Gas Sensors Based on Conducting Polymers

Since the discovery of conducting polymers (CPs), their unique properties and tailor-made structures on-demand have shown in the last decade a renaissance and have been widely used in fields of chemistry and materials science. The chemical and thermal stability of CPs under ambient conditions greatly enhances their utilizations as active sensitive layers deposited either by in situ chemical or by electrochemical methodologies over electrodes and electrode arrays for fabricating gas sensor devices, to respond and/or detect particular toxic gases, volatile organic compounds (VOCs), and ions trapping at ambient temperature for environmental remediation and industrial quality control of production. Due to the extent of the literature on CPs, this chapter, after a concise introduction about the development of methods and techniques in fabricating CP nanomaterials, is focused exclusively on the recent advancements in gas sensor devices employing CPs and their nanocomposites. The key issues on nanostructured CPs in the development of state-of-the-art miniaturized sensor devices are carefully discussed. A perspective on next-generation sensor technology from a material point of view is demonstrated, as well. This chapter is expected to be comprehensive and useful to the chemical community interested in CPs-based gas sensor applications

Advanced nanoporous material–based QCM devices: A new horizon of interfacial mass sensing technology

Mass interfacial processes have been considered as one of the crucial factors supporting fundamental research. Due to the low cost and conceptual simplicity, significant advancements have been achieved in the development of methodologies based on piezoelectric devices for in situ determination of mass changes on the surfaces of deposited materials under various conditions. The introduction of nanomaterials for designing sensors and monitoring systems becomes essential to create advanced detection systems for selective sensing of toxic analytes for environmental remediation. The integration of materials with predesignated nanostructures into sensor devices, such as surface acoustic wave (SAW), quartz crystal microbalance (QCM), and QCM with dissipation (QCM-D) monitoring, has led to an immense progress in the sensing applications of toxic target analytes at the nanogram range. Here, an overview is introduced of recent advancement in the fabrication of piezoelectric devices for the interfacial mass sensing of targeted chemical vapors and ions through combination with nanoporous materials including mesoporous materials carbon-based nanomaterials, metal–organic frameworks (MOFs), MOF-derived nanoporous carbons, Prussian blue (PB) and its analogues (PBA), zeolites and related materials. Challenges and future prospect are also summarized by the advanced QCM technique associated with properties of nanostructured materials

Nanoarchitectured Graphene-Based Supercapacitors for Next-Generation Energy-Storage Applications

Tremendous development in the field of portable electronics and hybrid electric vehicles has led to urgent and increasing demand in the field of high‐energy storage devices. In recent years, many research efforts have been made for the development of more efficient energy‐storage devices such as supercapacitors, batteries, and fuel cells. In particular, supercapacitors have great potential to meet the demands of both high energy density and power density in many advanced technologies. For the last half decade, graphene has attracted intense research interest for electrical double‐layer capacitor (EDLC) applications. The unique electronic, thermal, mechanical, and chemical characteristics of graphene, along with the intrinsic benefits of a carbon material, make it a promising candidate for supercapacitor applications. This Review focuses on recent research developments in graphene‐based supercapacitors, including doped graphene, activated graphene, graphene/metal oxide composites, graphene/polymer composites, and graphene‐based asymmetric supercapacitors. The challenges and prospects of graphene‐based supercapacitors are also discussed

Preparation of various Prussian blue analogue hollow nanocubes with single crystalline shells

We report the preparation of monocrystalline Prussian blue (PB) analogue hollow nanocubes by applying a controlled chemical etching method with assistance of polyvinylpyrrolidone (PVP). The hollow particles obtained possess the original single-crystalline structures, with retention of the high surface areas. Our synthetic route based on chemical etching is quite simple, and it can be scaled up for mass production

Trace-level gravimetric detection promoted by surface interactions of mesoporous materials with chemical vapors

Chemical-vapor detection was enhanced by coating high-surface-area mesoporous materials over a Au electrode for gravimetric QCM sensing, referred to as the "meso-QCM system". The AlPO-based meso-QCM system is very promising for quantitative detection at a trace level from several tens of ppb to several ppb due to selective interaction of the framework surfaces

