A hybrid electrochemical system for spontaneous green‑hydrogen production with simultaneous desalination using catechol oxidation

• Published in: Desalination Vol. 580; p. 117541
• Main Authors: Kim, Na Hyeon, Kim, Byeongkyu, Kim, Yong Seok, Mule, Anki Reddy, Chung, Chan-Hwa
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2024
• Subjects: Catechol oxidation; Electrochemical desalination; Green hydrogen; Hydrogen evolution reaction; Spontaneous hybrid system; Green hydrogen; Hydrogen evolution reaction; Electrochemical desalination; Spontaneous hybrid system; Catechol oxidation
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2024.117541

Green hydrogen, commonly produced through water electrolysis, has attracted considerable attention owing to its energy-efficient and eco-friendly properties. However, since conventional water electrolysis system has fatal drawbacks owing to the high process cost and energy requirements, various approaches are being adopted to increase its energy efficiency. In this study, a novel hybrid system for green hydrogen production was designed by replacing the oxygen evolution reaction (OER) with electrochemical oxidation of catechol (CAT). CAT is an environmental pollutant generated by diverse industries and needs to be further treated because of its toxicity to humans and nature. Accordingly, to facilitate the degradation of CAT and increase the energy efficiency, the pH values of the anolyte (containing CAT) and catholyte were adjusted to alkali and acid, respectively. Two types of ion-exchange membranes (IEMs; anion-/cation-exchange membranes) were coupled to divide the hybrid cell into three compartments, and a buffer solution (NaCl solution) was injected between the IEMs. As a result, the hybrid system output 3.75 mW/cm2 of electricity, spontaneously produced hydrogen with 4.2 mL/h of hydrogen production rate and removed ions from the buffer solution with 0.46 mg/cm2∙min of high desalination rate. A spontaneous green-hydrogen production system with simultaneous desalination of saltwater was suggested using catechol oxidation reaction. This system output 3.75 mA/cm2 of power and spontaneously generated 4.2 mL/h of green hydrogen of constant current at 5 mA/cm2, resulting in a fast desalination rate of 0.46 mg/cm2·min without external energy supply. [Display omitted] •Green hydrogen is produced spontaneously with simultaneous desalination of brine.•Electro-oxidation of catechol is paired with hydrogen evolution reaction.•The spontaneous hybrid system is organized by controlling pH of electrolytes.•4.2 mL/h of green hydrogen is produced with 0.46 mg/cm2∙min of desalination rate.