Combination of a reaction cell and an ultra-high vacuum system for the in situ preparation and characterization of a model catalyst

An in-depth understanding of the structure-activity relationship between the surface structure, chemical composition, adsorption and desorption of molecules, and their reaction activity and selectivity is necessary for the rational design of high-performance catalysts. Herein, we present a method for studying catalytic mechanisms using a combination of in situ reaction cells and surface science techniques. The proposed system consists of four parts: preparation chamber, temperature-programmed desorption (TPD) chamber, quick load-lock chamber, and in situ reaction cell. The preparation chamber was equipped with setups based on the surface science techniques used for standard sample preparation and characterization, including an Ar+ sputter gun, Auger electron spectrometer, and a low-energy electron diffractometer. After a well-defined model catalyst was prepared, the sample was transferred to a TPD chamber to investigate the adsorption and desorption of the probe molecule, or to the reaction cell, to measure the catalytic activity. A thermal desorption experiment for methanol on a clean Cu(111) surface was conducted to demonstrate the functionality of the preparation and TPD chambers. Moreover, the repeatability of the in situ reaction cell experiment was verified by CO2 hydrogenation on the Ni(110) surface. At a reaction pressure of 800 Torr at 673 K, turnover frequencies for the methanation reaction and reverse water-gas shift reaction were 0.15 and 7.55 Ni atom(-1) s(-1), respectively.