Modern societies are powered by fossil fuels but the extensive use of these resources has unintentionally caused substantial harm to our environment. In future, we need to cut down the carbon emissions and shift to renewable, clean, and sustainable energy technologies. Green hydrogen produced through overall water splitting (OWS) catalysis has become the preferred choice given its low carbon emissions and high energy efficiency. However, the production of hydrogen through water splitting relies on the use of noble metal electrocatalysts to † These authors contributed equally achieve low overpotentials and rapid kinetics in the oxygen evolution (OER) and hydrogen evolution reactions (HER). Currently, the best commercial catalysts for OER and HER are based on noble metal oxides, such as IrO 2 /RuO 2 and Pt-based compounds, respectively. However, their low abundance and high cost present limit their use in industrial applications. Hence, there is a large demand for cost-effective, stable, and efficient water splitting catalysts made of earth-abundant elements. In the pursuit of more efficient OWS, a plethora of different types of transition-metal -based HER and OER electrocatalysts have been designed and synthesized during the past decade. Examples include oxides, sulfides, borides, phosphides, carbides, and nitrides, as well as metal-organic frameworks (MOFs) and layered double hydroxides (LDHs). Besides new materials, it has also been shown that morphological control is an effective way of improving electrocatalytic activity. For instance, amorphous materials often exhibit increased electrocatalytic performance as compared to their crystalline counterparts due to structural and chemical disorder, the presence of defects, dangling bonds, and structural flexibility. In general, the amorphization of crystalline materials has been viewed as a powerful way to improve HER and OER kinetics and the overall performance towards electrochemical water splitting. One realization of the combined material development and amorphization strategies is the design of transition metal-based LDHs, which attract considerable attention due to their high (photo)electrocatalytic activity towards various reactions. In particular, LDHs containing nickel (Ni), cobalt (Co), and iron (Fe) have exhibited very promising electrocatalytic performance, low overpotential, and long-term durability for the OER. LDHs are, however, less used in the HER due to weak hydrogen adsorption, which induces a substantial energy barrier for HER and consequently leads to sluggish water splitting kinetics. Therefore, various chemical and physical strategies have been investigated and applied to improve the (photoelectro)catalytic properties of LDHs, including morphology control and the creation of defects and vacancies. Nevertheless, LDHs still encounter issues regarding sluggish reaction kinetics and slow mass transfer, low concentration of electroactive sites, and limited electronic conductivity. The electrocatalytic activity of Ni/Fe/Co-LDHs remains constrained by two crucial factors: intrinsic reaction kinetics and mass transfer. To overcome these issues, different catalyst design strategies have been employed. One approach involves the introduction of transition metal cations or non-metal atoms to modify the electronic structure, the presence of structural defects, and the local reaction or coordination environment at the LDH surface. Additionally, the insertion of various anions or molecules between the LDH layers can alter their spacing, charge density, and hydrophilicity. Another strategy entails controlling the mesoscopic structure through atomic vacancies or pores within the LDHs to increase their surface area, to expose more active sites, and to facilitate mass transfer. LDHs can also be interfaced and combined with other conductive materials or substrates to enhance their electrical conductivity, stability, and OWS activity. Some notable choices include metal clusters and molybdenum compounds, for instance. The incorporation of 2D molybdenum sulfide (MoS 2 ) sheets, which are active HER electrocatalysts, has been shown to activate LDHs towards HER by introducing new active sites. Moreover, as the electronic properties of MoS 2 nanostructures depend sensitively on their size, they have also been used to improve the (photo)electrocatalytic activity by introducing narrow and tunable band gaps. The size-and morphology-dependent electronic structures make the MoS 2 nanostructures highly appealing as co-catalysts for (photo)electrocatalytic HER. After carefully considering the above aspects, we hypothesized that 1) NiFeCo-LDHs are an ideal materials class for OER, 2) the introduction of large, high-valence metal atoms (Mo) will lead to more pronounced amorphization of the LDH structure, 3) the incorporation of MoS 2 nanostructures on the LDH surface can enhance the HER and OER (photo)electrocatalytic activity by introducing more active sites, and 4) the mass transfer, conductivity, and electrocatalytic active surface area to electroactive sites can be improved by depositing the catalyst material on a highly porous conducting substrate.