Overall, our computational results show that control over the metal ratio, Mo doping, and MoS 2 incorporation are efficient ways of controlling the electronic structure and electrocatalytic properties of LDH heterostructures. The electronic structure analysis shows that doping Mo into and the deposition of MoS 2 QDs onto NiFeCo-LDH make the catalyst metallic, which likely increases conductivity. The MoS 2 deposition also leads to significant electron transfer from the LDH to the QD, which likely promotes electrocatalytic activity towards HER near the QD and towards OER on the LDH. We also find that the thermodynamic overpotentials can explain the experimentally observed HER activity across the studied materials; this indicates that the HER activity of LDH heterostructures can be understood based on reaction thermodynamics and explains why the MoS 2 -NiFeCo-Mo(doped)-LDH is such an active HER electrocatalyst. The OER is significantly more complex and the experimental results cannot be understood without accounting for reaction kinetics in addition to the thermodynamics. However, even for OER, the thermodynamic analysis helps to identify how different modifications change the reaction mechanism and thermodynamics. In particular, when one considers that OOH * formation determines both the thermodynamics and kinetics, it appears that one can explain the high OER activity of MoS 2 -NiFeCo-LDH by considering the thermodynamics of the RDS only. However, it needs to be stressed that the experimentally measured overpotential is kinetic in nature, which means that accounting for reaction kinetics, incorporating solvent, cation, and electrode potential effects, and coupling of DFT and microkinetic modeling are needed to make reliable and self-consistent predictions on the OER activity. 3 Conclusions