The d band center dependent catalytic activity of n-doped carbon nanospheres with wrinkled cages supported PdPt alloy catalysts in transfer hydrogenation of bicarbonate with glycerol

Abstract

Catalytic transfer hydrogenation of bicarbonate, a typical product of CO2 captured in an alkaline solution, with glycerol (GLY) as a hydrogen donor to formate (FA) and lactate (LA) is a sustainable and green approach for simultaneous valorization of CO2 and the major byproduct from biodiesel production. Conventional monometallic noble metal catalysts can catalyze this transfer hydrogenation reaction, but generally required a high reaction temperature, leading to a low yield of FA. In this work, N-doped carbon spheres with wrinkled cages (NCSWCs) supported PdPt alloy catalysts were prepared and their electronic structures were determined by Valence Band Spectra (VBS) and Density Functional Theory (DFT). It was found that the relationship between the d band center and catalytic activity exhibits volcano-shaped behaviors, where Pd2Pt1/NCSWCs is on the top of the curve, 85.4% of GLY conversion with 67.3% yield of LA and 56.5% yield of FA can be achieved at 200 °C. DFT calculations also revealed that Pd2Pt1/NCSWCs possessed an intermediate d band center, which tunes the adsorption and dissociation energy of H species on its surface, allowing maximum H transfer during the transfer hydrogenation of bicarbonate, leading to high catalytic activity. Such a d band center catalyst tuning could be efficient way to design new catalysts.