Lipids play a critical role in cell membrane integrity, signaling, and energy storage. However, in-depth structural characterization of lipids is still challenging and not routinely possible in lipidomics experiments. Techniques such as collision-induced dissociation (CID) tandem mass spectrometry (MS/MS), ion mobility (IM) spectrometry, and ultrahigh-performance liquid chromatography are not yet capable of fully characterizing double-bond and sn-chain position of lipids in a high-throughput manner. Herein, we report on the ability to structurally characterize lipids using large-area triboelectric nanogenerators (TENG) coupled with time-aligned parallel (TAP) fragmentation IM-MS analysis. Gas-phase lipid epoxidation during TENG ionization, coupled to mobility-resolved MS3 via TAP IM-MS, enabled the acquisition of detailed information on the presence and position of lipid C═C double bonds, the fatty acyl sn-chain position and composition, and the cis/trans geometrical C═C isomerism. The proposed methodology proved useful for the shotgun lipidomics analysis of lipid extracts from biological samples, enabling the detailed annotation of numerous lipid isobars.

Nanomaterials offer innovations in water purification technology with decreased operational and capital cost, reduced dosage, and improved pollutant selectivity. In particular, inorganic nanoparticles (NPs)/cellulose hybrid nanocomposites have attracted growing interest due to the unique properties of cellulose and high specific surface area of NPs and their pollutant selectivity. The integration with cellulose brings benefits to inorganic NPs for water treatment, including preventing agglomeration, ensuring colloidal stability, and allowing for separation by magnetic nanoparticles after purification. In this review, firstly, conventional water treatment technologies are introduced (Section 1). Following this, an overview of inorganic NPs/cellulose composites for water treatment (Section 2) is presented. Moreover, engineering of such hybrid composites is discussed (Section 3). Furthermore, water purification of inorganic NPs/cellulose through adsorption of pollutants (Section 4) and non-adsorption (catalytic, photocatalytic, and antibacterial) activities (Section 5) are highlighted. Finally, conclusions and outlook are provided (Section 6).

Mass-manufactured stretchable negative Poisson's ratio yarn TENG as a fundamental material for environmental energy harvesting and self-powered sensors.

It is well known that the photovoltaic effect produces a direct current (DC) under solar illumination owing to the directional separation of light-excited charge carriers at the p-n junction, with holes flowing to the p-side and electrons flowing to the n-side. Here, it is found that apart from the DC generated by the conventional p-n photovoltaic effect, there is another new type of photovoltaic effect that generates alternating current (AC) in the nonequilibrium states when the illumination light periodically shines at the junction/interface of materials. The peak current of AC at high switching frequency can be much higher than that from DC. The AC cannot be explained by the established mechanisms for conventional photovoltaics; instead, it is suggested to be a result of the relative shift and realignment between the quasi-Fermi levels of the semiconductors adjacent to the junction/interface under the nonequilibrium conditions, which results in electron flow in the external circuit back and forth to balance the potential difference between two electrodes. By virtue of this effect, the device can work as a high-performance broadband photodetector with extremely high sensitivity under zero bias; it can also work as a remote power source providing extra power output in addition to the conventional photovoltaic effect.

Increasing performance demand associated with the short lifetime of consumer electronics has triggered fast growth in electronic waste, leading to serious ecological challenges worldwide. Herein, a robust strategy for judiciously constructing flexible perovskite solar cells (PSCs) that can be conveniently biodegraded is reported. The key to this strategy is to capitalize on meniscus‐assisted solution printing (MASP) as a facile means of yielding cross‐aligned silver nanowires in one‐step, which are subsequently impregnated in a biodegradable elastomeric polyester. Intriguingly, the as‐crafted hybrid biodegradable electrode greatly constrains the solvent evaporation of the perovskite precursor solution, thereby generating fewer nuclei and in turn resulting in the deposition of a large‐grained dense perovskite film that exhibits excellent optoelectronic properties with a power conversion efficiency of 17.51% in PSCs. More importantly, the hybrid biodegradable electrode‐based devices also manifest impressive robustness against mechanical deformation and can be thoroughly biodegraded after use. These results signify the great potential of MASP for controllably assembling aligned conductive nanomaterials for biodegradable electrodes. As such, it represents an important endeavor toward environmentally friendly, multifunctional and flexible electronic, optoelectronic, photonic, and sensory materials and devices.

