The diffusion mechanism of an excess proton in imidazole molecule chains: first results of an ab initio molecular dynamics study

Blend membranes based on sulfonated poly(ether ether ketone) and polysulfone bearing benzimidazole side groups for proton exchange membrane fuel cells

“…The protons hop between the nitrogen of benzimidazole and phosphoric acid by forming benzimidazolium cation and dihydrogenphosphate anion [4,5], facilitating proton conduction by a Grotthuss-type mechanism, unlike the vehicle-type mechanism in Nafion. Similar complexed systems have also been pursued by replacing water by heterocycles as proton solvents [6][7][8][9][10][11]. For example, high proton conductivity could be achieved by replacing water by imidazole in Nafion [6] but its performance in fuel cell is poor due to the poisoning effect of imidazole on the platinum catalyst [8,10].…”

Synthesis and proton conductivity of anhydrous dendritic electrolytes

“…FT-IR of PEG-HAxIm confirmed the partial protonation of imidazole from the "free" nitrogen side. The proton exchange reactions between neighboring protonated and unprotonated imidazoles is described by structure diffusion (Grotthuss mechanism) where imidazole acts as proton donor and acceptor in the conduction process [18]. The protonic defects may cause local disorder by forming a hydrogen bonded network, i.e., Him-(HimH+)-imH), which enhance long range proton transport.…”

Effect of Electron and Proton on Hydrogen-Bonded Imidazole Chains

“…The Car-Parrinello molecular dynamics (CPMD) simulations 21 on protonated IH chains demonstrated that the reorientation of IH is a rate limiting step of proton conduction. The excess proton leads to local disorder by forming a rotational IH and protonated IH-HIH + -IH configuration.…”

“…55565758 It has been pointed out that the rotation of IH fragments is inevitable during the proton transfer process. 7,13,21,32,59 The twodimensional proton transfer potential energy surfaces (PESs) of water mediated IH system has been performed, with a barrier of a few kcal/mol, 30 while the effect of electronic and protonic state, as well as the rotational sequence of each IH fragment on the proton transfer are not revealed. Here, the rotational barriers of every IH fragments in various states are explored and expressed in Figure 7.…”