Notably, a distinct pattern of gas output flow was observed during this experiment, with a sharp increase during light exposure and a corresponding decrease when the light was turned off. This outcome demonstrates the indispensable role of irradiation in CO2 release. Moreover, the observed pattern suggests a predominant photoacid effect rather than a photothermal effect, as photothermal effect may exhibit a gradual gas output during the light-on phase, followed by a gradual decline during the light-off phase. We performed a cyclic experiment of CO2 capture and release utilizing the pyranine photoacid system (Figure ). The standard solution, consisting of 100 mM pyranine and 100 mM K2CO3 saturated with 15% CO2, was prepared. The experiment involved repeated cycles of 30 minutes of irradiation for CO2 release, followed by 10 minutes of contact with 15% CO2 at a flow rate of 50 mL/min for CO2 capture. The results of multiple cyclic CO2 release are presented in Figure . Over the course of 5 cycles, the amount of CO2 released through irradiation was approximately 0.1 mmol for each cycle. To ensure the photostability of pyranine during the experiment, we performed NMR spectroscopy under the operational conditions for 5 cycles, as shown in Figure . Although CO2 release was observed through irradiation using the pyranine photoacid system, the current capacity of CO2 released (0.13 mmol of CO2 released per cycle using 500 mmol of pyranine) is limited. We attribute this low capacity to the short half-life of the excited species in the pyranine photoacid system. To address this limitation, we hypothesized that a photoacid with a longer half-life, capable of accumulating excited states over time, could provide a larger capacity for CO2 capture and release upon irradiation. Among the reported meta-stable state photoacids (mPAH), we selected Liao's photoacid as a model compound (Figure ). Liao's photoacid exhibits desirable values of pKa (7.8) and pKa* (1.7 -3.2) and possesses a long half-life of 70 s. Despite its extremely low solubility in water (0.19 mM), we successfully obtained a 71 mM solution by incorporating 3.5 M of nicotinamide as a hydrotropic agent in water. The photochemical working scheme of Liao's photoacid is depicted in Figure . The mPAH solution, saturated with 15% CO2, undergoes photochemical isomerization from E to Z upon irradiation.