A surfactant-free strategy for synthesizing reduced graphene oxide supported palladium nanoparticles with enhanced electrocatalytic performance towards formic acid oxidation

(Chemical Equation Presented) A simple noncovalent method is used to graft sulfonate (-SO₃H) groups on a graphene oxide (GO) surface by the π-π stacking interaction between 1-propylsulfonic-3-methylimidazolium chloride and GO. The immobilization of sulfonate groups on the GO surface is confirmed by various physical techniques, such as X-ray photoelectron spectroscopy, ultraviolet and visible spectroscopy, and zeta potential analysis, etc . The as-prepared sulfonate functionalized GO composites (GO-SO₃H) are further used as supporting material to anchor PdO·H₂O nanoparticles through the slow hydrolysis of PdCl₂. The sulfonate functionalized reduced GO composites (rGO-SO₃H) supported Pd nanoparticles composites (Pd/rGO-SO₃H) are obtained through the simultaneous reduction of PdO·H₂O and the GO-SO₃H with sodium borohydride. As shown by transmission electron microscopy, Pd nanoparticles with good dispersity effectively anchor on the rGO-SO₃H surface. The as-prepared Pd/rGO-SO₃H composites display the improved electrocatalytic activity and long-term stability towards the formic acid oxidation reaction compared to the un-sulfonated counterpart.