While solid-liquid interfaces play a key role in emerging fields of photo-and electro-catalysis, relatively little is understood about the fundamentals of electron-transfer processes at semiconductor-liquid interfaces and how the interfacial architecture impacts electron-transfer and subsequent electro- and photo-catalytic processes. Sp3-hybridized carbon (diamond) can be readily and inexpensively fabricated in planar and nanoparticulate form, and has properties that make it uniquely suited as a substrate for photo- and electrocatalysis. Here, I will describe two recent studies. In the first, molecular catalysts can be covalently tethered to surfaces of conductive diamond, yielding surfaces that can selectively reduce CO2 to CO. Contrary to popular thought, a deeper analysis of electron-transfer processes at molecule-solid interfaces shows that the disorder in the molecular layers plays a key role in enabling electron-transfer processes. A second example comes from recent work demonstrating that illumination of diamond (including inexpensive diamond powder) with ultraviolet light leads to direct electron emission into water, producing solvated electrons. Solvated electrons have been described as the chemist's perfect reducing agent. We demonstrate the potency of this approach using the reduction of N2 to NH3, the world's most energy-intensive chemical reaction.
Prof. Christine Payne (404-385-3125).