High Electrical Output Research Articles

Polystyrene Waste-ZnO nanocomposite film for energy harvesting via hydrophobic triboelectric nanogenerator: Transforming waste into energy

This research aimed to generate electricity from polystyrene waste materials combined with zinc oxide (ZnO) nanomaterials. Developing alternative polystyrene waste materials for generating electricity in triboelectric nanogenerator (TENG) could be beneficial in a circular economy and sustainable development. With the motivation to reduce environmental pollution by using polystyrene waste, a recycled polystyrene-ZnO nanocomposite film (rPS-ZnO NF) was synthesized and served as a triboelectric material for energy harvesting applications. ZnO nanopowder was produced by a low-temperature solution immersion method in conjunction with a simple film-casting method to prepare the rPS-ZnO NF. The effects of varying amounts of toluene as a solvent medium and the immersion time in stearic acid (SA) solution treatment on the structural properties, wettability behavior, surface morphology, chemical bonding properties, surface characteristics, and TENG performance were investigated. In this work, rPS film, rPS-ZnO NF, and SA-treated rPS-ZnO NF were paired with Kapton film as the opposite triboelectric material in constructing the vertical contact-separation mode TENG. Compared to rPS TENG, the rPS-ZnO TENG exhibited a two-fold enhancement in performance (8.2 V) in output voltage and ∼4.5 fold enhancement (28.1 μW/cm2) in power density. Furthermore, following SA treatment, the triboelectric performance further improved, reaching the highest open circuit voltage of ∼8.8 V and the highest power density of 32.0 μW/cm2 for repeated 2 N-solenoid tapping force. The hydrophobic behavior was also improved with the highest water contact angle of 134.7 (when the SA treatment immersion time was 1 h). These findings demonstrate that SA-treated rPS-ZnO NF could be a promising candidate for efficient mechanical energy harvesting with high electrical output and excellent surface wettability. This research not only exhibits an excellent output performance of SA-treated rPS-ZnO TENG, but it also sheds new light on the sustainable approach of converting polystyrene waste into energy-harvesting material.

Stable and High-performance Flow H2 -O2 Fuel Cells with Coupled Acidic Oxygen Reduction and Alkaline Hydrogen Oxidation Reactions.

Conventional H2 -O2 fuel cells suffer from the low output voltage, insufficient durability, and high-cost catalysts (e.g., noble metals). Herein, this work reports a conceptually new coupled flow fuel cell (CF-FC) by coupling asymmetric electrolytes for acidic oxygen reduction reaction and alkaline hydrogen oxidation reaction. By introducing an electrochemical neutralization energy, the newly-developed CF-FCs possess a significantly increased theoretical open-circuit voltage. Specifically, a CF-FC based on a typical transition metal single-atom Fe-N-C cathode catalyst demonstrates a high electricity output up to 1.81V and durability with an ultrahigh retention of 91% over 110h, far superior to the conventional fuel cells (usually, < 1.0V, < 50% retention over 20h). The output performance can even be significantly enhanced easily by connecting multiple CF-FCs into the parallel, series, or combined parallel-series connections at a fractional cost of that for the conventional H2 -O2 fuel cells, showing great potential for large-scale practical applications. Thus, this study provides a platform to transform conventional fuel cell technology through the rational design and development of advanced energy conversion and storage devices by coupling different electrocatalytic reactions.

Bacterial cellulose/multi-walled carbon nanotube composite films for moist-electric energy harvesting

Generation of renewable and clean electricity energy from ubiquitous moisture for the power supply of portable electronic devices has become one of the most promising energy collection methods. However, the modest electrical output and transient power supply characteristics of existing moist-electric generator (MEG) severely limit its commercial application, leading to an urgent demand of developing a MEG with high electrical output and continuous power generation capacity. In this work, it is demonstrated that a flexible bacterial cellulose (BC)/Multi-walled carbon nanotube (MWCNT) double-layer (BM-dl) film prepared by vacuum filtration can maintain the moisture concentration difference in the film MEG. Unlike previous studies on cellulose based MEG, BM-dl film has a heterogeneous structure, resulting in a maximum output power density of 0.163 μW/cm2, an extreme voltage of 0.84 V, and current of 2.21 μA at RH = 90 %. BM-dl MEG can generate a voltage of 0.55 V continuously for 45 h in a natural environment (RH = 63–77 %, T = 26–27 °C), which is in a leading level among existing reported cellulose-based MEGs. In summary, this study provides new ideas for innovative design of MEG, which is highly competitive in terms of energy supply for the Internet of Things and wearable devices.

