coding system based on a plasmonic holographic disk utilizing both spin and orbital angular momenta of photons. Anisotropically photo-oxidized metal nanoparticles accurately distinguish the polarization state and topological charge of the vortex light field in holographic reconstruction. Ultra-stable readout of the encrypted holographic grating array is realized after coating a water-soluble polymer onto a large-area nanoparticle film. This work provides an important research strategy for integrated nanodevices for use in high-density memory, all-optical computing, and cryptographic displays.

Synergistic functionalization of interface coagulation stimulation and liquid absorption capacity is the key to improve the hemostatic efficiency of hemostats. Herein, we prepared a graphene-ophicalcite (OPH) heterogeneous composite sponge (GOCS) by using the heterogeneous gradient composite strategy. The sponge took cross-linked graphene sponge (CGS) as the main skeleton, allowing the OPH to be controllably positioned on the surface of GOCS. The heterogeneous strategy gave full play to the advantages of the material. On the one hand, GOCS had excellent liquid absorption ability, which enriched blood cells and other coagulation components at the wound interface after contacting blood. On the other hand, the OPH at the interface obviously activated platelets and rapidly triggered coagulation cascade reactions, exhibiting fast response and feedback characteristics for coagulation signals. Under the synergistic effects, the blood clotting index value of GOCS was reduced to 33.87 ± 9.97%, which was significantly lower than those of OPH (46.33 ± 16.85%) and CGS (67.53 ± 5.35%). Importantly, GOCS rapidly stopped bleeding within 51 s in the rat femoral artery model, suggesting its great potential in the field of hemostasis. Therefore, this study provides a new idea for the design and preparation of hemostatic materials via heterogeneous strategy.

Hybrid organic–inorganic perovskite, CH3NH3PbI3 (MAPbI3), has attracted great attention as promising building blocks for resistive switching memory. However, the reproductive switching uniformity a...

Efficient light harvesting is essential for advanced photonic devices. Complex micro/nano surface relief structures can be produced via light-triggered mechanical movement, but limited in organic active molecular units. In this Letter, we propose to embed noble-metal particles into light-inactive polyvinyl alcohol matrix to construct a light harvesting system driven by plasmon for inscription of surface relief gratings. Ultra-small-sized silver nuclei are generated in the polymer by pre-thermal treatment, acting as an accelerator for the subsequent photoinduced particle growth, hydrogen group cleavage, and matrix softening. Based on such properties, a complex plasmonic array carrying ultra-high-density information is achieved with peristrophic multiplexing holography. This Letter paves a bright way to realize data storage, information encryption, and optical microcavity.

A neuromorphic computing chip that can imitate the human brain’s ability to process multiple types of data simultaneously could fundamentally innovate and improve the von-neumann computer architecture, which has been criticized. Memristive devices are among the best hardware units for building neuromorphic intelligence systems due to the fact that they operate at an inherent low voltage, use multi-bit storage, and are cost-effective to manufacture. However, as a passive device, the memristor cell needs external energy to operate, resulting in high power consumption and complicated circuit structure. Recently, an emerging self-powered memristive system, which mainly consists of a memristor and an electric nanogenerator, had the potential to perfectly solve the above problems. It has attracted great interest due to the advantages of its power-free operations. In this review, we give a systematic description of self-powered memristive systems from storage to neuromorphic computing. The review also proves a perspective on the application of artificial intelligence with the self-powered memristive system.

Pectin nanofiber mats prepared with periodate oxidation–electrospinning–adipic acid dihydrazide crosslinking strategy are promising for biomedical applications. In this study, we systematically examined the effects of electrospinning and crosslinking conditions on the properties of pectin nanofiber mats. The properties of mats were tunable in the range of 200–400 nm fiber size, 11–21% ADH residue content, 13–28 times absorbency, 13°–21° contact angle, 2 weeks or longer degradation time, 1.5–2.2 MPa tensile strength, 40–70% elongation, and 0.25–0.27 g/(cm2·24 h) permeability. Increasing polymer concentration, adipic acid dihydrazide amount, time or temperature could increase fiber size and its tensile strength, and decrease the absorbency, hydrophilicity, degradation rate, and elongation. These results indicate that controlling the process parameters can effectively regulate the properties of pectin nanofiber mats and meet the requirements of various biomedical applications.

