Molecular doping of conjugated carbon nitride (CN) with thiophene donors was applied for the modification of CN photocatalysts. The incorporation of electron-rich thiophene entities in the conjugated polymer matrix can effectively change the intrinsic bulk and surface features of CN, such as engineering the electronic structure with tunable bandgap and promoting the charge-carrier migration and separation via forming surface dyadic structures. A significant alteration in the texture, morphology, and crystalline was also observed for the thiophene-modified CN samples. The combined benefits of the molecular doping in terms of bulk, surface, and texture properties lead to an improvement in the photocatalytic activity for H-2 generation with visible light, which underlines the importance of organic chemistry protocols for the chemical modification of newly developed metal-free, polymeric photocatalysts. (C) 2013 Elsevier Inc. All rights reserved.