  The small spin-orbit interaction of carbon atoms in graphene promises a long
spin diffusion length and potential to create a spin field-effect transistor.
However, for this reason, graphene was largely overlooked as a possible
spin-charge conversion material. We report electric gate tuning of the
spin-charge conversion voltage signal in a single-layer graphene. Using spin
pumping from yttrium iron garnet ferrimagnetic insulator and ionic liquid top
gate we determined that the inverse spin Hall effect is the dominant
spin-charge conversion mechanism in a single-layer graphene. From the gate
dependence of the electromotive force we showed dominance of the intrinsic over
Rashba spin-orbit interaction: a long-standing question in graphene research.
