Directional charge transportation and Rayleigh scattering for the optimal in-band quantum yield of a composite semiconductor nano-photocatalyst

In this work, we propose a novel technique based on wavelength dispersive in situ fluorescence spectroscopy (WDIFS) for diagnosing the wavelength-dependent directional charge transportation and Rayleigh scattering enhanced in-band quantum yield. For the first time, it is clearly demonstrated that the formation of the 2D electron gas in CuO/ZnO and upward Schottky barriers in ZnO/Ag facilitate the photocatalytic performance in the ultraviolet spectral range, and that utilization of the visible spectrum relies on the band alignment between the energy level of the dopants and the Fermi level of Ag. Moreover, it is shown that the wavelength-dependent in-band quantum yield can be controlled through particle size photon scattering, in which the strong Rayleigh scattering based photon harvesting brings about a significant increase in the photocatalytic performance in the ultraviolet spectrum. Eventually, it is forecast that systematic use of the proposed technique for a systematic diagnosis should help towards the production of efficient ZnO-based photocatalysts.