The SEM and TEM analyses in Figures and clearly illustrate that Mo doping in NiFeCo-LDH results in the formation of thicker and denser nanosheets. While decreasing the LDH nanosheet thickness has been observed to improve the charge conductivity and to increase the electrocatalytic activity, our findings show that doping the NiFeCo-LDH with Mo leads to both thicker sheets and increased HER activity. This discrepancy between our and previous results can be explained by the XRD results shown in Figure and the highresolution TEM images in Figure -h which show that Mo doping causes the amorphization of the crystalline NiFeCo-LDH structures. Most notably, the higher degree of amorphization has been correlated with enhanced electrocatalytic activity due to the increased number of active sites and structural flexibility. On the other hand, the deposition of MoS 2 QDs reduces the overall LDH thickness, increases the distance between the LDH layers, and introduces new active sites on the LDH sheets as can be seen from the SEM, HR-TEM, and XRD analysis (Figures and). Correlating the XRD, HR-TEM and SEM analysis with electrocatalytic studies indicates the enhanced electrocatalytic activity following MoS 2 deposition is not due to increased amorphization. The combination of Mo doping and MoS 2 QDs deposition both increases amorphization, decreases the sheet thickness, and creates new active sites: these effects result in an increased ECSA (Figure ). It appears that the increased amorphization and thickness due to Mo doping enhance the (photo)electrocatalytic HER activity while OER benefits only from the increased ECSA (Figure ).