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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]

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]

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]

A foldable array of patterned graphene/ZnO nanoparticle UV sensor and asymmetric micro-supercapacitors (AMSCs) integrated on a paper substrate with patterned liquid metal interconnections is reported. The resistor type UV sensor based on graphene/ZnO nanoparticles is patterned to be driven by the stored energy of the integrated AMSCs. The AMSC consists of MnO2 nanoball deposited multiwalled carbon nanotubes (MWNTs) and V2O5 wrapped MWNTs as positive and negative electrodes, respectively. As an electrolyte, propylene carbonate-poly(methyl methacrylate)-LiClO4, an organic solvent-based gel, is used. The UV sensor and AMSCs can be easily integrated on a liquid metal, Galinstan, patterned, waterproof mineral paper and show a mechanically stable UV sensing, regardless of repetitive folding cycles. This work demonstrates a novel foldable nanomaterial based sensor system driven by integrated energy storage devices, applicable to future wearable and portable electronics. [ABSTRACT FROM AUTHOR]

This paper demonstrates, for the first time, the use of paper-based electrochemical devices coupled to external solid working electrodes. The paper-based electrochemical cells were fabricated using inexpensive and largely available office paper, according to a simple protocol that consists on the creation of hydrophobic barriers using paraffinized paper and preheated metal stamp. The counter and reference electrodes were integrated to the paper platform through the deposition of carbon and silver inks, respectively. The electrochemical paper analytical device (ePAD) was coupled to external glassy carbon rod electrode modified with reduced graphene oxide doped with Cu nanoparticles through meniscus configuration. The analytical usefulness of this electrochemical approach was demonstrated through the simultaneous determination of paracetamol and caffeine in biological samples. The analytes were successfully quantified in real urine samples and limits of detection of 24.6 nM (paracetamol) and 36.1 nM (caffeine) were obtained. The paper platform showed good stability (RSD of 1.07 % for the peak currents and 1.43 % for the peak potentials) and satisfactory performance. The use of solid electrodes coupled to paper electrochemical devices, firstly demonstrated here, opens new possibilities for the utilization of ePADs in electrochemistry and electroanalytical chemistry and offers advantages such as the extremely reduced consumption of reagents and the minimal generation of wastes. [ABSTRACT FROM AUTHOR]

A single-step laser scribing process is used to pattern nanostructured electrodes on paper-based devices. The facile and low-cost technique eliminates the need for chemical reagents or controlled conditions. This process involves the use of a CO2 laser to pyrolyze the surface of the paperboard, producing a conductive porous non-graphitizing carbon material composed of graphene sheets and composites with aluminosilicate nanoparticles. The new electrode material was extensively characterized, and it exhibits high conductivity and an enhanced active/geometric area ratio; it is thus well-suited for electrochemical purposes. As a proof-of-concept, the devices were successfully employed for different analytical applications in the clinical, pharmaceutical, food, and forensic fields. The scalable and green fabrication method associated with the features of the new material is highly promising for the development of portable electrochemical devices. [ABSTRACT FROM AUTHOR]

To circumvent the bottlenecks of non-flexibility, low sensitivity, and narrow workable detection range of conventional biosensors for biological molecule detection (e.g., dopamine (DA) secreted by living cells), a new hybrid flexible electrochemical biosensor has been created by decorating closely packed dendritic Pt nanoparticles (NPs) on freestanding graphene paper. This innovative structural integration of ultrathin graphene paper and uniform 2D arrays of dendritic NPs by tailored wet chemical synthesis has been achieved by a modular strategy through a facile and delicately controlled oil-water interfacial assembly method, whereby the uniform distribution of catalytic dendritic NPs on the graphene paper is maximized. In this way, the performance is improved by several orders of magnitude. The developed hybrid electrode shows a high sensitivity of 2 μA cm−2 μ m−1, up to about 33 times higher than those of conventional sensors, a low detection limit of 5 n m, and a wide linear range of 87 n m to 100 μ m. These combined features enable the ultrasensitive detection of DA released from pheochromocytoma (PC 12) cells. The unique features of this flexible sensor can be attributed to the well-tailored uniform 2D array of dendritic Pt NPs and the modular electrode assembly at the oil-water interface. Its excellent performance holds much promise for the future development of optimized flexible electrochemical sensors for a diverse range of electroactive molecules to better serve society. [ABSTRACT FROM AUTHOR]

