Boron-iron nanochains for selective electrocatalytic reduction of nitrate

Abstract The electrocatalysis of nitrate reduction reaction (NRR) has been considered to be a promising nitrate removal technology. Developing a highly effective iron-based electrocatalyst is an essential challenge for NRR. Herein, boron-iron nanochains (B-Fe NCs) as efficient NRR catalysts were prepared via a facile low-cost and scalable method. The Fe/B ratio of the B-Fe NCs-x can be elaborately adjusted to optimize the NRR catalytic performance. Due to the electron transfer from boron to metal, the metal-metal bonds are weakened and the electron density near the metal atom centers are rearranged, which are favor of the conversion from NO3− into N2. Moreover, the well-crosslinked chain-like architectures benefit the mass/electron transport to boost the exposure of abundant catalytic active sites. Laboratory experiments demonstrated that the optimized B-Fe NCs catalyst exhibits superior intrinsic electrocatalytic NRR activity of high nitrate conversion (∼80%), ultrahigh nitrogen selectivity (∼99%) and excellent long-term reactivity in the mixed electrolyte system (0.02 mol/L NaCl and 0.02 mol/L Na2SO4 mixed electrolyte), and the electrocatalytic activity of the material shows poor performance at low chloride ion concentration (Nitrate conversion of ∼61% and nitrogen selectivity of ∼57% in 0.005 mol/L NaCl and 0.035 mol/L Na2SO4 mixed electrolyte). This study provides a broad application prospect for further exploring the high-efficiency and low-cost iron-based functional nanostructures for electrocatalytic nitrate reduction.