Hybrid Piezoelectric/Triboelectric Wearable Nanogenerator Based on Stretchable PVDF-PDMS Composite Films.

Hybrid piezoelectric/triboelectric nanogenerators combine the merits of piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs), possessing enhanced electrical output and sensitivity. However, the structures of the majority of hybrid nanogenerators are rather complex in integrating both functions, limiting their practical application in wearable electronics. Herein, we propose to construct a piezoelectric/triboelectric hybrid nanogenerator (PT-NG) with a simple structure based on a composite film to simultaneously achieve the coupling of piezoelectric charge generation and triboelectrification with improved energy conversion efficiency. The composite film consists of electrospun PVDF nanofibers embedded in the surface of the PDMS film, which not only forms a rough nanomorphology on the surface of PDMS but also provides structural protection to the PVDF nanofibers by PDMS during compressive deformation. The results have shown that the PT-NG can generate much higher electrical outputs than individual TENG and PENG devices. The PT-NG devices exhibit a high level of mechanical-to-electrical energy conversion efficiency with superior performance in charging capacitors and functioning as self-powered wearable sensors for the detection of different signals from finger movement, the recognition of various gestures, and the monitoring of respiration. More importantly, the composite device possesses an impressive structure durability, maintaining its layered structure over 5000 testing cycles without noticing any obvious damage on the nanofibers or detachment between the layers. Our results have demonstrated that the combining of piezoelectric nanofibers and triboelectric substrate is an efficient way to fabricate highly efficient energy harvesting devices for intelligent identification and health monitoring.

Multifunctional PVDF/CeO2@PDA nanofiber textiles with piezoelectric and piezo-phototronic properties for self-powered piezoelectric sensor and photodetector

In recent years, multifunctional sensors have attracted significant attention due to their ability to detect different types of signals. However, it still remains a challenge to develop flexible materials with multiple sensing functions. Herein, we propose a strategy to fabricate multifunctional flexible textiles (PCP) that can apply piezoelectric and piezo-phototronic effects to self-powered piezoelectric sensor and photodetector (PD) by utilizing the synergistic effect of polydopamine-coated cerium oxide (CeO2@PDA) nanoparticles and poly (vinylidene fluoride) (PVDF). The CeO2@PDA nanoparticles served as local nucleating agents and photosensitizers for the PVDF, enhancing the polar crystalline phase and inducing piezoelectric effect, semiconductor, and optical process coupling in PCP textiles. The piezoelectric sensors consisting of PCP textiles produced extremely high sensitivity (1–10 kPa: 1.27 V/kPa; 10–50 kPa: 0.085 V/kPa; 50–100 kPa: 0.02 V/kPa) and significant electrical output (25.5 V and 0.37 μA). Besides, the piezoelectric sensor had extensive applications including pulse wave measurement, limb motion detection, and active voice recognition. It's especially noteworthy that the PD based on PCP textiles is sensitive for the detecting of sunlight illumination as confirmed by response time (tOn = 2 s and tOff = 4.6 s). Meanwhile, the fabricated self-powered PD showed significant improvement in output current, confirming the realization of the piezo-phototronic effect in PCP textiles. In this work, the low-cost and high-efficiency multifunctional sensing materials were successfully prepared, providing a novel approach for the next generation of self-powered piezoelectric sensors and photodetectors.

