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Flexible graphene‐based paper electrodes (FGPEs) are a new class of study and the research on this electrode material has been carried out for approximately ten years. FGPEs have many advantages compared to classical solid electrodes such as being flexible, foldable, adaptable to flexible electronics, being cut, easily shaped, and effective and adjustable modification. In this work, the applicability of FGPEs modified with polyindole (PIN) thin films and zinc oxide nanoparticles (ZnO‐NPs) to energy‐storage systems as a supercapattery design is presented, and especially the limitations of ZnO‐NPs for energy‐storage applications are revealed to inform researchers working for a similar purpose. Capacitance calculations have been performed using both cyclic voltammetry (CV) and galvanostatic charge‐discharge (GCD) experiments. It was observed that the rGO/PIN paper demonstrated almost 30 times more energy‐storage capacity than that of the rGO/PIN/ZnO paper due to the electrochemical instability of ZnO‐NPs on the flexible electrode platform at the applied potential region in 1.0 M HClO4 solution. The rGO/PIN paper with a highly flexible property exhibited an energy density of 74.5 W h cm−2 and a power density of 2258 W cm−2 at a current density of 2.2 mA cm−2, revealing hopeful results for future modular and flexible approaches. [ABSTRACT FROM AUTHOR]

Microfluidic based sensors are one of the emerging alternatives for bringing solutions studies on paper platforms. Microfluidic paper assisted platform was developed over here through a simple, easy, cost effective and instrument free process. The self‐same method of waxing through crayoning, was estimated thoroughly on different paper platforms. Varied parameter including type of crayoning, way of patterning, color effect, wicking rate and channel optimization was performed on paper milieus. Optimized time of baking for obtaining controlled penetration ranges from 2 min to 8 min depending on the type of paper used. Wax crayoning was preferred over oil pasteling for making hydrophobic barriers uniformly, solid as well fully penetrated within paper inner layers. Fabrication through this easy cost‐effective route allows a formation of hydrophilic reaction or sensing zone of 0.25 cm2 with sufficient reactive area. Further sensing of dopamine on paper platform was carried using paper chip adsorbed with fluorescent modified graphene quantum dots as sensing material. The patterned paper showed advantage as only few microliter (5 μl to 10 μl) range of sample volume was required for testing. Fluorescence quenching with increase of concentration was witnessed where around 25–75 μM dopamine concentration was positively tested through naked eye; which for the first time was demonstrated here via robust wax crayoning method for developing paper based biosensor. [ABSTRACT FROM AUTHOR]

The present study reports the fabrication of reduced graphene oxide (rGO)/gold nanoparticles (AuNP) nanocomposites modified cellulose fiber paper‐based electrochemical biosensor for procalcitonin (PCT) biomarker detection. PCT is a biomarker specific for bacterial infection (BI) detection and has gained much attention as a potential solution to the problems associated with determining appropriate antibiotic use. In sepsis and other severe infections, serum PCT levels increase to values above 100 ng mL−1 in response to pro‐inflammatory stimulation. The structural and morphological characterization of the rGO‐AuNP composite are investigated using UV‐Vis spectroscopy, FTIR spectroscopy, X‐ray diffraction, and scanning electron microscopy. Monoclonal antibodies specific to PCT were covalently immobilized onto the rGO‐AuNP nanocomposite modified paper to fabricate an electrochemical biosensor. The fabricated biosensor exhibits linearity in the PCT concentration range 10 −15×103 pg mL−1, with a low detection limit 10 pg mL−1. Furthermore, the proposed biosensor also exhibited good selectivity and could detect PCT biomarkers even in the presence of other interfering electroactive species such as glucose, oxalic acid, and urea. The proposed CF‐based biosensor has been proven as an accelerated simple point‐of‐care (POC) exploratory approach for early PCT diagnosis in inadequate areas with limited production facilities, computational techniques, and highly skilled experts. [ABSTRACT FROM AUTHOR]

