Boron-Enriched Benzene Boronic Acid Based Hyper-Cross-Linked Polymer for Selective Electrocatalytic N₂ Reduction to Ammonia

The nitrogen (N2) electro-reduction to ammonia (NH3) at ambient conditions is considered a promising substitute for the Haber–Bosch (H–B) process. Considering the low Faradaic efficiency (FE) and slow reaction kinetics of the nitrogen reduction reaction (N2RR), it is important to design robust catalysts that can address the above-mentioned challenges. A boron-enriched hyper-cross-linked polymer (Poly-BBA) based on benzene boronic acid synthesized by a fast microwave-assisted approach has reportedly been used as metal-free electrocatalyst for efficient N2 electro-reduction to NH3. The Poly-BBA was synthesized using microwave power of 400 W at 45 °C for 30 min and aging at 100 °C for 30 min. The successful synthesis of Poly-BBA was conducted by state-of-the-art analytical techniques. The N2 sorption analysis demonstrates a hierarchical porous structure with a high SABET of 1080 m2 g–1 and a total pore volume of 0.7 cm3 g–1. The Poly-BBA shows selective reduction of N2 to NH3 with an FE of 21.9% in 0.05 M H2SO4 solution at −0.5 V vs RHE. The presence of boron in the synthesized material resulted in the redistribution of electron density and provided electron-deficient sites for adsorption and activation of N2 molecules.