Broadband metamaterials absorbers with high absorption, ultrathin thickness and easy configurations are in great demand for many potential applications. In this paper, we first analyse the coupling resonances in a Ti/Ge/Ti three-layer absorber, which can realise broadband absorption from 8 to 12 μm. Then we experimentally demonstrate two types of absorbers based on the Ti/Ge/Si3N4/Ti configuration. By taking advantage of coupling surface plasmon resonances and intrinsic absorption of lossy material Si3N4, the average absorptions of two types of absorbers achieve almost 95% from 8 to 14 μm (experiment result: 78% from 6.5 to 13.5 μm). In order to expand the absorption bandwidth, we further propose two Ti/Si/SiO2/Ti absorbers which can absorb 92% and 87% of ultra-broadband light in the 14–30 μm and 8–30 μm spectral range, respectively. Our findings establish general and systematic strategies for guiding the design of metamaterial absorbers with excellent broadband absorption and pave the way for enhancing the optical performance in applications of infrared thermal emitters, imaging and photodetectors., Ultra-broadband metamaterials absorbers with high absorption, ultrathin thickness and easy configurations are designed and demonstrated, which pave the way for enhancing the optical performance in applications of infrared thermal emitters, imaging and photodetectors.

Organic thin‐film transistors (OTFTs) are identified to be the most promising candidate for next‐generation wearable and implantable electronics because of their unique advantages including their flexibility, low cost, long‐term biocompatibility, and simple packaging. However, commercialization of organic transistors remains an enormous challenge due to their low mobility and lack of scalable strategy for high‐precise soft devices. Here, a novel photolithography fabrication strategy is proposed, which is completely compatible with various commercial organic semiconductor materials, for the first demonstration of the fully photolithographic top‐contact conformable OTFTs with the device density as high as 1523 transistors cm−2. Excellent electrical and mechanical properties with device yield as high as 100%, field‐effect mobility up to 1–2 cm2 V−1 s−1, and outstanding conformability are shown. This work provides a new strategy that can fully maximize the advantages of organic materials and photolithography technology, showing a great prospect in the development of high‐performance, high‐precise organic devices toward the commercialized and industrialized soft electronic products., A novel photolithography strategy that is completely “compatible with” various commercial organic semiconductor materials is proposed for the first demonstration of the fully photolithographic top‐contact organic thin‐film transistors (OTFTs). This strategy offers a general and facile route to incorporate photolithography technology into organic electronics, and presents potential for developing skin‐like soft electronic devices with high device density and high performance.

International audience; A squeezing Carboniferous formation was met at a depth of 300 m during the excavation of the Saint-Martin-la-Porte access gallery (SMP2) in France within the Lyon-Turin railway link project. Large, time-dependent and anisotropic deformation was observed around the tunnel wall during and after excavation, and difficulties related to tunneling in squeezing ground have been encountered. An anisotropic visco-elastic plastic constitutive law (Tran- Manh et al. 2015) has been proposed in order to model the ground behavior. This model was validated by field auscultation carried out in SMP2. As a part of the base tunnel, a new survey gallery (SMP4) began to be excavated in the recent years across the same squeezing rock formation at a depth of about 600 m. A yield control support system was adopted in the zones of large deformation, which contains highly deformable concrete elements to stabilize the high convergence (Bonini and Barla 2012). In the present work, the studies of SMP2 are extended to SMP4 by considering the constitutive model developed for SMP2. The innovative excavation and support method is taken into account. Numerical modeling is performed using FLAC3D to analyze the tunnel response. A good agreement can be obtained between the field measurements and the numerical results.

