In contrast to conventional Au24Pt(SR)18 NCs, 3 and 4 synthesized in the present work have only 12 TBBT ligands. The remaining six bulky TBBT ligands are replaced by three chainlike TDT or PDT dithiolate ligands. This reduction in the number of bulky ligands is expected to enhance catalytic activity by facilitating the access of reaction substrates to the active sites of 3 and 4. Therefore, the HER activities of [Au24Pt(C6)18] 0 and 2-4 as representative Au24Pt NCs were evaluated by performing electrochemical measurements using CB loaded with these NCs. Au L3-edge X-ray absorption fine structure and transmission electron microscopy assessments confirmed that the electronic/geometric structures of these NCs did not change during the catalyst preparation process (Figure ).