Graphene Fibers Research Articles

Flexible thermocouple using a thermoelectric graphene fiber with a seamless junction

Temperature is an important physical variable that indicates the condition of the human body and artificial systems. Advanced wearable applications require the development of temperature sensors with different form factors. In this study, a fiber-shaped thermoelectric temperature sensor is fabricated using a continuous graphene fiber whose two halves possess different reduction states. A seamless junction is formed by partially reducing a wet-spun graphene oxide fiber with hydroiodic acid (HI) solutions of different concentrations. One-half of the fiber is mildly reduced with 0.97 wt% HI, while the other half is highly reduced with 30.6 wt% HI. The different reduction states of the graphene composite fiber result in different Seebeck coefficients, allowing for the fabrication of a fiber-shaped graphene thermocouple without any laborious assembly. The flexible graphene thermocouple exhibits high sensitivity with a thermopower of 12.5 μV K–1 in the temperature range of room temperature to ∼70 °C. Furthermore, it exhibits high linearity with a correlation coefficient exceeding 0.995 and fast response with a time constant of 0.24 s. Owing to its mechanical robustness and flexibility, the stand-alone graphene thermocouple can be knitted into a cotton fabric glove, which presents a fast response to environmental changes without any external power source. This work offers a unique fabrication method for producing a high-performance, flexible thermocouple that features a seamless and clear junction without the use of additional materials. This alternative method eliminates the complicated assembly processes typically required for conventional thermocouples.

Road use and electrothermal performance of graphene-conductive asphalt-recycled pervious concrete under severe cold environment

Conductive-asphalt-recycled pervious concrete alleviates the urban “heat island effect” and “rain island effect” to realize the resourceful and efficient use of waste concrete and also reduces the probability of urban snow and ice disasters to ensure the safety of winter operation of asphalt pavements in cold areas. This study presents a theoretical and technical basis for ensuring the winter operational safety of asphalt pavements in cold regions. First, we compound graphene and carbon fiber as conductive phase materials and prepare graphene-conductive asphalt-recycled permeable concrete using recycled coarse aggregates with straight top and bottom holes. Then, we analyzed the electrical conductivity, road performance, and electrothermal performance of the specimens prepared using different recycled coarse aggregate substitution rates under different snowfall levels to determine their snow melting efficiency and verify their application in cold regions. The results indicate that the quality of the recycled aggregates is high, the optimal conductive filler ratio is 0.3% polyacrylonitrile-based carbon fiber and 1.5% graphene by mass of asphalt, and the resistivity of the specimens is only 3.2 Ω·m. Moreover, the conductivity and road performance of the graphene-conductive asphalt-recycled concrete decreases with an increase in the replacement rate of the recycled coarse aggregate, and the artificially prefabricated upper and lower through holes affect the conductivity of the specimens to a certain extent. Further, the graphene-conductive asphalt-recycled pervious concrete shows excellent snow melting potential, and as the required snow melting thickness and snow melting time increase, the effect of pervious asphalt slabs for snow melting efficiency becomes more significant. Moreover, when the replacement rate of the recycled concrete aggregate is within the range of 0–50%, it can be completed in 2–3 h under different snowfall levels of snow melting requirements.

Comparative analysis between Graphene and Carbon Nanotube reinforced epoxy composite

Composite structures are very high in demand because of their high strength-to-weight ratio and directional strength. The arrangement of fibers in the matrix is the major design criterion for the composites. Past studies prove that the fiber reinforcement of carbon nano allotropes such as Carbon Nanotubes (CNTs) and Graphene fibers develop reliable and durable structures for different applications. In this work, three different composite laminate sheets are designed and modeled using finite element analysis (FEA) software. Carbon nano allotropes, CNTs, Graphene, and CNT-Graphene fibers are used as reinforcements in the resin epoxy matrix. The modeled laminate sheets are analyzed for deformation and stress distribution using Hashin’s Failure criteria. The FEA results indicate that the CNTs fiber-reinforced laminate shows minimum deformation (0.000064 mm) and experiences minimum stress (3.81 MPa) compared to Graphene and CNT-Graphene reinforced laminates. The results of FEA can be used as a research basis for further study of composites in the future.

