Acidic nitrogen electrofixation offers the benefits of abundant proton sources and improved solubility of N2 that can facilitate the reaction kinetics at three-phase interfaces. However, excessive protons would simultaneously boost competitive hydrogen evolution that consume electrons otherwise for nitrogen electrofixation, leading to low selectivity to ammonia. In this paper, we report an acid-stable ebonex (Ti4O7) characteristic of excellent catalytic performances in a 0.1 M HCl electrolyte (pH 1). With the incorporation into continuous-flow cells, the catalyst demonstrates an optimal faradaic efficiency of 23.57% and a large ammonia yield rate of 45.52 μg h–1 cm–2, which is 2 orders of magnitude higher than that in traditional H-type cells. A further mechanism study has been conducted using density functional theory (DFT) calculations and X-ray absorption near-edge structure (XANES), which indicate the structural advantages of ebonex,such as intrinsic electrical conductivity and low oxidation valence of Ti and Jahn–Teller-type structural distortion. Consequently, the ebonex catalyst can suppress hydrogen evolution, leading to a favorable associative alternating nitrogen electrofixation pathway with the rate-limiting step of N2* → NNH*.