Surface modification of carbon catalysts for efficient production of H 2 O 2 in bioelectrochemical systems

• Published in: Environmental science water research & technology 2022-10, Vol.8 (10), p.2304-2313
• Main Authors: Eom, Hyunji, Jwa, Eunjin, Jeung, Yoon-Cheul, Hwang, Kyo Sik, Jeong, Namjo, Mok, Young Sun, Nam, Joo-Youn
• Format: Article
• Language: English
• ISSN: 2053-1400; 2053-1419
• DOI: 10.1039/D2EW00418F

Bioelectrochemical systems (BESs) can harvest electrical energy and produce H 2 O 2 simultaneously through oxygen reduction reaction on a cathode. In this study, a carbon-based electrode was modified using physico/chemical methods to enhance H 2 O 2 production. In addition, the performance of the developed cathodes was evaluated in continuous-flow BESs. Carbon catalysts were obtained through different treatments, namely heat treatment (CB-Heat), acid treatment (CB-Acid), and simultaneous heat and acid treatment (CB-H + A); among these methods, the simultaneous heat and acid treatment was particularly effective in improving the H 2 O 2 yields. Abiotic half-cell tests showed that CB-H + A was superior because the carbon powder had a large Brunauer–Emmett–Teller surface area (172.3 m 2 g −1 ), pore volumes (micropore 0.0386 cm 3 g −1 , mesopore 0.3100 cm 3 g −1 , and macropore 0.0018 cm 3 g −1 ), and oxygen functional groups (O atomic percentage 4.79%). Rotating ring-disk electrode results also showed that CB-H + A had the highest H 2 O 2 selectivity (max 68.3%). In the continuous-flow BESs, all the developed carbon catalysts demonstrated stable current generation. The catalyst with the highest H 2 O 2 production was CB-H + A, which produced about 260 ± 5 mg L −1 of H 2 O 2 , followed by CB-Heat (211.1 ± 4.1 mg L −1 ) and CB-Acid (126.8 ± 5.5 mg L −1 ), and the production concentration was stable over the course of the continuous operation periods. In addition, the maximum H 2 O 2 conversion efficiency (78.9%) also had the highest value compared to the other catalysts.