Surface electron traps on semiconductor photoanodes mediate surface recombination and deteriorate the photoelectrochemical (PEC) water oxidation performance of the photoanode. Developing convenient methods to reduce surface electron traps is therefore essential for high efficiency PEC water oxidation on semiconductor photoanodes, particularly for nanostructured photoanodes with large surface area. Herein, we employ a O2 plasma treatment to boost the PEC water oxidation performance of Ti-doped Fe2O3 (Ti-Fe2O3) nanowires photoanodes, aiming to reduce surface oxygen vacancies, the dominant electron traps on Ti-Fe2O3 surface. X-ray diffraction (XRD), scanning electron microscopy and spectroscopic analyses show that the oxygen plasma treatment changes the structural, morphological and optical properties negligibly, but it does reduce the content of surface oxygen vacancies, as estimated from O1s X-ray photoelectron spectroscopy spectra. An optimal O2 plasma treatment (200 W, 70 s) increases the photocurrent density of the Ti-Fe2O3 nanowire photoanode to 2.14 mA·cm−2 (1.23 V vs. RHE) under air mass 1.5G simulated solar light, which is 1.95 times higher than the pristine Ti-Fe2O3 nanowire photoanode. The surface hole transfer efficiency is also improved by 1.66 times due to the reduced surface recombination. The work suggests that O2 plasma treatment is a convenient but effective method to boost the PEC water oxidation performance of Ti-Fe2O3 photoanode and might be applicable to other semiconducting oxide photoanodes for high efficiency PEC water splitting.

Fabrication process, optical setup, diffraction kinetics, TEM and AFM images

Contribution - The acquisition of analytical competencies is a desirable outcome of a technical graduate program. We present a process to align the program curriculum with an industry-standard to ensure those competencies. The result is not necessarily to create certified students (although that is certainly desirable) but to confirm that the program helps students acquire the analytical competencies as outlined in an industry standard. We describe a path for alignment of programs to develop these desirable competencies and our experience with the process. Background - We selected the INFORMS Certified Analytics Professional certification as a vendor-neutral book of knowledge and knowledge structure for analytics professionals and a well-developed credential in the profession. We used well-documented processes to align a university curriculum to industry needs, employed in aligning similar programs to such competencies as a project manager using the PMI PMP certification. Research questions - To align the curriculum to the INFORMS CAP, we asked: (1) whether students graduating from the program had acquired adequate analytical competencies; and (2) If they had not, how can the curriculum be modified to help gain those competencies. Methods - The curriculum was reviewed, and we assured initially that topical coverage of the pertinent course of study aligned adequately with the INFORMS CAP knowledge structure. Results - Using the existing curriculum, we found that a majority of the students could pass the INFORMS CAP certification practice exam at the end of their program of study. The exam results were sufficiently granular to modify the curriculum and course contents to improve future assessments’ passing rate.

The authors report an indium tin oxide (ITO) decorated solar-blind deep ultraviolet photodetectors (PDs) based on high quality β-Ga2O3 single crystal microwires (MWs). An ultrahigh photo-to-dark current (I photo/I dark) ratio ∼107 of the PDs has been realized. Compared with In/β-Ga2O3/In metal-semiconductor-mental (MSM) PD, the device with ITO as the interlayers between In and β-Ga2O3 show excellent performances, such as the high responsivity of 1720.2 A W−1 and 438.8 A W−1 under 260 nm illumination with reverse and forward bias, respectively. In addition, the device exhibited a very low dark current as low as 2.0 × 10−13 A and a photocurrent up to 1.0 × 10−6 A at the bias of −6 V (under 1.95 mW cm−1@260 nm). The rise and fall time of the device were 0.5 s and 0.2 s, which was significantly faster than MSM structure. Moreover, the device exhibited an ultrahigh solar-blind/visible rejection ratio (R 260 nm/R 400 nm) of 1.09 × 105, a detectivity D* of 1.23 × 1014 Jones and the external quantum efficiency of 4180.3%. The excellent performances of the PDs are attributed to the improved carrier separating process at the ITO/β-Ga2O3 interfaces and the reduced carrier trapping behavior induced by the β-Ga2O3 surface states. The introduction of ITO between MWs and the electrodes is of great significance for the application of β-Ga2O3 based detectors.

