Operando Cell for Synchrotron Studies of Gas Sensors

A cell for conducting operando measurements of X-ray absorption spectra for gas-sensitive sensors based on ZIF-8/ZIF-67 nanofilms is developed and fabricated. The cell is made of stainless steel, which makes it possible to study, among other things, corrosive gases. The possibility of heating and continuous measurement of the sensor temperature during an operando experiment to evaluate the dynamics of sorption in the processes of heating/cooling the cell. The isolated sensor holder has contacts for measuring the capacitance/resistance of the sensor. To measure X-ray absorption spectra for gas-sensitive gas-sensor materials, an X-ray transparent window is provided. For sensors based on ZIF-8 and ZIF-67 nanofilms, the X-ray absorption spectra are measured for the K edges of Zn and Co, respectively. It is found that after exposure to NO₂ in a gas-sensitive material based on ZIF-8/ZIF-67 nanofilms, long-range order is lost and the film undergoes amorphization. The X-ray absorption spectra measured for a gas-sensitive material based on ZIF-8/ZIF-67 nanofilms before and after exposure to NO₂ indicate a change in the local atomic and electronic structures near cobalt atoms.