Liquid metals may deliver greener and more sustainable chemical reactions

Chemical reactions account for about 12% of global greenhouse gas emissions and a large portion of the world’s total energy consumption (1). Many contemporary chemical processes rely on multiple facilities that use solid-state catalytic materials for specific reactions. Solid catalysts normally possess fixed atomic arrangements that form active sites (2). Despite their capacity to lower energy barriers for reactions, the absence of atomic-level flexibility can limit efficiency and selectivity for certain reactions. By contrast, liquid metals—metals and alloys that are liquid near or at room temperature—can rearrange interfacial atom positions in response to processes that occur at their surface. This can guide reactions, a capacity that could be viewed as a type of innate intelligence. This intelligence involves steering freely moving liquid-state atoms into desired locations for more efficient functionalities. This behavior thus promises energy favorable reaction pathways as well as reactions that are not feasible in solid-state systems...

...Liquid metals—which constitute a family of low–melting point metals and alloys, such as mercury (Hg)– and gallium (Ga)– based liquids at near room temperature and tin (Sn) and bismuth (Bi) alloys at higher temperatures—present opportunities for diverse chemical reactions (6). Incorporating noble and transition metals into liquid metals bestows the resulting alloys with tailored catalytic properties. Liquid metals offer high surface entropy by keeping elements energetic and highly dispersed, allowing them to naturally provide a multitude of dynamically changing active sites for bond formation and dissociation reactions (7). These active sites may exhibit greater capability for driving reactions compared with solid-state surfaces, and the overall thermodynamic barriers at the liquid metal surfaces may be decreased...

...The surfaces of liquid metals naturally inhibit van der Waals attraction. Consequently, if solid species are formed as by-products on active sites as the result of a reaction, they naturally exfoliate with minimal mechanical agitation. Hence, the reactive surface remains accessible and resists having the active sites blocked by processes such as the buildup of carbon (coking) and surface reactions that inactivate the catalyst (poisoning). One investigation revealed that surface deactivation is mitigated to allow the continuous production of carbonaceous solids as the main product from CO₂ feedstock on liquid metal surfaces (11)...