Herein, we prepared a bisuppport‐based bimetallic nanoparticle composite AuFe/ZIF‐8‐graphene. It exhibited high peroxidase activity compared to those hybrids without graphene support, which demonstrated the regulatory effect of graphene on the catalytic activity. SEM, TEM, EDX, XRD, FT‐IR and XPS characterization showed that Au and Fe3O4 NPs were successfully immobilized on ZIF‐8‐rGO carriers. Kinetic analysis confirmed that the fabricated composites showed better Km and Vmax for H2O2 than HRP and some other reported peroxidase mimics. Under the optimal conditions, a sensing assay for H2O2 determination was constructed with a linear detection range of 0.01–2.5 mM and a detection limit of 0.63 μM. On this basis, a colorimetric test paper with its standard card was prepared for rapid visualization detection. It realized H2O2 detection in the range of 0.01‐500 mM and was further successfully applicated in the semi‐quantitative detection of H2O2 in actual spiked water samples. This achievement was expected to encourage the development of rapid visual detection for other pollutants in environmental and medical field. [ABSTRACT FROM AUTHOR]

Carbon paper‐supported graphene aerogels are examined as anode electrodes for lithium‐ion batteries, employing a hydrothermal process and a freeze‐drying step. Triethylenetetramine (TETA) and o‐phenylenediamine (OPD) prove to promote graphene aerogel formation and its chemical bonding onto the surface of carbon paper. The electrochemical results demonstrate that the electrode treated with the former diamine has a remarkable rate capability with higher capacities as compared with the electrode treated with the latter diamine and better stability. [ABSTRACT FROM AUTHOR]

The flexible electrodes are the crucial components for fabricating wearable supercapacitors. In this study, we present a quick and convenient method to prepare graphene paper (GP) as a flexible current collector on a large scale by an easy one‐step method. The composite electrode integrated with GP and MnO2 as a flexible supercapacitor was obtained by an electrochemical deposition method without using binder or conductive agent. The substrate (GP) of electrode not only provides mechanical strength, but also contributes energy storage capacity. The MnO2 nanoparticles deposited on the surface of GP further improved the electrochemical performance of composite. The neat GP can give a specific capacitance of 184 F/g at a current density of 1 A/g. At a current density of 1 A/g, the specific capacitance of the GP/MnO2 composite with a deposition time of 30 s is as high as 410 F/g. The method presented here shows great potential for the development of flexible electrode materials in practical energy storage devices. [ABSTRACT FROM AUTHOR]

The cycling and rate capabilities of LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode material under high cut‐off voltage (≥4.5 V) and high current density have attracted much attention. However, the material's insufficient intrinsic electronic/ion conductivity and interface instability are still key issues restricting its electrochemical performance.In this paper, a graphene/Ta2O5 co‐coating layer is successfully fabricated on the surface of NCM523 to form a cathode material of GTa‐NCM523 to enhance both the electron and lithium‐ion transport during cathode operation. The GTa‐NCM523 cathode material achieves a discharge specific capacity of 147.4 mAh g−1 after 600 cycles at a voltage of 3.0–4.5 V and a rate of 1 C (180 mA g−1) with a capacity retention rate of 81.4 %. In contrast, the uncoated NCM523 only retains 63.2 % of its capability. At an elevated rate of 10 C (1800 mA g−1), the GTa‐NCM523 can achieve a discharge‐specific capacity of up to 113.5 mAh g−1, which is 43.7 % higher than the uncoated NCM523. The co‐coating layer can inhibit HF erosion and accelerate the movement of lithium‐ions and electrons, which account for the superior electrochemical characteristics of the co‐coating layer comprised of graphene and Ta2O5. [ABSTRACT FROM AUTHOR]

The use of TiO2/graphene composites as catalysts for photodegradation of dyes has been widely investigated. TiO2/graphene composites are usually obtained by coating TiO2 on the surface of pre‐prepared graphene. However, graphene is prone to curling and stacking, which makes it difficult to uniformly coat TiO2 on its surface, resulting in poor photocatalytic performance. In this paper, a non‐conventional approach to prepare TiO2/graphene nanocomposites based on the use of porous SiO2/graphene spheres as supports is presented. SiO2/graphene spheres with intercalated structure and dendritic pores were prepared as supports by a one‐step hydrothermal method. Then, TiO2 was coated into the pores of SiO2/graphene spheres by sol‐gel method to obtain SiO2/graphene@TiO2 composites (SGT). After 90 min of visible light irradiation, the degradation rate of RhB by SGT catalyst was 68.9 %, which was significantly higher than that of P25 by 39.3 %. A mechanism of the RhB removal by the SGT composites was proposed. [ABSTRACT FROM AUTHOR]

