AgCu/TiO2 hot-electron device for solar water splitting: the mechanisms of LSPR and time-domain characterization

More and more metal/semiconductor nanostructures have been served as a hot-electron device with the localized surface plasmonic resonance (LSPR) effect to boost hydrogen evolution from solar water splitting. In this work, bimetallic AgCu with optimal ratio are deposited onto TiO2 nanopore/nanotube arrays to construct AgCu/TiO2 photoanode for photoelectrochemical water splitting, a novel simulation characterization to visualize the LSPR process is proposed. The near electric field enhancement and plasmon resonance energy transfer mechanisms of single Ag and Cu are inferred by time-domain characterization, illustrating the contradictory photocurrent under AM 1.5 illumination with its LSPR effect based on the particle size. The variation of local electric field over time within the interfaces of AgCu bimetals and bimetal/TiO2 models reveals the migration of hot electrons from Ag into Cu and the synergetic effect of different LSPR mechanisms. The resulting higher photoelectrochemical activities of AgCu/TiO2 also verifies the positive roles of the coexistence of AgCu on electron generation and energy transfer to interband excitation of TiO2.