Defects boost graphitization for highly conductive graphene films.

Fabricating highly crystalline macroscopic films with extraordinary electrical and thermal conductivities from graphene sheets is essential for applications in electronics, telecommunications and thermal management. High-temperature graphitization is the only method known to date for the crystallization of all types of carbon materials, where defects are gradually removed with increasing temperature. However, when using graphene materials as precursors, including graphene oxide, reduced graphene oxide and pristine graphene, even lengthy graphitization at 3000°C can only produce graphene films with small grain sizes and abundant structural disorders, which limit their conductivities. Here, we show that high-temperature defects substantially accelerate the grain growth and ordering of graphene films during graphitization, enabling ideal AB stacking as well as a 100-fold, 64-fold and 28-fold improvement in grain size, electrical conductivity and thermal conductivity, respectively, between 2000°C and 3000°C. This process is realized by nitrogen doping, which retards the lattice restoration of defective graphene, retaining abundant defects such as vacancies, dislocations and grain boundaries in graphene films at a high temperature. With this approach, a highly ordered crystalline graphene film similar to highly oriented pyrolytic graphite is fabricated, with electrical and thermal conductivities (∼2.0× 104 S cm-1; ∼1.7 × 103W m-1 K-1) that are improved by about 6- and 2-fold, respectively, compared to those of the graphene films fabricated by graphene oxide. Such graphene film also exhibits a superhigh electromagnetic interference shielding effectiveness of ∼90dB at a thickness of 10μm, outperforming all the synthetic materials of comparable thickness including MXene films. This work not only paves the way for the technological application of highly conductive graphene films but also provides a general strategy to efficiently improve the synthesis and properties of other carbon materials such as graphene fibers, carbon nanotube fibers, carbon fibers, polymer-derived graphite and highly oriented pyrolytic graphite.

Anisotropic Shape Memory Composite for Dynamically Adjustable Electromagnetic Interference Shielding

Smart electromagnetic interference (EMI) shielding materials that enable dynamical adjustment of electromagnetic wave transmission are highly desirable for various applications. Nevertheless, ordinary materials show nonadjustable EMI shielding performance after deployment. Herein, an anisotropic smart EMI shielding composite is presented, which shows tunable EMI shielding effectiveness by rotation, shape memory, and simple stacking. The composite possesses a sandwich structure consisting of two graphene fibrous films (GFFs) with intermediate shape memory poly(ethylene-co-vinyl acetate) (EVA). Owing to the aligned graphene fibers of GFF, the GFF/EVA composite showed anisotropic mechanical property, shape memory property, and shielding effectiveness. The composite shows high tensile strength but declined shape memory property in the axial direction (0°) of the graphene fibers. In the 0° direction of the GFF/EVA composite, a total shielding effectiveness (SET) of >40.8 dB in the X-band is observed, which is much higher than that in the 90° direction (vertical, <8.1 dB). The rotation-modulated EMI shielding of GFF/EVA is achieved by the anisotropy-dependent EMI shielding performance. Moreover, tunable EMI shielding is demonstrated through the shape memory process of the composite and the average SET can be adjusted in the range from 43.2 to 33.1 dB by fixing a tensile strain from 0 to 100%. Furthermore, the EMI shielding of the multilayered composite can be modulated by stacking individual GFF/EVA composites at different angles. The smart GFF/EVA composite with tunable and function-switchable features is demonstrated, which will contribute to the development of smart EMI shielding materials and devices for electromagnetic applications in various fields.

Preparation and Properties of Composite Graphene/Carbon Fiber Pouring Conductive Asphalt Concrete.

