Highly efficient photocatalytic C:Fe:TiO2 nanobelts, in which C and Fe were in-situ co-doped, were synthesized on Si (001) substrates without the use of any metal catalysts at 510 degrees C using simple and low-cost metallorganic chemical vapor deposition (MOCVD). Residual C, a by-product of MOCVD reaction, was utilized effectively to be self-doped in TiO2 for visible-light photocatalysis. Moreover, both UV and visible-light photocatalytic reactivities of the nanobelts were enhanced significantly with the deliberately in-situ doped Fe. The Fe doping content was reliably controlled by varying the sublimation temperature of the Fe precursor. The visible-light photocatalytic efficiency shows a maximum at a Fe content of 0.9 atom%. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.053202jes] All rights reserved.