Electrochemical Pilot H 2 O 2 Production by Solid‐State Electrolyte Reactor: Insights From a Hybrid Catalyst for 2‐Electron Oxygen Reduction Reaction

Abstract The electrochemical oxygen reduction reaction (ORR) offers an alluring and sustainable alternative to the traditional anthraquinone process for hydrogen peroxide (H₂O₂) synthesis. However, challenges remain in developing scalable electrocatalysts and cost‐effective reactors for high‐purity H₂O₂ production. This study introduces a simple yet effective mechanical mixing method to fabricate a hybrid electrocatalyst from oxidized carbon nanotubes and layered double hydroxides (LDHs). This easily accessible and low‐cost catalyst achieves near‐perfect Faradaic efficiency (∼100%) with low overpotentials of 73 mV at 10 mA cm⁻ 2 and 588 mV at 400 mA cm⁻ 2 in a solid electrolyte cell. Through theoretical calculations and in‐situ analyses, we uncover the pivotal role played by the LDH co‐catalyst in fine‐tuning the local pH at the catalyst/solid‐electrolyte interface that drives both the activity and selectivity. We also design a low‐cost solid‐state reactor using cation‐exchange resin (CER) as both a proton conductor and a microchannel for efficient mass transfer, achieving a production rate of 5.29 mmol cm⁻ 2 h⁻¹ and continuous output concentrations of 11.8 wt.% H₂O₂. Scaled to an industrial area of 2 × 100 cm 2 , the pilot reactor achieves an impressive H₂O₂ production rate of approximately 127.0 mmol h⁻¹ at 15 A, marking a significant advancement in sustainable H₂O₂ production.