(260s) Engineering Supraparticle Assemblies for Catalysis

Nature has developed highly specific and efficient catalysts that can synthesize complex organic compounds, such as the synthesis of sugars in photosynthesis. Due to the efficiency of these reactions, great effort has been put towards developing artificial reaction schemes that can replicate the complexity found in nature. Inorganic nanoparticles are a plausible choice for the development of a biomimetic system due to similarities with proteins found in nature.  The advancement of NPs allow for tunable size, shape, charge, and surface functionality, allowing them to self-assemble into terminal superstructures similar to biological components.  These superstructures, also known as supraparticles (SPs), can achieve the same catalytic functionality as natural enzymatic systems,  and show improved functionality over their NP constituents due to collective and synergistic interactions.

The development of SP assemblies does not only provide a cost-effective and more stable alternative to enzymes but they can improve the activity when compared to current inorganic NP catalysts. The tight structural integration of NPs in SPs present the capacity to enhance the stability of catalysts, and mitigate the aggregation of individual constituents by offering separation while remaining immobilized. SPs are capable of combining the individual properties of constituents to produce enhanced catalysts.

This work will focus on reactions that occur under mild reaction conditions; thereby, the main component of inorganic SPs will be iron sulfide (Fe_xS_x). Iron sulfide is an Earth-abundant, non-toxic, cost effective mineral that is commonly used in solar-based applications.  It is a key part of the synthesis/redox of organic compounds occurring via the reduction of CO₂ in the presence of H₂. The ample amount of Fe_xS_x and the ability to tune the bandgap of bulk Fe_xS_x (0.95 eV) to Fe_xS_x NPs (up to values of 2.75 eV), show the potential of iron sulfides in various catalysis applications.