To solve the problem of snow on steel bridge areas endangering traffic safety and low road traffic efficiency in winter, conductive gussasphait concrete (CGA) was prepared by mixing conductive phase materials (graphene and carbon fiber) into Gussasphalt (GA). First, through high-temperature rutting test, low-temperature bending test, immersion Marshall test, freeze-thaw splitting test and fatigue test, the high-temperature stability, low-temperature crack resistance, water stability and fatigue performance of CGA with different conductive phase materials were systematically studied. Second, the influence of different content of conductive phase materials on the conductivity of CGA was studied through the electrical resistance test, and the microstructure characteristics were analyzed via SEM. Finally, the electrothermal properties of CGA with different conductive phase materials were studied via heating test and simulated ice-snow melting test. The results showed that the addition of graphene/carbon fiber can significantly improve the high-temperature stability, low-temperature crack resistance, water stability and fatigue performance of CGA. The contact resistance between electrode and specimen can be effectively reduced when the graphite distribution is 600 g/m2. The resistivity of 0.3% carbon fiber + 0.5% graphene rutting plate specimen can reach 4.70 Ω·m. Graphene and carbon fiber in asphalt mortar construct a complete conductive network. The heating efficiency of 0.3% carbon fiber + 0.5% graphene rutting plate specimen is 71.4%, and the ice-snow melting efficiency is 28.73%, demonstrating good electrothermal performance and ice-snow melting effect.

Three-Dimensional Hollow Reduced Graphene Oxide Tube Assembly for Highly Thermally Conductive Phase Change Composites and Efficient Solar-Thermal Energy Conversion.

Due to their extraordinary mechanical strength and electrical and thermal conductivities, graphene fibers and their derivatives have been widely utilized in various functional applications. In this work, we report the synthesis of a three-dimensional (3D) hollow reduced graphene oxide tube assembly (HrGOTA) using the same wet spinning method as graphene fibers. The HrGOTA has high thermal conductivity and displays the unique capability of encapsulating phase change materials for effective solar-thermal energy conversion. The HrGOTA comprises layers of moisture-fused hollow reduced graphene oxide tubes (HrGOTs), whose individual thermal conductivity is up to 578 W m-1 K-1. By impregnating 1-octadecanol into HrGOTs, a 1-octadecanol-filled HrGOT phase change composite (PCC) with a latent heat of 262.5 J g-1 is obtained. This high latent heat results from the interfacial interaction between 1-octadecanol and the reduced graphene oxide tube, as evidenced by the shifts in XRD patterns of 1-octadecanol-filled and 1-octadecanol/multiwalled carbon nanotube-filled HrGOTA samples. In addition, 1 wt % multiwalled carbon nanotubes are added to the PCC to enhance visible light absorption. Because of their high thermal conductivity and visible light absorption rates, these new PCCs display high solar-thermal energy conversion and storage efficiencies of up to 81.7%, commensurate with state-of-the-art carbon-based PCCs but with significantly lower carbon weight percentages.

Precursor-mediated in situ growth of hierarchical N-doped graphene nanofibers confining nickel single atoms for CO2 electroreduction

Despite the various strategies for achieving metal-nitrogen-carbon (M-N-C) single-atom catalysts (SACs) with different microenvironments for electrochemical carbon dioxide reduction reaction (CO2RR), the synthesis-structure-performance correlation remains elusive due to the lack of well-controlled synthetic approaches. Here, we employed Ni nanoparticles as starting materials for the direct synthesis of nickel (Ni) SACs in one spot through harvesting the interaction between metallic Ni and N atoms in the precursor during the chemical vapor deposition growth of hierarchical N-doped graphene fibers. By combining with first-principle calculations, we found that the Ni-N configuration is closely correlated to the N contents in the precursor, in which the acetonitrile with a high N/C ratio favors the formation of Ni-N3, while the pyridine with a low N/C ratio is more likely to promote the evolution of Ni-N2. Moreover, we revealed that the presence of N favors the formation of H-terminated edge of sp2 carbon and consequently leads to the formation of graphene fibers consisting of vertically stacked graphene flakes, instead of the traditional growth of carbon nanotubes on Ni nanoparticles. With a high capability in balancing the *COOH formation and *CO desorption, the as-prepared hierarchical N-doped graphene nanofibers with Ni-N3 sites exhibit a superior CO2RR performance compared to that with Ni-N2 and Ni-N4 ones.

