(583eh) Nanostructured Catalysts for Solar Driven Chemical Transformations

In this work, we show two examples where well-defined nanostructured heterogeneous catalytic systems are designed that exploit nanostructuring to enhance the efficiency of solar driven chemical conversion.

The first example is focused on the design of efficient Pt-based heterogeneous photocatalysts for oxidation reactions. Bulk metals exhibit very low efficiency for driving photocatalytic reactions based on the low energy of photon-induced electron excitations and fast charge carrier relaxation due to electron-electron scattering.  Here we show that confining Pt to nanoscales (< 5nm particles) introduces new photon absorption mechanisms that allow for a unique and efficient pathway for photocatalytic transformations without needing a semiconductor absorber. We will show experimental signatures of nanoscale-induced photochemistry and discuss theoretical frameworks that capture salient qualitative characteristics of the process.  

In the second example, we show how we have designed a multifunctional system with two active sites co-localized on the same support for efficient execution of artificial photosynthesis (CO₂ + 2H₂O --> CH₄ + 2O₂).  One active site is designed to perform photocatalytic endothermic water splitting and the other is designed to perform thermo-catalytic exothermic CO₂ methanation thereby providing a unique pathway to execute artificial photosynthesis through a combined photocatalytic and thermocatalytic reaction pathway.