A parallel-plate electrochemical microreactor for the continuous production of hydrogen peroxide

This study presents a comprehensive evaluation of a microfluidic electrochemical system for the controlled generation and detection of hydrogen peroxide (H 2 O 2 ). The integrated microreactor with a three-electrode configuration in combination with optical sensors enabled real-time monitoring of dissolved oxygen and H 2 O 2 concentrations during chronoamperometric operation. Glassy carbon (GC) electrodes exhibited high selectivity toward the two-electron oxygen reduction reaction (2e − ORR), a key requirement for efficient H 2 O 2 electrosynthesis. Cyclic voltammetry (CV), rotating ring-disk electrode (RRDE) analyses and electrochemical testing in real system identified 0.4 V vs. RHE as the optimal working potential. Flow rate experiments revealed a decline in H 2 O 2 production with increasing flow rates, consistent with electrical charge measurements and oxygen consumption data. A mathematical model, validated with experimental data, reliably predicted H 2 O 2 outlet concentration as a function of flow rate (residence time). The model captured the interplay between mass transport and surface electrocatalytic reactions and enabled the identification of an optimal operating window (25–50 μL min −1 ), supporting model-based reaction optimization. Post-experiment surface characterization using SEM-EDS, XPS, and μ-FTIR revealed increased oxygen-containing functional groups on the GC working electrode, indicating surface oxidation that may enhance catalytic performance. Overall, this system offers a scalable, sustainable platform for on-demand H 2 O 2 production, supporting cleaner, decentralized electrochemical synthesis with reduced environmental impact and greater adaptability for modern industrial applications. • Developed a microfluidic electrochemical system with optical sensors for real-time O 2 and H 2 O 2 monitoring. • GC electrodes demonstrated high selectivity for the 2e − ORR, which is essential for efficient H 2 O 2 generation. • A validated model predicts H 2 O 2 concentration based on flow rate and residence time to optimize the process. • Post-analysis revealed GC surface oxidation, which enhanced catalytic activity and efficiency. • Achieved high Faradaic efficiency at 50 μL min −1 , balancing performance, throughput, and sustainability.