Mechanics of reinforcement in a hybrid graphene and continuous glass fibre reinforced thermoplastic

Hybrid nanomaterial-fibre-reinforced polymer composites show considerable promise but are often limited by the poor dispersion of the nanofillers, with filtering by the fibre weave being a common issue. Herein, a hybrid continuous glass fibre reinforced polymer (GFRP) was prepared based upon a polypropylene matrix, woven E-glass fibre (GF) and graphene nanoplatelets (GNP). The GNP flakes were melt-mixed with a polypropylene-graft-maleic anhydride (PP-MAH) compatibiliser and then melt-coated onto the GF mats, followed by layer-by-layer assembly using polypropylene films and coated fibre mats in a hot press. It was found that the stiffness and strength of the GFRP were increased by up to ∼3 GPa (25%) and ∼120 MPa (95%), respectively, by the addition of up to only ∼ 1.7 vol% of the GNP, to the composite. The experimental results enable us to extend our previous theory of mechanics of reinforcement by 2D materials to FRP. In-situ Raman band shift measurements on the flakes close to the glass fibres under strain found that the effective modulus of the flake is ∼130 GPa, indicating that a higher reinforcing efficiency of graphene was obtained in the FRP than in neat polymers due to improved local reinforcement effect of the matrix in the FRP.

Thermoresponsive Conductivity of Graphene-Based Fibers.

Smart materials are versatile material systems which exhibit a measurable response to external stimuli. Recently, smart material systems have been developed which incorporate graphene in order to share on its various advantageous properties, such as mechanical strength, electrical conductivity, and thermal conductivity as well as to achieve unique stimuli-dependent responses. Here, a graphene fiber-based smart material that exhibits reversible electrical conductivity switching at a relatively low temperature (60°C), is reported. Using molecular dynamics (MD) simulation and density functional theory-based non-equilibrium Green's function (DFT-NEGF) approach, it is revealed that this thermo-response behavior is due to the change in configuration of amphiphilic triblock dispersant molecules occurring in the graphene fiber during heating or cooling. These conformational changes alter the total number of graphene-graphene contacts within the composite material system, and thus the electrical conductivity as well. Additionally, this graphene fiber fabrication approach uses a scalable, facile, water-based method, that makes it easy to modify material composition ratios. In all, this work represents an important step forward to enable complete functional tuning of graphene-basedsmart materials at the nanoscale while increasing commercialization viability.

Analysis of thermoelectric effect of wet spun graphene fiber composites

Abstract In this manuscript, we have theoretically reanalyzed data prepared and already published by Foroughi et al. (RSC Adv 2016;6:46427–32). These data concern the thermal energy dependence of the electrical conductivity of the samples: graphene fiber, graphene/poly(3,4-ethylenedioxythiophene) (graphene/PEDOT), graphene/carbon nanotube (graphene/CNT) and graphene/carbon nonotube/poly(3,4-ethylenedioxythiophene) (graphene/CNT/PEDOT) composite fibers. We investigate the behavior of the thermal conductivity for these four samples. These samples are considered as thermoelectric materials or green energy conversion materials using the Seebeck effect to transform heat into electrical energy and vice versa. In this context, the optimization of the merit factor ZT remains a challenge for the scientific community. The objective of this investigation is to evaluate and characterize the thermoelectric efficiency of the above-mentioned samples. We confront the experimental data with the existing theoretical models. The thermoelectric efficiency is generally characterized by the merit factor ZT. The maximum ZT of about 1,2 is obtained in the graphene fiber and between 0,1 and 0,2 in the others samples. The performance of the material depends on ZT; indeed a high ZT ($\mathrm{ZT}\ge 1$) corresponds to a better optimization of the composite.

