Compact dual-cathode stack enables industrially viable H₂O₂ electrosynthesis with high throughput and operability

Renewable electricity-driven hydrogen peroxide (H₂O₂) electrosynthesis technology has recently emerged as a multidisciplinary research frontier as its distributed deployment capability can provide enhanced versatility for various potential niche applications. Despite significant progress in screening advanced electrocatalysts and fundamental understanding of microscopic reaction mechanisms, industrially viable electrolysis devices suitable for this technology are still lacking due to technical challenges such as low space/electrode utilisation and single-pass yield as well as poor operability. Here, we demonstrate a membrane-free dual-cathode stack reactor featuring compactness (inter-electrode distance configured to flow field plate thickness) and ideal electrode utilisation (two cathodes paired with one anode). Structurally discontinuous carbon films with self-sustained aeration are assembled as cathodes, which enables open air-fed O₂-to-H₂O₂ conversion and thus effectively simplifies operation. Even with low electrolyte concentrations (0.05 M Na₂SO₄), this design demonstrates efficient H₂O₂ production from bench- to industrial-scale operating current densities (75–200 mA cm⁻²) at relatively low cell voltages (5.9–11.0 V). Impressive single-pass H₂O₂ accumulations of 959.6–2332.1 mg L⁻¹ with current efficiencies of 55.1 %–90.7 % can be achieved at low hydraulic retention times of 15–60 s. The practicality and reliability of the device can be further elucidated by its robustness in decentralized wastewater remediation scenarios. This all-material/components-commercial design paves the way for advancing the technology readiness level of H₂O₂ electrosynthesis processes.