# Two-Dimensional Metal-Organic Frameworks and Their Derivative Electrocatalysts for Water Splitting
## 3 Application of 2D MOFs and Their Derivatives for Water Splitting
### Oxygen Evolution Reaction
By doing so, the material was found to achieve an impressive \(\eta\) value, driving a current density of 10 mA cm\({}^{-2}\) with an overpotential of only 310 mV. [PERSON] [179] added triethylamine to promote MOF nanosheet synthesis and prepared 2D MOF-Fe/Co by simple stirring at room temperature. The MOF-Fe/Co (1:2) exhibits outstanding electrocatalytic performance, with a low overpotential of only 238 mV required to achieve a current density of 10 mA cm\({}^{-2}\) in an alkaline solution. Additionally, it has a low CdI value of 66.9 mF cm\({}^{2}\), indicating its high electrocatalytic activity and fast electron transfer rate. [PERSON] [180] used bimetallic LDH nanomaterials as a sacrificial template to prepare 2D NiFe MOF, as shown in Figure 10e,f, and the width of the prepared NiFe MOF was approximately 0.4-0.6 \(\upmu\)m in 2D planar nanosheets. The prepared MOFs possess the activity sites for oxygen evolution, bimetallic components, and coordination environment from LDHs. The carboxylated organic ligands can be used as intermediates to transfer protons due to their ability to ionize hydrogen ions, which improves the proton transfer efficiency and OH adsorption of 2D MOF nanosheets. The freestanding NiFe-2D MOF nanosheets drive a current density of 10 mA cm\({}^{-2}\), requiring only 260 mV overpotential (Figure 10g). When nickel foam is used to fabricate LDH nanosheets, the overvoltage is even as low as 221 mV. \[\mathrm{OH^{-}+^{*}\to HO^{*}+e^{-}} \tag{7}\]1 Mechanism of OER [177]. Copyright 2018, Springer Nature. The introduction of metalloids in MOFs regulates the electronic structure and increases the electrical conductivity. The introduction of non-metallic elements in MOFs can create atomic vacancies and defects and increase additional active sites in catalytic reactions. [PERSON] [181] prepared Te,Cl-NiFe MOF by introducing Cl and Te elements into the NiFe MOF, which exhibited uniform 2D nanosheets. The participation of Te elements in the MOF facilitates the transport of electrons from Fe to Te and improves the kinetics of the reaction. In contrast, the participation of halogenated elements promotes the oxidation of Cl due to the larger electronegativity of Cl atoms, which can induce more active sites. Thus, the Cl and Te co-doped NiFe MOFs grown on nickel foam demonstrated remarkable OER performance, achieving a current density of 30 mA cm\({}^{-2}\) with an overpotential of only 224 mV (Figure 10h). Furthermore, these materials displayed exceptional long-term stability, maintaining their activity for over 120 h (Figure 10i). The 2D MOFs can be obtained as derivatives by appropriate treatment, and their morphology can be kept the same as the previous. [PERSON] et al. [182] designed and synthesized FeNi\({}_{3}\)-Fe\({}_{3}\)O\({}_{4}\) hierarchical nanoparticles homogeneously immobilized on carbon nanotubes and MOF nanosheets (FeNi\({}_{3}\)-Fe\({}_{3}\)O\({}_{4}\) NPs/MOF-CNT). Due to the 3D multiporous nanos  
\[\mathrm{OH^{-}+^{*}\to HO^{*}+e^{-}} \tag{7}\]2 (**a**) SEM of 2D ZIF-67. (**b**) SEM of 5% NiCo-MOF. (**c**) XPS spectra of 5% NiCo-MOF. (**d**) XPS spectra of Co 2p. Reproduced with permission. [178] Copyright 2021, Elsevier. (**e**) SEM image of NiFe MOF nanosheets. (**f**) TEM image of NiFe MOF nanosheets. (**g**) LSV plots of NiFe MOF for OER. Reproduced with permission. [180] Copyright 2022, Wiley-VCH. (**h**) Te,Cl-NiFe MOF polarization curves. (**i**) Te,Cl-NiFe MOF electrochemical stability. Reproduced with permission [181] Copyright 2022, Elsevier. tructure of the MOF precursor and the modification of the electronic configuration of Ni by Fe\({}_{3}\)O\({}_{4}\), the FeNi\({}_{3}\)-Fe\({}_{3}\)O\({}_{4}\) NPs/MOF-CNT drives a current density of 10 mA cm\({}^{-2}\) requiring only 234 mV overpotential, while the slope of Tafel is 37.0 mV dec\({}^{-1}\). [PERSON] [183] used 2D Co-TCPP (Fe) MOF as a precursor to obtaining MOF-derived Fe-CoP/C composite nanoplatelets by high-temperature carbonization and phosphorylation of carbon cloth.