N/Si co-doped oriented single crystalline rutile TiO2 nanorods for photoelectrochemical water splitting

Chemical modification of the aligned single crystalline TiO2 nanorods provides possibilities to improve their photoelectrochemical (PEC) activity under visible light. This work reports on the N/Si co-doped single crystal rutile TiO2 nanorods fabricated by a flexible one-step hydrothermal procedure for PEC water splitting, exhibiting a photocurrent of 1.77 mA cm(-2) at 1.23 V vs. RHE and a noticeable visible-light response under standard testing conditions (xenon lamp with an AM 1.5 G filter, 100 mW cm(-2)). The excellent PEC activity can be attributed to the synergetic effect of N and Si co-dopants, which enhances the incident photon to current conversion efficiency both in ultraviolet and visible regions, and improves the charge transfer at the photoanode/electrolyte interface. A solar-powered water splitting device has been designed by combining an efficient perovskite solar cell with the N/Si co-doped TiO2 NRs-based PEC system, achieving an overall solar-to-hydrogen efficiency of 1.1%. This has been the highest value reported for TiO2-based PEC systems so far.