Graphene quantum dots/graphene fiber nanochannels for osmotic power generation

Graphene quantum dots were intercalated into graphene fiber nanochannel as a nano-charger for high surface charge density. The hybrid nanochannel shows efficient ion transport behaviors and ion selectivity facilitating superior osmotic power generation.

Iron(II) and copper(II) paratungstates B: a single-crystal X-ray diffraction study

Paratungstate B is a common isopolytungstate (IPOT) built of the [W12O40(OH)2]10− anion and exhibits a cluster-like construction of 12 W-centred distorted octahedra. Due to a high surface charge density, the paratungstate anion acts as a multidentate ligand forming high-dimensional extended structures, which exhibit unique catalytic and magnetic properties. Two new paradodecatungstate B compounds decorated by iron(II) or copper(II), namely Na5Fe2.5[W12O40(OH)2]·36H2O (Na5Fe2.5paraB) and Na4Cu3[W12O40(OH)2]·28H2O (Na4Cu3paraB), have been synthesized by a convenient aqueous solution method, and structurally characterized by single-crystal and powder X-ray diffraction, IR spectroscopy, elemental analysis and thermogravimetric analysis. Both compounds crystallize in the triclinic P\overline{1} space group. In both compounds, the [W12O40(OH)2]10− polyanion acts as a multidentate ligand that links transition-metal and sodium cations, forming a three-dimensional framework.

A multi-dielectric-layered triboelectric nanogenerator as energized by corona discharge

A multi-dielectric-layered vertical contact-separation mode TENG through a corona discharge approach results in outstanding output performances, i.e., a high surface charge density of 283 μC m−2 and excellent cycling stability (92.6% retention after 200 000 cycles).

Polystyrene latex particles obtained by emulsifier-free emulsion polymerization and their interaction with bentonite

Polystyrene latex particles were prepared by using an emulsifier-free emulsion polymerization with two ionic initiators: potassium persulfate (KPS) and 2,2’-azobis(2-amidinopropane)dihydrochloride (AIBA). The purpose of this study was to obtain polystyrene latex with a good stability in time, a high surface charge density and a small particle size (between 100 and 1000 nm). We used two distinctive molar concentrations for both initiators: 5.5 mM and 55 mM based on aqueous phase. The analysis showed that in the case of KPS initiator the latexes stability was better. With AIBA as initiator smaller latex particles can be achieved. A high surface charge density was measured for large initiator concentration. We achieved satisfying results with both initiators, the optimal condition of polymerization depending on the subsequent utilization of the latex. The SEM images showed that latexes containing bentonite and latexes with no clay have similar size.

Novel Application of Amorphous Silicon in Electrostatic Loudspeakers

ABSTRACTA thin film of amorphous silicon (a-Si:H) has been developed for application as the charge retention layer in electrostatic loudspeakers. The vibrating diaphragm in this type of loudspeakers is usually coated with a thin film in order to assure homogeneous charge distribution across the surface. This thin film should be capable of maintaining a high surface charge density and possess a high lateral resistivity to prevent charge displacement. Furthermore, it should be mechanically stable, capable of accomodating mechanical deformation, and resistant against humidity. Conventionally, a graphite layer is used in these applications. However, the conventional layers are frequently unstable and suffer from charge displacement effects eventually leading to electric breakdown. Further requirements are that the film can be deposited continuously and homogeneously over large areas in excess of 1 m2 and that the deposition technique is compatible with the properties of the thin membrane. We investigated small-area prototypes of electrostatic loudspeakers with a-Si:H thin films deposited on polyimide substrates in the Utrecht deposition system, ASTER. Plasma-deposited amorphous silicon films fabricated under certain conditions are shown to meet all of the above requirements.