Hierarchical porous Rh nanosheets for methanol oxidation reaction

Hierarchical porous precious metal-based nanosheets with ultrathin structures and highly exposed active surfaces are desirable in energy conversion technology, while robust synthetic strategies remain challenging. Here, we report a facile 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP)-mediated approach to synthesize hierarchical porous Rh nanosheets (HP-Rh NSs), following the formation mechanism of emulsion-induced soft template. When HP-Rh NSs are applied to the methanol oxidation reaction (MOR), abundant edge/grain-boundary atoms and the ultrathin porous structure endow HP-Rh NSs with a mass activity of 333 A g−1 at 0.63 V, which are 5.8-fold enhancements compared with traditional commercial Pt black (57.4 A g−1). Meanwhile, the peak potential of MOR on HP-Rh NSs is 0.2 V lower than that on commercial Pt black. With the aid of theoretical calculations, larger methanol adsorption energy and the lower energy barrier reaction path are responsible for superior MOR activity on Rh HP-Rh NSs than commercial Pt black.