Boosting hydrogen spillover over carbon nanotube anchored ultrafine Co/Co ₂ O ₃ nanoparticles for efficient neutral H ₂ O ₂ electrosynthesis

Abstract Neutral H 2 O 2 electrosynthesis via two‐electron oxygen reduction reaction (2e − ‐ORR) is a promising alternative to replace traditional anthraquinone processes. However, it still remains significantly challenging to develop efficient electrocatalysts due to sluggish neutral 2e − ‐ORR kinetics. Herein, we reported abundant ultrafine Co/Co 2 O 3 nanoparticles (NPs) anchored oxidic nitrogen‐doped carbon nanotubes (Co/Co 2 O 3 @OCNT) derived from the pyrolysis of the mixed OCNT and Co@Tpy, presenting synergistical enhancement effect on the water dissociation to supply active hydrogen coupling with O 2 to produce H 2 O 2 at positive onset potential of 0.66 V vs. RHE. As a result, Co/Co 2 O 3 @OCNT achieves a record current density of 4.0 mA cm −2 at 0.2 V vs. RHE and nearly 100% H 2 O 2 selectivity at the potential from 0 to 0.5 V vs. RHE. In situ observations demonstrated that ultrafine Co/Co 2 O 3 NPs and nitrogen‐doped carbon supports would synergistically improve the active hydrogen feeding further to facilitate the formation of key intermediate *OOH. Furthermore, based on the sandwiched configuration of the flow cell, Co/Co 2 O 3 @OCNT shows a superior performance with the yield rate of salt‐free aqueous H 2 O 2 solution around 63.4 mol g cat −1 h −1 at 200 mA cm −2 and the corresponding Faradaic efficiency of 85%. Moreover, integration of Co/Co 2 O 3 @OCNT into this cell achieves high real‐time production concentration of H 2 O 2 around 20 mM at 200 mA cm −2 by varying the pure water flow rate to 1 mL min −1 , suggesting the huge potential of salt‐free H 2 O 2 solution production. This work provides a novel strategy for developing efficient neutral electrocatalysts and feasible process of neutral H 2 O 2 production.