Facile route for C-N/Nb₂O₅ nanonet synthesis based on 2-methylimidazole for visible-light driven photocatalytic degradation of Rhodamine B

Herein, we fabricated a C and N co-modified Nb₂O₅ nanonet structure (C-N/Nb₂O₅NNs) from niobium oxalate using 2-methylimidazole (Hmim) as a source for C and N via a simple hydrothermal route. The obtained nanonets are robust and cost-effective with excellent recycling stability. Compared with N-doped TiO₂ (N-TiO₂) and a Nb₂O₅ control sample (Nb₂O₅-CS), the resulting nanonets exhibited the highest performance toward the photocatalytic degradation of Rhodamine B (RhB) upon visible light irradiation (λ > 420 nm). Through this study, we revealed that the synergetic effects of C and N on the nanonet surface, which were effectively incorporated into the surface of the Nb₂O₅ nanonet structure, not only remarkably enhanced the visible light response by decreasing the bandgap to 2.9 eV but also improved the light utilization efficiency and photo-induced electron-hole pair separation efficiency of our nanonet structure. We also proposed that the presence of carbonate species (CO_x) and nitrogen species (NO_x) increased the population of generated holes (h⁺) that had the key role in the photodegradation mechanism of RhB, suggesting reasonable importance for the modification of Nb₂O₅ with C and N. This synergism offers a new view to reveal the origin of photodegradation processes, introducing h⁺ as a key intermediate. Our approach provides a new insight to design 2D nanostructures with potential applications in catalysis, solar energy conversion, and environmental protection.