Superior stability and photocatalytic activity of Ta3N5 sensitized/protected by conducting polymers for water splitting.

Abstract In the study, we used two conducting polymers, polyaniline (PANI) and polypyrrole (PPy), to sensitize Ta 3 N 5 , thereby enhancing its photocatalytic activity, and then applied this novel photocatalyst to overall water splitting to produce hydrogen and oxygen even under visible light irradiation. The two polymers increased the charge transfer efficiency, prevented the recombination of the generated electrons and holes of the Ta 3 N 5 photocatalyst, and thereby enhanced its electron-hole separation efficiency and improved its photocatalytic activity for efficient visible light water splitting. The two polymers completely covering the Ta 3 N 5 particles facilitated charge transfer for quick migration of the generated electrons and holes to the polymer surface and thus prevented contact between the holes and nitride of Ta 3 N 5. Therefore, these conducting polymers also protected the Ta 3 N 5 particles from self-photocorrosion during long-term water splitting. Because of the existence of the protonated nitrogen (-N+) state in PPy, the electric conductivity of PPy was lower than that of PANI, which lowered the sensitizing ability of PPy compared to that of PANI. Thus, the water splitting efficiency of Ta 3 N 5 /PANI was higher than that of Ta 3 N 5 /PPy. The production rates of H 2 and O 2 generated from water splitting of Ta 3 N 5 /PANI were 60.5 and 30.2 (μmol. g−1cat. h−1), respectively. Graphical abstract Image 1 Highlights • Polymer sensitizers enhanced the separation of e−/h+ pairs and prolonged the Ta 3 N 5 lifetime. • Polymer cover protected Ta 3 N 5 from self-photocorrosion (oxidation of generated holes). • Ta 3 N 5 /polymers greatly exhibited overall photocatalytic water splitting. • Lower electric conductivity lowered the sensitizing ability of the polymer. • PANI was better than PPy for enhancing the photocatalytic activity of Ta 3 N 5. [ABSTRACT FROM AUTHOR]