A long debate on the charge identity and the associated mechanisms occurring in contact‐electrification (CE) (or triboelectrification) has persisted for many decades, while a conclusive model has not ...yet been reached for explaining this phenomenon known for more than 2600 years! Here, a new method is reported to quantitatively investigate real‐time charge transfer in CE via triboelectric nanogenerator as a function of temperature, which reveals that electron transfer is the dominant process for CE between two inorganic solids. A study on the surface charge density evolution with time at various high temperatures is consistent with the electron thermionic emission theory for triboelectric pairs composed of Ti–SiO2 and Ti–Al2O3. Moreover, it is found that a potential barrier exists at the surface that prevents the charges generated by CE from flowing back to the solid where they are escaping from the surface after the contacting. This pinpoints the main reason why the charges generated in CE are readily retained by the material as electrostatic charges for hours at room temperature. Furthermore, an electron‐cloud–potential‐well model is proposed based on the electron‐emission‐dominatedcharge‐transfer mechanism, which can be generally applied to explain all types of CE in conventional materials.
Real‐time charge transfer in contact electrification (CE) is investigated quantitatively as a function of temperature via a triboelectric nanogenerator, revealing that electron transfer is the dominant process for CE between two inorganic solids. An electron‐cloud–potential‐well model is proposed for understanding all types of CE in conventional materials.
Cellulose‐based triboelectric nanogenerators (TENGs) have gained increasing attention. In this study, a novel method is demonstrated to synthesize cellulose‐based aerogels and such aerogels are used ...to fabricate TENGs that can serve as mechanical energy harvesters and self‐powered sensors. The cellulose II aerogel is fabricated via a dissolution–regeneration process in a green inorganic molten salt hydrate solvent (lithium bromide trihydrate), where. The as‐fabricated cellulose II aerogel exhibits an interconnected open‐pore 3D network structure, higher degree of flexibility, high porosity, and a high surface area of 221.3 m2 g−1. Given its architectural merits, the cellulose II aerogel‐based TENG presents an excellent mechanical response sensitivity and high electrical output performance. By blending with other natural polysaccharides, i.e., chitosan and alginic acid, electron‐donating and electron‐withdrawing groups are introduced into the composite cellulose II aerogels, which significantly improves the triboelectric performance of the TENG. The cellulose II aerogel‐based TENG is demonstrated to light up light‐emitting diodes, charge commercial capacitors, power a calculator, and monitor human motions. This study demonstrates the facile fabrication of cellulose II aerogel and its application in TENG, which leads to a high‐performance and eco‐friendly energy harvesting and self‐powered system.
Cellulose II aerogels, with the features of high flexibility, porosity, and surface area, are integrated with triboelectric nanogenerators to yield green, sustainable energy harvesting, and sensing devices. By blending other natural polysaccharides to introduce electron‐donating and electron‐withdrawing groups, the performance of the cellulose II aerogel‐based triboelectric nanogenerators can be significantly improved and used for mechanical energy harvesting and motion monitoring.
Co-infection has been reported in patients with severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome, but there is limited knowledge on co-infection among patients with ...coronavirus disease 2019 (COVID-19). The prevalence of co-infection was variable among COVID-19 patients in different studies, however, it could be up to 50% among non-survivors. Co-pathogens included bacteria, such as Streptococcus pneumoniae, Staphylococcus aureus, Klebsiella pneumoniae, Mycoplasma pneumoniae, Chlamydia pneumonia, Legionella pneumophila and Acinetobacter baumannii; Candida species and Aspergillus flavus; and viruses such as influenza, coronavirus, rhinovirus/enterovirus, parainfluenza, metapneumovirus, influenza B virus, and human immunodeficiency virus. Influenza A was one of the most common co-infective viruses, which may have caused initial false-negative results of real-time reverse-transcriptase polymerase chain reaction for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Laboratory and imaging findings alone cannot help distinguish co-infection from SARS-CoV-2 infection. Newly developed syndromic multiplex panels that incorporate SARS-CoV-2 may facilitate the early detection of co-infection among COVID-19 patients. By contrast, clinicians cannot rule out SARS-CoV-2 infection by ruling in other respiratory pathogens through old syndromic multiplex panels at this stage of the COVID-19 pandemic. Therefore, clinicians must have a high index of suspicion for coinfection among COVID-19 patients. Clinicians can neither rule out other co-infections caused by respiratory pathogens by diagnosing SARS-CoV-2 infection nor rule out COVID-19 by detection of non-SARS-CoV-2 respiratory pathogens. After recognizing the possible pathogens causing co-infection among COVID-19 patients, appropriate antimicrobial agents can be recommended.
