Yujue Wang

Porous solid electrolyte (PSE) reactors have attracted increasing interest in H2O2 electrosynthesis and other electrochemical processes (e.g., CO2 reduction). However, scaling up PSE reactors for practical applications faces several challenges, including the difficulty in uniformly packing PSE (typically resin microspheres) in large reactors, the high pressure drop across the reactor, and the limited durability of anion-exchange membranes (AEM). Here, to address these challenges, we fabricated robust PSE wafers with both high ion conductivity and porosity by premolding resin microspheres, a conductive binder, and a pore-forming agent. These premolded wafers can be easily installed in reactors, thereby simplifying the reactor assembly and scalability. Moreover, due to their high porosity (ε = 39%), the PSE wafers dramatically reduced the pressure drop across the reactor by a factor of ∼5 compared to resin microsphere-packed beds (ε = 11%). Consequently, the wafer reactors could be stably operated without the need for an AEM for preventing electrode flooding, circumventing the barrier to the long-term stability of PSE reactors. The AEM-free wafer reactor produced ∼11 wt % pure H2O2 solutions with a high Faradaic efficiency of 92% and a low energy consumption of 6.10 kWh/kg H2O2 under an industrial current density of 100 mA/cm2, and the scaled-up reactor (10 cm × 10 cm wafer) maintained stable H2O2 production over 200 h. By addressing the bottlenecks of conventional PSE reactors, the wafer reactor provides a robust and scalable platform for practical H2O2 electrosynthesis.

Porous solid electrolyte (PSE) reactors have attracted worldwide interest in H₂O₂ electrosynthesis and other electrochemical processes (e.g., CO₂ reduction). However, scaling up PSE reactors for industrial applications faces several challenges, including the difficulty in uniformly packing PSE (typically resin microspheres) in large reactors, the high pressure drop across the reactor, and the limited durability of anion exchange membranes (AEM). Here, to address these challenges, we fabricated robust PSE wafers with both high ion conductivity and porosity by pre-molding resin microspheres, conductive binder, and pore-forming agent. These pre-molded wafers can be easily installed in reactors, thereby simplifying the reactor assembly and scalability. Moreover, due to their high porosity, the PSE wafers dramatically reduced the pressure drops across the reactor by a factor of ~ 5–7 compared to resin microsphere-packed beds. Consequently, the wafer reactors could be stably operated without the need of an AEM for preventing electrode flooding, circumventing the barrier to long-term stability of PSE reactors. By addressing these bottlenecks, the wafer reactor provide a robust and scalable platform for practical H₂O₂ electrosynthesis.

The recently developed porous solid electrolyte (PSE) reactor for electrosynthesis of hydrogen peroxide (H₂O₂) has attracted significant global interest. However, scaling up the PSE reactor for practical applications poses challenges, particularly due to performance decline in enlarged reactors. Here we systematically investigate how factors such as material selection, assembly parameters, flow field patterns, and operating conditions influence H₂O₂ electrosynthesis in the PSE reactor. Our findings reveal that the performance decline during reactor scale-up is primarily caused by the uneven flow field in the PSE layer. Based on these insights, we optimize the reactor design and develop a 12-unit modular electrode stack PSE reactor with a total electrode area of 1200 cm². The scaled-up reactor maintains efficient H₂O₂ electrosynthesis without significant performance decline. It operates stably for over 400 h and can produce up to 2.5 kg pure H₂O₂ (~83 kg 3% H₂O₂ solutions) per day with considerably lower energy costs (0.2‒0.8 USD/kg H₂O₂) than the market prices of H₂O₂ stocks. This work represents a crucial advancement in the development of PSE reactor technology for practical H₂O₂ electrosynthesis.

Heterogeneous surface processes such as adsorption and oxidation with surface-adsorbed reactive oxygen species (ROS_ad, e.g., adsorbed oxygen atom (*O_ad) and hydroxyl radicals (^•OH_ad)) have been suggested to play an important role in pollutant abatement during heterogeneous catalytic ozonation (HCO). However, to date, there is no reliable method to quantitatively evaluate the contribution of heterogeneous surface processes to pollutant abatement (f_S) during HCO. In this study, we developed a method by combining probe compound-based experiments with kinetic modeling to distinguish heterogeneous surface processes from homogeneous bulk reactions with aqueous O₃ and ROS (^•OH and superoxide radicals (O₂^•-) in the abatement of various pollutants (e.g., atrazine, ibuprofen, tetrachloroethylene, and perfluorooctanoic acid) during HCO with reduced graphene oxide. The results show that the pollutants that have a low affinity for the rGO surface (e.g., ibuprofen and tetrachloroethylene) were essentially abated by homogeneous bulk reactions, while the contribution of heterogeneous surface processes was negligible (f_S < 5%). In contrast, heterogeneous surface processes played an important or even dominant role in the abatement of pollutants that have a high surface affinity (e.g., f_S = 32-82% for atrazine and perfluorooctanoic acid). This study is a critical first step in quantitatively evaluating the role of heterogeneous surface processes for pollutant abatement during HCO, which is crucial to understanding the mechanism of HCO and designing catalysts for effective pollutant abatement.