Enhancing the photoelectrochemical performance of ZnO nanopagoda photoanode through sensitization with Ag and Ag2S NPs co-deposition

Abstract

ZnO nanopagoda arrays (NPGs) modified with Ag and Ag2S nanoparticles (NPs) were fabricated using aqueous downward growth and SILAR techniques and investigated as photoanodes for the photoelectrochemical system. The crystal structure, morphology, elemental composition, optical characteristics, and photoelectrochemical performance of the fabricated samples were studied. The obtained results disclosed that the successful deposition of Ag and Ag2S NPs on ZnO NPGs’ surface not only enhanced the visible light-harvesting but also promoted the e−/h+ separation and injection. In addition, various SILAR cycles were investigated. The optimum eight SILAR cycles for Ag–Ag2S NPs deposition on ZnO NPGs achieved the maximum photocurrent of 2.91 mA cm−2 at 1.23 V vs. reversible hydrogen electrode (RHE), about five folds superior to that of bare ZnO NPGs. It also demonstrated the improved applied bias photon-to-current conversion efficiency of 0.43% at 0.6 V vs. RHE. The charge transfer and PEC mechanisms for the fabricated ZnO NPGs/Ag–Ag2S NPs photoanodes were also proposed. This study offers a facile fabrication of a distinctive ZnO NPGs morphology and an improvement of the PEC performance through the synergistic effect of the LSPR effect of Ag NPs and visible light sensitization of Ag2S NPs.