Creation of functional solids based on nanoparticle assemblies: When the whole is more, less, or different than the sum of its parts

The synthesis of inorganic nanoparticles using solution-phase strategies enables exquisite control of size, shape and polydispersity—all factors that dictate the properties of the ensemble (the sum of the individual constituents). However, that control is achieved through passivating the inorganic nanoparticle surface with organic ligands, creating insulating barriers around the particles and inhibiting their ability to “talk” to each other through space. This limits opportunities for exploitation of functional properties based on movement of e.g., excitons, electrons, ions, etc., underscoring a need for methods to link nanoparticles in 3-D via direct particle-particle connections. Moreover, to interface to the environment, an architected pore-matter network is desirable as it enables each distinct nanoparticle within a macroscopic network to engage with the ambient.

This presentation will describe the formation of porous 3-D architectures from metal chalcogenide nanoparticles via an oxidative assembly approach, and the consequences of assembly on the properties of the ensemble (no longer a simple sum of the individual constituents). Methods that enable formation of multicomponent networks with controlled heterogeneity, and the compositional conversion of those gels via post-synthetic cation exchange, will be described, along with their utilization for applications that require a “wired” network, such as photocatalysis and chemoresistive sensing. Finally, efforts to describe the structure-function relationship in the network using graph theory will be discussed.