Surface modification

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

Fabrication of a Core–Shell-Type Photocatalyst via Photodeposition of Group IV and V Transition Metal Oxyhydroxides: An Effective Surface Modification Method for Overall Water Splitting

Abstract: The design of optimal surface structures for photocatalysts is a key to efficient overall water splitting into H2 and O2. A unique surface modification method was devised for a photocatalyst to effectively promote overall water splitting. Photodeposition of amorphous oxyhydroxides of group IV and V transition metals (Ti, Nb, Ta) over a semiconductor photocatalyst from corresponding water-soluble metal peroxide complexes was examined. In this method, amorphous oxyhydroxide covered the whole surface of the photocatalyst particles, creating a core–shell structure. The water splitting behavior of the novel core–shell-type photocatalyst in relation to the permeation behavior of the coating layer was investigated in detail. Overall water splitting proceeded successfully after the photodeposition, owing to the prevention of the reverse reaction. The photodeposited oxyhydroxide layers were found to function as molecular sieves, selectively filtering reactant and product molecules. By exploiting the selective perm...

Enhanced field emission from printed carbon nanotubes by mechanical surface modification

Abstract: A method is presented where the morphology of screen printed carbon nanotube pastes is modified using an adhesive tape. In this way, the organic matrix material is preferentially removed leaving an optimal emitter surface of sparsely distributed and well-aligned carbon nanotubes. From these emitter surfaces, homogeneous emission was observed with emitter site densities of at least 104 emitters cm−2 and extracted current densities over 500 mA cm−2.

Surface Condition Changes in Lithium Metal Deposited in Nonaqueous Electrolyte Containing HF by Dissolution‐Deposition Cycles

Abstract: The dissolution‐deposition cycle behavior of Li metal electrodeposited in nonaqueous electrolyte containing a small amount of HF was investigated. In the first deposition process, Li particles with a smooth hemispherical shape were deposited on Ni in 1.0 M carbonate containing HF. The morphology of these fine Li particles is due to electrodeposition via migration of ions through a thin and compact surface film consisting of a bilayer, which was produced via surface modification by HF. After the first dissolution process, a residual film was observed on the entire surface of the Ni substrate. This residual film is derived from the surface film on the Li particles. Moreover, the residual film continuously accumulated on the electrode during the cycling. On the other hand, it was found that the coulombic efficiency of Li deposition‐dissolution during cycling was much improved by the addition of HF. Unfortunately, the formation of dendritic Li was observed after the 45th cycle, suggesting that the accumulated thick residual film on the Li surface inhibits the supply of HF to the Li surface during the deposition process. © 1999 The Electrochemical Society. All rights reserved.

Insights into the thermolytic transformation of lignocellulosic biomass waste to redox-active carbocatalyst: Durability of surface active sites

Abstract: The thermolytic transformation of lignocellulosic spent coffee grounds to superior redox-active carbocatalyst (denoted as NBC) via nitrogen functionalization in a pyrolytic environment at various temperatures was investigated. The intrinsic (e.g. surface chemistry, degree of graphitization, etc.) and extrinsic (e.g. specific surface area, morphology, etc.) properties of the catalysts were systematically studied using various characterization techniques. The three main N configurations conducive to redox reactions, namely pyrrolic N, pyridinic N and graphitic N were present at different compositions in all the NBCs prepared at pyrolysis temperature ≥500 °C. The NBCs were used as peroxymonosulfate (PMS) activator for degrading bisphenol A. It was found that NBC-1000 (prepared at 1000 °C) has the highest catalytic performance (kapp = 0.072 min−1) due to the relatively higher specific surface area (438 m2 g−1), excellent degree of graphitization, and optimum N bonding configuration ratio. Based on the radical scavenger and electron paramagnetic resonance studies, the nonradical pathway involving 1O2 generation is identified as the prevailing pathway while the radical pathway involving SO4 −and OH generation is the recessive pathway. Further investigation of the durability of surface active sites revealed that the active sites undergo N bonding configuration reconstruction and cannibalistic oxidation (increase in surface oxygen content) during PMS activation reaction. The graphitic N manifest greater catalytic activity and stability compared to pyridinic N and pyrrolic N under oxidizing environment. The results demonstrated that reaction optimization is critical to improve the durability of the catalyst. This study provides useful insights in converting lignocellulosic biomass waste into functional catalytic material, and the strategy to improve the durability of carbocatalysts for redox-based reactions.