NbO₆ octahedra of high-dimensional Nb₂O₅ boosting H₂O₂ electrosynthesis for sewage pollutants degradation

Two-electron oxygen reduction reaction (2e⁻ ORR) to produce hydrogen peroxide (H₂O₂) presents an efficient, secure, and sustainable method. However, the competing four-electron pathway produces H₂O, yielding low H₂O₂ selectivity (~ 70%). In this work, a high-dimensional rod-like structure of niobium oxide (Nb₂O₅-HD) containing NbO₆ octahedra was synthesized using a hydrothermal method combined with a calcination strategy. Under 50 mA·cm⁻², the Faradaic efficiency (FE) of H₂O₂ reached 94%, with the H₂O₂ yield reaching as high as 874 mmol·g_cat⁻¹·h⁻¹. After 34 h of operation, FE was still 76%, and the stability is great. In situ Raman spectroscopy analysis and experiments revealed that the NbO₆ octahedra on Nb₂O₅-HD were the key factor for its excellent ORR activity and H₂O₂ FE. This inspires the development of high-performance ORR transition metal electrocatalysts.