Hydrogen-intercalation PdZn bimetallene for urea electro-synthesis from nitrate and carbon dioxide

Abstract

Electrochemical co-reduction of carbon dioxide and nitrate is a green technology to replace traditional energy-intensive methods for urea synthesis, and the development of high-performance catalysts is still a great challenge. Here, we propose the incorporation of nonmetallic hydrogen and oxophilic zinc into palladium metallene for the preparation of hydrogen-intercalation PdZn (H-PdZn) bimetallene, serving as an active electrocatalyst for co-reduction of carbon dioxide and nitrate to synthesize urea via the C–N coupling reaction. The H-PdZn bimetallene affords a high urea yield of 314.17 μg h⁻¹ mg⁻¹ and a Faraday efficiency of 24.39%, better than those of PdZn bimetallene (144.25 μg h⁻¹ mg⁻¹ and 16.03%). The strong electronic interaction between the Pd, Zn and H atoms can induce the downshift of the Pd d-band center of H-PdZn bimetallene, which can promote the formation of the key intermediates of *NH₂ and *CO, and lower the energy barrier for their C–N coupling to synthesize urea. This work offers a hydrogenation strategy for the construction of advanced PdH-based metallenes towards electrochemical C–N coupling to synthesize urea.