Ultrasensitive, Fast-Responsive, Directional Airflow Sensing by Bioinspired Suspended Graphene Fibers

The development of high-performance miniaturized and flexible airflow sensors is essential to meet the need of emerging applications. Graphene-based airflow sensors are hampered by the sluggish response and recovery speed and low sensitivity. Here we employ laser-induced graphene (LIG) with poststructural biomimicry for fabricating high-performance, flexible airflow sensors, including cotton-like porous LIG, caterpillar fluff-like vertical LIG fiber, and Lepidoptera scale-like suspended LIG fiber (SLIGF) structures. The structural engineering changes the deformation behavior of LIGs under stress, among which the synchronous propagation of the scale-like structure of SLIGF is the most conducive to airflow sensing. The SLIGF achieves the shortest average response time of 0.5 s, the highest sensitivity of 0.11 s/m, and a record-low detection threshold of 0.0023 m/s, benchmarked against the state-of-the-art airflow sensors. Furthermore, we showcase the SLIGF airflow sensors in weather forecasting, health, and communications applications. Our study will help develop next-generation waterflow, sound, and motion sensors.

Soft Neural Interfacing based on Implantable Graphene Fiber Microelectrode Arrays.

Microelectrode Arrays (MEAs) neural interfaces are considered implantable devices that interact with the nervous system to monitor and/or modulate brain activity. Graphene-based materials are utilized to address some of the current challenges in neural interface design due to their desirable features, such as high conductance, large surface-to-volume ratio, suitable electrochemical properties, biocompatibility, flexibility, and ease of production. In the current study, we fabricated and characterized a type of flexible, ultrasmall, and implantable neurostimulator based on graphene fibers. In this procedure, wet-spinning was employed to create graphene fibers with diameters of 10 to 50 µm. A 10-channel polyimide Printed Circuit Board (PCB) was then custom-designed and manufactured. The fibers were attached to each channel by conductive glue and also insulated by soaking them in a polyurethane solution. The tips were subsequently exposed using a blowtorch. Microstructural information on the fibers was obtained using Scanning Electron Microscopy (SEM), and the measurements of Electrochemical Impedance Spectroscopy (EIS) were conducted for each electrode. Flexible MEAs were created using graphene fibers with diameters ranging from 10 to 50 microns with a spacing of 150 microns. This method leads to producing electrode arrays with any size of fibers and a variety of channel numbers. The flexible neural prostheses can replace conventional electrodes in both neuroscience and biomedical research.

Electrical Tracking, Erosion and Fire Retardancy Performance of Silicone Rubber Insulation Containing Aluminum Trihydrate, Graphene and Glass Fiber Additives

Electrical Tracking, Erosion and Fire Retardancy Performance of Silicone Rubber Insulation Containing Aluminum Trihydrate, Graphene and Glass Fiber Additives

Ultrafine Carbon-Nanofiber-Reinforced Graphene Fiber Electrodes for Flexible Supercapacitors with High Specific Capacitance and Durable Cycle Stability

Graphene fiber-based supercapacitors (FSCs) are one of the most promising energy storage devices for flexible electronics. However, the electrochemical performance of conventional graphene fiber electrodes fabricated by wet spinning is still limited by the low specific surface area (SSA), mismatched pore size distribution, and considerable interface resistance. Herein, we developed a scalable method to produce hierarchical porous carbon nanofibers/graphene hybrid fibers (CNGFs) for flexible supercapacitor electrodes with high specific capacitance and durable cycle stability. For energy storage applications, both ion storage accommodation and rapid electronic transfer are required, which could be achieved by the ultrahigh SSA and exceptional conductivity of CNGF electrodes. Therefore, the electrodes of CNGF30 (hybrid fibers with 30% carbon nanofiber loading) exhibit excellent electrochemical performance in terms of the area of areal-specific capacitance (409.1 mF/cm2) and cycle stability (97.7% over 10 000 cycles). Moreover, the well-designed CNGF30 offers remarkable mechanical flexibility for assembled FSCs.

