Rational Design of TaON/Potassium Poly(Heptazine Imide) Heterostructure for Multifunctional Environmental Remediation

Tantalum oxynitride (TaON) has recently attracted much attention due to its excellent performance as a semiconductor. However, its shortage in separation of photogenerated charges hinders the wide application, which, fortunately, can be made up by forming heterojunctions with other photocatalysts. In this study, the rational design of an inorganic-organic TaON/potassium poly (heptazine imide) (KPHI) heterojunction is reported to separate the photo charges on the two sides of this dyadic structure. The incorporation of 20 wt.% TaON into KPHI resulted not only in H2 generation but also in a wider set of environmental remediation applications under visible light, including Cr(VI) reduction and degradation of otherwise resilient antibiotics. 20TaON/KPHI effectively reduced 17.5 ppm Cr(VI) solution in 35 min under low-power blue light irradiation with a rate constant which is approximate to 6 and 30 times higher than that of pristine KPHI and TaON, respectively. Moreover, the composite demonstrated a 2- and 40-fold increase in H2 evolution rate in comparison to pure KPHI and TaON, respectively. This remarkable enhancement in photocatalytic activity is ascribed to the efficient electron-hole separation and formation of an effective Z-scheme heterojunction. This work offers a new paradigm for designing efficient photocatalytic systems for environmental applications under low-power LED and natural sunlight. This article proposes a multifunctional heterojunction for environmental remediation. A Z-scheme TaON/KPHI heterojunction is constructed by a facile ball milling process. The strong redox potentials retained by the Z scheme enable TaON/KPHI effective in H2 generation, Cr(VI) reduction, and antibiotics removal. image