The carbon-free electrocatalytic nitrogen reduction reaction (NRR) is an alternative technology to the current Haber-Bosch method, that can be conducted under ambient conditions, and directly converting water and nitrogen (N₂) into ammonia (NH₃). However, the limited activity and selectivity of NH₃ electrosynthesis hinder the practical applications of NRR. In this study, we present a novel type of electrocatalyst called boridene nanosheets enriched with metal vacancies that are specifically designed for efficient electrocatalytic NRR under ambient conditions. Electrochemical testing in a 0.1 M phosphate-buffered saline (PBS) electrolyte demonstrates that boridene exhibits a high Faradaic efficiency of 66.7 % for NH₃ production at -0.2 V vs. RHE, with a maximum NH₃ yield rate of 23.6 μg h