Interestingly, the Mo-doping seems to make the LDH electrodes less active towards OER while the opposite was observed for HER. In the OER region, the Mo-doped electrodes also have an oxidation peak at around 1.5 V vs RHE which is typically associated with the oxidation of Ni to a higher oxidation state. We attribute Mo-induced oxidation peaks to the presence of a highly electronegative Mo 6+ which facilitates the oxidation of Ni 2+ to Ni 3+ . This assignment is strongly supported by our electronic structure analysis (Figure ), which shows that Mo doping lowers the d-band center of Ni atoms by 1.62 eV (0.64 eV) in NiFeCo-LDH (MoS 2 @NiFeCo-LDH). This implies that the oxidation state of Ni is higher in the presence of Mo than without it. This Mo-induced oxidation is also the likely reason why Mo-doping reduces the OER activity, as it leads to easier oxidation and the formation of Ni 3+ , which increases the OER overpotential. The additional oxidation peaks were not observed when MoS 2 QDs were deposited on NiFeCo-LDH. Moreover, the LSV curves depicted in Figure indicate that Mo doping does not affect the activity of NiFeCo-LDH under light irradiation.