**5. Conclusions**

The MnOx-ZrO<sup>2</sup> mixed oxides exhibited promising performance in the removal of toluene and ethanol in the gas phase, especially in the multi-catalytic solar photothermal approach. The ionic interaction between the manganese and the zirconium ions exploited with the addition of a low amount of zirconium oxide allowed us to boost up the Mars–van Krevelen mechanism of the VOCs oxidation favouring the total oxidation of VOCs to CO2. Furthermore, with the photothermo-catalysis, a decrease of the conversion temperatures compared to the thermocatalysis was verified, and MnOx-5 wt.%ZrO<sup>2</sup> also showed good stability. Finally, with the same catalyst in the solar photocatalytic tests at room temperature, a similar activity of the most used TiO2-based materials was obtained, pointing to the fact that this sample can be promising for the VOCs remediation technologies, being cheaper, not critical, and performing considering the absence of noble metal co-catalysts.

**Supplementary Materials:** The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/catal12010085/s1, Figure S1: SEM images of the other investigated samples; Figure S2: XPS characterization of the MnOx-5% ZrO<sup>2</sup> sample; Figure S3: Photothermocatalytic oxidation of toluene: influence of different parameters on MnOx-5% ZrO<sup>2</sup> sample; Figure S4: thermocatalytic oxidation of ethanol; Figure S5: Photothermo-catalytic oxidation of ethanol.

**Author Contributions:** Conceptualization, R.F.; investigation, R.A.F., R.F., F.L.P., E.M.M., S.A.B.; writing—original draft preparation, R.F.; writing—review and editing, R.F.; supervision, R.F. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Acknowledgments:** The authors thank S. Scirè (University of Catania) for the use of the laboratory facilities and the Bio-nanotech Research and Innovation Tower (BRIT) laboratory of the University of Catania for the Smartlab diffractometer facility. R.F. thanks the PON "AIM" of the European Social Found for the support.

**Conflicts of Interest:** The authors declare no conflict of interest.