Calcium copper titanate incorporated polydimethylsiloxane flexible composite film-based triboelectric nanogenerator for energy harvesting and self-powered sensing applications

Triboelectric energy harvesters offer an efficient way to convert mechanical energy harvested by everyday human body actions into electrical energy. Triboelectric nanogenerators (TENGs) are an attractive solution for power supply concerns in the development of portable electronic gadgets and self-powered sensor applications. Herein, a dielectric calcium copper titanate (CaCu3Ti4O12 (CCTO)) ceramic material was synthesized by a solid-state reaction process. The synthesized particles were embedded in polydimethylsiloxane (PDMS) polymer to form a CCTO/PDMS flexible composite film (FCF)-based TENG, called a CCTO FCF-TENG, which is light-weight, simple, and suitable for use. The dielectric properties, surface charge density, and electrical conductivity of the FCF were greatly improved by the addition of the CCTO particles into the PDMS, resulting in excellent electrical output performance of the corresponding CCTO FCF-TENG. The CCTO FCF-TENG device was constructed with the CCTO/PDMS FCF, which functioned vertically against a cellulose paper to optimize a high and stable electrical output. Furthermore, the filler concentration and film thickness optimization was studied more to achieve the highest output power of the CCTO FCF-TENG. The optimized CCTO FCF-TENG exhibited the highest electrical output voltage, current, charge density, and power density of ∼250 V, ∼6.5 μA, ∼70 μC/m2, and ∼3.15 W/m2, respectively. The mechanical stability and durability of the CCTO FCF-TENG were systematically analyzed. The practical and real-time applications of the packed CCTO FCF-TENG were systematically investigated under various harsh environmental conditions. Finally, the packed CCTO FCF-TENG successfully powered several low-power portable electronics and was also used as a self-powered sensor to sense biomechanical actions in everyday human body activities.

Super-elastic microstructured triboelectric fibers and textiles fabricated by extrusion and thermal drawing for smart-home applications

Flexible and wearable textile-based triboelectric nanogenerators (TENGs) have attracted extensive attention in wearable electronics owing to their ability to convert waste mechanical energy from human motion into electrical energy. However, the performances of TENGs are lower than those of planar/film configurations due to the complex fiber fabrications and limited mechanical freedom. In this work, we demonstrate an extrusion method combined with thermal drawing (ETD method) for continuous and scalable triboelectric fiber fabrication, providing longitudinal uniform fibers for hundreds of kilometers. Based on the ETD method, super-elastic microstructured triboelectric fibers (SMTFs) were fabricated, consisting of hollow elastomeric and liquid metal cores (EGaIn). The SMTFs showed excellent superelasticity with clear and uniform microstructures. The fibers could withstand strain up to 1800% and exhibited excellent electrical output performance. Utilizing a single fiber as the medium for triboelectric energy collection, the average open circuit voltage and instantaneous power density are respectively up to 210 V/m and 21 μW/m with a 40 MΩ external load resistance. The SMTFs could also be woven into deformable textiles with high electrical outputs up to 160 V, 10 μA, and 50 nC. In addition, the SMTFs-based textiles were further demonstrated as completely soft and stretchable components for self-powered sensing in smart home applications.

Imine-vitrimer elastomer enabled triboelectric nanogenerators with remarkable electrical output and circular life cycles

Triboelectric nanogenerator (TENG) has garnered significant attention as a promising technology for energy harvesters and flexible electronics. However, the current state-of-the-art TENGs suffer from the low electrical output and limited lifespan, which pose significant obstacles to their broader implementation. Therefore, a TENG with ultra-high electrical output and circular life cycles is developed by combining dynamic covalent chemistry and TENG technologies. Specifically, imine-vitrimer elastomers (IVEs) with excellent compression resilience are synthesized and utilized to fabricate TENG as an electronegative tribolayer. The assembled TENG can generate ∼18-fold higher electrical charge density than traditional PTFE-based TENG. This substantial improvement enables the TENG to power over 2400 commercial LEDs, showcasing the great potential for high-sensitivity traffic sensors and energy intensive devices. Moreover, to solve inevitable wear or tear of the tribolayers during mechanical friction, efficient self-healing and recycling of the tribolayer are achieved, ensuring consistently high electrical output and durability. This study provides a new sight to fabricate the next generation TENG with high performance and circular life cycles.

