In-Situ Characterization Techniques for Mechanism Studies of CO 2 Hydrogenation.

The paramount concerns of global warming, fossil fuel depletion, and energy crises have prompted the need of hydrocarbons productions via CO 2 conversion. In order to achieve global carbon neutrality, much attention needs to be diverted towards CO 2 management. Catalytic hydrogenation of CO 2 is an exciting opportunity to curb the increasing CO 2 and produce value-added products. However, the comprehensive understanding of CO 2 hydrogenation is still a matter of discussion due to its complex reaction mechanism and involvement of various species. This review comprehensively discusses three processes: reverse water gas shift (RWGS) reaction, modified Fischer Tropsch synthesis (MFTS), and methanol-mediated route (MeOH) for CO 2 hydrogenation to hydrocarbons. Along with analysing the reaction pathways, it is also very important to understand the real-time evolvement of catalytic process and reaction intermediates by employing in-situ characterization techniques under actual reaction conditions. Subsequently, in second part of this review, we provided a systematic analysis of advancements in in-situ techniques aimed to monitor the evolution of catalysts during CO 2 reduction process. The section also highlights the key components of in-situ cells, their working principles, and applications in identifying reaction mechanisms for CO 2 hydrogenation. Finally, by reviewing respective achievements in the field, we identify key gaps and present some future directions for CO 2 hydrogenation and in-situ studies.