Combining traditional textiles with triboelectric nanogenerators (TENGs) gives birth to self-powered electronic textiles (e-textiles). However, there are two bottlenecks in their widespread application, low power output and poor sensing capability. Herein, by means of the three-dimensional five-directional braided (3DB) structure, a TENG-based e-textile with the features of high flexibility, shape adaptability, structural integrity, cyclic washability, and superior mechanical stability, is designed for power and sensing. Due to the spatial frame-column structure formed between the outer braided yarn and inner axial yarn, the 3DB-TENG is also endowed with high compression resilience, enhanced power output, improved pressure sensitivity, and vibrational energy harvesting ability, which can power miniature wearable electronics and respond to tiny weight variations. Furthermore, an intelligent shoe and an identity recognition carpet are demonstrated to verify its performance. This study hopes to provide a new design concept for high-performance textile-based TENGs and expand their application scope in human-machine interfacing.

It is well known that the photovoltaic effect produces a direct current (DC) under solar illumination owing to the directional separation of light-excited charge carriers at the p-n junction, with holes flowing to the p-side and electrons flowing to the n-side. Here, it is found that apart from the DC generated by the conventional p-n photovoltaic effect, there is another new type of photovoltaic effect that generates alternating current (AC) in the nonequilibrium states when the illumination light periodically shines at the junction/interface of materials. The peak current of AC at high switching frequency can be much higher than that from DC. The AC cannot be explained by the established mechanisms for conventional photovoltaics; instead, it is suggested to be a result of the relative shift and realignment between the quasi-Fermi levels of the semiconductors adjacent to the junction/interface under the nonequilibrium conditions, which results in electron flow in the external circuit back and forth to balance the potential difference between two electrodes. By virtue of this effect, the device can work as a high-performance broadband photodetector with extremely high sensitivity under zero bias; it can also work as a remote power source providing extra power output in addition to the conventional photovoltaic effect.

Despite recent progress in producing perovskite nanowires (NWs) for optoelectronics, it remains challenging to solution-print an array of NWs with precisely controlled position and orientation. Herein, we report a robust capillary-assisted solution printing (CASP) strategy to rapidly access aligned and highly crystalline perovskite NW arrays. The key to the CASP approach lies in the integration of capillary-directed assembly through periodic nanochannels and solution printing through the programmably moving substrate to rapidly guide the deposition of perovskite NWs. The growth kinetics of perovskite NWs was closely examined by in situ optical microscopy. Intriguingly, the as-printed perovskite NWs array exhibit excellent optical and optoelectronic properties and can be conveniently implemented for the scalable fabrication of photodetectors.

Commercial lithium-ion batteries (LIBs), limited by their insufficient reversible capacity, short cyclability, and high cost, are facing ever-growing requirements for further increases in power capability, energy density, lifespan, and flexibility. The presence of insulating and electrochemically inactive binders in commercial LIB electrodes causes uneven active material distribution and poor contact of these materials with substrates, reducing battery performance. Thus, nanostructured electrodes with binder-free designs are developed and have numerous advantages including large surface area, robust adhesion to substrates, high areal/specific capacity, fast electron/ion transfer, and free space for alleviating volume expansion, leading to superior battery performance. Herein, recent progress on different kinds of supporting matrixes including metals, carbonaceous materials, and polymers as well as other substrates for binder-free nanostructured electrodes in LIBs are summarized systematically. Furthermore, the potential applications of these binder-free nanostructured electrodes in practical full-cell-configuration LIBs, in particular fully flexible/stretchable LIBs, are outlined in detail. Finally, the future opportunities and challenges for such full-cell LIBs based on binder-free nanostructured electrodes are discussed.

The ability to reproducibly create a surface enhanced Raman scattering (SERS) substrate renders an effective means of detecting and degrading organic contaminants. Vertically aligned (VA) nanomaterials have been extensively explored as highly efficient catalysts due to their excellent electron transportability and high concentration of exposed active edge sites. Herein, we report on a ternary ultrafast-electron-transfer heterostructure composed of Pt nanoparticles in-situ grown on VA-MoS2 nanosheet edge sites decorated on TiO2 nanotube arrays (NTAs) (denoted Pt/VA-MoS2/NTAs). Compared with pristine TiO2 NTAs, the Pt/VA-MoS2/NTAs possess a strong resonant SERS effect for detecting rhodamine 6G and an outstanding UV-assisted self-cleaning effect, displaying an excellent photocatalytic performance under visible light irradiation. Such markedly improved performance of the ternary Pt/VA-MoS2/TiO2 NTAs nanocomposites can be attributed to the synergy of catalytic activity of Pt-deposited MoS2 edge sites, the ultrafast electron transfers of VA-MoS2 NS/TiO2 NTAs, and the appropriate band alignment among these three constituents. As such, it represents a robust mean of developing advanced energy utilization nanocomposites for high-performance catalysts and sensors.

