Negative Emissions as the New Frontier of Photoelectrochemical CO2 Reduction

The remaining carbon budgets compatible with limiting global warming to 1.5 or 2 degrees C above preindustrial levels are shrinking rapidly. An already firmly anticipated, but highly controversial measure to mitigate this challenge is the large-scale implementation of negative emissions, removing carbon dioxide from the atmosphere. Many of the currently considered negative emission technologies (NET) are based on natural photosynthesis, associated with large land footprints. Photoelectrochemical carbon sinks, on the other hand, promise to combine high conversion efficiencies with versatile storage options. Efficient sink products differ from the products typically considered for solar fuels, which will require novel catalysts and device designs. The development of efficient devices also has to take into account climatic parameters of the local environment as especially the ambient temperature affects device operation. While still in an early stage of development, carbon drawdown by such an artificial photosynthesis approach could be a valuable extension of the portfolio of NET.