Synergistic Effects in N,O-Comodified Carbon Nanotubes Boost Highly Selective Electrochemical Oxygen Reduction to H 2 O 2 .

Electrochemical 2-electron oxygen reduction reaction (ORR) is a promising route for renewable and on-site H 2 O 2 production. Oxygen-rich carbon nanotubes have been demonstrated their high selectivity (≈80%), yet tailoring the composition and structure of carbon nanotubes to further enhance the selectivity and widen working voltage range remains a challenge. Herein, combining formamide condensation coating and mild temperature calcination, a nitrogen and oxygen comodified carbon nanotubes (N,O-CNTs) electrocatalyst is synthesized, which shows excellent selective (>95%) H 2 O 2 selectivity in a wide voltage range (from 0 to 0.65 V versus reversible hydrogen electrode). It is significantly superior to the corresponding selectivity values of CNTs (≈50% in 0-0.65 V vs RHE) and O-CNTs (≈80% in 0.3-0.65 V vs RHE). Density functional theory calculations revealed that the C neighbouring to N is the active site. Introducing O-related species can strengthen the adsorption of intermediates *OOH, while N-doping can weaken the adsorption of in situ generated *O and optimize the *OOH adsorption energy, thus improving the 2-electron pathway. With optimized N,O-CNTs catalysts, a Janus electrode is designed by adjusting the asymmetric wettability to achieve H 2 O 2 productivity of 264.8 mol kg cat -1 h -1 .