Hierarchical ultrathin NiAl layered double hydroxide nanosheet arrays on carbon nanotube paper as advanced hybrid electrode for high performance hybrid capacitors

To effectively improve the power density and rate capability of layered double hydroxide (LDH) based supercapacitors, a hybrid supercapacitor (HSC) comprising of hierarchical ultrathin NiAl-LDH nanosheet arrays on carbon nanotube paper (CNP-LDH) is developed with porous graphene nanosheets as the negative electrode for the first time. SEM image shows that hierarchical NiAl LDH nanosheet arrays are assembled by numerous ultrathin nanosheets with thickness of a few to tens of nanometers. Remarkably, with an operating voltage of 1.6 V, the HSC possesses a high energy density of 50.0 Wh kg-1 at an average power density of 467 W kg-1. Even at a fast discharging time of 3.9 s, a high energy density (23.3 Wh kg-1) could also be retained at a power density of 21.5 kW kg-1. Moreover, the HSC exhibits cycling stability with a retention rate of 78% after 5000-cycle charge-discharge test at 5 A g-1. The results inspire us to propose our high-performance CNP-LDH as a promising electrode for energy storage applications

Novel enzyme-free multifunctional bentonite/polypyrrole/silver nanocomposite sensor for hydrogen peroxide detection over a wide pH range

Precise designs of low-cost and efficient catalysts for the detection of hydrogen peroxide (H2O2) over wide ranges of pH are important in various environmental applications. Herein, a versatile and ecofriendly approach is presented for the rational design of ternary bentonite-silylpropyl-polypyrrole/silver nanoarchitectures (denoted as BP-PS-PPy/Ag) via the in-situ photo polymerization of pyrrole with salinized bentonite (BP-PS) in the presence of silver nitrate. The Pyrrolyl-functionalized silane (PS) is used as a coupling agent for tailoring the formation of highly exfoliated BP-PS-PPy sheet-like nanostructures ornamented with monodispersed Ag nanoparticles (NPs). Taking advantage of the combination between the unique physicochemical properties of BP-PS-PPy and the outstanding catalytic merits of Ag nanoparticles (NPs), the as-synthesized BP-PS-PPy/Ag shows a superior electrocatalytic reduction and high-detection activity towards H2O2 under different pH conditions (from 3 to 10). Intriguingly, the UV-light irradiation significantly enhances the electroreduction activity of H2O2 substantially, compared with the dark conditions, due to the high photoelectric response properties of Ag NPs. Moreover, BP-PS-PPy/Ag achived a quick current response with a detection limit at 1 μM within only 1 s. Our present approach is green, facile, scalable and renewabl

Layer-by-Layer Materials for the Fabrication of Devices with Electrochemical Applications

The construction of nanostructured materials for their application in electrochemical processes, e.g., energy storage and conversion, or sensing, has undergone a spectacular development over the last decades as a consequence of their unique properties in comparison to those of their bulk counterparts, e.g., large surface area and facilitated charge/mass transport pathways. This has driven strong research on the optimization of nanostructured materials for the fabrication of electrochemical devices, which demands techniques allowing the assembly of hybrid materials with well-controlled structures and properties. The Layer-by-Layer (LbL) method is well suited for fulfilling the requirements associated with the fabrication of devices for electrochemical applications, enabling the fabrication of nanomaterials with tunable properties that can be exploited as candidates for their application in fuel cells, batteries, electrochromic devices, solar cells, and sensors. This review provides an updated discussion of some of the most recent advances on the application of the LbL method for the fabrication of nanomaterials that can be exploited in the design of novel electrochemical devices.Depto. de Química FísicaFac. de Ciencias QuímicasTRUEUnión Europea. Horizonte 2020Ministerio de Ciencia e Innovación (MICINN)pu

Hybrid polypyrrole and polydopamine nanosheets for precise Raman/photoacoustic imaging and photothermal therapy