A polarization sorting metamaterial with polarization filtering and absorption is proposed. When unpolarized incident light strikes the metamaterial, one polarization component is completely absorbed, and the other polarization component is completely transmitted. We achieved an absorption extinction ratio of up to 350 and a transmission extinction ratio of 425 simultaneously in the LWIR. Unlike the 50% energy utilization limit of other polarization absorbers due to the complete reflection of another polarization component, our proposed metamaterial can be composed of layered polarization selective absorption devices to achieve more than 90% energy utilization. Therefore our design can provide a new solution for real-time polarization detection.

Mimicking Pavlovian conditioning by memristive synapse is significant to implement neuromorphic computing at the hardware level. In this work, we demonstrated the Pavlovian conditioning based on the artificial synapse architecture of one-transistor/one-resistor (1T1R), which included an AgInSbTe/α-C-based memristor as a variable resistance and an N-MOS transistor. Thanks to stable resistance switching behavior of memristor and outstanding controllability of device conductance by transistor gating of 1T1R, the experimental demonstration of the acquisition and extinction of Pavlovian conditioning were realized. Moreover, the temporal relation between the conditioned and unconditioned stimuli was also established in which the memory time of associative learning decreased with the increase in the interval of two stimuli. This work provided an idea to biorealistically mimic the Pavlovian conditioning, paving the way for memristive neuromorphic computing.

Silver composites with an inhomogeneous structure have been designed and prepared through spark plasma sintering (SPS) with carbon nanotubes reinforced Cu foams (CNTs/Cuf) as the reinforcing 3-dimentional skeletons. The composites simultaneously exhibit enhanced strength, good ductility and high conductivity, with the ultimate tensile strength (UTS) of 198.8 MPa, the fracture elongation of 38.5% and electrical conductivity of 98.53% IACS, respectively. After subsequent heat treatments, diffusion layers have formed with the thickness of about 10 μm at the interface between skeletons and the silver matrix, causing further improvements of the UTS and slight reduction of the ductility and conductivity. The structures, properties and possible mechanisms of the composites are studied and discussed in this paper.

Pressure/proximity sensing as the essential function of electronic skin (e-skin) has become an emerging technological goal for new-generation electronic devices in a wide variety of application fields, for example, smart electronics, human-machine interaction, and prosthetics. However, the current research lacks pressure/proximity detection of the stretched e-skin, which ignores the key elastic characteristic of skin and hinders the development of e-skin. Here, the pressure/proximity detection of the transparent e-skin in the stretching state is demonstrated based on poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)/single-walled carbon nanotube (SWCNT). The high transparency of the e-skin realizes the visual imperception for wearable electronic systems. The perfect combination of stretchable SWCNT and highly conductive PEDOT:PSS endows the sensors with high stretchability and high discrimination capability toward strain, providing an effective way to overcome the interference of strain to realize accurate pressure/proximity detection of stretched e-skin at different strains.

Gas sensors based on polymer field-effect transistors (FETs) have drawn much attention owing to the inherent merits of specific selectivity, low cost, and room temperature operation. Ultrathin (10 nm) and porous polymer semiconductor films offer a golden opportunity for achieving high-performance gas sensors. However, wafer-scale fabrication of such high-quality polymer films is of great challenge and has rarely been realized before. Herein, the first demonstration of 4 in. wafer-scale, cobweb-like, and ultrathin porous polymer films is reported via a one-step phase-inversion process. This approach is extremely simple and universal for constructing various ultrathin porous polymer semiconductor films. Thanks to the abundant pores, ultrathin size, and high charge-transfer efficiency of the prepared polymer films, our gas sensors exhibit many superior advantages, including ultrahigh response (2.46 × 10

The poor water resistance of the eletrospun hyaluronic acid (HA) nanofibers prevents their biomedical applications. In this manuscript, we crosslinked HA nanofibers with the periodate oxidation − adipic acid dihydrazide (ADH) crosslinking strategy. Quantification results showed that ∼ 57 % of aldehydes in oxidized HA were crosslinked by ADH and the crosslinking density could reach 75.7 %. Correspondingly, the crosslinked HA nanofiber mats exhibited wet tensile strength up to 0.88 MPa and could maintain their nanofibrous morphology after 14 days in simulated body fluid. Although ∼ 28 % of the aldehydes in oxidized HA were unreacted, the crosslinked HA nanofibers did not cause toxicity to L929 fibroblast cells, possibly because that the unreacted aldehyde groups were linked on macromolecular fragments and could not go across cell membranes. The water resistant and biocompatible HA nanofibers are expected to seek extensive applications in biomedical fields such as wound healing, adhesion prevention, and tissue engineering.

