To assess the stability of these NCs under applied electrochemical conditions and their catalytic effectiveness, chronoamperometric measurements were conducted at -1.2 V (vs. RHE) over 12 hours (Figure ). The results for Cu11PTT NC reveal that the total FE gradually increases, and remains stable thereafter. The rise in total FE is largely attributed to contributions from all three products, with the HER being the dominant factor. A quite similar upward trend in FE was observed for the other two NCs. We assume that this improvement in total FE is associated with an increase in the reactivity of the NCs, likely due to the partial loss of ligands during prolonged electrochemical measurements. However, Cu K-edge insitu XANES spectra revealed no notable alterations in spectral features compared to each as synthesized NC, indicating the structural stability of the NCs (Figure ). This was further corroborated by insitu FT-EXAFS spectra, which confirmed the stability of Cu-S or Cu-P bonds under electrochemical conditions (Figure ). To further evaluate the stability of these NCs outside the electrochemical environment post-electrocatalysis, TEM imaging demonstrated the structural integrity of the clusters, as evidenced by their consistent size (Figure ). However, FT-IR analysis revealed a persistent P=O peak, which is likely due to the loss of neutral PPh3 ligands from the NCs (Figure ). This loss of neutral ligands does not significantly alter the electronic environment of the NCs, preserving their stability. Notably, the removal of bulky ligands from the NC surface enhances the reactivity of these NCs under electrochemical conditions, resulting in an increased total FE after a certain period. Once this initial ligand loss stabilizes, the NCs maintain their reactivity and total FE over extended durations, consistent with their performance after 10 hours.