## 2 MOFs for Fuel-Cell Applications
### MOFs as Electrode Application
#### 2.1.1 H\({}_{2}\)/O\({}_{2}\) Fuel Cells
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Catalyst** & **MOF** & **Devices** & **Voltage (V)** & **Current** & **Power Density** & **Cycling Life** \\  & & & & **(mAcm\({}^{-2}\))** & **(mWcm\({}^{-2}\))** & **Cycling Life** \\ \hline Fe-N-C [55] & Fe-ZIF-8 & PEMFC & 0.6 V & 1650 & 1141 & - \\ \hline Fe-SAs/NPS-HC [56] & ZIF-8/Fe@PZS & H\({}_{2}\)/O\({}_{2}\) fuel cell & 0.8 V & 50 & 333 & - \\ \hline Ferrocene [57] & ZIF-8 & PEMFC & 0.7 V & 1100 & 775 & 32.2\% (10 h) \\ \hline C-FeHZ8@g-C\({}_{3}\)N\({}_{4}\)*950 [58] & Fe-ZIF-8@g-C\({}_{3}\)N\({}_{4}\) & PEMFC & 0.8 V & 133 & 628 & 48.7\% (8 h) \\ \hline Fe-N-C [59] & ZIF-8 & PEMFC & 0.7 & 1050 & 690 & 42\% (50 h) \\ \hline FeN\({}_{4}\)/HOPC-c-1000 [60] & Fe-ZIF-8 & PEMFC & 0.6 V & 690 & 420 & 53\% (100 h) \\ \hline Fe-Fe\({}_{3}\)C [35] & ZIF-8 & H\({}_{2}\)-O\({}_{2}\) Fuel Cell & 0.8 V & 100 & 760 & - \\ \hline
20 Mn-NC [61] & Mn-ZIF-8 & PEMFC & 0.6 V & 350 & 460 & \textgreater{}1000 h \\ \hline
20-Co-NC-1100 [62] & Co-ZIF-8 & H\({}_{2}\)/O\({}_{2}\) fuel cell & 0.7 V & - & 560 & - \\ \hline C-Fe-ZIF-8@g-C\({}_{3}\)N\({}_{4}\)[63] & Fe-ZIF-8 & PEMFC & 0.8 V & 1000 & 481 & 82\% (667 h) \\ \hline Co-N-C@F127 [64] & Co-ZIF-8 & H\({}_{2}\)/O\({}_{2}\) fuel cell & \textgreater{}0.7 V & 30 & 870 & 100 h \\ \hline Fe-ZIF/CN-UC [65] & Fe-ZIF-8 & H\({}_{2}\)/O\({}_{2}\) fuel cell & 0.2 V & 2000 & 484 & - \\ \hline H-Fe-N\({}_{x}\)-C [66] & ZIF-8@Fe-TA & PEMFC & 0.43 V & 1550 & 655 & 30 h \\ \hline H-Co-N\({}_{x}\)-C [66] & ZIF-8@Co-TA & PEMFC & 0.43 V & 103 & 457 & 30 h \\ \hline H-FeCo-N\({}_{x}\)-C [66] & ZIF-8@FeCo-TA & PEMFC & 0.43 V & 104 & 459 & 30 h \\ \hline FeNi-N\({}_{6}\)[67] & ZIF-8 & PEMFC & 0.8 V & - & 216 & \textgreater{}5000 cycles \\ \hline Fe-Fe\({}_{3}\)@Fe-N-C [35] & MIL-100/ZIF-8 & PEMFC & 0.8 V & 100 & 760 & - \\ \hline GNPCSs-800 [68] & ZIF-8/GO & DMFC & 0.71 V & - & 33.8 & 94\% (-8 h) \\ \hline GO-MOF [69] & Cu-MOF & PEMFC & 0.6 V & - & 110.5 & - \\ \hline Fe-N-C-10/1-950 [70] & NH2-MIL- 88B/ZIF-8 & PEMFC & 0.6 V & 1240 & 770 & - \\ \hline Ptcu@NCC [71] & ZIF-8 & DFAFC & 0.8 V & 400 & 121 & 71\% (40 h) \\ \hline MOF-800 [72] & Cu-bipy-BTC & MFC & 0.588 V & - & 326 & \textgreater{}30 days \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Performances of MOF-based electrode materials in superior Fuel-cell devices. tures on a porous carbon (FeN\({}_{4}\)/HOPC-C-1000) skeleton, [PERSON] et al. [60] carbonized the MOF Fe-ZIF-8 at 1000 \({}^{\circ}\)C. FeN\({}_{4}\)/HOPC-c-1000 using a bimetallic mechanism demonstrating a current density of 0.69 A cm\({}^{-2}\) at 0.6 V, which exceeds current expectations up to 0.5 A cm\({}^{-2}\) for FeN\({}_{4}\)/C, and a power density of 0.42 W cm\({}^{-2}\) at 0.57 V (0.35 W cm\({}^{-2}\) for FeN\({}_{4}\)/C). Aside from this, the catalyst also exhibited impressive durability when annealed at 0.55 and 0.7 V. These results suggest an atomically dispersed FeN\({}_{4}\) with catalytic centres that exhibit a porous structure when annealed at optimum temperatures. An alternative method of the binary ligand strategy aimed at a higher surface area was also presented by using 2-methylimidazole (mlm) and 2-undecylimidazole (ulm) as ligands. This study has offered new methods for the controlled preparation for electrocatalysts of the Fe-N-C type [60; 77] (Figure 4). As a result of their higher stability and remarkable catalytic activity, other transition-metal-based catalysts have also been examined in H\({}_{2}\)/O\({}_{2}\) fuel cells. The Fenton reactions (Fe\({}^{2+}\) + H\({}_{2}\)O\({}_{2}\)) used by Fe-N-C catalysts were addressed by developing a Mn-N-C type SAC with MnN\({}_{4}\) species being chemically distributed through the calcination of Mn-doped ZIF-8 precursors in an acid environment [61].