Tafel recombination, transfer

We discuss acid solutions in greater detail. Two different mechanisms have been established. The first is the Volmer- Tafel mechanism, which consists of a proton-transfer step followed by a chemical recombination reaction ... 

The initial step, reaction (20), in the HER is charge transfer, leading to the formation of an adsorbed intermediate MH containing the metal M. The MH can either recombine to form molecular hydrogOT by reaction (21) or interact with H+ and an electron to form hydrogen by reaction (22). The former step is termed the recombination or Tafel reaction and the latter, 4he electrdchemical desorption or Horiuti-Heyrovsky mechanism. 

We have performed calculations for a fair amount of systems, but the representative examples given earlier should suffice. Besides the Volmer and the Heyrovsky reaction discussed earlier, there are also a few systems, for which the chemical recombination (Tafel reaction) determines the rate. Since this does not involve electron transfer, it can be calculated by standard DFT therefore, we have not discussed it in any detail. 

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