## 2 MOFs for Fuel-Cell Applications
### MOFs as Electrode Application
#### 2.1.2 Organic Fuel Cells  
A Pt-free electrocataly was been developed based upon the M-N\({}_{\mathrm{x}}\) active sites that have already been broadly employed as catalysts for accelerating the ORR process in H\({}_{2}\)/O\({}_{2}\) fuel cells. They have proven to be effective at accelerating the ORR process in hydrocarbon fuel cells. A process of oxidizing the organic fuel also encompasses the ORR, and the result is the transformation of chemical energy into its electrical and thermal forms. An analogy can also be made with the oxidation of hydrogen and oxygen fuel cells. The use of methanol fuel cells for high energy density is a good example of a fuel cell that can be used for a variety of organic fuels. In order to ensure that the ORR catalysts used in direct methanol fuel cells (DMFCs) have good methanol tolerance, durability, and stability, the need to design them with good ORR tolerance and structure is paramount [81,82]. The use of ZIF-8 on graphene oxide after being subjected to thermal treatment at 800 \({}^{\circ}\)C reported the fabrication of a carbon porous framework that utilized a graphene-based layered material (GNPCSs-800) [83]. Furthermore, this Pt/C catalyst exhibits significant performance improvements over other conventional Pt/C catalysts in terms of open circuit voltage as well as methanol tolerance. This is partially due to the synergy linking the surface modification of graphene to accommodate the N-doped porous carbon layers.  
Furthermore, carbon materials generally have the ability to perform as catalysts in fuel cells and are extremely resistant to organic media. As a way to exploit the excellent catalytic capability of Cu centres, [PERSON] et al. designed and fabricated a composite containing GO and Cu-structured MOFs in order to additionally enhance their ORR/OER activity [84]. Theywere also able to integrate the sealing and electrical properties of GO into the composite. In a polymer electrolyte membrane fuel cell, MOF composite catalysts produced power densities that were comparable to those of platinum-based catalysts [43]. The NH\({}_{2}\)-MIL-88B and ZIF-8 iron and carbon sources, respectively, were utilized in order to make a structure that was shown to resemble a bamboo structure mimicked by a carbon nanotube complex with Fe-positioned active-site nodes. A metal catalyst, which is open-source, was tested in the polymer electrolyte membrane fuel cell and showed excellent results when used as a catalyst [70].  
There is no doubt that when designing MOF-based electrocatalysts, it is very critical to make sure that organic material tolerances and acidic medium tolerances are taken into account, because each of these factors is able to enhance the cycling durability under several conditions. In acidic conditions, it can be beneficial to utilize metallic catalysts with a lower active site such as Cu in order to protect the metal active sites, or it can be beneficial to develop metal-free catalytic systems comprising heteroatoms or metal active sites encapsulated in carbon to prevent them from being oxidized. In this study, we examined the relationship between MOF structure, composite composition, and electrochemical performance to profit from the understanding of the materials' perspective and their impact on the potential of particle-based components for the enhancement of high-performance Fuel-cell systems.