Effective Synthesis of Well-Graphitized Carbon Nanotubes on Bimetallic SBA-15 Template for Use as Counter Electrode in Dye-Sensitized Solar Cells

Boosting catalytic activity of niobium/tantalum-nitrogen active-sites for triiodide reduction in photovoltaics

To fabricate high-quality catalysts with abundant active sites, a series of transition-metal-modified nitrogenous carbon catalysts (Ta-NOC, Nb-NOC, and Nb/Ta-NOC) was successfully fabricated via pyrolysis and ion exchange. Owing to the high conductivity and ion transport capacity of its unique nitrogen-carbon structure, and synergistic effect of dual-metal active sites on modulating electronic structure, Nb/Ta-NOC catalyst exhibited an excellent catalytic performance and a remarkable electrochemical stability in triiodide reduction reaction (IRR) and hydrogen evolution reaction (HER). Nb/Ta-NOC catalyst achieved an ideal conversion efficiency of 8.45% for IRR in solar cells, which was higher than that of Pt electrode (7.63%). Furthermore, Nb/Ta-NOC catalyst exhibited a small overpotential of 145 mV at a current density of 10 mA·cm^-2 and a Tafel slope of 77 mV dec^-1 for HER. This work provided a new approach for the rational design of the active-sites-rich electrocatalysts for energy conversion applications.

Large-scale synthesis of coiled-like shaped carbon nanotubes using bi-metal catalyst

Carbon nanomaterials (CNMs), especially carbon nanotubes (CNTs) with coiled structure exhibit scientifically fascinating. They may be projected as an innovative preference to future technological materials. Coiled carbon nanotubes (c-CNTs) on a large-scale were successfully synthesized with the help of bi-metal substituted α-alumina nanoparticles catalyst via chemical vapor deposition (CVD) technique. Highly spring-like carbon nanostructures were observed by field emission scanning electron microscope (FESEM) examination. Furthermore, the obtained material has high purity, which correlates the X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) analysis. Raman spectroscopy reveals that the carbon multi layers are well graphitized and crystalline, even if they have defects in its structure due to coiled morphology. High-resolution transmission electron microscope (HRTEM) describes internal structure and dia of the product. Ultimately, results support the activity of bi-metal impregnated α-alumina nanoparticles catalyst to determine the high yield, graphitization and internal structure of the material. We have also studied the purified c-CNTs magnetic properties at room temperature and will be an added advantage in several applications.

A PVdF-based electrolyte membrane for a carbon counter electrode in dye-sensitized solar cells

This research demonstrates the design and operation of a dye-sensitized solar cell (DSSC) with a multi-walled carbon nanotube counter electrode (CE) and a pore-filled membrane consisting of polyvinylidene fluoride-co-hexafluoropropylene (PVdF-co-HFP) as an electrolyte.

Determination of Tetracycline Antibiotic Residues in Honey and Milk by Miniaturized Solid Phase Extraction Using Chitosan-Modified Graphitized Multiwalled Carbon Nanotubes

A rapid, simple, and strongly selective miniaturized solid phase extraction (SPE) technique, requiring only small amounts of sorbent (24 mg) and elution solvent (600 μL), coupled with ultrahigh-performance liquid chromatography and quadrupole time-of-flight mass spectrometry was developed for detecting tetracycline antibiotics. These analytes were extracted from honey and milk using chitosan-modified graphitized multiwalled carbon nanotubes (G-MWNTs) as the solid sorbent and acetonitrile/acetic acid (8:2, v/v) as the eluent in miniaturized SPE. Under the optimum experimental conditions, a satisfactory linearity (r(2) > 0.992) was obtained, and the limits of detection were in the range of 0.61-10.34 μg/kg for the analytes. The mean recoveries of the five tetracycline antibiotic residues in the real samples were between 81.5 and 101.4%. The results demonstrated that chitosan-modified G-MWNTs comprise a promising material for the enrichment of tetracycline antibiotics from complex food matrices.

Carbon nanotube and hydrogen production from waste plastic gasification over Ni/Al–SBA-15 catalysts: effect of aluminum content

The acidic sites of Ni/Al–SBA-15 catalysts strikingly promoted the activity of carbon nanotubes and H₂ production in waste plastic gasification.

In-situ electrochemically deposited polypyrrole nanoparticles incorporated reduced graphene oxide as an efficient counter electrode for platinum-free dye-sensitized solar cells

This paper reports a rapid and in-situ electrochemical polymerization method for the fabrication of polypyrrole nanoparticles incorporated reduced graphene oxide (rGO@PPy) nanocomposites on a ITO conducting glass and its application as a counter electrode for platinum-free dye-sensitized solar cell (DSSC). The scanning electron microscopic images show the uniform distribution of PPy nanoparticles with diameter ranges between 20 and 30 nm on the rGO sheets. The electrochemical studies reveal that the rGO@PPy has smaller charge transfer resistance and similar electrocatalytic activity as that of the standard Pt counter electrode for the I₃(-)/I(-) redox reaction. The overall solar to electrical energy conversion efficiency of the DSSC with the rGO@PPy counter electrode is 2.21%, which is merely equal to the efficiency of DSSC with sputtered Pt counter electrode (2.19%). The excellent photovoltaic performance, rapid and simple fabrication method and low-cost of the rGO@PPy can be potentially exploited as a alternative counter electrode to the expensive Pt in DSSCs.

Preparation of nitrogen-doped TiO₂/graphene nanohybrids and application as counter electrode for dye-sensitized solar cells

The preparation of nitrogen-doped TiO2/graphene nanohybrids and their application as counter electrode for dye-sensitized solar cell (DSSC) are presented. These nanohybrids are prepared by self-assembly of pyrene modified H2Ti3O7 nanosheets and graphene in aqueous medium via π-π stacking interactions, followed by thermal calcination at different temperatures in ammonia atmosphere to afford nitrogen-doped TiO2/graphene nanohybrids. H2Ti3O7 nanosheets were synthesized from TiOSO4·xH2O by a hydrothermal reaction at 150 °C for 48 h. The microstructure of the obtained mixed-phase nanohybrids was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transforms infrared spectroscopy (FTIR). Moreover, the performances of the as-prepared nanohybrids as counter electrode materials for DSSC was investigated, and the results indicated that the nanohybrids prepared at higher nitridation temperature would lead to higher short-circuit current density than those prepared at lower nitridation temperature, indicating that it can be utilized as a low-cost alternative to Pt for DSSCs and other applications.