Structural evolution of bimetallic Pd-Ru catalysts in oxidative and reductive applications

Effect of Co‐catalyst on the Selective Electrooxidation of Glycerol over Ruthenium‐based Nanomaterials

“…Ru contributes to the bimetallic patterns with the (100), (101), (110), and (103) planes at 2 θ =38.60, 43.88, 68.48, and 78.04°, respectively. These contributions change from narrow peaks in the XRD pattern of Pt and Pd to broad reflection planes in the PtRu and PdRu materials . The Pd 71 Ru 29 /C pattern also presents a small peak at 2 θ =35°, which can be assigned to the tetragonal structure of RuO 2 ( P 4 2 / mnm ).…”

“…As stated at the beginning of this manuscript, the electrooxidation of glycerol has been investigated for many decades. Previous reports describe the selectivity and effectiveness of the electrode material as a function of the pH of the electrolyte and of the applied potential to show ensemble effects and bifunctional properties in the resulting electrodes . The fact that the oxidation of glycerol on palladium generates glycerate and tartronate has opened a discussion related to the role of the co‐catalyst, such as bismuth, in the process; the co‐catalyst might orient the conversion of glycerol into DHA on Pt .…”

“…Ru contributest ot he bimetallic patterns with the (100), (101), (110), and (103) planes at 2 q = 38.60, 43.88, 68.48, and 78.048,r espectively.T hese contributions change from narrow peaks in the XRD pattern of Pt and Pd to broad reflection planes in the PtRu and PdRu materials. [7,[42][43][44] The Pd 71 Ru 29 /C pattern also presentsasmall peak at 2 q = 358, which can be assigned to the tetragonal structure of RuO 2 (P4 2 /mnm). According to the phase diagram, am ixture of PdRu (fcc) and Ru (hexagonal close packing, hcp) should be expected, because Ru is not soluble at temperatures lower than 773 K. [37] Besides the different configurations, the fact that the redox potential of Pd II /Pd 0 (0.95 V) is more positive than the redox potentialo fR u III /Ru 0 (0.62 V) corroborates phase segregation,b ecause these potentials favor fast reduction of Pd in aR uPd mixture.…”

“…Previous reports describe the selectivitya nd effectiveness of the electrode materiala safunction of the pH of the electrolyte and of the appliedp otentialt os how ensemblee ffects and bifunctional properties in the resulting electrodes. [23,24,42,46] The fact that the oxidation of glycerol on palladium generates glycerate and tartronate [7] has openedadiscussion related to the role of the co-catalyst, such as bismuth, in the process;t he cocatalystm ight orient the conversion of glycerol into DHA on Pt. [13] The presentw ork emphasizes the role ruthenium plays in the Pt andP da node materials to give selectiveo xidation of glycerolt oe ither DHA or glycerate.…”