Decomposition electrocatalytic

Wagner was first to propose the use of solid electrolytes to measure in situ the thermodynamic activity of oxygen on metal catalysts.17 This led to the technique of solid electrolyte potentiometry.18 Huggins, Mason and Giir were the first to use solid electrolyte cells to carry out electrocatalytic reactions such as NO decomposition.19,20 The use of solid electrolyte cells for chemical cogeneration , that is, for the simultaneous production of electrical power and industrial chemicals, was first demonstrated in 1980.21 The first non-Faradaic enhancement in heterogeneous catalysis was reported in 1981 for the case of ethylene epoxidation on Ag electrodes,2 3 but it was only... 

Since Ru02 and Ir02 are usually prepared by thermal decomposition of suitable precursors on an inert support, the morphology of the active layer is very like that of a compressed powder [486]. The surface area plays an important role since the roughness factor can be between 102 and 103. However, the low Tafel slope observed is a clear indication of electrocatalytic effects and the high surface area is the factor which extends the low Tafel slope to much higher current densities. Thus, the combination of these two factors renders these oxides very efficient electrocatalysts for H2 evolution. 

Another point is that the reduction and oxidation potential limits (electrochemical window) are defined as the potentials at which the current density reaches a predefined value that is arbitrarily chosen [40, 48], Ue et al. also mention that the same problem arises in the choice of the sweep rate [40]. For example Egashira and coworkers obtained a log I- U line shifted to a higher position at a faster potential scan in comparison to a slower scan because of non-Faradaic currents such as the larger charging currents of the double-layer, and the decomposition of impurities [41]. The last factor affecting the electrochemical window is the electrode itself, its composition and its morphological surface structure, which defines the electrocatalytic properties [40]. 

It had not been realized until recently that electrocatalysis in the water decomposition processes at photoactive semiconductor electrodes was as important as the band-structure properties of the semiconductor material itself. However, it is clear that the effective voltage, beyond the 1.23 V limit, or 1.23 F - hv, required to photoelectrolyze water at some net rate will also be determined, as with metals, by the electrocatalytic properties of the semiconductor surfaces. 

Case Study Electrocatalytic Membranes for Decomposition of Organic Pollutants. 1081... 

CASE STUDY ELECTROCATALYTIC MEMBRANES FOR DECOMPOSITION OF ORGANIC POLLUTANTS... 

The electrocatalytic oxygen reduction in DMFC systems requires the development of highly selective electrodes in the presence of methanol. Present electrolyte membranes based on Nafion 117 are permeable to methanol (crossover effect), which depolarizes the platinum cathode [81,82]. For this reason, our strategy, some years ago, was to produce electrocatalytic materials from the thermal decomposition of some neutral transition-metal carbonyl compounds in the presence... 

Guo and co-workers have synthesized trioctyl phosphine oxide (TOPO) stabilized iron nanoparticles by the microemulsion method with an average diameter of 3 nm [192]. The amorphous particles are known to effectively catalyze reactions such as the decomposition of H2O2. A specific advantage of this method is that the presence of O2 does not hamper the electrocatalytic currents obtained for H2O2. Gold colloids capped with a mixed monolayer of alkylthiol and amidoferrocenyl-... 

Considering reactions (1) and (2), chlorine and sodium amalgam are formed in the electrolysis cell. The amalgam can be extracted and undergoes a decomposition reaction in a separate reactor (decomposer, denuder). The electrocatalytic process is... 

The system was first applied for development of chemosensors for gaseous hydrogen chloride. Polyaniline, and its copolymers with different derivates of aniline were used. Then a similar approach was tested in the author s group for optimization of amperometric biosensors for glucose based on electrocatalytical detection of hydrogen peroxide. A pigment Prussian blue was used as an electrocatalyst for decomposition of this product of enzymatic oxidation of... 

For molecular electrocatalysts otherwise, and especially transition metal macrocycles, the electrocatalytic activity is often modified by subtle structural and electronic factors spanning the entire mechanistic spectrum, that is, from strict four-electron reduction, as for the much publicized cofacial di-cobalt porphyrin, in which the distance between the Co centers was set at about 4 A [12], to strict two-electron reduction, as in the monomeric (single ring) Co(II) 4,4, 4",4" -tetrasulfophthalo-cyanine (CoTsPc) [20] and Co(II) 5,10,15,20-tetraphenyl porphyrin (CoTPP) [21]. Not surprisingly, nature has evolved highly specific enzymes for oxygen transport, oxygen reduction to water, superoxide dismutation and peroxide decomposition. 

Apart from poisoning by adsorbing impurities, the working electrode potential can also contribute to suppress electrocatalytic activity. Platinum metals, for instance, passivate or form surface oxygen and oxide layers above 1 V (Section IV,D), which inhibit Oj reduction (779,257,252) and oxidation of carbonaceous reactants (7, 78, 253, 254) however, decomposition of hydrogen peroxide on platinum is accelerated by oxygen layers (255). Some electrocatalysts may corrode or dissolve, especially in acidic electrolytes, while reactants may contribute to dissolution. Thus, ethylene oxidation on palladium to acetaldehyde proceeds via a Pd-ethylene complex, which releases colloidal palladium in solution (28, 29). Equivalent to this is the surface roughening and the loss of Pt in gas phase ammonia oxidation (256, 257). 

Electrodes based on doped SnO2 have received attention in the last years. In its pure form, SnO2 is an n-type semiconductor with relatively high electrical conductivity due to a level of nonstoichiometric impurities. This electrical conductivity can be enhanced upon addition of small amounts of dopants such as Sb, F, Cl, and Br. Good performances have been reported by codoped materials for instance, Gd-Sb-doped SnO2 deposited over Ti plates (Feng et al., 2008) exhibits a significant performance for the electrocatalytic decomposition of phenol. 

For Teflon-bonded gas-fed electrodes prepared from carbons that have little peroxide-decomposing activity, the OERR at the highest current densities appears to be limited by converging characteristics related to carbon itself, its electrocatalytic activity for oxygen reduction to peroxide and peroxide decomposition, the gas mass transport, and the electronic conductivity. 

The difference between a true catalytic and a specific electrocatalytic reaction involves the addition of a certain type of additive inside or in another phase. According to the catalytic reaction theory, the increase in the rate of the reaction is the result of the fast formation and decomposition of the intermediates between two reactants and the additive known as the catalyst. Considering the integrated kinetic law of Arrhenius, we can say that the rate of the catalytic reaction, v, is... 

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