Mutual effect of extrinsic defects and electronic carbon traps of M-TiO2 (MÂ =Â V, Co, Ni) nanorod arrays on photoexcited charge extraction of CdS for superior photoelectrochemical activity of hydrogen production

204Raman spectra of M − TiO2 nanorod arrays are showing the increasing trends of electronic carbon traps (black arrow) and extrinsic defects (green arrow). While, photocurrent density and voltage plot of transition metal doped M-TiO2/CdS (M = V, Co, Ni) show its primary dependence upon amount of carbon content in M − TiO2 determined through Raman spectroscopy and secondary dependence upon its extrinsic defects i.e., oxygen vacancies, mid gap energy states. The primary dependence is indirect i.e., higher the amount of carbon content in transition metal (TM) doped M − TiO2, thus lower is the output photocurrent density in the corresponding heterojunction bilayer.