Metal doped tubular carbon nitride (tC3N4) based hematite photoanode for enhanced photoelectrochemical performance

Abstract

Metal doped tubular carbon nitride (M-tC3N4) photocatalyst is synthesized and successfully integrated with the hematite thin films photoanodes for enhanced photoelectrochemical water splitting performance. SEM and TEM analysis revealed that the tubular structures of carbon nitride are formed due to cobalt doping and subsequent high temperature (700 °C) annealing under nitrogen atmosphere. It has been demonstrated that cobalt based bimetal doping with Fe or Ni is useful in enhancing the photoelectrochemical performance in terms of high photocurrent density, low photocurrent onset potential and improved photo-stability under the visible light illumination. The prepared CoNi-tC3N4/α-Fe2O3 photoanode exhibits swift separation of photo-induced change carriers and achieved a photocurrent density of ∼2.73 mA/cm2 at 1.23 V vs. RHE, which is significantly high as compared to g-C3N4/α-Fe2O3, Co-tC3N4/α-Fe2O3 and CoFe-tC3N4/α-Fe2O3 photoanodes. The remarkably high photoelectrochemical performance is probably due to the tailored structural morphology which increases the surface area of the catalyst, high optical absorption in visible region and improved electronic properties which enhances the carrier concentration and finally efficient separation and transfer of photogenerated charge carriers at the semiconductor-electrolyte junction.