Advancing Microbial Electrochemical H2O2 Synthesis by Tailoring the Surface Chemistry of Stereolithography-Derived 3D Pyrolytic Carbon Electrodes

Microbial electrosynthesis of H2O2 offers an economical and eco-friendly alternative to the costly and environmentally detrimental anthraquinone process. Three-dimensional (3D) electrodes fabricated through additive manufacturing demonstrate significant advantages over carbon electrodes with two-dimensional (2D) surfaces in microbial electrosynthesis of H2O2. Nevertheless, the presence of oxygen-containing free acidic groups on the prototype electrode surface imparts hydrophilic properties to the electrode, which affects the efficiency of the two-electron oxygen reduction reaction for H2O2 generation. In this study, we elucidated that the efficiency of microbial H2O2 synthesis is markedly enhanced by utilizing oxygen-free 3D electrodes produced via additive manufacturing techniques followed by surface modifications to eradicate oxygen-containing functional groups. These oxygen-free 3D electrodes exhibit superior hydrophobicity compared to traditional carbon electrodes with 2D surfaces and their 3D printed analogues. The oxygen-free 3D electrode is capable of generating up to 130.2 mg L–1 of H2O2 within a 6-h time frame, which is 2.4 to 13.6 times more effective than conventional electrodes (such as graphite plates) and pristine 3D printed electrodes. Additionally, the reusability of the oxygen-free 3D electrode underscores its practical viability for large-scale applications. Furthermore, this investigation explored the role of the oxygen-free 3D electrode in the bioelectro-Fenton process, affirming its efficacy as a tertiary treatment technology for the elimination of micropollutants. This dual functionality accentuates the versatility of the oxygen-free 3D electrode in facilitating both the synthesis of valuable chemicals and advancing environmental remediation. This research introduces an innovative electrode design that fosters efficient and sustainable H2O2 synthesis while concurrently enabling subsequent environmental restoration.