Owing to its up-conversion photoluminescence, photo-induced electron transfer property, and excellent conductivity, carbon quantum dots (CQDs) have been established as effective sensitizers in combination with Fe2O3 nanowires for enhancing the catalytic activity of photoelectrochemical water oxidation. In comparison to pristine Fe2O3 nanowires, Fe2O3 nanowires decorated with CQDs demonstrate 27 orders of magnitude increase in photo-current density at 0.23 V vs. Ag/AgCl. The mechanism of enhanced photoelectrochemical activity of CQDs/Fe2O3 composite was also investigated. Thereby, it is confirmed that the enhanced optical absorption, accelerated interfacial charge carrier transfer and effective separation of photogenerated electron-hole pairs induced by CQDs decoration account for the enhancement of CQDs/Fe2O3 nanowire arrays in photoelectrochemical application. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.