The liberated hydroxide can capture CO2. After the light source is removed, recombination of the ion pair back to the photobase, an energetically favourable process, drives the release of CO2. Dashed curves highly how the ground state potential energy must be tuned to strike a thermodynamic balance for reversible CO2 capture. If the initial photobase is too high in energy (blue), CO2 will be captured without photoirradiation. Conversely, if the photobase is too low in energy (red), hydroxide photorelease will be less efficient, and the capacity to capture CO2 is reduced.