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Electrochemical reduction of CO2(CO2RR) is expected to play a key role among the various strategies being explored to limit global warming. In this scenario, Layered Double Hydroxides (LDHs) are emerging as a promising class of electrocatalysts to replace the most used noble metals. In this work three Zn-Al LDH with different Zn2+/Al3+ratio were synthesized and characterized by means of XRD, STEM-EDX and HR-TEM. Their suitability for CO2RR to CO was assessed by means of a custom-made three-compartment cell, showing an increase in CO selectivity by decreasing the Zn2+/Al3+ratio. The CO2interaction with the samples was firstly characterized by means of volumetric adsorption measurements, exhibiting an increase in capture capacity by decreasing the Zn2+/Al3+ratio. The evolution of the samples in interaction with a CO2-saturated liquid flow was then deeply investigated by means of in-situATR-IR spectroscopy. The samples displayed a different evolution in the vibrational region of the carbonate-like species (1800–1200 cm−1). To better discriminate the different carbonate cyclohexane was also employed. A definitive assignment of the main IR bands of the carbonate was carried out by studying the spectral behavior of the different bands observed in the ATR-IR experiments and by comparing these results with the existing literature. Interestingly, Zn-Al 1:2 LDH, the most efficient electrocatalyst for CO2RR, is also the sole sample exhibiting a higher monodentate to total bidentate carbonates ratio, suggesting that the existence of a higher content of low coordination oxygen anions with stronger basic character can influence the final catalytic activity.

In this work, the behavior of the double perovskite Sr2FeMo0.6Ni0.4O6-δ (SFMN) under cathodic polarization was investigated. The structural changes due to the exsolution process caused by polarization or by chemical reduction were studied by X-ray diffractometry and by electron microscopies and electrochemical performances of a H2-SOFC electrode were analyzed to clarify the role of the different phenomena involved in the structural transformation of the double perovskite.

The CO2adsorption performances of a Linde-Type A (LTA) zeolite and a natural Clinoptilolite (Clino) zeolite, both in shaped form, were investigated as such or after an ion-exchange procedure and compared to assess their potential application as solid adsorbents for Carbon Capture and Storage (CCS). The samples were characterized following a multi-technique approach. Their structural and textural properties were evaluated to investigate the accessibility of the different ions present inside the microporous structure and the strength of their interaction with the adsorbates. The CO2adsorption tests were carried out performing pure CO2adsorption/desorption isotherms and dynamic breakthrough measurements in a wide range of temperature (298–423 K). The ion-exchange enhanced the adsorption capacity of the synthetic zeolite, while no significant increment in the CO2adsorption performances is observed for the natural one. Nonetheless, the CO2adsorption reversibility is affected by the cation exchange process in both synthetic and natural zeolites. The CO2adsorption capacities of LTA zeolites are higher at lower temperatures, whereas the CO2adsorption performances of natural Clino are interesting also at medium-high temperature, being the most performant material at 423 K. By performing IR experiments with specific probe molecules, the presence of a consistent number of Fe2+ions in the framework of natural Clino, responsible for the capacity of this material to strongly interact with CO2also at medium-high temperatures, was proved. The peculiar adsorption behavior of natural Clino, its low cost and availability in shaped form are some of the essential features for its possible implementation in real CCS technologies.