Mechanical and Acoustic-Driven BiFeO3 Composite Films-Based Hybrid Nanogenerator for Energy Harvesting and Sensing Applications.

Nanogenerators for acoustic energy harvesting are still in the early stage of development, and many challengessuch asthe optimization of device structure and the design of efficient and sensitive materialsneed to beaddressed.To solve the above-mentioned problems,herein, advancement in synthesized multiferroic material for hybridizing the nanogenerator and efficient harvesting of various energies such as acoustic, mechanical, and vibrational energies is reported. Initially, bismuth ferrate (BiFeO3, BFO)-based composite films are prepared with high ferroelectric and dielectric coefficients. The hybrid nanogenerator (HNG) based on a 3D-printed structure has the highest electrical output which is further improved depending on the BFO loading concentration in the composite film. The 0.5 wt% BFO-loaded PVDF-based HNG offers the enhanced open circuit voltage, short circuit current, and charge density values of ≈30V, ≈1µA, and ≈10 µC/m2, respectively. The optimized HNG is employed to harvest mechanical energy from everyday human life. Furthermore, the HNG layers are used in the fabrication of a multi-energy harvester/sensor (MEH/S) which can harvest/sense various vibrational and acoustic energies under different acoustic frequencies and amplitudes, respectively. The harvested energy from the MEH/S is tested to power portable electronics.

Improved Electrical Output Performance of Cellulose-Based Triboelectric Nanogenerators Enabled by Negative Triboelectric Materials.

Cellulose-based triboelectric nanogenerators (TENGs) have attracted widespread attention due to the low cost and environmentally friendly characteristics of cellulose. However, achieving high electrical energy output from these generators still presents significant challenges. Here, cellulose is dissolved-regenerated to form a composite aerogel with high specific surface area, in which cellulose-based composites with excellent negative triboelectric properties are developed by coupling the rich 3D network structure of the regenerated cellulose aerogel, modified barium titanate, and poly(vinylidene fluoride). The TENGs assembled from the composite materials exhibit an output voltage of 1040V and a current of 1.165mA at an external force of 8 N and a frequency of 4Hz, outperforming all cellulose-based negative triboelectric materials. In addition, the nanogenerators have a stable electrical energy output capacity, with no significant property degradation in 100000 contact-separation tests. The excellent electrical output property of the composite materials enables them to harvest energy from human movement and waterdrops, demonstrating their great application prospects in wearable devices, energy harvesting devices, self-powered sensors, and other fields.

Achieving Ultra‐Durability and High Output Performance of Triboelectric Nanogenerators

AbstractWith rapid development of the Internet of Things (IoTs) era, a variety of miniaturized and distributed electronics appear in every corner of industrial production and daily life. The shortage of fossil fuels requires renewable clean energy to replace traditional energy to meet the needs of smart and low‐power devices. Triboelectric nanogenerator (TENG) is a new technology for converting high‐entropy mechanical energy into electric energy to power these devices. However, improving the output energy and durability of TENG remains a considerable challenge for practical applications. To solve these problems and push forward its commercialization process, this paper systematically reviews how to improve the durability of the sliding mode TENG (S‐TENG) from the aspects of material optimization and structural design. Besides, a variety of ways are introduced to improve the electric output of the S‐TENG under the premise of high durability. At last, challenges and future research focus in this field are also predicted, which provide a guideline for the research of the high electric output and ultra‐durability TENG for highly efficient energy harvesting and self‐powered sensing applications in the IoTs.

