In-situ/operando soft and hard XAS cell enabling the investigation of thermal catalytic reactions at pressures of up to 20 bar

A new high-pressure/high-temperature cell was developed for the Operando Absorption and Emission Spectroscopy (OAESE) endstation of the EMIL laboratory at the BESSY II synchrotron facility (Berlin, Germany) that enables in-situ/operando XAS measurements with both soft and hard X-rays for studying heterogeneous gas-solid reactions under realistic reaction conditions.A SiNx membrane on a conventional silicon wafer was used to separate the high-pressure reaction volume from the UHV beamline and measurement chamber, serving also as substrate for the sample.This design minimizes the intensity loss of the soft X-rays beam and the emitted radiation from the sample, while at the same time allows for operation at high pressure, verified at 23.5 bar and 300 C.At lower pressure, temperatures of more than 400 C can be achieved.To demonstrate the functionality of the cell under high pressure and temperature conditions, we performed redox cycling of a 10 nm CoMnOx thin-film sample while in-situ probing the Co and Mn L-edges and the O K-edge.Faster oxidation of both Co and Mn under 10 bar air flow compared to the ambient pressure experiment at the same temperature (250 C) was clearly observable in the spectroscopic data, demonstrating the ability of the technique to examine the influence of oxygen partial pressure on the reaction kinetics under high pressure and temperature conditions.These are the first in-situ soft XAS measurements performed at 10 bar pressure and elevated temperature, opening new capabilities for studying chemical structure modifications during heterogeneous thermal catalytic reactions under realistic working conditions.