Long-Term Evaluation of CNT-Clad Stainless-Steel Cathodes in Multi-Channel Microbial Electrolysis Cells Under Variable Conditions

Kevin Linowski, Md Zahidul Islam, Luguang Wang, Fei Long, Choongho Yu and Hong Liu ()
Additional contact information
Kevin Linowski: Department of Biological and Ecological Engineering, Oregon State University, Corvallis, OR 97331, USA
Md Zahidul Islam: Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA
Luguang Wang: Department of Biological Engineering, Utah State University, Logan, UT 84322, USA
Fei Long: Department of Biological and Ecological Engineering, Oregon State University, Corvallis, OR 97331, USA
Choongho Yu: Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA
Hong Liu: Department of Biological and Ecological Engineering, Oregon State University, Corvallis, OR 97331, USA

Energies, 2025, vol. 18, issue 19, 1-23

Abstract: Microbial electrolysis cells (MECs) present a viable platform for sustainable hydrogen generation from organic waste, but their scalability is limited by cathode performance, cost, and durability. This study evaluates three hybrid carbon nanotube (CNT) cathodes—acid-washed CNT (AW-CNT), thin layer non-acid-washed CNT (TN-NAW-CNT), and thick layer non-acid-washed CNT (TK-NAW-CNT)—each composed of stainless-steel-supported CNTs coated with molybdenum phosphide (MoP). These were benchmarked against woven carbon cloth (WCC) under varied operational conditions. A custom multi-channel reactor operated for 341 days, testing cathode performance across applied voltages (0.7–1.2 V), buffer types (phosphate vs. bicarbonate), pH (7.0 and 8.5), buffer concentrations (10–200 mM), and substrates including acetate, lactate, and treated acid whey. CNT-based cathodes consistently showed higher current densities than WCC across most conditions with significant difference found at higher applied voltages. TK-NAW-CNT achieved peak current densities of 259 A m −2 at 1.2 V and maintained >41 A m −2 in real-waste conditions with no added buffer. Long-term performance losses were minimal: 4.5% (TN-NAW-CNT), 0.1% (TK-NAW-CNT), 10.8% (AW-CNT), and 6.8% (WCC). CNT cathodes showed improved performance from reduced resistance and greater electrochemical stability, while proton transfer improvements benefited all materials due to buffer type and pH conditions. These results highlight CNT-based cathodes as promising, scalable alternatives to WCC for energy-positive wastewater treatment.

Keywords: microbial electrolysis cell; carbon nanotube; acid whey; electrode stability; hydrogen production; bicarbonate buffer (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/1996-1073/18/19/5241/pdf (application/pdf)
https://www.mdpi.com/1996-1073/18/19/5241/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:18:y:2025:i:19:p:5241-:d:1763814

Access Statistics for this article

Energies is currently edited by Ms. Cassie Shen

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().