MEMS Seminar: Nanotechnology-Based Catalysts for the Electrochemical Synthesis of Low Carbon Fuels and Fertilizers
The arrangement of active sites on a nanostructured catalyst can yield new ways to influence complex reaction mechanisms. The Center for Nanophase Materials Sciences has developed a textured carbon comprised of 50-80nm graphene spikes with ~5% nitrogen dopants for electrochemical catalysis. Two reactions for this electrocatalyst will be discussed: first, when co-doped with ~50nm copper nanoparticles, the electrocatalyst converts CO2 to ethanol with high Faradaic efficiency (63% at -1.2V vs reversible hydrogen electrode (RHE)) and high selectivity (84%) in aqueous bicarbonate and at ambient temperature and pressure. Electrochemical analysis and density functional theory calculations suggest a mechanism in which active sites on the Cu nanoparticles and the carbon nanospikes work in tandem to control the electrochemical reduction of carbon monoxide dimer to alcohol.
Second, the sharp tips of the nanospikes, which typically reach a radius of ~1nm, achieve very high electric fields over a large number of active sites. When coupled to the proper electrolyte, and without a metal co-catalyst, the carbon nanospikes are active for nitrogen electroreduction to ammonia with an average Faradaic efficiency of 9.25% at -1.19 V vs RHE. Lunch will be served at 11:30 am.