Graphene due to its ambipolarity, can transport electricity with electrons and holes. But does any ion take part in this transportation? How holes are generated? How can I calculate generation-recombination rate of carriers or life time?
The conduction in Gr mostly dominated by carrier transport through pi bond hopping. At atmospheric conditions O2 and OH from atmosphere, provide some sort of p-type doing to graphene and promote hole conduction. If you take Gr to high Vac condition and remove Oxygen effects, you can easily observe Gr's ambipolarity. Generally, there is no ion (charged atom) conduction in Gr. Hope this will provide some information to your question.