In this paper, we report the in-situ growth of vertically standing nanoedge-enriched molybdenum oxycarbide nanosheets (MoOxCy) through plasma-enhanced chemical vapor deposition (PECVD) based on salts as precursors to achieve ultrahigh-throughput acidic electrocatalytic hydrogen evolution at high current densities up to 10 A cm -2 . The plasmastructured nanoedge-enriched MoOxCy catalysts offer the following benefits toward HER: 1) Significantly improved thermodynamic stability of catalysts because of the non-equilibrium plasma-engineered structures, which are kinetically unfavorable to obtain through conventional equilibrium thermal methods; 2) Strong localized electric field near the ultrasharp edges of the catalysts, enabling fast diffusion of H3O + from the electrolyte to catalyst surface; 3) Efficient hydrogen bubble detachment from the nanoedge-enriched structure with high roughness, maintaining continuous exposure of catalytic sites to the surrounding electrolyte. Benefiting from the unique plasma-induced morphology and chemical composition, the MoOxCy exhibits outstanding HER performance with a low overpotential (η) of 415 mV at an ultrahigh current density (j) of up to 10 A cm -2 for 1,000 h in 0.5 M H2SO4. This performance leads to an ultrahigh H2 throughput of 4,477.4 L cm -2 , substantially outperforming the state-of-the-art transition metal-and even noble metal-based catalysts. This work paves new avenues for the development of high-efficiency catalysts for practical industrial applications in electrocatalytic hydrogen evolution.