Defect-meditated efficient catalytic activity toward p-nitrophenol reduction: A case study of nitrogen doped calcium niobate system.

This work reported on the synthesis of a series of nitrogen doped Ca2Nb2O7 with tunable nitrogen content that were found to be efficient and green noble-metal-free catalysts toward catalytic reduction of p-nitrophenol. XPS and ESR results indicated that the introduction of nitrogen in Ca2Nb2O7 gave rise to a large number of defective nitrogen and oxygen species. Defective nitrogen and oxygen species were found to play synergetic roles in the reduction of p-nitrophenol. The underlying mechanism is completely different from those reported for metallic nanoparticles. Moreover, the more negative conduction band edge potential enabled nitrogen doped Ca2Nb2O7 to show photo-synergistic effects that could accelerate the reduction rate toward p-nitrophenol under UV light irradiation. This work may provide a strategy for tuning the catalytic performance by modulating the chemical composition, electronic structure as well as surface defect chemistry.