Manipulation of nanoparticles by light induced forces is widely used in nanotechnology and bioengineering. In normal cases, when a nanoparticle is illuminated by light waves, the transfer of momentum from light to the nanoparticle can push it to move along the light propagation direction. On the other hand, the lateral optical force can transport an object perpendicular to the light propagation direction, and the optical pulling force can attract an object toward the light source. Although these optical forces have drawn growing attention, in situ tuning of them is rarely explored. In this paper, tuning of both lateral optical forces and optical pulling forces is numerically demonstrated via a graphene/α‐phase molybdenum trioxide (α‐MoO3) bilayer structure. Under plane‐wave illumination, both the amplitude and direction of the optical forces exerted on a nanoparticle above this bilayer structure can be tuned in the mid‐infrared range. The underlying mechanism can be understood by studying the corresponding isofrequency contours of the hybrid plasmon‐phonon polaritons supported by the graphene/α‐MoO3 bilayer. The analytical study using the dipole approximation method reproduces the numerical results, revealing the origin of the optical forces. This work opens a new avenue for engineering optical forces to manipulate various objects optically. [ABSTRACT FROM AUTHOR]

The nanoporous graphene papers (NGPs) was prepared by the hard-template method. The Pt−Pd modified NGPs hybrid was prepared by the self-assembly method. Then a glassy carbon electrode (GCE) modified with Pt−Pd bimetallic nanoparticles-functionalized nanoporous graphene composite has been prepared for the electrochemical determination of Xanthine (XA). The Pt−Pd/NGPs hybrid was characterized by transmission electron microscopy, scanning electron microscope and X-ray diffraction. The electrochemical behavior of XA on Pt−Pd/NGPs/GCE was investigated by cyclic voltammetry and amperometric i-t. The Pt−Pd/NGPs modified electrode exhibited remarkably electrocatalytic activity towards the oxidation reaction of XA in phosphate buffer solution (pH=5.5). Under the optimal conditions, the determination of XA was accomplished by using amperometric i-t, the linear response range from 1.0×10−5∼1.2×10−4 M. The detection limit was 3.0×10−6 M (S/N=3). The proposed modified electrode showed good sensitivity, selectivity, and stability with applied to determine XA in human urine. [ABSTRACT FROM AUTHOR]

Researchers are trying to tackle water scarcity in numerous ways. One of those ways is the use of nanotechnology in water processing and purification. The current work involves the fabrication and optimization of activated carbon and graphene‐based hybrid water purification system. Five different concentrations of methylene blue and deionized water (DI) dye solutions were used, and they were filtered in three different cycles. For the potential usage on the consumer side, a small‐scale, low‐cost water filter is developed using activated carbon, commercial filter paper, and graphene nanoplatelets. The filter paper is used to hold mixtures of the activated carbon and graphene nanoplatelets within the water filter. The conductivity, TDS, and pH are measured for the feed water and the processed water using an Oakton EcoTestr and Apera Instruments PH60 Premium Pocket pH meter, respectively. A UV‐Vis spectrometer is used to measure the absorption of solutions. The distribution and adsorption of the dye particles were observed by scanning electron microscopy. Practitioner points: These results show the effectiveness of the system in the removal of dye particles above a given particle size.The concentration of the dye solution decreased after every cycle.The GnPs filtration system more effectively dye particles as compared to the filtration system containing only Activated carbon.UV‐Vis spectroscopy results showed that the methylene blue dye particles decreased after every cycle.This research can open a broad area of projects toward waste/wastewater practice for particles above a certain particle size. [ABSTRACT FROM AUTHOR]

Nitrogen doped carbon materials containing transition metal nanoparticles have attracted much attention as bifunctional oxygen electrocatalysts. In this paper, the template etching method is used to obtain the nitrogen‐doped graphene with abundant macropores embedded with cobalt nanoparticles (Co@N−C). The prepared Co@NC‐800 catalyst has a half‐wave potential (E1/2=0.835 V) close to Pt/C and good stability in excess of Pt/C for oxygen reduction reaction (ORR). At the same time, the catalyst has good oxygen evolution reaction (OER) performance. In addition, zinc‐air batteries (ZABs) based on the Co@NC‐800 catalyst show good cycle stability of up to 200000 s and high power density of 73.5 mW cm−2. The synergistic effect of the integrated component between nitrogen‐doped graphene and cobalt nanoparticles as well as the macroporous structure endow Co@NC‐800 with abundant exposed active sites and mass/electron transfer capacity, thus leading to the high electrocatalytic activity. This work shows potential for practical applications in electrochemistry. [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]

