Boosting hydrogen spillover over carbon nanotube anchored ultrafine Co/Co2O3 nanoparticles for efficient neutral H2O2 electrosynthesis

Neutral H2O2 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/Co2O3 nanoparticles (NPs) anchored oxidic nitrogen-doped carbon nanotubes (Co/Co2O3@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 O2 to produce H2O2 at positive onset potential of 0.66 V vs. RHE. As a result, Co/Co2O3@OCNT achieves a record current density of 4.0 mA cm−2 at 0.2 V vs. RHE and nearly 100% H2O2 selectivity at the potential from 0 to 0.5 V vs. RHE. In situ observations demonstrated that ultrafine Co/Co2O3 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/Co2O3@OCNT shows a superior performance with the yield rate of salt-free aqueous H2O2 solution around 63.4 mol gcat−1 h−1 at 200 mA cm−2 and the corresponding Faradaic efficiency of 85%. Moreover, integration of Co/Co2O3@OCNT into this cell achieves high real-time production concentration of H2O2 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 H2O2 solution production. This work provides a novel strategy for developing efficient neutral electrocatalysts and feasible process of neutral H2O2 production.