Modulation of Lewis and Brønsted acid centers with oxygen vacancies for Nb2O5 electrocatalysts: Towards highly efficient simultaneously electrochemical ozone and hydrogen peroxide production

Assembling two desirable half-reactions of green oxidants hydrogen peroxide (H 2 O 2 ) and ozone (O 3 ) into efficient paired electrolysis is highly valuable in terms of efficiency and environmental-friendliness. However, rational design and construction of electrocatalysts with regulable active sites for the paired electrosynthesis of green oxidants of H 2 O 2 and O 3 remain a significant challenge. Herein, A new strategy was developed for tunning the active sites of pseudo-hexagonal centers (TT, Lewis acid sites) and orthogonal centers (T, Brønsted acid sites) in Mxene layered structure niobium pentoxide (Nb 2 O 5 ) with abundant oxygen vacancy (O V ) for the paired electrolysis of 2e - oxygen reduction reaction (ORR) and electrochemical ozone production (EOP). The TT-300 and T-400 electrocatalysts exhibited outstanding electrochemical activity of 2e - ORR (H 2 O 2 selectively of 92% at 0.4 V RHE ) and EOP (gaseous ozone FE of 13% at 50 mA cm −2 ), respectively. The excellent performance was mainly attributed to the TT-300 (Lewis acid sites) and T-400 (Brønsted acid sites) with abundant O V that improve the oxygen-containing intermediates formation of OOH* and deprotonation of water. In addition, the in-situ electro-degradation of organic compounds experiments indicated that the synergistic degradation of O 3 and H 2 O 2 possessed a faster kinetic constant compared with a single electrolysis system of O 3 and H 2 O 2 . The work provides meaningful insights into the rational design and construction of advanced solid acid electrocatalysts for efficient simultaneously electrocatalytic hydrogenation and oxidation to produce green oxidants of O 3 and H 2 O 2 .