Surface modification

About: Surface modification is a research topic. Over the lifetime, 35544 publications have been published within this topic receiving 859567 citations.

Nitrogen modification of highly porous carbon for improved supercapacitor performance

Abstract: Nitrogen is added to porous carbon, in both the bulk network as heteroatoms and coated on the surface of the pores, to increase the capacitance of electrodes for supercapacitor applications. Surface modification increases the amount of nitrogen by four times when compared to unmodified carbon that only contains nitrogen in the bulk. Pyrolysis of the modified carbon at a lower temperature also retains up to three times more nitrogen than high temperature pyrolysis. The surface modification dramatically improves the wetting behavior of the porous carbon and produces a capacitance that is nearly twice that of the unmodified carbon through a combination of double-layer formation and pseudocapacitive reactions.

Effects of functionalization on thermal properties of single-wall and multi-wall carbon nanotube-polymer nanocomposites.

Abstract: Carboxylic functionalization (−COOH groups) of carbon nanotubes is known to improve their dispersion properties and increase the electrical conductivity of carbon-nanotube–polymer nanocomposites. We have studied experimentally the effects of this type of functionalization on the thermal conductivity of the nanocomposites. It was found that while even small quantities of carbon nanotubes (∼1 wt %) can increase the electrical conductivity, a larger loading fraction (∼3 wt %) is required to enhance the thermal conductivity of nanocomposites. Functionalized multi-wall carbon nanotubes performed the best as filler material leading to a simultaneous improvement of the electrical and thermal properties of the composites. Functionalization of the single-wall carbon nanotubes reduced the thermal conductivity enhancement. The observed trends were explained by the fact that while surface functionalization increases the coupling between carbon nanotube and polymer matrix, it also leads to formation of defects, which ...

Electronic functionalization of the surface of organic semiconductors with self-assembled monolayers

Abstract: Self-assembled monolayers (SAMs) are widely used in a variety of emerging applications for surface modification of metals and oxides. Here, we demonstrate a new type of molecular self-assembly: the growth of organosilane SAMs at the surface of organic semiconductors. Remarkably, SAM growth results in a pronounced increase of the surface conductivity of organic materials, which can be very large for SAMs with a strong electron-withdrawing ability. For example, the conductivity induced by perfluorinated alkyl silanes in organic molecular crystals approaches 10(-5) S per square, two orders of magnitude greater than the maximum conductivity typically achieved in organic field-effect transistors. The observed large electronic effect opens new opportunities for nanoscale surface functionalization of organic semiconductors with molecular self-assembly. In particular, SAM-induced conductivity shows sensitivity to different molecular species present in the environment, which makes this system very attractive for chemical sensing applications.

Controllable fabrication of nanostructured materials for photoelectrochemical water splitting via atomic layer deposition

Abstract: Photoelectrochemical (PEC) water splitting is an attractive approach to generate hydrogen as a clean chemical fuel from solar energy. But there remain many fundamental issues to be solved, including inadequate photon absorption, short carrier diffusion length, surface recombination, vulnerability to photo-corrosion, and unfavorable reaction kinetics. Owing to its self-limiting surface reaction mechanism, atomic layer deposition (ALD) is capable of depositing thin films in a highly controllable manner, which makes it an enabling technique to overcome some of the key challenges confronted by PEC water splitting. This tutorial review describes some unique and representative applications of ALD in fabricating high performance PEC electrodes with various nanostructures, including (i) coating conformal thin films on three-dimensional scaffolds to facilitate the separation and migration of photocarriers and enhance light trapping, as well as realizing controllable doping for bandgap engineering and forming homojunctions for carrier separation; (ii) achieving surface modification through deposition of anti-corrosion layers, surface state passivation layers, and surface catalytic layers; and (iii) identifying the main rate limiting steps with model electrodes with highly defined thickness, composition, and interfacial structure.