Hybrid PV/PRC energy system for thermal management of photovoltaics and nocturnal radiative cooling

Under high climatic conditions and intense sunlight, the efficiency and reliability of photovoltaic (PV) systems can rapidly deteriorate due to elevated temperatures. Passive radiative cooling (PRC) technology is a common solution for the thermal optimization of PV systems, as it offers an energy-efficient and environmentally conscious cooling process. This research proposes an advanced hybrid energy system that integrates a radiative cooler, in the form of a photonic structure, with a C-Si solar cell. The photonic structure consists of a multilayer design with a SiO2 grating surface positioned on top. This configuration reduces the operating temperature of the solar cell and preserves its transmissivity within the conversion bandgap range.Numerical results, based on thermal diffusion theory, demonstrate that the hybrid design can generate a very high diurnal electricity output of 83w/m2, with a nighttime cooling capacity of 147w/m2. This represents a 10 % and 40 % improvement compared to bare silicon. Furthermore, when the proposed cooler is applied to the front surface of the solar panel, it induces a PRC effect, resulting in a temperature decrease of approximately 3 K. We believe that the radiative cooler can also be applied to other types of solar cells, including those based on thermoelectric generators, to extract electricity from the radiative cooler during nighttime.

ELECTROCHEMICAL PARAMETERS OF MICROBIAL FUEL CELLS BASED ON THE MICROCOCCUS LUTEUS STRAIN, NEW ION-EXCHANGE MEMBRANES AND VARIOUS SUGARS

We studied the physicochemical and electrochemical characteristics of microbial fuel cells (MFCs) with a new proton-exchange membrane. It was synthesized on the basis of zeolite-doped polyvinyl alcohol cross-linked with sulfosuccinic acid (PVA-SSA-BEA). An MF-4SK industrial membrane (Plastpolymer, Russia) was used as a comparative sample. Various sugars were added as substrates (glucose, arabinose, galactose, xylose). The role of the bioagent was performed by the strain Micrococcus luteus 1-i. MFCs with PVA-SSA-BEA and MF-4SK membranes showed rather close electrochemical characteristics. A higher electricity output was performed with the addition of glucose, galactose, the lowest - with the use of xylose. The data obtained indicate that the proposed PVA-SSA-BEA membrane is promising for use as an alternative to proton-exchange membranes widely used in fuel cell technology.

Robust integration of energy harvesting with daytime radiative cooling enables wearing thermal comfort self-powered electronic devices

Wearable triboelectric nanogenerators (TENGs) exhibit high flexibility and electric output, and are highly desirable in wearable electronics, soft robotics, and healthcare. Despite significant progress in wearables, achieving versatile integration (e.g. elasticity and permeability) and ensuring thermal comfort when wearing TENGs remain challenging. We mitigate this challenge by fabricating an ultra-stretchable, waterproof, and air/moisture permeable nonwoven textile via the electrospinning of styrene–ethylene–butylene–styrene assisted by electrospraying poly(vinylidene fluoride-co-hexafluoropropylene)/SiO2 to integrate passive radiative cooling technology into the TENG system. The co-deposited PVDF-HFP/SiO2 micro-nanoparticles exhibit excellent triboelectric and radiative cooling performances and can serve as binders and hydrophobic agents. Combining this with the stretchable liquid metal–superlyophilic electrode, our wearable TENG device offers an excellent triboelectric output (114.5 V, 445 mW/m2 under 25 N) that can be used to power small electronics and monitor human movements (e.g. finger tapping and walking). Moreover, the integrated TENG-based radiative cooling textile with high values of Rsolar (83%) and εLWIR (95%) offers cooling by ∼9.5 °C under sunlight as compared with cotton. This study contributes to the development of wearing thermal comfort textile-based TENGs for electricity generation, self-powered sensing, and zero-energy input cooling.

Sustainable Solutions for Oral Health Monitoring: Biowaste-Derived Triboelectric Nanogenerator.

