Cathode materials and novel strategies for improving bioenergy production in microbial electrolysis cell: A review

Abstract

Recovering bioenergy from wastewater by sustainable technologies is crucial to address environmental and energy concerns. Microbial electrolysis cell (MEC) combines electrochemical and microbial metabolic processes and are considered a promising technology. The material properties of cathodes are the primary determinants of production efficiency since they directly participate in the generation of H₂ and byproducts. Previous reviews mainly focused on the production process and mechanism of bioenergy, but little about cathode materials and their optimization. Based on the mechanism of MEC and its coupling technologies, this review comprehensively examines and contrasts the production efficiency of precious metals, carbon-based materials, Ni-based materials, metal-organic frameworks, and biocathodes. Ni-based materials are employed as excellent catalysts or cathode support materials because of their high conductivity, good stability, and low cost. To improve the cathode production efficiency, novel strategies to boost (i) conductivity, (ii) catalysis, (iii) specific surface area, and (iv) H source are discussed. Significantly, electrical conductivity has a greater impact on cathode properties which is attained by constructing layered structures and doping heteroatoms. Finally, we anticipate the future research directions of MEC to address the challenges facing this area.