As industrial development and over‐consumption of fossil fuel resources lead to an increasing demand for renewable and sustainable energy sources, making solar energy an ideal source of energy. Graphene has attracted much attention in the field of solar cells due to its unique electronic, optical, thermal, and mechanical properties, as well as its high specific surface area, high carrier mobility, and high Young's modulus. In this comprehensive review article, we summarize the theoretical advances of graphene and its derivatives, such as graphene oxide, reduced graphene oxide, graphene quantum dots, hybridized graphene, and graphene doped with heteroatoms, in the field of solar cells. The observed enhancement of solar cell performance due to the incorporation of graphene and its derivatives is explained in detail by first‐principles. The purpose of this paper is to analyze the fundamental mechanisms of the interactions between graphene and its derivatives solar cells through first‐principles to provide theoretical support for their continued development in the field of solar cells, while paving the way for the creation of new strategies to improve solar cell performance and advance the development of sustainable energy technologies. [ABSTRACT FROM AUTHOR]

In this research paper, we investigated the impact of soft segment crystallization, the cross‐linking density (CLD) and elastic modulus of the synthesized thermoset polyurethanes on their shape memory performance (SMP). A group of tri‐block copolymers of poly(ϵ‐caprolactone) (PCL) and poly(tetramethylene glycol) (PTMG) with PCLx‐PTMG2000‐PCLx architecture were synthesized and used as polyols in a thermoset polyurethane (PU) structure. Crystallization of the soft segments was controlled through changing PCLx blocks' length. Graphene nanoplatelets, with a fixed content of 0.50 wt.%, was used as the cross‐linker and the nano‐filler to tune elasticity of the PUs. Analysis of crystallization showed that by increasing PCLx's length from 0 to 2000 D caused a drastic change in the crystallization behavior of the polyols. The polyols used in the thermoset PU nanocomposite led to a wide spectrum of elastic modulus at temperatures close to room temperature. The elastic modulus at room temperature ranged from 20 to 100 MPa. The changes in elastic modulus, CLD and soft segments' crystallization resulted in a complex SMP behavior, which was studied in‐detail. The shape recovery rate was also studied, which showed the impact of crystallites' melting, CLD and elastic modulus through a three‐stage shape recovery. [ABSTRACT FROM AUTHOR]

Graphene Quantum Dots (GQDs) have attracted significant attention and applications in the field of biosensors, particularly for early detection of cervical cancer, due to their excellent electrochemical, optical, and biocompatibility properties. In this review, recent results on green methods for the synthesis of GQDs as well as their characterization techniques are discussed, with particular emphasis on structural, morphological, elemental, optical, and functional group analysis. In addition, a comprehensive overview of how the electrochemical and biocompatibility properties of GQDs enable their use in the development of sensing elements for biosensing applications is presented. This paper also highlights the most recent developments in the fabrication of GQDs‐based biosensors for cervical cancer detection. Finally, the future prospects are critically discussed to assist researchers in identifying the shortcomings of the existing biosensors and establishing new methods centered on the development of unique, efficient, sensitive and selective GQDs‐based biosensors. [ABSTRACT FROM AUTHOR]

Graphene Quantum Dots (GQDs) are carbon‐based, nanoscale particles that display remarkable physical and organic properties. They are chemically and physically stable and eco‐friendly due to their non‐toxic and biologically inert nature. Various bioresources are used to synthesize GQDs to ensure biosafety and cost‐effectiveness. In this work, a critical review has been done by focusing on top‐down and bottom‐up synthesis strategies. GQDs by valorizing various bioresources like bamboo, neem leaves, mango leaves, paper fibers, rice husk, starch, honey, wood charcoal, coffee grounds, corn powder, and lime oil extract is highlighted in the present review. State‐of‐the‐art and future outlooks on the development and advancement of GQDs applications are also being addressed. Based on the surveyed literature, GQDs provide extensive use in various areas like bioimaging, nanomedicine, photocatalysis, light‐emitting diodes, solar cells, and sensors. [ABSTRACT FROM AUTHOR]