An all-carbon memristive synapse is highly desirable for hardware implementation in future wearable neuromorphic computing systems. Graphene oxide (GO) can exhibit resistive switching (RS) and may be a feasible candidate to achieve this objective. However, the digital-type RS often occurring in GO-based memristors restricts the biorealistic emulation of synaptic functions. Here, an all-carbon memristive synapse with analog-type RS behavior was demonstrated through photoreduction of GO and N-doped carbon quantum dot (NCQD) nanocomposites. Ultraviolet light irradiation induced the local reduction of GO near the NCQDs, therefore forming multiple weak conductive filaments and demonstrating analog RS with a continuous conductance change. This analog RS enabled the close emulation of several essential synaptic plasticity behaviors; more importantly, the high linearity of the conductance change also facilitated the implementation of pattern recognition with high accuracy. Furthermore, the all-carbon memristive synapse can be transferred onto diverse substrates, showing good flexibility and 3D conformality. Memristive potentiation/depression was stably performed at 450 K, indicating the resistance of the synapse to high temperature. The photoreduction method provides a new path for the fabrication of all-carbon memristive synapses, which supports the development of wearable neuromorphic electronics. A graphene-based device can help computer chips behave more like human brains by transmitting current across thread-like wires. Neural synapses store memories by accessing different types of conductive states. Chinese researchers led by Haiyang Xu at Northeast Normal University in Changchun and Zhenhui Kang at Soochow University in Suzhou now demonstrate that graphene sheets with different conductivity levels—caused by adding or removing oxygen atoms—can also exhibit synapse-like behavior. The team developed a carbon-nitrogen composite to sandwich between two graphene electrodes with high and low levels of conductivity. Exposing the composite to ultraviolet light created numerous tiny filaments between the electrodes that physically restrict electron flow and provide gradual smooth transitions between the graphene electrodes’ two conductive states. The organic framework of this device also provides inherent flexibility for wearable devices. All-carbon memristive synapse is built through photo-reduction of a nanocomposite comprised of graphene oxide and N-doped carbon quantum dots. The analog-type resistive switching was demonstrated, which enabled the emulation of synaptic learning and pattern recognition with high accuracy. The all-carbon devices possess excellent transferability, flexibility and resistance to high temperature, showing the potential for the development of wearable neuromorphic computing system.

Highly transparent and active Pt-Mo

Room-temperature gas sensors have emerged as effective platforms for sensing explosive or toxic gases in ambient environment. However, room-temperature gas sensor usually suffers from extremely poor sensitivity and sluggish response/recovery characteristics due to the low reacting activity at low temperature. Herein, we present a room-temperature NO

Metal nanowire networks (MNNs) are promising as transparent electrode materials for a diverse range of optoelectronic devices and also work as active materials for electrical heating and electromagnetic interference (EMI) shielding applications. However, the relatively low performance and poor durability of MNNs are limiting the practical application of the resulting devices. Here, we report a controllable approach to enhance the conductivity and the stability of MNNs with their transmittance remaining unchanged, in which reduced graphene oxide conformally wrapped silver nanowire networks (AgNW@rGO networks) are synthesized by selective electrodeposition of GO nanosheets on AgNWs followed by a pulsed laser irradiation treatment. Experimental characterizations and finite-difference time-domain simulations indicate that pulsed laser irradiation at a specific wavelength not only reduces the GO but also welds the AgNWs together through a surface plasmon resonance process. As a result, the AgNW@rGO networks exhibit low sheet resistance of 3.3 Ω/□, average transmittance of 91.1%, and good flexibility. Wrapping with rGO improves the maximum electrical heating temperature of the AgNW network transparent heaters due to the effective suppression of the oxidation and the migration of surface silver atoms. In addition, excellent EMI shielding effectiveness of up to 35.5 dB in the 8.2-12.4 GHz frequency range is obtained as a consequence of the combined effects of dual reflection, conduction loss, and multiple dielectric polarization relaxation processes.

