TiO2 is a commonly employed material for photoelectrochemical (PEC) solar water splitting due to its nontoxicity, abundance and great stability. However, TiO2 suffers from low PEC efficiency because of the weak absorption of visible light. Here, carbon quantum dots decorated C3N4/TiO2 heterostructure nanorod arrays (CQDs/C3N4/TiO2 NAs) were designed and fabricated to solve this shortcoming. The CQDs/C3N4/TiO2 NAs exhibit an increased solar to hydrogen conversion efficiency which is 5.8 times that of TiO2 NAs and excellent stability in strong alkaline electrolyte. The enhanced performance of the CQDs/C3N4/TiO2 NAs is attributed to the improved light absorption and charge separation and transfer induced by the C3N4 and CQDs. This work provides a promising approach for the design of low cost and environmentally friendly photoanodes for efficient and stable PEC applications. (C) 2017 The Electrochemical Society. All rights reserved.