Summary: Hydrogen-substituted graphdiyne (HsGDY), as a new rising star of carbon materials family, demonstrates high conjugation, robust chemical stability, and versatility for modification. However, grand challenges, including low production rate, disordered topology, and amorphous structure, greatly hinder its large-scale applications. Herein, we report, for the first time, the scalable synthesis (up to gram-level) of two-dimensional (2D) crystalline HsGDY nanosheets with Zn as a substrate. Moreover, as a metal-free catalyst for electrochemical N, fixation, 2D HsGDY achieves an ultrahigh yield of 103 μg h, mg, with a potential of −0.2 V vs reversible hydrogen electrode (RHE), which is comparable with that of noble metals and single-atom catalysts. Different from the heteroatom active sites in carbon-based catalysts reported before, the inner alkynyl C itself in 2D HsGDY was identified as the active site, which adsorbs and activates N,N due to the positive charge and high spin density triggered by the slight O doping in the form of C,O at the outer alkynyl C. We believe that this Zn-templated scalable production of high-quality HsGDY paves the way for its large-scale production and provides a new playground for the multiple research fields.,This work reports, for the first time, the scalable synthesis (up to gram-level) of two-dimensional crystalline hydrogen-substituted graphdiyne (HsGDY) nanosheets with Zn as a substrate. The novel interface polymerization substrate and the as-generated scalable synthesis method pave the way for the high-quality preparation of HsGDY and its analogues.