Colored wide‐bandgap semiconductor oxides with abundant mid‐gap states have long been regarded as promising visible light responsive photocatalysts. However, their catalytic activities are hampered by charge recombination at deep level defects, which constitutes the critical challenge to practical applications of these oxide photocatalysts. To address the challenge, a strategy is proposed here that includes creating shallow‐level defects above the deep‐level defects and thermal activating the migration of trapped electrons out of the deep‐level defects via these shallow defects. A simple and scalable solution plasma processing (SPP) technique is developed to process the presynthesized yellow TiO2 with numerous oxygen vacancies (Ov), which incorporates hydrogen dopants into the TiO2 lattice and creates shallow‐level defects above deep level of Ov, meanwhile retaining the original visible absorption of the colored TiO2. At elevated temperature, the SPP‐treated TiO2 exhibits a 300 times higher conversion rate for CO2 reduction under solar light irradiation and a 7.5 times higher removal rate of acetaldehyde under UV light irradiation, suggesting the effectiveness of the proposed strategy to enhance the photoactivity of colored wide‐bandgap oxides for energy and environmental applications., Solution plasma brings H doping into oxygen vacancy type TiO2. The H dopant bridges the gap between the oxygen vacancy (Ov) and conduction band (CB), resulting in photothermal extraction of trapped electrons at the Ov to CB. The solution plasma strategy endows a 300 times higher conversion rate for CO2 reduction under solar light at 393 K than that at 298 K.

The international community has generally recognized the key role of developing countries’ cities in reducing carbon emissions, an elemental way to mitigate climate change. However, few have empirically analyzed the impact of market-based instruments such as emission trading system on urban carbon emissions in developing economies. This paper examines the effect of China’s pilot carbon trading markets, the first emission trading system in developing economies, on cities’ carbon intensity. We also explore the mechanism by which the emission trading system achieves its influence. The PSM-DID method is used to analyze the panel data including China’s 273 prefecture-level cities from 2010 to 2016. The results illustrate that the emission trading system significantly decreased pilot cities’ carbon intensity and this effect endured; as time progressed, the reduction effect was increasing. Through mediating effect analysis, we find that the emission trading system reduced the carbon intensity via increasing the proportion of tertiary industry output value in GDP and decreasing the energy intensity. Overall, the empirical results suggest that the Chinese government should drive the establishment and improvement of a national carbon market, proactively adjust industry structure, and consider the possible influence caused by the potential energy rebound effect.

Hologram is regarded as a key platform for large-volume data storage and information encryption. Diversity of plasmonic nanostructures makes it being a kind of vibrant hologram memory media. However, recording of amplitude, phase and polarization of light is restricted by difficulty to obtain anisotropic morphology of metal particles. Photocatalysis approach allows wide size distribution of Ag plasmonic nanoparticles after a long growth time on titania but suffers from the disadvantage that the shape of plasmonic nanostructures is mostly isotropic, which weakens optical vector sensitivity and information stability. Herein, Ag nanocubes exhibiting high polarization response ability are deposited on orderly mesoporous titania via UV photocatalysis. Recording efficiency of hologram by orthogonally linearly polarized lights is enhanced and the memorized information can be resistant to UV-erasure, both benefiting from the distal resonance of Ag nanocubes. This work delivers a guideline for long-term data storage and high-efficiency display devices.

