Sensing or catalysis

ZnO is a semiconductor of interest for different optoelectronic applications due to its wide direct band gap (3.37 eV) and large exciton binding energy (60 meV). It is also used as a transparent conductor and has applications for gas sensing or catalysis. 

Immobilization of enzymes, polynucleotide, and antibodies for sensing or catalysis... 

Prussian blue (PB ferric ferrocyanide, or iron(III) hexacyanoferrate(II)) was first made by Diesbach in Berlin in 1704.88 It is extensively used as a pigment in the formulation of paints, lacquers, and printing inks.89,90 Since the first report91 in 1978 of the electrochemistry of PB films, numerous studies concerning the electrochemistry of PB and related analogs have been made,92 with proposed applications in electrochromism1 and electrochemical sensing and catalysis 93... 

Autocatalysis is a special type of molecular catalysis in which one of the products of reaction acts as a catalyst for the reaction. As a consequence, the concentration of this product appears in the observed rate law with a positive exponent if a catalyst in the usual sense, or with a negative exponent if an inhibitor. A characteristic of an autocat-alytic reaction is that the rate increases initially as the concentration of catalytic product increases, but eventually goes through a maximum and decreases as reactant is used up. The initial behavior may be described as abnormal kinetics, and has important consequences for reactor selection for such reactions. 

In the strictest sense, homogeneous catalysis involves catalytic reactions occurring in a single phase. However, as currently used, the term implies only that at least a portion of a particular reaction is known or suspected strongly to occur in the coordination sphere of a metal (most frequently a transition metal). Activation of substrates and likely the steric course of the reaction are then consequences of bonding in an in-... 

The search for catalysts has many features in common with the search for biologically active compounds, most importantly pharmaceuticals In both cases, the aim is the discovery of a property, an effect. In classical pharmaceutical (or catalysis) research (Scheme 3, top), compound isolation and characterization precedes testing. As a consequence, a lot of effort may be invested on compounds that eventually do not show the desired properties (4,5). In the combinatorial approach, (Scheme 3, bottom) characterization comes after the discovery of a desired property, and it is limited to those compounds that show the desired property. As summarized in Scheme 3 (bottom), the key features of the combinatorial approach to catalyst discovery (and optimization) are (i) the generation of libraries of catalyst candidates, and (ii) the screening of the libraries for catalytic activity. Both aspects are dealt with in a general sense in Sections LB and I.C below. Section I.D summarizes the features specific for library generation and screening in the field of biomimetic oxidation catalysis. 

There is no sense or profit in talking about theories of catalytic reactions in general. The theory of catalysis is the theory of chemical reaction velocity, and the methods of operation of catalysts are as diverse as the modes of chemical change. Normally the catalyst adds a new path of reaction of lowered activation energy, but sometimes it is the non-exponential factor for the new mechanism which is more favourable, as for example in a chain reaction. Anything, such as an extraneous source of radicals, which initiates a chain reaction is of course a catalyst. 

An enzyme (denoted here by E) is generally a protein which contains one or more active sites to which a reactant molecule can bind. In a sense, enzymatic catalysis is intermediate between homogeneous and heterogeneous catalysis in that the active site or sites are on the surface of the enzyme but the enzyme and reactant molecules are in the same solution phase. In the first step of the catalysed reaction, the reactant molecule, usually referred to as the substrate (S), binds to an active site on the enz5mie, in a process which is reversible and which generally utilises intermolecular forces, of the kind considered in Sect. 1.4, to form an enzyme-substrate complex (ES). As in other kinds of catalysis, the role of the enzyme is to... 

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