Advances in Porous Graphene and Scalable Wet-Spinning Fiber Assembly

ConspectusTwo-dimensional (2D) materials with astonishing properties and thickness dimensions are attractive for nanodevices and optoelectronics devices. Among them, 2D graphene─an atomically thin single layer with a strong covalently bonded sp2-hybridized hexagonal carbon network─has fascinating physicochemical properties. 2D graphene is at the tip of the iceberg of 2D materials. However, graphene is prone to self-restacking and agglomeration, deteriorating its properties. The introduction of porous structures to graphene sheets ameliorates their properties, e.g., increasing the surface area, providing ion transport channels, and enhancing the stability; thus, the performance of graphene-based materials is improved. Owing to their exciting properties, 2D holey graphene (HG) with nanoholes in its 2D basal plane and three-dimensional (3D) porous graphene with structural pores and interconnected architectures structural derivatives of graphene are promising for addressing the aforementioned challenges synergistically. Perforation in 2D graphene with tunable pore size, pore density, and uniformity is crucial for improving the performance of dense graphene. The unique pore structure and large exposed edges indicate the improved properties of porous graphene. Furthermore, macroscopically assembled one-dimensional (1D) fibrous electrodes of holey and porous graphene building blocks are promising, as they are lightweight, have high flexibility, and have strong wearability for future next-generation electronics.In this Account, we systematically highlight our efforts related to the conventional synthesis methodologies to recent emerging methods of “holey” or “porous” graphene/graphene oxide. First, we focus on the synthesis strategies and advances of 2D HG in-plane holes suitable for fast ion transport. Recent emerging synthesis methodologies are discussed for preparing 2D HG, which uses an environmentally benign approach with low toxicity compared to conventional etching methods, which frequently involve the use of hazardous or toxic oxidizing reagents, thereby causing severe environmental pollution. Second, compared with graphene, the 3D porous graphene comprises self-assembled graphene sheets (holey) containing structural macropores with a larger accessible surface area, high pore volume, and better flexibility, stability, and mechanical properties preferred for energy conversion and storage applications. Here, the recent progress and emerging synthesis approaches for 3D porous graphene-based nanomaterials are comprehensively discussed. Furthermore, the advantages of 2D HG and 3D porous graphene are discussed for water transport and electrochemical storage. Third, recent advances in the use of straightforward, large-scale wet-spinning processes to fabricate macroscopically assembled 1D fibrous electrodes with excellent mechanical flexibility and deformability using holey or porous graphene-based fibers (GFs) are described. Different approaches are discussed for preparing holey or porous GFs, such as wet-spinning assembly of holey graphene oxide (HGO), coagulant-assisted porous structures, and the post-activation process. Thus, the wet-spun holey or porous GFs are promising for miniaturized-based next-generation wearable electronic devices. Finally, we focus on the current status, fundamental understanding, future directions, and challenges of wet-spinning assemblies of holey/porous graphene-based nanomaterials for the next generation of wearable electronics.

Construction of Financial Risk Evaluation Index System for Biomass Graphene Fibre Industrialisation Project

Abstract In this paper, the biomass graphene fibre industrialisation project is taken as the research object. Moreover, the development characteristics of the project in the field of industrial application and the financial status of the current company are taken into comprehensive consideration. The financial data from 2014 to 2018 are selected for quantitative analysis. First of all, this paper specifically divides the risk into four dimensions, depending upon the project’s financial status, which involves financing risk, investment risk, business risk, and other risks These are analyzed and studied from the internal and external causes of enterprise risk. Secondly, by comparing various research methods, the author chooses the TOPSIS entropy weight method suitable for H Company to analyse its data in the past 5 years and identifies the main risk points faced by enterprises in the industry according to entropy weight. The results show that the risk index for each year is: 2017 &gt; 2021 &gt; 2019 &gt; 2020 &gt; 2018. In early 2017, the average financial status of all companies in the development of the whole project industry was at the bottom point, but in 2015, there was a huge improvement in the financial situation, and in 2019, it stabilised after the decline of the average safety index. At the same time, the average total assets of each company in the biomass graphene fibre industrialisation project showed an increasing trend from 2017 to 2021, with the most significant increase in 2019 (514.135 million yuan), an increase of 119.14% compared to 2018. Thirdly, the average value of debt also reached the highest in 2019, with the value of debt reaching 383.248 million yuan, an increase of 427.54% compared to 2018. The risk assessment system proposed in this paper provides good guidance for the risk assessment of biomass graphene fibre industrialisation projects.

