Decoration of semiconductors with plasmonic nanoparticles provides a new direction for efficient solar water splitting for hydrogen production. Herein, Ag nanoparticles as the plasmonic metal were electrodeposited on a TiO2 nanotube arrays (TNTA) photoelectrode by controlling deposition-charge density. The resulting Ag/TNTA electrode with 10-50 nm diameter Ag nanoparticles exhibited a higher photocurrent density and hydrogen production rate than a bare TNTA electrode under AM 1.5 irradiation. The origins of this enhancement were explored by analyzing the photoelectrochemical behaviors with the relevant optical properties. The absorption of these Ag/TNTA electrodes in the visible light region increased owing to the surface plasmon resonance (SPR) effect of the Ag nano-particles, and only low photocurrent densities under visible light irradiation were observed. The overall enhancement is owing to the greater incident photon-to-electron conversion efficiency in the 300-400 nm range that is more dependent on the interfacial charge transfer from TNTA to Ag nanoparticles. The localized electronic field of the SPR also reduces the electron transport time in the Ag/TNTA electrodes. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.