## 1 Introduction
The adaptable nature of metal nodes with the array of organic linker combinations that can be generated under controlled conditions can provide key insights into achieving highly ordered and tuneable MOFs possessing unique compositional and structural advantages over conventional materials (Figure 2). Figure 1: Illustrating the formation of MOFs and factors that affect their synthesis. PEMFC technology can be made more efficient by using MOF materials that possess appropriate physical and chemical properties. The most commercially studied and applied proton-exchange membranes are composition-based nafion membranes. In the presence of water in the range of 20-80 \({}^{\circ}\)C, the proton conductivity of nafion is achievable up to \(10^{-2}\) S cm\({}^{-1}\)[23; 24; 25]. Although nafion membranes and their derivative membranes have been widely investigated, they have limited use in fuel cells owing to the complex preparation process and high production costs, which become significant and commercially demanding at temperatures exceeding 80 \({}^{\circ}\)C and below 0 \({}^{\circ}\)C as mirrored by a considerable fall in conductivity [9; 26; 27]. Hence, the requirements for high proton conductivity (>100 S cm\({}^{-1}\)) and a broad temperature range (25-300 \({}^{\circ}\)C) considerably reduce its commercial value, necessitating a greater need for alternative proton-exchange membranes, which are less demanding in an industrial context [28]. MOFs are viewed as attractive replacement materials that demonstrate a wider physical and chemical property range, in conjunction with mechanical properties for durability. Investigations have shown that the coordination skeleton itself plays a leading role in delivering protons as a carrier [29; 30]. However, a significant disadvantage is the insufficient conductivity of MOFs due to the grain boundaries, which restrict proton migration, but the hybridization of MOFs using acid groups (-COOH, -HSO\({}_{3}\), -PO\({}_{3}\)H\({}_{2}\), etc.) offers an efficient strategy for resolving this problem [31; 32; 33]. Additionally, Fuel-cell efficiency is also dependent on the activity of the oxygen reduction reaction, which is classified among the essential half-reactions [34; 35; 36; 37]. For the development of durable fuel cells, the search for electrocatalysts with superior efficiencies is therefore a significant hurdle. More recently, MOFs have been attractive for ORR applications [38; 39; 40] where the use of metal ions or clusters and organic connectors can aid the development of advanced catalysts. The porous structure of MOF electrocatalysts  
Figure 2: The diagram shows the dependence of MOF composites and their derivatives on the base MOF structure. facilitates mass transfer in electrochemical reactions, and as a result of the uniform distribution of metal throughout the MOF precursors, the active sites of the catalyst are efficiently utilized [41; 42; 43; 44]. The purpose of the present review is to discuss the recent developments of the PEMFC electrode layer and electrolyte, highlighting the relevance to MOFs and their structures, modification and impact in advancing the next generation of PEMFC-based technologies. Future research directions and perspectives are also highlighted in Figure 3.