The objective of this article is to examine the influence of different weight percentages (wt%) of graphene nanoplatelets (GNPs) on the behavior of mechanical and abrasive wear. Furthermore, the influence of operating parameters, such as, different degrees of applied loads and abrading distance (5‐20 N and 100‐250 m, respectively) at a rotational speed of 200 rpm (1.047 m/s) against SiC paper of 400 grit size was studied. From the present study, it was possible to establish that performance of the glass fabric‐reinforced epoxy composite materials can be improved with incorporation of GNPs. Moreover, incorporation of a large amount (1 wt%) of GNPs was found to noticeably enhance the tribo‐performance, ILSS, and hardness of the composite materials. However, the tensile strength was noted to increase negligibly with incorporation of 1 wt% of GNPs as compared to 0.5 wt% of GNPs. To get an insight into the wear mechanisms, the abraded surface of the tribological samples was examined by scanning electronic microscopy and energy dispersive X‐ray. Their morphology was correlated with wear volume and specific wear rate data trends. Worn surface features analysis indicated that incorporation of GNPs mainly improved the fiber‐matrix interface, which resists easy pullout of fibers from matrix/fillers and enables higher wear resistance. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of adsorption of acridine yellow G (AYG) from aqueous solutions through the use of functionalized grapheme nanoplatelets/modified polybutadiene hybrid composite (FGNPs/MPB). The adsorption of AYG onto FGNPs/MPB was investigated based on the AYG concentration, pH, contact time, temperature, and adsorbent dose. A maximum adsorption capacity was obtained at a pH of 7 (23.7 mg/g), an adsorbent dose of 1.0 g/L (20.8 mg/g), and an initial AYG concentration of 28.5 mg/L (16.9 mg/g). The value of qe of FGNPs/MPB increases with an increase in temperature from 293 to 323 K. Equilibrium isotherm data were analyzed using the Langmuir and Freundlich isotherm models. The Langmuir model best describes the adsorption processes of AYG, which showed that the monolayer adsorption capacity of FGNPs/MBP is 22.9 mg/g. The pseudofirst‐order, pseudosecond‐order, and intraparticle diffusion models were used to study the kinetics of the AYG adsorption onto FGNPs/MPB. The pseudosecond‐order model better described kinetic data for the adsorption of AYG onto FGNPs/MPB. Thermodynamic parameters, such as the Gibbs free energy, enthalpy, and entropy, indicated that the AYG adsorption onto FGNPs/MPB was spontaneous feasible, and endothermic. [ABSTRACT FROM AUTHOR]

Defective 3D vertical graphene (VG) with a relatively large surface area, high defect density, and increased surface electrons is synthesized via a scalable plasma enhanced chemical vapor deposition method, together with a postsynthesis Ar‐plasma treatment (VG‐Ar). Subsequently, Cu@CuxO nanoparticles are deposited onto VG‐Ar (Cu/VG‐Ar) through a galvanostatic pulsed electrodeposition method. These Cu@CuxO nanocatalyst systems exhibit a superior electrochemical CO2 reduction performance when compared to Cu‐based catalysts supported on commercial graphene paper or pristine VG without postsynthesis Ar‐plasma treatment. The Cu/VG‐Ar achieves the highest CO2 reduction Faradaic efficiency of 60.6% (83.5% of which are attributed to liquid products, i.e., formate, ethanol, and n‐propanol) with a 5.6 mA cm−2 partial current density at −1.2 V versus reversible hydrogen electrode (RHE). The improved CO2 reduction performance of Cu/VG‐Ar originates from the well‐dispersed Cu@CuxO nanoparticles deposited on the defective VG‐Ar. The intrinsic carbon defects on VG‐Ar can suppress the hydrogen evolution reaction as well as tune the interaction between VG and Cu@CuxO, thus impeding the excessive oxidation of Cu2O species deposited on VG‐Ar. The defective VG‐Ar and stabilized Cu@CuxO enhances CO2 adsorption and promotes electron transfer to the adsorbed CO2 and intermediates on the catalyst surface, thus improving the overall CO2 reduction performance. [ABSTRACT FROM AUTHOR]

Molybdenum carbide (Mo2C) coupled with carbon materials has received widespread attention in catalysis and energy storge/conversion. However, most of the existing synthetic pathways involve high operating temperature, time‐consuming processes, and flammable gases. Herein, a novel, facile, and rapid method to synthesize Mo2C nanoparticles grown on a series of carbon substrates (such as graphene, carbon nanotubes, and commercial carbon black) in a few minutes by using the strong interaction between the microwave and the carbon materials, in which the carbon matrix acts as the in situ heating media and carbon sources to accelerate carbon diffusion during the formation of Mo2C, is presented. Moreover, this method can also be extended to prepare a self‐standing electrode (Mo2C/CF) in just 10 s, the uniformly dispersed Mo2C nanoparticles anchored on carbon fiber paper, which demonstrates superior catalytic performance and long‐term stability (>100 h) in both acid and alkaline conditions for hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