Polymeric Micelle Assembly for the Direct Synthesis of Platinum-Decorated Mesoporous TiO2 toward Highly Selective Sensing of Acetaldehyde

Platinum-decorated mesoporous TiO2 is synthesized by the self-assembly of polymeric micelles of an asymmetric triblock copolymer with three chemically distinct units in an acidic tetrahydrofuran solution. The strong hydrophobic interaction of platinum(II) 2,4-pentanedionate with a polystyrene core and electrostatic interaction of titanium tetraisopropoxide with a poly(vinylpyridine) shell enable us to directly synthesize crystalline mesoporous TiO2 with platinum nanoparticles. A thermally stable block copolymer prevents collapse of the ordered mesostructure during the calcination process. The platinum source is in situ reduced to form the platinum nanoparticles on the TiO2 walls. The sensing performance of platinum-decorated mesoporous TiO2 is studied in detail using a quartz crystal microbalance technique, and it is found that it shows excellent sensitivity for acetaldehyde

Large Cs adsorption capability of nanostructured Prussian Blue particles with high accessible surface areas

Very recently, we have reported preparation of several types of Prussian Blue (PB) particles with varying particle sizes by systematically tuning the synthetic conditions (Angew. Chem., Int. Ed., 2012, 51, 984-988). Here, the obtained PB particles are used for removal of Cs ions from aqueous solutions, which will be useful for remediation of nuclear waste. To evaluate the uptake ability of Cs ions into the PB particles, we utilize quartz crystal microbalance (QCM) for real-time monitoring of uptake behavior of Cs ions into the PB particles. The frequency of the QCM is promptly decreased after injection of Cs ions solution into the QCM cell. Hollow PB nanoparticles of 190 nm in diameter have very high surface area (338 m(2) g(-1)), in comparison with other PB particles, leading to efficient Cs adsorption capability eight times larger than that of the commercial PB particles. The diffusion in terms of dissociation constant (K-d), maximum amount of adsorbed Cs in PB particles (m(max)), and the adsorption kinetics (k) of Cs ions into the PB particles are also discussed. Due to the selective uptake for Cs ions based on K-d and k values, the PB particles can be proposed as good candidates in waste management consideration

Polymeric Micelle Assembly for the Direct Synthesis of Platinum-Decorated Mesoporous TiO₂ toward Highly Selective Sensing of Acetaldehyde

Platinum-decorated mesoporous TiO₂ is synthesized by the self-assembly of polymeric micelles of an asymmetric triblock copolymer with three chemically distinct units in an acidic tetrahydrofuran solution. The strong hydrophobic interaction of platinum­(II) 2,4-pentanedionate with a polystyrene core and electrostatic interaction of titanium tetraisopropoxide with a poly­(vinylpyridine) shell enable us to directly synthesize crystalline mesoporous TiO₂ with platinum nanoparticles. A thermally stable block copolymer prevents collapse of the ordered mesostructure during the calcination process. The platinum source is in situ reduced to form the platinum nanoparticles on the TiO₂ walls. The sensing performance of platinum-decorated mesoporous TiO₂ is studied in detail using a quartz crystal microbalance technique, and it is found that it shows excellent sensitivity for acetaldehyde

Study on adsorption of copper ion from aqueous solution by MOF-derived nanoporous carbon

Nanoporous carbons (NC) materials are synthesized by direct carbonization of zeolitic imidazolate framework (ZIF-8), a well-known metal organic framework (MOF). Here we study the efficiency of the obtained MOF-derived nanoporous carbon (MOF-NC) particles as adsorbent for the removal of copper (Cu) ions from an aqueous solution. The adsorption behavior is carefully studied from both kinetic and equilibrium point of view from which the obtained data can be described with different models. The efficiency of MOF-NC for removing Cu ion is compared with other carbonaceous adsorbents. The effect of solution pH and temperature on the removal percentage is also studied