The durability of the catalyst under HER conditions was evaluated using chrono-potentiometry (CP) with continuous current measurement at a current density of 10 mA cm -2 for over 48 h. As depicted in Figure , the best performing HER electrocatalyst, MoS 2 @NiFeCo-Mo(doped)-LDH exhibits a minimal change in the electrode potential, which again indicates high stability. This conclusion is supported by the minimal changes in the LSV curves (Figure ) recorded before and after 500-cycle voltammetry scans under dark conditions. MoS 2 @NiFeCo-Mo(doped)-LDH maintains its high stability and (photo)electrocatalytic activity even after being subjected to an additional 500 CV cycles under light illumination, as shown in Figure . This is rather surprising, as we initially assumed that the amorphization due to Mo doping would reduce the catalyst stability; in contrary to our expectations, MoS 2 @NiFeCo-Mo(doped)-LDH exhibited exceptional stability under (photo)electrocatalytic HER conditions. Currently, we do not understand the origin of the increased durability but it is clear that some complex synergistic effects between doped Mo, MoS 2 QDs, and NiFeCo-LDH result in a very stable (photo)electrocatalytic material. Nevertheless, our additional chrono-amperometry (CA) studies on the optimized MoS 2 @NiFeCo-Mo(doped)-LDH electrode show that it is highly stable even under industrially relevant HER current densities of 100, 500, and 1000 mA cm -2 (Figure ), with negligible performance degradation or changes in the potential over 75 hours.