Pulsing strategies to control reactivity and selectivity in photochemistry

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Creating a sustainable society requires that we stop using fossil-based carbon to produce chemicals and fuels, in order to stop increasing atmospheric levels of carbon dioxide (CO2). An alternative is to treat CO2 not simply as waste, but instead use it as a carbon-neutral feedstock for chemical synthesis. Recycling of CO2 in this way is a challenge because its transformation requires significant energy input and many different products can be produced, usually as an undesirable mixture. By combining renewable electricity as energy source and catalyst materials to help stimulate the desired reaction pathways, the electrochemistry approach is a promising emerging technology for CO2 conversion. But fundamental challenges persist when operating electrochemical devices under constant operating conditions, including large energy barriers and detrimental concentration gradients which limit the reaction efficiency and rate. We propose a strategy based on pulsed activation of electrochemical CO2 conversion reactions, stimulated by the input of pulsed light, which can provide strategies for minimizing reaction barriers and fine-tuning the reaction pathways. By combining light-absorbing semiconductors and organic or inorganic catalysts, we will study pulsed light photoelectrochemistry on hybrid devices with the goals of gaining new understanding of CO2 conversion mechanisms, demonstrating improved product selectivities, and establishing a new frontier in resonance catalysis.