Governing Interlayer Strain in Bismuth Nanocrystals for Efficient Ammonia Electrosynthesis from Nitrate Reduction

Abstract

Electrochemical ammonia (NH 3 ) synthesis from nitrate (NO 3 – ) reduction offers an intriguing approach for both sustainable ammonia synthesis and environmental denitrification, yet it remains hindered by a complicated reaction pathway with various intermediates. Here we present that the interlayer strain compression in bismuth (Bi) nanocrystals can contribute to both activity and selectivity improvement toward NH 3 electrosynthesis from NO 3 – reduction. By virtue of comprehensive spectroscopic studies and theoretical calculations, we untangle that the interlayer lattice compression shortens Bi–Bi bond to broaden the 6 p bandwidth for electron delocalization, promoting the chemical affinities of nitrogen intermediates. Such a manipulation facilitates NO 3 – activation to reduce the energy barrier for activity improvement, and also alleviates *NO 2 desorption to suppress nitrite generation. As a result, a strain-compressive Bi electrocatalyst yields a maximal Faradaic efficiency of 90.6% and high generation rate of 46.5 g h –1 g cat –1 with industrially scalable partial current density up to 300 mA cm –2 for NH 3 product at the optimized conditions, respectively.