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Characterization of atypical polyaniline nano-structures prepared via advanced techniques
摘要： Conductive polymers had been the topic of a vast number of investigations during the last decades, so, the synthesis of conducting polymers and study of their physical properties has been of prime importance. One of these conductive polymers is polyaniline. The current work is to prepare polyaniline (PANI) nanostructured material via four different preparation techniques which were sol-gel, rapid mixing, sonochemical and supercritical carbon dioxide (SC-CO2) assisted polymerization. The morphology of the prepared PANI samples was determined using Transmission electron microscopy (TEM) and Scanning Electron Microscope (SEM). The molecular structure of prepared PANI samples was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The electrical conductivity of the synthesized samples was assessed by using the four-probe method at room temperature. The surface area of the prepared samples was determined using Brunauer Emmett Teller (BET). The characterization results of the prepared PANI con?rm that the morphology, chemical composition, crystallinity, conductivity and surface area were altered signi?cantly as a consequence of its synthesis via atypical techniques.
关键词： Supercritical carbon dioxide assisted polymerization,Nanoparticles,Sonochemical,Polyaniline nano-structures,Nano?bers,Polyaniline characterization,Nanorods,Sol gel,Rapid mixing polymerization
更新于2025-09-23 15:23:52
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[Energy, Environment, and Sustainability] Advances in Solar Energy Research || Supercritical Carbon Dioxide Solar Thermal Power Generation—Overview of the Technology and Microchannel Receiver Development
摘要： The supercritical carbon dioxide (sCO2) power cycle is being considered for solar thermal central receiver systems in the United States. The cycle lends to increased high-temperature input that is expected of the next-generation concentrating solar thermal power (CSP) systems. Power block efficiencies of about 50% can be achieved for recompression cycles at an input temperature of approximately 720 °C. Additionally, the power block is compact and less complex, raising the possibility of using thermal-storage-coupled CSP sCO2 technologies for modular (*100 MW) peak-load power plants. Three pathways toward providing solar thermal input to the sCO2 cycle have been proposed by various research groups—the molten salt receiver pathway, the solid particle receiver pathway, and the gas-phase receiver pathway. The first two technologies have the advantage of sensible thermal storage within the solid/fluid medium passing through the receiver. In the gas receiver pathway, there is a need for coupling a sensible or latent heat storage technology. Several key technologies are needed to enable the realization of the sCO2 solar thermal technology, key among them being the receiver and thermal storage. In this chapter, some of the key gas-phase receiver technologies are discussed. The group’s past and recent work on the development of microchannel solar thermal receivers for sCO2 is emphasized.
关键词： Solar thermal,Efficiency,Supercritical carbon dioxide,Microchannel,Receiver,Concentrating solar power
更新于2025-09-23 15:21:21
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Boosting the efficiency of solution-based CZTSSe solar cells by using supercritical carbon dioxide treatment
摘要： Cu2ZnSn(S,Se)4 (CZTSSe) solar cells are receiving considerable attention in recent years, owing to the low cost and toxicity as well as high abundance of their constituent elements. Solution-based (mainly precursor solution) methods have been widely used in the fabrication of CZTSSe-based thin film solar cells. Though most record solar cells since 2009 have been achieved using solution-based methods, carbonaceous residues are always formed during post deposition treatment (PDT). These carbonaceous residues are detrimental to grain growth of CZTSSe to form large grains. The presence of unwanted small grains layers will increase the series resistance and reduce the fill factor of the solar cell, thus consequently hindering high efficiency in CZTSSe solar cells. Herein, we propose “green” supercritical carbon dioxide (SCCO2) treatment to overcome the challenge of carbonaceous residues. FT-IR、SEM、XRD and Raman characterizations were used to confirm the reducing of carbonaceous residues in CZTSSe films. The solar cell fabricated from selenized CZTSSe precursor film with SCCO2 treatment under optimal conditions showed the best conversion efficiency of 11.23 % (VOC = 0.456 V, JSC = 36.6 mA/cm2, FF = 67.1 %). To the best of our knowledge, it is the first report on boosting the efficiency of solution-based CZTSSe solar cells by using SCCO2 treatment. In addition, this unique SCCO2 treatment may also bring forth new ideas in other solution-based optoelectronic devices.
关键词： CZTSSe,Cu2ZnSn(S,Se)4,Carbonaceous residues,SCCO2 treatment,Supercritical carbon dioxide treatment
更新于2025-09-23 15:21:01
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Single-Stage Formation of Film Polymer Composites in Supercritical Colloid Solutions of Nanoparticles Obtained by Laser Ablation
摘要： A review of earlier studies is presented together with new results on the creation of highly concentrated colloid solutions with nanoparticles of noble metals (gold and silver) in a supercritical carbon dioxide (SC–CO2) medium and the development of a single-stage method for the production of polymer nanocomposites. The effect of the SC–CO2 density on the dynamics of the formation and decomposition of supercritical fluids (SCFs) of silver and gold nanocolloids in the process of pulsed laser ablation and after its termination is studied. The possibility of the formation of colloids from bimetallic nanoparticles was considered. The effective dielectric permittivity of a colloid solution of silver nanoparticles in SC–CO2 is calculated by the numerical modeling of extinction spectra in the dipole approximation at various densities, with consideration for the size of nanoparticles and the degree of their asphericity. The formation of various film nanocomposites based on a porous copolymer polytetrafluoroethylene—vinylidenefluoride with ruby nanoparticles and two modifications of pure porous polytetrafluoroethylene with silver nanoparticles in the same SCF reactor and with a single technological process is considered.
关键词： bimetallic nanoparticles,film nanocomposites,nanocolloid,supercritical carbon dioxide,porous polymers
更新于2025-09-23 15:21:01