A new type of lanthanum‐based high entropy perovskite oxide (HEPO) electrocatalyst for the oxygen evolution reaction is reported. The B‐site lattices in the HEPO consist of five consecutive first‐row ...transition metals, including Cr, Mn, Fe, Co, and Ni. Equimolar and five non‐equimolar HEPO electrocatalysts are studied for their OER electrocatalytic performance. In the five non‐equimolar HEPOs, the concentration of one of the five transition metals is doubled in individual samples. The performances of all the HEPOs outperform the single perovskite oxides. The optimized La(CrMnFeCo2Ni)O3 HEPO exhibits an outstanding OER overpotential of 325 mV at a current density of 10 mA cm−2 and excellent electrochemical stability after 50 h of testing.
Lanthanum‐based high entropy perovskite oxides (HEPOs) with a B‐site consisting of five consecutive first‐row transition metals are synthesized in both equimolar and non‐equimolar ratios. The HEPO electrocatalysts outperform the single perovskite oxides. The optimized La(CrMnFeCo2Ni)O3 HEPO exhibits an outstanding OER overpotential of 325 mV at 10 mA cm–2 and excellent stability after 50 h of testing.
Proton‐responsive photochromic molecules are attractive for their ability to react on non‐invasive rapid optical stimuli and the importance of protonation/deprotonation processes in various fields. ...Conventionally, their acidic/basic sites are on hetero‐atoms, which are orthogonal to the photo‐active π‐center. Here, we incorporate azulene, an acid‐sensitive pure hydrocarbon, into the skeleton of a diarylethene‐type photoswitch. The latter exhibits a novel proton‐gated negative photochromic ring‐closure and its optical response upon protonation in both open and closed forms is much more pronounced than those of diarylethene photoswitches with hetero‐atom based acidic/basic moieties. The unique behavior of the new photoswitch can be attributed to direct protonation on its π‐system, supported by 1H NMR and theoretical calculations. Our results demonstrate the great potential of integrating non‐alternant hydrocarbons into photochromic systems for the development of multi‐responsive molecular switches.
Incorporation of an azulene moiety into a diarylethene photoswitch gives rise to unprecedented acid‐dependent negative photochromism. The unusual photochromic behavior can be understood by direct protonation on the photoactive π‐system due to the unique electronic structure of azulene.
The interfacial properties for the buried junctions of the perovskite solar cells (PSCs) play a crucial role for the further enhancement of the power conversion efficiency (PCE) and stability of ...devices. Delicate manipulation of the interface properties such as the defect density, energy alignment, perovskite film quality, etc., guarantees efficient extraction and transport of photogenerated carriers. Herein, chlorobenzenesulfonic potassium salts are presented as a novel multifunctional agent to modify the buried tin oxide (SnO2)/perovskite interface for regular PSCs. The increasing number of carbon‐chlorine bonds (CCl) in 2,4,5‐trichlorobenzenesulfonic potassium (3Cl‐BSAK) exhibit efficient interaction with uncoordinated Sn, effectively filling oxygen vacancies in the SnO2 surface. Importantly, synergistic effects of the functional group‐rich organic anions and the potassium ion are achieved for reduced defect density, carrier recombination, and hysteresis. A champion PCE of 24.27% and the open‐circuit voltage (VOC) up to 1.191 V for modified devices are obtained. The unencapsulated devices maintain 80% of their initial PCE after aging at 80 °C for 800 h in the atmosphere and 95% after aging for 100 d. With 3Cl‐BSAK decoration, a high efficiency semitransparent PSC with a PCE of 12.83% and an average visible light transmittance (AVT) over 27% is also obtained.
A multifunctional chlorobenzenesulfonic potassium salt is developed to modify regular perovskite solar cells in order to inhibit charged defects at the SnO2/perovskite buried interface, suppressing the recombination of carriers and hysteresis. The reported devices demonstrate a champion power conversion efficiency of 24.27% and a champion open‐circuit voltage up to 1.191 V.
