Facile constructing ZnO/ZnCO_3 heterojunction for high-performance photocatalytic NO oxidation and reaction pathway study

摘要

The fast electron-hole recombination and low light utilization are two significant constraints to hinder the development of photocatalysis technology. Particularly, properly engineered heterojunction photocatalysts exhibit superior photoactivity because of spatial separation of photoinduced electron-hole pairs. Therefore, we prepared a heterojunction of zinc carbonate and zinc oxide by calcining precursor at 350 °C for 2 h. The as-prepared photocatalysts were obtained via a facile method and possessed promising photocatalytic activity for NO oxidation under UV light irradiation; the NO removal efficiency of heterojunction (42%) was better than that of pristine zinc oxide (28%) and precursor; the composites still maintained 88% activity after five cycles. Some relevant physicochemical properties were delicately investigated to elucidate that heterojunction can remarkably suppress the recombination of the electron-hole pairs, and promote the carriers transforming to activity species, which can participate in the redox reaction occurring on the surface of photocatalysts. More importantly, electron spin resonance measurement integrated with in situ DRIFTS spectra was applied to intuitively and dynamically monitor the reaction process and uncover the promotion mechanism. Finally, we believe that the synthesis strategy and mechanism analysis would provide guidance for understanding the gas-phase reaction.