Determination of the real quantum yield of the heterogeneous photocatalytic H₂production reaction and insights

Determination of the real quantum yield (QY) of a heterogeneous photocatalytic H2 production reaction is crucial and challenging. Here, we constructed a setup enabling the exact measurement of the number of incident photons received by photo-vessel, and the directly absorbed part by photocatalysts, thus achieving simultaneous determination of QY and apparent quantum yield (AQY). It turns out that over the whole investigated wavelength region, the value of AQY is significantly smaller than that of QY. For instance, the AQY and QY of Cd0.5Zn0.5S were measured as 40% and 70% at 420 nm, respectively. We have demonstrated that a lot of incident photons are scattered by the photocatalyst particles and dissipated, instead of being absorbed and converted. It indicates that the true photocatalytic performance of a photocatalyst could have been severely underestimated in the past by AQY in previous studies. Therefore, our work should be valuable for accurate catalytic efficiency evaluation of a photocatalyst, and contributes to the rapid development of the technology.