Surface complexation models protonation mechanism

In the site-binding model, therefore, the formation of surface complexes is the principal mechanism by which protons are released or consumed by a ceramic powder surface in an aqueous electrolyte solution. The concentration of... 

In order to study the possible reasons and mechanisms of the catalytic activity of conducting polymers (CP), the electronic structure of some molecular CPs clusters and its adsorption complexes with oxygen were modeled [6], In the CP-O2 complex, the CP surface is an electron density donor. For example, in the case of PANI, the bond orders in adsorbed O2 molecules decrease by about 30%, and the bond lengths L increase by about 24%. Thus, the adsorbed O2 molecules have a fairly high degree of activation and can readily interact with the protons. 

Molecular modeling of PT at dense interfacial arrays of protogenic surface groups in PEMs needs ab initio quantum mechanical calculations. In spite of fhe dramafic increase in computational capabilihes, it is still "but a dream" to perform full ab initio calculations of proton and water transport within realistic pores or even porous networks of PEMs. This venture faces two major obstacles structural complexity and the rarity of proton transfer events. The former defines a need for simplified model systems. The latter enforces the use of advanced compufahonal techniques that permit an efficient sampling of rare evenfs. ... 

Each of the three (3 subunits in the complete FqFi complex can bind ADP and Pj and catalyze ATP synthesis. However, the coupling between proton flow and ATP synthesis must be Indirect, since the nucleotide-binding sites on the (3 subunits of Fi, where ATP synthesis occurs, are 9-10 nm from the surface of the mitochondrial membrane. The most widely accepted model for ATP synthesis by the FqFi complex—the binding-change mechanism—posits just such an indirect coupling (Figure 8-26). 

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