▎ 摘　　要

MoS2 and WS2 have been prepared on a conductive graphene support by thermal reduction of tetrathiotungstate/tetrathiomolybdate and graphite oxide. Whereas the catalytic properties towards hydrogen evolution are strongly influenced by the Magneli phases formed as a byproduct during the synthesis, the catalytic activity towards oxygen reduction of these composite materials is not affected by this phenomenon and these materials exhibit high catalytic activity towards this industrially important reaction.