Seminar

Abstract

The rising level of CO₂ in the atmosphere is a primary environmental concern, significantly contributing
to global warming and climate change. Converting CO₂ into valuable chemicals, such as methanol,
offers a promising approach to mitigate its impact, aligning with the goals of sustainability and circular
carbon use. To understand CO₂ conversion, highlighting reaction mechanisms and exploring the roles
of thermal and photothermal conditions is necessary. The main catalytic system studied involves noble
metals supported on mixed-metal oxides. The hydrogenation of CO₂ to methanol occurs via the formate
mechanism, where CO₂ is directly hydrogenated to a formate intermediate, which then converts to
methanol. This pathway is often preferred over the alternative reverse water-gas shift route, which
initially reduces CO₂ to carbon monoxide (CO). Emphasizing the formate mechanism leads to higher
methanol selectivity and prevents the formation of undesirable CO byproduct, thereby improving the
overall efficiency of the process. While traditionally relying on thermal energy to drive the reaction,
advanced catalytic systems are increasingly exploring photothermal strategies for improved efficiency.
These photothermal methods, including both plasmonic phenomena in certain nanoparticles and
nonplasmonic light absorption by semiconductor materials, offer unique ways to deliver energy to the
reaction sites. Such light-driven activation can promote specific reaction pathways or lower activation
barriers, thereby enhancing overall catalytic performance.
The mechanism may be influenced by the particular noble metal dispersion and the attributes of the
support materials. Layered double hydroxides (LDHs) are highly versatile materials, widely employed
as precursors for the fabrication of multifunctional catalyst supports. Their tunable composition,
anionexchange capacity, and structural flexibility allow for the co-incorporation of a broad range of metal
cations, enabling precise control over catalytic properties. Upon calcination, LDH-derived mixed metal
oxides exhibit high surface area, adjustable basicity, and well-dispersed active sites. The noble metals
such as gold (Au) and palladium (Pd) can be introduced via ion exchange, ensuring uniform distribution
and strong metal-support interactions.