Controllable Synthesis of Supported PdAu Nanoclusters and Their Electronic Structure-Dependent Catalytic Activity in Selective Dehydrogenation of Formic Acid.

Abstract

We report the design and synthesis of uniform PdAu alloy nanoclusters immobilized on diamine and graphene oxide-functionalized silica nanospheres. The structure-dependent activity for selectively catalytic dehydrogenation of formic acid (FA) has been evaluated and optimized by controlling the Pd/Au mole ratio and the carrier components. The relationship between the catalyst structure and activity has been investigated via both experiments and characterization. High-resolution transmission electron microscopy (TEM) and X-ray diffraction (XRD) proved the formation of PdAu alloy nanoclusters. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure (XAFS) analyses verified the electron transfer between Au, Pd, and the support. An outstanding turnover frequency (TOF) value of 16 647 h-1 at 323 K, which is among the highest activity for FA dehydrogenation ever reported, can be achieved at optimized conditions and ascribed to the combination of the bimetallic synergistic effect and the carrier effect.