Photo-Induced Exciton Dynamics and Broadband Light Harvesting in ZnO Nanorod-Templated Multilayered Two-Dimensional MoS2/MoO3 Photoanodes for Solar Fuel Generation

The architectural design of multidimensional nanoheterostructures-based photoelectrodes is demonstrated by coupling the multilayered two-dimensional (2D) structure of MoS2 and MoO3 on the well-aligned arrays of one-dimensional (1D) ZnO nanorods template, with the expected effective synergic effects. The advantages of catalytically active sites of the 2D layered structure of transition-metal dichalcogenides/oxides is integrated with the distinctive dimensionality-dependent phenomena of 1D structure to achieve enormous surface area for light harvesting and photoelectrochemical reaction, along with the favorable photocarrier dynamics required for water splitting. The ZnO/MoS2 and ZnO/MoO3 nanoheterostructure photoanodes exhibit low onset potential and enhanced broadband light absorption, resulting in high photocurrent densities of 2.04 and 0.67 mA cm–2 at 1.23 V versus reversible hydrogen electrode under AM 1.5 G illumination, which corrospond to 334% and 43% increases in photocurrent, respectively, compared to that of pure ZnO nanorods. The nanoheterostructure photoanodes also exhibit enhanced applied bias photon-to-current conversion efficiency and superior spatial photo-induced exciton separation and transportation, because of the favorable interfacial band alignment at 2D–1D nanoheterointerfaces, and suppress the surface charge recombination, which promotes hole transportation at the nanoheterostructure/electrolyte interface and boost the surface oxygen evolution reaction, leading to enhanced photoelectrochemical performance.