Fig. 4: The comparison of mechanisms regarding Ce-HHTP for two different forms of memory in the artificial olfactory memory system.

a FTIR spectra of Ce-HHTP treated by propionaldehyde. The direction of the black arrow indicates a step by step increase of propionaldehyde. b In situ FTIR spectra of Ce-HHTP treated by propionaldehyde under vacuum and subsequent atmospheric conditions. The direction of the black arrows indicates the time-resolved FTIR spectra in the corresponding conditions. c XPS results before and after the Ce-HHTP was combined with propionaldehyde. d FTIR spectra of Ce-HHTP treated by propanol. The direction of the black arrow indicates a step-by-step increase of propanol. e In-situ FTIR spectra of Ce-HHTP treated by propanol under vacuum and subsequent atmospheric conditions. The direction of the black arrows indicates the time-resolved FTIR spectra in the corresponding conditions. f XPS results before and after the Ce-HHTP was combined with propanol. g DFT calculations of all the adsorption energy on Ce-HHTP. Atoms are colored as follows: O (red), C (black), Ce (light blue), and H (white). h, i Structural diagram of Ce-HHTP coordination with propionaldehyde and hydrogen binding with propanol. Atoms are colored as follows: O (red), C (black), Ce (light blue) and H (white).