Co-electrosynthesis of ammonia and formic acid over nitrogen-doped carbon-supported Bi2O3 and NiO catalysts

Abstract Coupling N 2 electroreduction with kinetically and/or thermodynamically favored oxidation reactions in one system can realize the co-production of NH 3 and value-added oxygen-containing fine chemicals at lower energy consumption. Here, a new N 2 electrolysis system based on nitrogen-doped carbon-supported Bi 2 O 3 and NiO catalysts (Bi 2 O 3 /NC and NiO/NC) is demonstrated, in which the methanol oxidation reaction in the anode to make formic acid is coupled with N 2 electroreduction for NH 3 . The optimal NH 3 yield of $$2.79 \, \mu{\rm g}_{{\rm NH}_3} \, {\rm h}^{-1} \, {\rm cm}^{-2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mn>2.79</mml:mn> <mml:mspace/> <mml:mi>μ</mml:mi> <mml:msub> <mml:mrow> <mml:mi>g</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>N</mml:mi> <mml:mi>H</mml:mi> </mml:mrow> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:msub> <mml:mspace/> <mml:msup> <mml:mrow> <mml:mi>h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mspace/> <mml:msup> <mml:mrow> <mml:mi>cm</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:math> is achieved at the voltage of 2.35 V with a high Faradaic efficiency of 5.04%, surpassing the state-of-the-art reported N 2 reduction-methanol oxidation coupling electrocatalysis system. This study highlights the critical role of anode coupling strategy in enabling efficient electrochemical NH 3 synthesis.