Covalent organic frameworks (COFs) are an emerging type of porous crystalline polymers with tunable nanopore size, high accessible surface area, predesigned building units, abundant active sites, devisable chain structures, and programmable topological architectures. These collective characteristics are essential in creating high-efficiency electrocatalysts for energy conversion and fuel generation in metal-air batteries and fuel cells. Recent years have witnessed considerable advances in rational design and controllable fabricate of COF-based electrocatalysts for oxygen reduction, oxygen evolution, hydrogen evolution, and CO2 reduction reactions. In this review, engineering strategies of COFs toward electrocatalysts are first summarized and given particular attention, highlighting their influence on intrinsic electrocatalytic performance. A systematic overview of the fundamental principles behind specific electrocatalysis reactions is then performed. Significant breakthroughs of COFs and their derivatives are presented in detail with an emphasis on the relationship between the molecular structures of COFs and their electrocatalytic performance. Lastly, current challenges and future perspectives on tailoring COFs for high-performance electrocatalysts are discussed. This review aims to identify general guidelines and the potential of COFs to outperform state-of-the-art electrocatalysts that use their noble metal-based counterparts.

Despite impressive advances in the synthesis of perovskite quantum dots (PQDs), the ability to craft PQDs of the same dimension yet different architectures (e.g., solid vs. hollow) remains a grand challenge. Moreover, precise control over the architectures and assemblies of PQDs renders new optical and optoelectronic properties. Herein, we report on a robust amphiphilic star-like block copolymer nanoreactor strategy to rapidly create monodisperse solid and hollow PQDs of the same external diameter in-situ. The dimension of PQDs can be readily regulated by utilizing star-like copolymers. Compared to solid PQDs, as the inner diameter of hollow PQDs increases, their photoluminescence progressively blue-shifts. Moreover, stripe patterns of PQDs can be conveniently formed via meniscus-assisted self-assembly (MASA) and subsequently anion-exchanged to yield multi-colored stripes with a heterostructured transition zone. Conceptually, an array of PQDs including all inorganic lead-free and organic-inorganic PQDs, can be easily accessed for applications in lasers, LEDs, and solar cells.

Schottky and Ohmic contacts-based electronics play an important role in highly sensitive detection of biomolecules and neural electric impulses, respectively. The reversible conversion between these two contacts appears especially important for multifunctional sensing by just one biosensor. Here, Schottky barrier height (SBH) is successfully tuned by triboelectric nanogenerator (TENG) and the same device is made to achieve reversible conversion between Schottky contact and Ohmic contact. In the same Schottky to Ohmic reversible (SOR) biosensor, highly sensitive detections of biomolecule (i.e., neurotransmitter) and neural electric signal are achieved at different contact states. The SOR biosensor reveals the feasibility of using one device to realize multifunctional detection. This work proposes a simple and significant method to achieve reversible tuning between the Schottky contact and Ohmic contact on one device by TENG, which exhibits great potential in developing multifunctional and high-sensitivity biosensors, rectifiers, and other functional electronic devices.

It has been demonstrated that substantial electric power can be produced by a liquid-based triboelectric nanogenerator (TENG). However, the mechanisms regarding the electrification between a liquid and a solid surface remain to be extensively investigated. Here, the working mechanism of a droplet-TENG was proposed based on the study of its dynamic saturation process. Moreover, the charge-transfer mechanism at the liquid-solid interface was verified as the hybrid effects of electron transfer and ion adsorption by a simple but valid method. Thus, we proposed a model for the charge distribution at the liquid-solid interface, named Wang's hybrid layer, which involves the electron transfer, the ionization reaction, and the van der Waals force. Our work not only proves that TENG is a probe for investigating charge transfer at interface of all phases, such as solid-solid and liquid-solid, but also may have great significance to water energy harvesting and may revolutionize the traditional understanding of the liquid-solid interface used in many fields such as electrochemistry, catalysis, colloidal science, and even cell biology.

Negative air ions (NAIs) have been widely harnessed in recent technologies for air pollutant removal and their beneficial effects on human health, including allergy relief and neurotransmitter modulation. Herein, we report a corona-type, mechanically stimulated triboelectric NAI generator. Using the high output voltage from a triboelectric nanogenerator, air molecules can be locally ionized from carbon fibre electrodes through various movements, with the electron–ion transformation efficiency reaching up to 97%. Using a palm-sized device, 1 × 10 13 NAIs (theoretically 1 × 10 5 ions cm −3 in 100 m 3 space) are produced in one sliding motion, and particulate matter (PM 2.5) can be rapidly reduced from 999 to 0 µg m −3 in 80 s (in a 5,086 cm 3 glass chamber) under an operation frequency of 0.25 Hz. This triboelectric NAI generator is simple, safe and effective, providing an appealing alternative, sustainable avenue to improving health and contributing to a cleaner environment.

