Understanding the Surface Chemistry of Porous Silicon for Applications in Hybrid (Photo)electrocatalysis
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Location: Sterling Chemistry Laboratory (SCL) 160
Online: https://yale.zoom.us/j/94534703506
Summary
The Center for Hybrid Approaches in Solar Energy to Liquid Fuels (CHASE) aims to produce hybrid catalysts that can use light and potential to drive the reduction of CO2 to more useful chemicals. These hybrid catalysts are constructed from molecular catalysts attached to a semiconducting support.
Porous silicon has proven to be a robust semiconducting platform for covalently attached molecular catalysts. Fabricating and characterizing these hybrid photoelectrodes is nontrivial, but the benefits in terms of product selection and stability during catalysis are significant.
The surface chemistry of porous silicon is a crucial factor in determining hybrid photoelectrode performance. After fabrication through an electrochemical etching method, the surface of porous silicon is covered in a monolayer of hydrides. Under catalytic conditions, H2 is produced from these Si-H bonds and the silicon oxidizes even under reducing conditions. Describing and controlling these effects are of prime importance for the design of improved hybrid photoelectrodes.
Beyond applications within catalysis, there is broad appeal in studying the fundamental surface chemistry of porous silicon. Porous silicon is used in a range of fields including drug delivery, energetic materials, and chemical sensors. All applications of porous silicon depend on the chemical environment on the surface, and often the modification of the Si-Hx bonds native to the fresh etched surface.
The overarching goal of the work presented herein is to gain insight into the surface chemistry of porous silicon. The conditions under which this surface chemistry is examined are related to catalysis, and indeed there are two examples of functional hybrid photoelectrodes presented here.
