N-doping Ta2O5 nanoflowers with strong adsorption and visible light photocatalytic activity for efficient removal of methylene blue

•Novel 3D N-doping Ta2O5 nanoflowers (NFs) photocatalysts were synthesized at different annealing temperatures ranging from 700 °C to 850 °C under a flowing NH3 atmosphere.•Systematic studies on adsorption kinetics, photocatalytic degradation kinetics and dye degradation products analysis for these photocatalysts were conducted for the first time.•The Ta2O5 NFs nitrided at 750 °C display high surface adsorption and photocatalytic activity towards the Methylene Blue (MB) due to the synergistic effect of large surface area, strong adsorption, light absorption and photoensitization.•Our experimental results show that the development of novel photocatalyst with 3D hierarchical structure and a broad light absorption window, constructed by non-metallic doping is promising for dye removal during wastewater treatment.

Novel 3D N-doping Ta2O5 nanoflowers (NFs) photocatalysts were synthesized at different annealing temperatures ranging from 700 °C to 850 °C. The microstructure, phase composition, and chemical states of those photocatalysts were characterized in details. The adsorption kinetics as well as photocatalytic performance under visible light irradiation were also investigated. Importantly, compared to N-doping Ta2O5 NFs samples obtained at other nitriding temperatures, the Ta2O5 NFs nitrided at 750 °C displayed high surface adsorption and photocatalytic degradation activity of Methylene Blue (MB) due to the synergistic effect of large surface area, strong surface adsorption, light absorption and photosensitization. The experiment results confirmed that the adsorption of MB to these samples and photocatalytic degradation follow the pseudo-second order chemisorption mechanism and pseudo first order degradation kinetics, respectively. The main reactive species were identified through the scavenging reaction following the order of h+ > OH > O2−. Additionally, degradation product analysis was conducted using liquid chromatography tandem mass spectrometry (LC-MS) technique combined with the UV-vis absorption spectrum. The results showed that the degradation was initiated by demethylation of the dye molecule. The current work may contribute to additional applications of these 3D N-doping Ta2O5 hierarchical nanostructures such as photoelectric chemical (PEC) water splitting, surface adsorption, supercapacitors, solar cells, etc.