Effect of precursors on graphene supported platinum monometalic catalysts for hydrothermal gasification of biomass compounds to hydrogen

•Catalysts for hydrothermal gasification of biomass compounds to H2 were developed.•Effect of precursors on Pt/graphene monometalic catalysts were studied.•PtI2, PtBr2, PtCl2 and H2PtCl2 precursors were evaluated.•Pt particles on graphene were smaller and uniform when PtCl2 precursor was used.•The catalysts prepared under sonication produced similar amounts of hydrogen.