In this paper, graphene oxide/ magnetite (GO/Fe3O4) nanocomposite was synthesized as a carrier and MRI contrast agent. X‐ray diffraction (XRD) indicated that the crystalline structure of Fe3O4 nanoparticles and Furrier transform infrared spectroscopy (FT‐IR) provided evidence for the presence of Fe3O4 and GO in the nanocomposite. The surface morphology of the nanocomposite was studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The magnetic properties of the synthesized nanocomposite was studied by a vibrating sample magnetometer (VSM). The drug loading and encapsulation efficiency of the curcumin were 22 and 96 %, respectively. The comparison between drug release from GO/Fe3O4 in neutral and acidic pH was shown high release in neutral conditions. MTT results demonstrated that the GO/Fe3O4 nanocomposite illustrates considerable toxicity due to which cell viability decreased to lower than 50 % at 140 μg ml−1 concentration. The results showed that curcumin and curcumin loaded nanocomposite has a similar power of antioxidant activities. GO/Fe3O4 nanocomposite is a good magnetic resonance T2 contrast agent under the T2‐imaging sequences. The novelty of this study is the application of water‐dispersed GO/Fe3O4 with pH‐dependent release properties for designing a new colon drug delivery. [ABSTRACT FROM AUTHOR]

It is an effective way to obtain high performance supercapacitors by increasing the surface area and conductivity of electrode materials. In this paper, three‐dimensional (3D) graphene with a small pore size, good electrical conductivity and high mechanical strength is fabricated by chemical vapor deposition using nickel nanoparticles as the template. Then, a polyaniline nanowire arrays (PANI NWAs)/3D graphene composite is fabricated by in‐situ polymerization. Due to the high conductivity and unique nano‐structure, the as‐prepared PANI NWAs/3D graphene composite exhibits an excellent capacitance of 680 F g−1 at current density of 1 A g−1. Moreover, a symmetric supercapacitor based on the PANI NWAs/3D graphene composite is assembled, and it shows an energy density of 6.43 Wh kg−1 at a power density of 0.4 kW kg−1. The assembled supercapacitor also exhibits a good cycling stability, which retains 78 % of its initial specific capacitance after 1000 cycles. [ABSTRACT FROM AUTHOR]

In this paper, 3‐Dimensional Graphene (3DG) prepared by watermelon was used as the supporter to synthesize Cu/3DG, Ce/3DG and Cu−Ce/3DG catalysts by the hydrothermal method, after which they were also investigated in NH3‐SCR. Synergistic mechanism between Ce and Cu was further explored. Experimental results indicated that the three catalysts all exhibited excellent low‐temperature nitrogen oxide reduction activity which reached 99 % and remained unchanged in the range of 250–400 °C. 2Cu‐3Ce/3DG displayed optimal NOx conversion rate, namely, its activity reached 92.9 % at 200 °C that mainly attributed to the increase of the Cu+, Ce3+ and the form of the abundant acid sites. Moreover, the sulfur and water resistance of 2Cu‐3Ce/3DG were tested. At 250 °C, the conversion rate of NOx was increased to 99.1 %, which showed excellent sulfur resistance. [ABSTRACT FROM AUTHOR]

The main graphene‐family materials used in biomedicine include graphene, graphene oxide, and reduced graphene oxide. They have been well documented for their distinctive microstructure and excellent physicochemical properties. Although they also have some shortcomings, such as slow biodegradation and dose‐dependent biotoxicity, these problems can be solved by using them in conjunction with other biomaterials. Silk fibroin (SF), a natural polymer material with many advantageous properties, has been used widely in biomedicine. However, SF requires modification by other biomaterials to improve its mechanical properties and control its degradation rate for further use. In recent years, the combined application of graphene‐family materials and SF has increased gradually, and the effects of it on cell behavior have been preliminary investigated, such as promoting cell adhesion, proliferation, and differentiation. Further studies of the combined use have been conducted in biomedicine, including tissue engineering, biosensor, and other biomedical usage. In this paper, this combined application has been outlined and summarized, and some envisioned challenges and future perspectives have been mentioned. We hope that this review will provide some reference and inspiration for the combined application of graphene‐family materials and SF in biomedicine in the future. [ABSTRACT FROM AUTHOR]

