Electronic nitrate reduction reaction (NO₃RR) is an expected process to obtain green ammonia and bring a hot topic on electrocatalyst constructing. Nevertheless, NO₃RR processes a complex path with multiple adsorption and desorption so that the adsorbed selectivity is one of the key points. Herein, based on the catalysis of Cu₂O-Fe₃O₄ on N-doped carbon nanotubes (NCNTs), B-doped sites were introduced for enhancing the adsorption of NO₃⁻ and thereby increasing the local concentration on surface of the electrode. After confirming the catalytic sites mainly from Cu₂O and Fe₃O₄ nanoparticles, the B,N-doped carbon nanotube (BNCNT) substrate was discovered accelerating the NO₃RR with high yield NH₃ and positive-shift of onset potential. The enhancement from B-sites was also testified by the performance comparison using different substrate and series of metal oxide/BNCNTs, presenting the general strategy for promoting NO₃RR. This work provides a new perspective for modulating catalytic process, especially in the complex electrocatalysis with high-required selectivity and concentration-dependence.