Oral healthcare monitoring is a vital aspect of identifying and addressing oral dental problems including tooth decay, gum pain, and oral cancer. Day by day, healthcare facilities and regular checkups are becoming more costly and time-consuming. In this context, consumers are moving toward advanced technology, such as bite sensors, to obtain regular data about their occlusal chewing patterns and strength. The triboelectric nanogenerator (TENG) can potentially eliminate the need for a battery by simply converting abundant vibrations from nature or human motion into electrical energy. In this work, biomaterials are obtained from biowastes such as cellulose from wood waste, chitosan from crab shells, and gelatin from fish scales. All wastes are biodegradable, and our work aims at sustainability and waste hierarchy. The single electrode mode-based TENG was designed and fabricated using biodegradable poly(vinyl alcohol) (PVA)-biomaterial composites, rice paper as a substrate, and edible silver leaf as an electrode. The highest electrical output was obtained for PVA/chitosan 10 wt % composite-based TENG (PC10) of about 20 V, 200 nA, and 12 nC. The biomechanical energy harvesting was measured, and powering of LED was demonstrated using a PC10 TENG device. A biocompatible bite sensor based on the TENG was used to measure the biting force of a dummy teeth model to demonstrate its potential use in dental health applications. It indicates the promising future value of disposable oral medication devices without any invasive surgery or injection.

Tribo-sanitizer: A portable and self-powered UV device for enhancing food safety

Food safety is of constant major concern worldwide. Each year, hundreds of millions of people fall ill due to consuming contaminated food, and the resulting economic loss runs into hundreds of billions of dollars. To mitigate these issues, we developed Tribo-sanitizer, which utilizes a freestanding rotational triboelectric nanogenerator (FSR-TENG) to convert mechanical energy into sustainable, low-cost or free electricity that powers an ultraviolet-C (UVC) lamp for food-safety applications. Thanks to the air gap in its circuit – a design inspired by a natural phenomenon, lightning, which can lead to electrical breakdown of air – the optimal FSR-TENG can generate a high voltage output of more than 4,000 V. This high electrical output, in turn, enables brighter illumination of the UVC lamp. Tribo-sanitizer’s decontamination efficacy was evaluated against a gram-positive bacterial strain (Listeria monocytogenes) and a gram-negative one (Escherichia coli O157:H7) inoculated in a liquid buffer, on a polymer widely used in the food-packaging industry, and on two types of fresh produce. Tribo-sanitizer achieved a 5.03-log reduction and a 5.95-log reduction for E. coli O157:H7 in buffer solution and on polyethylene terephthalate (PET), respectively, in line with the 5-log reduction recommended in government guidelines for microbial control. The log reductions for L. monocytogenes in buffer solution and on PET were 4.36 and 3.81, respectively. Lesser effectiveness was observed with the apples and romaine lettuce, likely due to these fresh produce samples’ greater surface roughness as compared to PET, one of the most widely used polymers for the construction of food packaging and drinks bottles. Our results also demonstrate that biomechanical motions can provide Tribo-sanitizer with sufficient power to achieve bacterial inactivation, demonstrating its excellent potential for use in low-resource settings. With further improvements, it could help mitigate severe food-safety problems around the world, leading to a more secure and sustainable food system.

Optimizing the design of wide magneto-mechano-electric generators to maximize their power output and lifetime in self-powered environmental monitoring systems

Magneto-mechano-electric (MME) generators are increasingly being investigated as a sustainable power source for Internet of Things (IoT) systems owing to their ability to efficiently harvest electrical energy from stray magnetic field noise. However, to be practical, this technology must achieve a longer lifespan while maintaining high-power output and withstanding magnetic field fluctuations. To address this, extensive numerical simulations and experimental verifications have been performed to amplify the magneto-mechanic vibration by increasing the magnetic proof mass volume, generate high electrical output through a larger active piezoelectric volume, and enhance lifetime by optimizing the cantilever structure in a wide-structural MME architecture. MME generators with a wide and short (WS) trapezoidal structure (WS-MME) have demonstrated excellent performance, with a high output power of 7.4 mW (equivalent power density of 0.58 mW/cm3. Oe) and an excellent lifespan of over 1012 fatigue cycles under a magnetic noise field level of 3 Oe. Moreover, a self-powered environmental IoT sensor node has been demonstrated by continuously powering the multifunctional (temperature, humidity, light, sound noise, UV index, pressure, discomfort index, and heatstroke) sensor and wireless communication systems by utilizing the stray magnetic field noise around the electrical power cables of various home appliances. In conclusion, the combination of a longer lifespan and high-power generation achieved with WS-MME generators is a significant step towards the commercialization of MME generators for powering wireless sensor technology.

