AbstractDeveloping high-performance metal-free electrocatalysts for acidic oxygen evolution reaction (AOER) is highly desirable but remains great challenge. Here we report a rationally substitutingsp-C strategy for the synthesis of methyl- and hydrogen-substituted graphdiyne (MGDY, HGDY) nanowires arrays as 3D porous flexible metal-free electrodes for AOER. Methyl group in MGDY with stronger electron-pushing effect makes electrons around the acetylenic carbon atoms more delocalized, resulting in more uneven distributed surface charge, and higher intrinsic catalytic activities for AOER than HGDY, with the smaller overpotential of 406 mV at 10 mA cm⁻²than HGDY and previously reported metal-free electrocatalysts. Our results reveal that the modulation of the electronic structure of GDY by selectively substitutingsp-C allows for facilitating charge transfer kinetics, improving adsorption of reaction intermediate, and thereby accelerating the sluggish kinetics of AOER. This work provides us an ideal opportunity for studying the exact hydrogen evolution reaction/oxygen evolution reaction mechanisms of metal-free carbon materials.