The development of near-infrared light (NIR)-responsive conductive polymers provides a useful theranostic platform for malignant tumours by maximizing spatial resolution with deep tissue penetration for diagnosis and photothermal therapy. Herein, we demonstrated the self-assembly of ultrathin two-dimensional (2D) polypyrrole nanosheets utilizing dopamine as a capping agent and a monolayer of octadecylamine as a template. The 2D polypyrrole-polydopamine nanostructure (DPPy) had tunable size distribution which showed strong absorption in the first and second near-infrared windows, enabling photoacoustic imaging and photothermal therapy. The hybrid double-layer was demonstrated to increase Raman intensity for 3D Raman imaging (up to two orders of magnitude enhancement and spatial resolution up to 1 μm). The acidic environment drove reversible doping of polypyrrole, which could be detected by Raman spectroscopy. The combined properties of the nanosheets could substantially enhance performance in dual-mode Raman and photoacoustic guided photothermal therapy, as shown by the 69% light to heat conversion efficiency and higher cytotoxicity against cancer spheroids. These pH-responsive features highlight the potential of 2D conductive polymers for applications in accurate, highly efficient theranostics

Recent advances in functional nanostructures as cancer photothermal therapy.

Being a non-invasive and relatively safe technique, photothermal therapy has attracted a lot of interest in the cancer treatment field. Recently, nanostructure technology has entered the forefront of cancer therapy owing to its ability to absorb near-infrared radiation as well as efficient light to heat conversion. In this study, key nanostructures for cancer therapy including gold nanoparticles, magnetite iron oxide nanoparticles, organic nanomaterials, and novel two-dimensional nanoagents such as MXenes are discussed. Furthermore, we briefly discuss the characteristics of the nanostructures of these photothermal nanomaterial agents, while focusing on how nanostructures hold potential as cancer therapies. Finally, this review offers promising insight into new cancer therapy approaches, particularly in vivo and in vitro cancer treatments

High-performance solid-state flexible supercapacitor based on reduced graphene oxide/hierarchical core-shell Ag nanowire@NiAl layered double hydroxide film electrode

All-solid-state flexible supercapacitor (AFSC) is a promising energy storage device due to its high flexibility, security, and environmental friendliness. However, high electrical resistance and low specific capacitance of electrodes limit its application for potential portable electronic devices. In this study, we design a novel hybrid film electrode composed of reduced graphene oxide (rGO)/silver nanowire (Ag NW)@nickel aluminum layered double hydroxide (NiAl LDH; herein, GAL) possessing high electrochemical performance by using hydrothermal and vacuum filtration techniques. The Ag NW@NiAl LDH (AL) composites with hierarchical core-shell structure are utilized to increase electroactive surface area and improve electrical conductivity, while the rGO nanosheets serve as a prominent carbon material with outstanding electrical conductivity and mechanical flexibility. The freestanding GAL electrode shows high specific capacitance of 1148 F g−1 at 1 A g−1 compared with rGO/NiAl LDH (GL) of 765.2 F g−1 at 1 A g−1. Furthermore, the bind-free symmetric AFSC device is successfully prepared using GAL hybrid film as electrodes and PVA-KOH as solid-state gel electrolyte. The GAL//GAL AFSC device delivers a superior specific capacitance of 127.2 F g−1 at 1 A g−1, a high energy density of 35.75 mWh cm−3 at a power density of 1.01 W cm−3, and great cycling ability of 83.2% over 10,000 cycles at 5 A g−1. This study introduces a novel design of flexible electrode structure for advanced energy storage applications

Polymer Nanocomposite-Based Electrochemical Sensors and Biosensors

Polymer nanocomposites (PNCs) play a significant role in modern day life and are widely studied for extensive properties which make them appealing to numerous applications. They are synthesized with scalable processing procedures with several nanoscale variations of fillers and forms leading to specific sensing applications. In this chapter, PNC-based electrochemical sensors and biosensors like DNA biosensors and immunosensors are discussed. These sensors related PNC applications uses nanofillers of various combinations like conductive polymers with graphene (Grp), carbon nanotubes (CNTs), and metal nanoparticles, which endow high electrical conductivity, effective surface area, and fast electron transfer rate. Currently, wearable devices based on electrochemical Sensors and biosensors have been of great interest in the detection of both physiological and environmental analytes