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MAX phases are layered ternary carbides or nitrides that are attractive for catalysis applications due to their unusual set of properties. They show high thermal stability like ceramics, but they are also tough, ductile, and good conductors of heat and electricity like metals. Here, we study the potential of the Ti 3 AlC 2 MAX phase as a support for molybdenum oxide for the reverse water-gas shift (RWGS) reaction, comparing this new catalyst to more traditional materials. The catalyst showed higher turnover frequency values than MoO 3 /TiO 2 and MoO 3 /Al 2 O 3 catalysts, due to the outstanding electronic properties of the Ti 3 AlC 2 support. We observed a charge transfer effect from the electronically rich Ti 3 AlC 2 MAX phase to the catalyst surface, which in turn enhances the reducibility of MoO 3 species during reaction. The redox properties of the MoO 3 /Ti 3 AlC 2 catalyst improve its RWGS intrinsic activity compared to TiO 2 - and Al 2 O 3 -based catalysts., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

CO 2 is a promising renewable, cheap, and abundant C1 feedstock for producing valuable chemicals, such as CO and methanol. In conventional reactors, because of thermodynamic constraints, converting CO 2 to methanol requires high temperature and pressure, typically 250 °C and 20 bar. Nonthermal plasma is a better option, as it can convert CO 2 at near-ambient temperature and pressure. Adding a catalyst to such plasma setups can enhance conversion and selectivity. However, we know little about the effects of catalysts in such systems. Here, we study CO 2 hydrogenation in a dielectric barrier discharge plasma-catalysis setup under ambient conditions using MgO, γ-Al 2 O 3 , and a series of Co x O y /MgO catalysts. While all three catalyst types enhanced CO 2 conversion, Co x O y /MgO gave the best results, converting up to 35% of CO 2 and reaching the highest methanol yield (10%). Control experiments showed that the basic MgO support is more active than the acidic γ-Al 2 O 3 , and that MgO-supported cobalt oxide catalysts improve the selectivity toward methanol. The methanol yield can be tuned by changing the metal loading. Overall, our study shows the utility of plasma catalysis for CO 2 conversion under mild conditions, with the potential to reduce the energy footprint of CO 2 -recycling processes., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)