In this report, sandwiched Ni2P nanoparticles encapsulated by graphene sheets are first synthesized by directly encapsulating functional units in graphene sheets instead of fabricating separate graphene sheets and then immobilizing the functional components onto the generated surfaces. In this strategy, we use low-cost, sustainable and environmentally friendly glucose as a carbon source and NiNH4PO4 ⋅H2O nanosheets as sacrificial templates. This unique structure obtained here cannot only prevent the nanoparticles from aggregation or loss but also enhance the electronic conductivity compared to the independent nanoparticles. Furthermore, the novel sandwich-like Ni2P/C can be applied in plenty of fields, especially in electrical energy storage. In this paper, a series of electrochemical tests of the sandwich-like Ni2P/C are carried out, which demonstrate the excellent cyclic stability and rate capacity for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Vertically-oriented graphene (VG) with predominantly edge plane structure is considered as a promising catalyst support candidate for the methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). Inspired by the fact that catalyst nanoparticles are spontaneously attached to the exposed graphene edges, a novel highly-branched vertically-oriented graphene (HBVG) based catalyst support is proposed in the current work. With employing atmospheric normal glow discharge (ANGD) and microwave plasma-enhanced chemical vapor deposition (PECVD) methods, HBVG and maze-like VG (MVG) are synthesized on the surface of carbon paper (CP), respectively. Pt nanoparticles are deposited on pristine CP, HBVG-CP, and MVG-CP with the same route of repeated double-potential pulse electrodeposition (RDPE). Experimental results show that HBVG-CP with dense open graphitic edge planes can desirably provide a considerable number of nuclei sites for the fast nucleation and well dispersion of Pt nanoparticles. Meanwhile, a certain amount of oxygen-containing functional groups on the HBVG surface will benefit the rapid removal of CO and accumulated carbonaceous species. Based on the electrochemical measurements on Pt utilization efficiency, catalytic activity, CO tolerance, and long-term stability, Pt/HBVG-CP is demonstrated to be able to present enhanced catalytic performance over the Pt/CP and Pt/MVG-CP counterparts, holding a great potential for fuel cell applications. [ABSTRACT FROM AUTHOR]

In this paper, ultrathin graphene (GN) nanosheets were uniformly decorated with nickel (Ni) nanoparticles, as confirmed by scanning electron microscopy and transmission electron microscopy. This GNNi hybrid exhibited excellent accumulation and catalytic capacity for the simultaneous detection of sunset yellow and tartrazine, two colorants commonly found mixed in foodstuffs. The electrochemical reaction mechanism of sunset yellow and tartrazine were studied in detail on the GNNi nanocomposite modified glassy carbon electrode. In square wave voltammetry measurements, the oxidation peak potentials of sunset yellow and tartrazine were separated by about 250 mV. This novel proposed voltammetric method has good selectivity which was successfully applied for the simultaneous determination of sunset yellow and tartrazine in some food sample extracts. [ABSTRACT FROM AUTHOR]

A general strategy based on the nanoscale Kirkendall effect is developed to grow hollow transition metal (Fe, Co or Ni) oxide nanoparticles on graphene sheets. When applied as lithium‐ion battery anodes, these hollow transition metal oxide based composites exhibit excellent electrochemical performance with high reversible capacities and long‐term stabilities at a high current density, superior to most transition metal oxides reported to date. More information can be found in the Full Paper by Y. Chen, C. Sun, P. Gao et al. on page 1638 ff. [ABSTRACT FROM AUTHOR]

New Pd and Pt catalysts with high catalytic efficiency have been fabricated by means of a self‐assembly strategy and are composed of four components, that is, noble metal, CeO2, Fe3O4, and reduced graphene oxide (RGO). The as‐obtained Pd and Pt catalysts have relatively high catalytic activity and stability in the selective hydrogenation of p‐nitrophenol; they are also stable in air and exhibit a good magnetic response. For more details see the Full Paper by H. Zhang et al. on page 5169 ff. [ABSTRACT FROM AUTHOR]

A new and general fabrication strategy towards encapsulation of nanoparticles, such as Ni, Co and Co3O4, in sandwiched graphene sheets is reported in the Full Paper by Y. Wang et al. on page 3340 ff. The nanoparticles‐encapsulated sandwiched graphene sheets possess unique structures, in which nanoparticles are strictly confined inside and the graphene sheets are layered on both outer sides like a three‐layered sandwich, and substantially enhanced properties derived from the synergic effect among the individual functional components. The picture also shows the Chongqing University founded in 1929. The Chinese words in silver white mean top left to bottom right: “Unity, Diligence, Truth, Innovation” as the University motto. [ABSTRACT FROM AUTHOR]