Bifunctional PtCu Nanooctahedrons for the Electrochemical Conversion of Nitrite and Sulfion Into Value‐Added Products

Abstract

The electrochemical reduction of nitrite (NO2−) contaminants to ammonia (NH3) is a sustainable and energy‐saving strategy for NH3 synthesis. However, this multi‐electron reduction process requires an efficient electrocatalyst to overcome the kinetic barrier. Herein, the Pt2Cu1 nanooctahedrons are synthesized through a liquid‐phase chemical reduction process. The synergistic effect of bimetallic Pt and Cu sites in the Pt2Cu1 nanooctahedrons is indispensable for accelerated NO2− hydrogenation, originating from the strong hydrogen‐atoms adsorption capacity at Pt site and the strong NO2− adsorption capacity at Cu site. Specifically, the introduction of Pt sites can accelerate the accumulation of hydrogenated species on the catalyst surface, which promotes the formation of NH3. In 0.5 m Na2SO4 solution, the Pt2Cu1 nanooctahedrons can reduce NO2− to NH3 at a yield of 4.22 mg h−1mgcat−1 and a Faraday efficiency of 95.5% at a potential of −0.14 V versus RHE. Meanwhile, the Pt2Cu1 nanooctahedrons also exhibit excellent activity for the sulfion oxidation reaction (SEOR). Using Pt2Cu1 nanooctahedrons as bifunctional electrocatalyst, a coupled electrolysis system combining the nitrite electrochemical reduction reaction (NO2−ERR) with the SEOR requires only 0.3 V total voltage, enabling energy‐saving electrochemical NH3 production and collective value‐added recovery of nitrite and sulfion waste.