(294e) Conductive Alumina-Graphene Catalytic Condenser for Programmable Solid Acid

Charge manipulation of materials at the interface allows for optimization of electronic properties that can enhance catalytic properties in reactions such as the Lewis acid catalyzed 2-propanol dehydration. Combining the concepts from metal-oxide-semiconductor field-effect transistors and heterogeneous catalysts, we successfully fabricated a catalytically active high-k layered device that allows for voltage modulation to affect activity. This concept device, i.e. a catalytic condenser, relies on a high-k dielectric layer and 2D monolayer graphene to accumulate or deplete charge from the catalytic layer. In this study of 2-propanol dehydration, alumina (am-Al₂O₃), the model catalyst for this reaction, was chosen as the active material and it was synthesized on the device in the form of an amorphous thin-film by Atomic Layer Deposition (ALD). Unlike bulk alumina, which is an insulator (band gap of 9.9 eV), this thin film am-Al₂O₃ made by ALD with a shorter band gap ~3.2 eV, acted much like a ‘poor insulator’ or defective semiconductor, allowing charge to pass through the layer to the conductive graphene layer below. Voltage modulation on rates of these devices were then demonstrated using a voltage-biased temperature programmed surface reaction (v-TPSR) on a customized vacuum-based reactor, and the device was successfully characterized by TEM, SEM, Raman, UPS, and more. Overall, the results indicate that continuous and fast electronic control of semiconductor-like oxide can be achieved with the catalytic condenser device.