Novel overall photocatalytic water splitting of tantalum nitride sensitized/protected by conducting polymers

Abstract

Polyaniline (PANI) and polythiophene (PTh) conducting polymers have been used to sensitize Tantalum Nitride (Ta3N5) to enhance its photocatalytic activity. The synthesized materials exhibited novel photocatalytic activity for overall water splitting to produce hydrogen and oxygen even excited by visible light irradiation. The used PANI and PTh sensitizers enhanced the charge transfer efficiency and minimized the high recombination rate of the photo-excited electrons (e-) and holes (h+) of the Ta3N5 photocatalyst (enhanced e-/h+ separation efficiency of the Ta3N5) leading to increase in its photocatalytic activity for efficient visible light water splitting. We also investigated that the used PANI and PTh completely covering the Ta3N5 particles could acted as charge acceptors for quick migration of the produced h+ to their surface and thus minimizing contact between the nitride of the Ta3N5 and the produced h+, which could oxidize the nitride. It means that the used conducting polymers also protected the Ta3N5 particles from self-photocorrosion. Therefore, the synthesized tantalum nitride sensitized/protected by PANI or PTh could be applied for long-term water splitting. The production rates of H2 and O2 generated from water splitting of Ta3N5/PANI were higher than that of the Ta3N5/PTh because the electric conductivity of the PANI was higher than that of the PTh.