In this paper, uniform TiO2 nanowires (TiO2 NWs) on reduced graphene oxide (RGO) nanosheets were successfully synthesized by a simple and low‐cost hydrothermal method. The high capacitance (202.5 F⋅g−1 at 1 A⋅g−1) and excellent cyclic stability (81.9% capacity retention after 5000 cycles) were achieved for TiO2 NWs‐RGO nanocomposite as supercapacitor electrode. The excellent electrochemical performance is due to the synergistic effect of one‐dimensional TiO2 NWs with chemical stability and RGO with excellent conductivity. Moreover, TiO2 NWs can effectively avoid agglomeration, shorten the ion diffusion length and greatly facilitate the charge transfer both at the contact interfaces and within the electrode materials during the electrochemical process. A symmetric supercapacitor was successfully assembled using the TiO2 NWs‐RGO nanocomposite. It possesses a remarkable performance with a specific capacitance of 45.7 F⋅g−1, an energy density of 9.08 Wh⋅kg−1 at a power density of 598 W⋅kg−1. The TiO2 NWs‐RGO was successfully synthesized by a simple and low‐cost hydrothermal method. And it exhibited excellent electrochemical performance in supercapacitor. The enhanced electrochemical performance is due to TiO2 NWs providespseudocapacitance for TiO2 NWs–RGO nanocomposite, which makes up for the shortage of double‐layer capacitance of graphene. Moreover, one‐dimensional TiO2 NWs can effectively avoid agglomeration, shorten the ion diffusion length and greatly facilitate the charge transfer both at the contact interfaces and within the electrode materials during the electrochemical process. [ABSTRACT FROM AUTHOR]

Abstract: Graphene oxide (GO) is an important material used as precursor for the synthesis of graphene, its derivatives and various graphene based composite materials. In this paper we would like to demonstrate that highly‐oxidized graphene oxide can be prepared much faster and, moreover, it has almost identical chemical composition compared to the previously published and currently broadly used standard procedures. We prepared two samples: one using the usual Tour's method and the other one using the novel method. The main advantage of this improved method is the shorter synthesis time which can be reduced six times allowing scaling and speeding up of large scale production. Oxidation shortening also led to reduction of defect concentration. Both graphene oxides were characterized in detail showing almost identical structure as well as chemical composition and concentration of oxygen functionalities typical for graphene oxide prepared by permanganate methods. In addition the sorption capacity towards heavy metals (zinc, cadmium and lead) was also studied showing a comparable sorption capacity with standard graphene oxide prepared by Tour method. Graphene oxide prepared by rapid oxidation can form mechanically stable transparent membranes. Our developed method of graphene oxide synthesis is time‐efficient, cost‐efficient and can help to introduce graphene oxide to industrial scale production. [ABSTRACT FROM AUTHOR]

An electrochemical sensor has been developed using PBNCs/AuNPs/RGO ternary nanocomposite, in which gold nanoparticles (AuNPs) are deposited on Prussian blue nanocubes (PBNCs) and reduced graphene oxide (RGO) using two‐step in‐situ synthetic approach. The synthesized ternary nanocomposite shows high catalytic activity towards H2O2 sensing due to the synergistic effect of gold nanoparticles and RGO. The material was prepared by the co‐precipitation method, and the morphology of the synthesized composites was characterized using X‐Ray diffraction (XRD), scanning electron microscopy (SEM), and High‐resolution Transmission electron microscopy (HR‐TEM). Electrochemical measurements were performed by modifying glassy carbon electrodes (GCE) with bare PBNCs, PBNCs/RGO, and PBNCs/AuNPs/RGO for low‐level detection of H2O2 using Cyclic Voltammetry (CV) and Chronoamperometry. The interference property was analyzed using ascorbic acid (AA), uric acid (UA), and glucose as interfering agents. The modified electrode shows high sensitivity of 5.47 nA/nM and a limit of detection of 260 pM for H2O2 at (S/N=3). This electrochemical sensor observed a linear range of detection from 0.66 nM to 10.53 nM. The proposed sensor exhibits good stability, better selectivity, and a picomolar concentration detection limit for H2O2. [ABSTRACT FROM AUTHOR]