The underlying mechanism on contact electrification (CE) has remained a topic of debate over centuries, and it is argued to be due to electron transfer, ion transfer, and/or even material species transfer. Recently, a previous study shows that CE is dominated by electrons, at least for solid–solid cases. Herein, by using a model detailing the charge transfer between triboelectric surfaces and thermionic emission of electrons via employing a sliding mode Ti–SiO 2 triboelectric nanogenerator (TENG), surface charge decay behavior is scrutinized in lateral‐sliding mode during operation at high temperature. The temperature dependence of TENG electric output contributes to characteristic metal–dielectric and dielectric–dielectric CEs, thereby providing further evidence that electrons are the dominating transferred charges in CE. The total surface charge output of the TENG is rationalized as a direct consequence of the coupling of the rate of electron thermionic emission, the charge transfer rate of CE, and the changing rate of the contacted area between the two materials. When the contacting area is larger than the displaced area, the CE between the two materials is the major contributor to measured surface charge. Conversely, the thermionic emission of the exposed surfaces dictates when the contacting area is smaller.

Contact electrification (CE) has been known for more than 2600 years but the nature of charge carriers and their transfer mechanisms still remain poorly understood, especially for the cases of liquid–solid CE. Here, we study the CE between liquids and solids and investigate the decay of CE charges on the solid surfaces after liquid–solid CE at different thermal conditions. The contribution of electron transfer is distinguished from that of ion transfer on the charged surfaces by using the theory of electron thermionic emission. Our study shows that there are both electron transfer and ion transfer in the liquid–solid CE. We reveal that solutes in the solution, pH value of the solution and the hydrophilicity of the solid affect the ratio of electron transfers to ion transfers. Further, we propose a two-step model of electron or/and ion transfer and demonstrate the formation of electric double-layer in liquid–solid CE.

It is known that contact-electrification (or triboelectrification) usually occurs between two different materials, which could be explained by several models for different materials systems ( Adv. Mater. 2018, 30, 1706790; Adv. Mater. 2018, 30, 1803968). But contact between two pieces of the chemically same material could also result in electrostatic charges, although the charge density is rather low, which is hard to understand from a physics point of view. In this paper, by preparing a contact-separation mode triboelectric nanogenerator using two pieces of an identical material, the direction of charge transfer during contact-electrification is studied regarding its dependence on curvatures of the sample surfaces. For materials such as polytetrafluoroethylene, fluorinated ethylene propylene, Kapton, polyester, and nylon, the positive curvature surfaces are net negatively charged, while the negative curvature surfaces tend to be net positively charged. Further verification of the above-mentioned trends was obtained under vacuum (∼1 Pa) and higher temperature (≤358 K) conditions. Based on the received data acquired for gentle contacting cases, we propose a curvature-dependent charge transfer model by introducing curvature-induced energy shifts of the surface states. However, this model is subject to be revised if the mutual contact mode turns into a sliding mode or more complicated hard-pressed contact mode, in which a rigorous contact between the two pieces of the same material could result in nanoscale damage/fracture and possible species transfer. Our study provides a primitive step toward understanding the basics of contact-electrification.

Silicon photonics is now widely accepted as a key technology in a variety of systems. But owing to material limitations, now it is challenging to greatly improve the performance after decades of development. Here, we show a high-performance broadband photodetector with significantly enhanced sensitivity and responsivity operating over a wide wavelength range of light from near-ultraviolet to near-infrared at low power consumption. The specially designed textured top ceiling electrode works effectively as an antireflection layer to greatly improve the absorption of near-infrared light, thereby overcoming the absorption limitation of near-infrared light. Instead of the conventional p-n junction and p-intrinsic-n junction, we introduce a similar to 15 nm thick alumina insulator layer between a p-type Si substrate and n-type ZnO nanowire (NW) arrays, which significantly enhances the charge carrier separation and collection efficiency. The photosensing responsivity and sensitivity are found to be nearly 1 order of magnitude higher than that of a reference device of p-Si/n-ZnO NW arrays, significantly higher than the commercial silicon photodiodes as well. The light-induced charge carriers flow across the appropriate thickness of insulator layer via the quantum mechanical Fowler-Nordheim tunneling mechanism. By virtue of the piezo-phototronic effect, the charge density at the interfaces can be tuned to alter the energy bands and the potential barrier distance for tunneling. Additionally, along with the use of incident light of different wavelengths, the influence of the insulator layer on the transport of electrons and holes separately is further investigated. The demonstrated concepts and study would lead to sensitivity improvement, quality enhancement of data transfer, decrease of power consumption, and cost reduction of silicon photonics.