Reducible supports can affect the performance of metal catalysts by the formation of suboxide overlayers upon reduction, a process referred to as the strong metal–support interaction (SMSI). A combination of operando electron microscopy and vibrational spectroscopy revealed that thin TiO _x overlayers formed on nickel/titanium dioxide catalysts during 400°C reduction were completely removed under carbon dioxide hydrogenation conditions. Conversely, after 600°C reduction, exposure to carbon dioxide hydrogenation reaction conditions led to only partial reexposure of nickel, forming interfacial sites in contact with TiO _x and favoring carbon–carbon coupling by providing a carbon species reservoir. Our findings challenge the conventional understanding of SMSIs and call for more-detailed operando investigations of nanocatalysts at the single-particle level to revisit static models of structure-activity relationships.

We report a systematic evaluation of the influence of the use of nitric acid at elevated temperature (80 °C) as purification and functionalization treatment for four different types of multi wall carbon nanotubes (MWCNTs) and for carbon microparticles upon their physico-chemical properties. We used BET, Raman spectroscopy, high resolution X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy measurements for MWCNTs characterization. We found that nitric acid treatment significantly changes physico-chemical properties of MWCNTs and that these changes vary significantly between different MWCNTs. Therefore we urge researchers to be careful when relying on the physico-chemical properties measured on different MWCNTs samples.

The most promising and utilized chemical sensing materials, WO₃ and SnO₂ were characterized by means advanced synchrotron based XPS, UPS, NAP-XPS techniques. The complementary electrical resistance and sensor testing experiments were also completed. A comparison and evaluation of some of the prominent and newly employed spectroscopic characterization techniques for chemical sensors were provided. The chemical nature and oxidation state of the WO₃ and SnO₂ thin films were explored at different depths from imminent surface to a maximum of 1.5 nm depth from the surface with non-destructive depth profiling. The adsorption and amount of chemisorbed oxygen species were precisely analyzed and quantified as a function of temperature between 25–400 °C under realistic operating conditions for chemical sensors employing 1–5 mbar pressures of oxygen (O₂) and carbon monoxide (CO). The effect of realistic CO and O₂ gas pressures on adsorbed water (H₂O), OH⁻ groups and chemisorbed oxygen species ( $O_{2\left(ads\right)}^{-}, O_{\left(ads\right), }^{-}{O}_{2\left(ads\right)}^{2-}$ ) and chemical stability of metal oxide surfaces were evaluated and quantified.