Uncovering the structure of socioeconomic systems and timely estimation of socioeconomic status are significant for economic development. The understanding of socioeconomic processes provides ...foundations to quantify global economic development, to map regional industrial structure, and to infer individual socioeconomic status. In this review, we will make a brief manifesto about a new interdisciplinary research field named Computational Socioeconomics, followed by detailed introduction about data resources, computational tools, data-driven methods, theoretical models and novel applications at multiple resolutions, including the quantification of global economic inequality and complexity, the map of regional industrial structure and urban perception, the estimation of individual socioeconomic status and demographic, and the real-time monitoring of emergent events. This review, together with pioneering works we have highlighted, will draw increasing interdisciplinary attentions and induce a methodological shift in future socioeconomic studies.
In the growing list of 2D semiconductors as potential successors to silicon in future devices, metal‐halide perovskites have recently joined the family. Unlike other conversional 2D covalent ...semiconductors such as graphene, transition metal dichalcogenides, black phosphorus, etc., 2D perovskites are ionic materials, affording many distinct properties of their own, including high photoluminescence quantum efficiency, balanced large exciton binding energy and oscillator strength, and long carrier diffusion length. These unique properties make 2D perovskites potential candidates for optoelectronic and photonic devices such as solar cells, light‐emitting diodes, photodetectors, nanolasers, waveguides, modulators, and so on, which represent a relatively new but exciting and rapidly expanding area of research. In this Review, the recent advances in emerging 2D metal‐halide perovskites and their applications in the fields of optoelectronics and photonics are summarized and insights into the future direction of these fields are offered.
Metal‐halide perovskites exhibit great promise in photonics and optoelectronics applications. Here, a timely review of recent advances in 2D metal‐halide perovskites and their applications in the fields of optoelectronics and photonics for triggering new possibilities in the conceptual development of novel 2D metal‐halide perovskite materials, architectures, and devices is presented.
Vibration is a common mechanical phenomenon and possesses mechanical energy in ambient environment, which can serve as a sustainable source of power for equipment and devices if it can be effectively ...collected. In the present work, a novel soft and robust triboelectric nanogenerator (TENG) made of a silicone rubber‐spring helical structure with nanocomposite‐based elastomeric electrodes is proposed. Such a spring based TENG (S‐TENG) structure operates in the contact‐separation mode upon vibrating and can effectively convert mechanical energy from ambient excitation into electrical energy. The two fundamental vibration modes resulting from the vertical and horizontal excitation are analyzed theoretically, numerically, and experimentally. Under the resonant states of the S‐TENG, its peak power density is found to be 240 and 45 mW m−2 with an external load of 10 MΩ and an acceleration amplitude of 23 m s−2. Additionally, the dependence of the S‐TENG's output signal on the ambient excitation can be used as a prime self‐powered active vibration sensor that can be applied to monitor the acceleration and frequency of the ambient excitation. Therefore, the newly designed S‐TENG has a great potential in harvesting arbitrary directional vibration energy and serving as a self‐powered vibration sensor.
A novel soft and robust triboelectric nanogenerator (TENG) made of a silicone rubber‐spring helical structure with nanocomposite based elastomeric electrodes is designed. Such a spring based TENG structure operates in contact‐separation mode upon vibrating and can effectively convert mechanical energy from arbitrary direction excitation into electrical energy. It can also serve as a self‐powered sensor for vibration monitoring.
Materials with tunable long persistent luminescence (LPL) properties have wide applications in security signs, anti‐counterfeiting, data encrypting, and other fields. However, the majority of ...reported tunable LPL materials are pure organic molecules or polymers. Herein, a series of metal‐organic coordination polymers displaying color‐tunable LPL were synthesized by the self‐assembly of HTzPTpy ligand with different cadmium halides (X=Cl, Br, and I). In the solid state, their LPL emission colors can be tuned by the time‐evolution, as well as excitation and temperature variation, realizing multi‐mode dynamic color tuning from green to yellow or green to red, and are the first such examples in single‐component coordination polymer materials. Single‐crystal X‐ray diffraction analysis and theoretical calculations reveal that the modification of LPL is due to the balanced action from single molecule and aggregate triplet excited states caused by an external heavy‐atom effect. The results show that the rational introduction of different halide anions into coordination polymers can realize multi‐color LPL.
By delicate design of coordination polymers incorporating different halogens, multi‐mode color‐tunable long persistent luminescence (LPL) from green to yellow or green to red was possible. The LPL emission colors can be tuned by time, excitation, and temperature, revealing the counter‐balanced mechanisms from single‐molecule and aggregate triplet excited states resulting from an external heavy‐atom effect.
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