Fig. 1. (a) Schematic illustration of the measurement of the photocatalytic activity of single CdS NPs by lighting up H2 nanobubbles with R6G molecules. A 488 nm laser excites an evanescent wave at the surface of the glass coverslip, leading to the photochemical production of H2 nanobubbles at a single CdS nanoparticle. Spontaneous accumulation of R6G molecules at the nanobubble surface results in FL emission (orange color) under a FL microscope. (b) FL trajectory curves of two adjacent CdS NPs. Mono-exponential fitting is displayed as blue (NP1, up panel) and red (NP2, bottom panel). Snapshots of FL images at four moments (109, 516, 1016, and 1412 second) are presented in the inset. Zoom-in curves of two nanobubble events at NP1 (c) and NP2 (d) are also displayed to clarify the kinetic features.