Ultraviolet luminescence holds potential for diverse applications. Further development of ultraviolet-luminescence technology, however, is hindered by the common but very inconvenient photoluminescence form. Here we create a form of ultraviolet emission-persistent luminescence in the narrowband ultraviolet-B (NB UVB) region (309--313 nm) upon illumination by a blue light-emitting diode. On this basis, we study the dynamic competition between an up-conversion charging excitation and a photostimulated detrapping upon illumination by the light-emitting diode. Such a competition mechanism, as well as the associated manipulation technique, appears to be generally applicable for many existing phosphors. As a proof of concept, we present an imaging demonstration, showing the potential of the NB-UVB persistent luminescence in the optical tagging field. This work can potentially revolutionize the ways for utilizing persistent luminescence, leading NB-UVB applications to another level.

TiO

Carrier-exciton interactions in two-dimensional transition metal dichalcogenides (TMDs) is one of the crucial elements for limiting the performance of their optoelectronic devices. Here, we have experimentally studied the carrier-exciton interactions in a monolayer MoS

Artificial photosynthesis by a semiconductor-oxide-based photocatalysis is presently challenging due to low CO2 conversion rates and poor product selectivity. To promote CO2 reduction, Pt/TiO2 has been deemed as a classic photocatalyst. In this study, we restudy Pt/TiO2 for the thermally assisted photocatalytic reduction of CO2 and reveal a different story between photocatalysis and photothermal catalysis. For example, when using disordered Pt/TiO2-x, the CO2 conversion via photocatalysis at 298 K is not impressive. However, when the system temperature is increased to 393 K, the CO2 conversion rate is significantly enhanced by a factor of 155 as compared to that obtainable from pristine TiO2; further, surprisingly high selectivity of CH4 (87.5%) could be achieved. Thermally coupled photocatalysis yields the enhanced evolution of H2 side products over Pt (4.06 nm)/TiO2 and promoted H2 splitting over Pt (2.33 nm)/TiO2, which is seldom observed in conventional Pt/TiO2 photocatalysis. The synergy of improved charge separation at the Pt/TiO2-x interface induced by surface disordering and accelerated H2 consumption near smaller Pt nanoparticles by thermal assistance are believed to be critically important for the simultaneous enhancement of CO2 conversion rates and CH4 product selectivity. This study inspires revisiting not only Pt/TiO2 but also reactivating other semiconductor-oxide-based photocatalysts for use in thermally assisted photocatalysis.

The development of strain sensors with high sensitivity and stretchability, which can accurately detect different human activities such as subtle physiological signals and large-scale joint motions is essential for disease diagnosis and human health monitoring. However, achieving both high sensitivity and stretchability is still an enormous challenge at the moment, particularly for intrinsically stretchable strain sensors. Herein, utilizing large differences in the conductivity and stretchability of micropatterned Au and SWCNTs, we present an ultrasensitive intrinsically stretchable strain sensor by a one-step photolithography process. Its high sensitivity is inspired from spiders' slit organ and the high stretchability is enlightened from spiders' neural pathway. The skin-like sensor exhibits many superior merits, including ultrahigh sensitivity (gauge factors of 7.1 × 104 to 3.4 × 106), wide detection range (up to 100% strain), excellent durability (1000 cycles), ultralow limit of detection (0.1% strain), fast response (1.3 ms), and minimal feature size (≤100 μm). These fascinating merits allow the strain sensor to precisely detect diverse human activities. This work opens up a feasible path to fabricate highly sensitive and stretchable strain sensors, presenting their promising potential in future personalized healthcare, as electronic skins, and being a portable friendly human-machine interaction system.

Designing and constructing one-dimensional (1D) discrete heterojunctions comprise an ideal strategy to improve the charge-separation efficiency and enhance the photocatalytic activities of semiconductor materials. Here, a novel architecture of discrete heterojunction nanofibers (DH-NFs) was obtained by growing Bi

