Self-supported Pd_xBi catalysts for the electrooxidation of glycerol in alkaline media

Highly active self-supported Pd_xBi catalysts are synthesized by the sacrificial support method. Self-supported Pd_xBi catalysts have a porous nanostructured morphology with high surface areas (in the range from 75 to 100 m² g^-1), making Pd_xBi a state-of-the-art catalyst. Pd₄Bi displays the highest activity toward glycerol oxidation. In situ Fourier transform infrared spectroscopy highlights the unique catalytic behavior of self-supported Pd_xBi materials due to their particular structure and morphology. The confinement of reactants and intermediates in pores acting as nanoreactors is responsible for the high selectivity as a function of the electrode potential: aldehyde and ketone at low potentials, hydroxypyruvate at moderate potentials, and CO₂ at high potentials. Moreover, the selectivity depends on the electrode history: it is different for the positive potential scan direction than for the reverse direction, where the catalyst becomes selective toward the production of carboxylates.