Surface Carbonized Natural Wood via Hydrogen–Oxygen Flame for Electricity Generation from Water Evaporation

Water evaporation-induced power generation technologies based on the interaction between water and nanomaterials have received wide attention over the years. Herein, a natural wood-based water evaporation-induced power generator (EIPG) via the surface carbonization technique under high-temperature hydrogen–oxygen flame was developed. The unique surface carbonization strategy made the internal layer (uncarbonized layer) maintain high hydrophilicity to satisfy the stable and continuous capillary flow for the transport of ions. The internal layer possessed a higher surface charge density, promoting the establishment of the electric double layer (EDL), which ensured high selectivity of the wood channels for positive ions. Meanwhile, the external carbonized layer could effectively adsorb positively charged ions through strong cation−π interactions to strengthen the EDL effect. The carbonized layer also provided an electrical charge transportation channel, lowering the resistance of the device. The device could continuously generate power with an open-circuit voltage (Voc) of ∼170 mV and a short-circuit current (Isc) of ∼730 nA over 24 h, exhibiting excellent stability. Moreover, a higher electric output was generated by the water EIPG through assembling several devices in series or parallel and applied successfully in charging capacitors and powering a commercial digital calculator. This work provides a different strategy for developing an environment-friendly and low-cost water EIPG utilized in harvesting green energy, with no chemical treatment.

Bioinspired and Biodegradable Functionalized Graphene Oxide/Deacetylated Cellulose Acetate Composite Janus Membranes for Water Evaporation-Induced Electricity Generation

Harvesting electricity from natural water evaporation has recently become a popular research direction owing to its spontaneity, ubiquitousness, and sustainability. In this study, we demonstrate a bioinspired composite Janus membrane based on functionalized graphene oxide (FGO)/deacetylated cellulose acetate (dCA) nanofiber. FGO has a high surface charge and a low oxygen to carbon atom ratio (OAC/CAC), which helps attract ions and facilitate the transfer of carriers. The hydrophilic dCA not only provides a driving force for water and ion transport in FGO but also accelerates water evaporation in the composite Janus membrane, thereby increasing the electrical output. As a result, a small piece of the membrane can provide ∼316 mV and ∼997 nA of voltage and current, respectively. The high electric energy output could be easily achieved through series and parallel expansion of the membrane and utilized to supply power to electronics or for capacitor charge. Once the generator has reached the end of its life cycle, dCA can be effortlessly biodegraded within a week without posing a threat to the environment. This work establishes a new paradigm for developing high-performance biodegradable electricity generators powered by water evaporation.

Research on nano-film composite lubricated triboelectric speed sensor for bearing skidding monitoring

Triboelectric speed sensors (TSS) have the advantage of easy integration to be used to monitor the bearing skidding. However, dry friction between materials can reduce the durability and stability of TSS and interfere with the operation of the cage. In this paper, BaTiO3/polyimide (BTO/PI) nanocomposite films and lubricants are introduced to triboelectric nanogenerator (TENG) and the effects of lubricant species and nanoparticles doping mass fraction on tribological and electrification performance are investigated. The results show that the TENG with squalane and BTO/PI nanocomposite film of 20 wt% has a lower friction coefficient and mass loss while higher output and stability. Then, the nano-film composite lubricated TSS (NFCL-TSS) integrated with bearing is constructed based on the rotary freestanding TENG (RF-TENG) with optimal nanocomposite film and squalene, where the signal processing circuit with wireless transmission is integrated on the back of RF-TENG stator to improve the integration of the sensing system. The results show that the NFCL-TSS has 84.81% lower mass loss, 95.26% and 97.75% higher electrical output and stability than that of the TSS with pure PI under dry conditions, respectively. Moreover, the cage speed before and after installation of NFCL-TSS remains mostly unchanged, and the error between the cage speed measured by NFCL-TSS and commercial sensor is below 0.26%. Finally, based on the bearing test platform, the monitoring of skidding is achieved by NFCL-TSS under different speeds and loads. This study provides a new strategy for the design of TSS with high durability, stability and integration.