Abstract
Polymer electrolyte fuel cells (PEFCs) are attractive energy resources in transportation and portable applications due to their low operational temperatures, excellent energy densities, and simplicity of storage. For the past decade, metal oxides (MO) have been identified as plentiful supplies with excellent electrochemical properties, low cost, an abundance of hydroxyl groups, and environmentally acceptable alternative to currently available materials. Their intriguing properties such as extremely large surface area, low synthesis cost, and so on, make them ideals for many applications. This review covered MO structure, characteristics, and current preparation methods. MO/metal nanoparticles and MO/carbon nanoparticles are also addressed as electrocatalysts, co-catalysts, or supports, especially in PEMFC and DMFC applications. This review also examined the effects of different MO nanoparticles in polymer and biopolymer membranes on membrane characteristics. Finally, the existing issues and future perspectives of MO nanoparticles are also discussed in this review.
GRAPHICAL ABSTRACT
Disclosure statement
No potential conflict of interest was reported by the author(s).
Funding
The authors would like to express their gratitude to Universiti Kebangsaan Malaysia (UKM) and the Ministry of Higher Education for providing financial assistance through a Fundamental Research [Grant Scheme FRGS/1/2021/STG05/UKM/02/10].
Declaration of interest statement
The authors whose names are listed immediately below certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript. Author names: Yusra Nadzirah Yusoff, Norazuwana Shaari, Siti Hasanah Osman.