Two-terminal memristor is promising for data storage and neuromorphic computing with low-power consumption, fast switching speed, and high scalability. Optoelectronic memristor with optical and electrical hybrid stimulus is particularly attractive because it allows synergistic coupling of electronic, photonic, and ionic processes. The use of optical stimuli can expand the application scope of memristor to a variety of optoelectronic applications such as optoelectronic memory, optoelectronic logic operation, visual information sensor, optogenetics-inspired synaptic, etc. In addition, photons have the advantage of high bandwidth and fast transmission speed. The combination of photons and memristor may provide a platform for photonic computing to beyond the von Neumann bottleneck. In this chapter, we present an overview of two-terminal optoelectronic memristors on their microscopic mechanisms, and diverse applications. The microscopic mechanisms of optoelectronic memristors, including the photomediated interfacial barrier, photoassisted filament formation/dissolution, photomodulated charge trapping/detrapping, photoinduced material conformation evolution are introduced. Then, selected application examples of optoelectronic memristors on multilevel memory, logic operations, and neuromorphic vision sensors are presented. Furthermore, photoinvolved synaptic functions emulated by optoelectronic memristors are discussed. In the end, a discussion on the challenges and perspectives for further development of optoelectronic memristor is presented.

An analytical model was proposed to simulate the resistive switching (RS) process of electrochemical metallization memory (ECM) device with a dual-layer structure, in which the AgInSbTe (AIST) buffer layer was introduced to combine with the amorphous carbon (a-C) dielectric layer. This dual-layer ECM device presented good memory performance, such as high switching uniformity, however, a suitable model was absent to understand its RS mechanism. The analytical model of Ag/AIST/a-C/Pt device was developed based on the formation and dissolution of the Ag-ion-based CF. Comparing to the common RS model considering one-step set/reset process, the multi-step of set/reset was utilized to fit with the dual-layer structure. The set/reset always occurs in the AIST layer at first step and in the a-C layer subsequently due to the lower active energy and thermal conductivity of AIST layer. Random disturbances were also introduced to simulate the device variation during the cycling process. Eventually, this model can well fit with the experimental data, providing an analytical tool for describing the RS process of ECM device.

Silica/Cu composites generally fail to achieve the high strength due to the weak interfacial bonding between SiO2 and Cu. In the current work, the first use of silica quantum dots (SiO2 QDs) as a copper-based composite reinforcement. Silicon quantum dots (Si QDs) and copper acetate are employed as raw materials for spray pyrolysis to obtain an interconnected structure of SiO2 QDs/Cu2O, which achieve well-dispersion of the reinforcement and good interface combination in one step. The SiO2 QDs/Cu2O composite block is obtained by ball milling, hydrogen reduction, and SPS sintering. Micro interface structure and strengthening mechanism of the composites are investigated and presented in detail. Microstructural analysis discovers the Cu2O transition layer between SiO2 QDs and Cu matrix and well-dispersed SiO2 QDs in the Cu matrix. The good bonding of grain interface can significantly enhance the mechanical properties. The 1.2 wt% SiO2 QDs/Cu composite block exhibits an excellent ultimate tensile strength of 456.63 MPa, which is 101.68% higher than that of unreinforced Cu (227.39 MPa). Furthermore, the composite block maintains the high conductivity (83.27% IACS) and elongation (8.86%). Moreover, this work can promote the development of Cu matrix composites using ceramic reinforcement with an improved interface bonding.

Catalyst immobilization is of much significance not only for maintaining the high activity of the ultrafine catalyst, but also for the separation of catalyst during the practical application. Herein, a novel support material, three-dimensional hierarchically porous silica (HPS) with interconnected micro-meso-macro pores and high specific surface area was successfully fabricated though a freeze-drying technique in the presence of poly(vinyl alcohol) (PVA) and subsequent calcination process. A series of characterizations revealed that the specific surface area of HPS can be well adjusted by changing the addition of PVA. The specific surface area of HPS was as high as 360 m2 g−1, which was 211-fold higher than HPS-0 (silica prepared without using PVA). To demonstrate the potential application of such novel support material, highly dispersed silver nanoparticles (AgNPs) were immobilized on the surfaces of HPS and HPS-0 through in-situ reduction. By contrast, the catalytic activity of AgNPs anchored on HPS (531 s−1 g−1) was about 42-fold higher than that of AgNPs anchored on HPS-0 (12.67 s−1 g−1). The significantly enhanced catalytic activity of AgNPs/HPS was believed to be related to their high specific surface area and interconnected macroporous scaffolds, which could provide numerous reactive sites and mass transfer routes for the reactants.