Specifically, the η values for HCP-MoOC at current densities of 5 A cm -2 and 10 A cm -2 are 358 mV and 415 mV, respectively, lower than those of the existing advanced acidic HER catalysts , as shown in Figure . The relationship between current density and the ratio of overpotential change to logarithmic current density change (Δη/Δlog|j|) of different catalysts is analyzed and shown in Figure . This metric is a critical indicator of the electrocatalysts' performance at high current densities, which is essential for practical hydrogen evolution applications .