Topic
Chemisorption
About: Chemisorption is a research topic. Over the lifetime, 16298 publications have been published within this topic receiving 554989 citations.
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TL;DR: It is proposed that surface Cd vacancies function as nonradiative recombination centers and the adsorption of a Lewis base to the QD raises the surface vacancy energy close to, or above, the conduction band edge and eliminates electron capture by the surface vacancies.
Abstract: We report on the effects of Lewis bases and other ligands on radiative recombination in CdSe quantum dots (QDs) in several solvents. Long-chain primary amines are found to be the most efficacious capping agents for CdSe QDs in nonpolar solvents. Primary alkylamines are superior to secondary and tertiary alkylamines. The kinetics of chemisorption and desorption in less polar solvents, such as hexane or chloroform, are temperature controlled and obey a Langmuir isotherm. Mercaptan adsorption also obeys a Langmuir isotherm, and alkylmercaptans rapidly displace amines, leading to luminescence quenching. In more polar solvents, such as toluene, ligands desorb, leading to luminescence quenching. It is proposed that surface Cd vacancies function as nonradiative recombination centers. The adsorption of a Lewis base to the QD raises the surface vacancy energy close to, or above, the conduction band edge and eliminates electron capture by the surface vacancies. Solvent polarity has a strong effect on luminescence since the solvent determines the extent of ligand adsorption to the QD surface.
495 citations
TL;DR: In this paper, the authors investigated the sensing mechanisms of ZnO nanowire films by performing transient photocurrent measurements and found that the current jumps upon ultraviolet or green laser illumination.
Abstract: Sensing mechanisms of ZnO nanowire films are investigated by performing transient photocurrent measurements. The current jumps upon ultraviolet or green laser illumination. The amplitude in the jump is strongly dependent on the ambient atmosphere. The decay rate is much more sensitive to the ambient atmosphere than the rise rate. The fast rise is due to rapid photogenerated carriers and the slow decay is controlled by slow surface process. Our experimental results indicate that the oxygen physisorption rate is slower than the chemisorption rate.
481 citations
TL;DR: In this article, the present understanding of the electronic, geometric, and chemisorption properties of metal oxide surfaces is reviewed and interpreted in terms of surface electronic and geometric structure, and some recent electron and photon-stimulated desorption results on oxides are also reviewed.
Abstract: The author reviews the present understanding of the electronic, geometric and chemisorption properties of metal oxide surfaces. It is restricted to experimental and theoretical studies of single-crystal oxide surfaces since only for those systems has it been possible to correlate surface properties with specific site geometry, ligand coordination, defect structure, etc. The geometric structures of the oxide surfaces that have been investigated to date are described in relation to bulk crystal structure and cation ligand coordination. The electronic structure of both perfect and defect surfaces is discussed for the various classes of metal oxides, and similarities and differences in their behaviour are correlated with surface geometry and cation electronic configuration. The chemisorption of several types of atoms and molecules on single-crystal oxide surfaces, both nearly perfect and containing point defects is reviewed and interpreted in terms of surface electronic and geometric structure. Some recent electron- and photon-stimulated desorption results on oxides are also reviewed, as the measurements of surface phonon and plasmon modes.
481 citations
TL;DR: In this paper, a review of the structure and chemical reactions on well-defined cerium oxide surfaces is presented, and the growth, characterization and properties of these thin-films are also examined.
480 citations
TL;DR: In this paper, the degradation of mild steel/1-methyl-4[4]-styryl pyridinium iodides (X: H, CH3 and OCH3)/hydrochloric acid systems was studied at different temperatures by means of hydrogen evolution (HE) and weight loss (WL) measurements.
479 citations