Synthesis And Catalytic Study Of Hybrid Pt-Ni/NiAl-LDH Multifunctional Catalysts Through A Modified Dealloying Process

The surface geometric and electronic structure of metal catalyst is closely coupled to their intrinsic catalytic property and functionality. Some crucial issues such as exposed crystal face, lattice strain, d-band centre, and surface ligands have provoked fast-growing interest for manufacture of efficient metal catalysts. In such concerns, the manipulation of surface structure of metallic sites usually facilitates the catalytic performance by tuning the adsorption and activation energies. In addition, it is believed that most of the catalytic processes involve multiple types of catalytic centers and steps, and the synergistic effect of different reactive sites need to be considered For that purpose, substantial efforts have been paid to artificially design of hybrid metal nanostructures such as metal/metal, metal/metal oxides, metal/semiconductor and so on in the purpose of gaining superior activity and selectivity. As such, establishing the suitable interfaces between multicomponent active sites is central to the development of energy conversion and chemical transformations.Basic sites can usually facilitate the catalytic performance besides metallic sites by stabilizing the intermediate or accelerating the pilot processes, especially in some tandem reactions. Traditionally, the integration of metallic site and basic sites can be achieved either by using some solid base catalyst such as zeolite or metal-organic framework to confine the metal within their cavities or just introducing base as additives. In the former case, the confinement usually results in the loss of active metallic sites and some problems of mass transfer. In the latter, usually in homogeneous catalysis, the addition of base such as amines or alkoxide suffers from the intrinsic drawbacks including recycling and activity decay of metal catalysts due to the strong coordination between amino group and metal.Up to now, it is still great challenge to control the interfaces between metal and basic sites at nanoscale without losing the active metal sites. Our work mainly contains following aspects:(1)We firstly combined the dealloying process of Pt-Ni alloy and the growth of NiAl-layered double hydroxide (LDH), together to sophisticatedly constructed the Pt-Ni/NiAl-LDH (Pt-Ni/LDH) composite catalyst. The chemical etching endow the dealloyed Pt-Ni alloy a significantly increased metallic sites on the surface. (2) The in-situ growth Pt-Ni/LDHs were characterized deliberately.The in-situ formed NiAl LDH covering the Pt-Ni surface show their excellent flexibility of layered structures, which will greatly expand the surface area of catalyst without causing the problem of mass transfer. Moreover, we studied the possiblegrowingmechanism and calculated it using DFT (Discrete Fourier Transform).(3)As a typical solid base catalyst, the close integration of metal and base sites guarantees this Pt-Ni/LDH catalyst superior activity and selectivity by serving basic sites during the catalytic process. In our work, we chose hydrogenation of furfuraldehyde, dehydrogenation of benzylamine and Oxygen Reduction Reaction as model reactions. The Pt-Ni/LDH catalystshowed superior performance than the initial Pt-Ni alloys and LDHs.This previously unreported dealloying strategy allow imparting basicity to a bimetallic surface and shed light to the new family of bimetallic NPs/LDH with controlled interfaces.