Silk fibroin reinforced graphene fibers with outstanding electrical conductivity and mechanical strength

High-performance graphene fiber with intriguing functionality and mechanical strength is expected for wide potential applications. However, it still demands reliable means to realize the rapid wet-spinning of highly aligned fibers because of the insufficient gel strength of graphene oxide (GO) dope and the possible structural imperfections in the obtained fibers. Here, we demonstrate the fabrication of highly conductive and strong graphene fibers by regulating the rheology and spinnability of trace-carbonyl GO dispersion with silk fibroin (SF). The amphiphilic SF can form hydrogen bonds and π-π interactions with GO sheets to significantly enhance the gel strength of spinning dopes, enabling the conformation adjustment and sheet alignment under large drawing ratio and performance enhancement of the GO/SF fibers. After a chemical reduction, the highly orientated and stacked structure endows the fibers with an exceptional tensile strength of 938.6 MPa and a high electrical conductivity of 1501.7 S cm−1. Even more, the conductivity can be further increased to 2700.7 S cm−1, which is among the highest values for chemically reduced GO fibers. This work offers a promising method to produce strong, flexible, and robust graphene fibers for versatile applications in multifunctional fabrics, energy conversion, and health protection areas.

Stabilized Preparation of Fiber-Shaped Perovskite Solar Cells with Ti and Graphene Substrates

Organic–inorganic hybrid metal halide perovskite solar cells (PSCs) have made dramatic progress over the past few years. Fiber-shaped PSCs (FPSCs) extend the application of PSCs to wearable and portable electronics. The one-dimensional flexible structure of the fiber substrate and the high efficiency photoelectric conversion ability of the perovskite materials make FPSCs promising for energy applications. However, FPSCs have limited preparation methods and show poorer optoelectronic performance compared to conventional PSCs. In our work, we present a multiple quantitative coating preparation method, which was optimized by controlling the PbI2 concentration and the cycle number of coating process. We demonstrated the effectiveness of the methods in improving the film performance, with a photoelectric conversion efficiency (PCE) of 5.2% under air. The applicability of the multiple quantitative coating methods was studied by the FPSCs fabricated on reduced graphene fibers (rGFs), which present PCEs of about 1.5%. In addition, by extending the length of rGFs, the device performance was further improved. Thus, we demonstrated a stable fabrication method of FPSCs based on rGFs, which exhibited significant potential for using PSCs as a power source in wearable devices.

Highly stable polyaniline array@ partially reduced graphene oxide hybrid fiber for high-performance flexible supercapacitors

The development of flexible supercapacitors (SCs) with high energy density, excellent deformation and cycling stability has great meaning for flexible electronic. Herein, polyaniline array@carbon nanotubes/partially reduced graphene oxide hybrid fiber (PANI@CNT/PRGO) was rationally designed and fabricated. The PANI array were vertically and uniformly grown on CNT/PRGO fiber by controlling the nucleation sites on the fiber. This unique structure enabled the ion to rapid diffusion and the electron to fast transport and sufficient utilization of active sites. The strong interfacial interaction between PANI and CNT/PRGO fiber can reduce the risk of PANI shedding from the fiber during mechanical deformation and long-term cycling. As a consequence, a fiber-shaped SC fabricated by PANI@CNT/PRGO fiber can deliver high volumetric capacitance of 50.2 F cm−3 at a current density of 60 mA cm−3 with 62.5% capacitance retention at 2000 mA cm−3. More encouragingly, the device not only possesses outstanding flexibility and deformation stability (Retention 96.6% after 2000 bending cycles) but also owns prominent long-term stability (Retention 95.8% after 20,000 cycles). Furthermore, the device can yield an outstanding energy density up to 6.97 mWh cm−3. This findings may carve out a new path for regulating the nucleation sites to control the distribution of nanomaterials on graphene fiber, thus obtain hybrid fiber electrodes with outstanding electrochemical performances.