Boosting urea synthesis in simulated flue gas electroreduction by adjusting W–W electronic properties

Abstract

The development of electrocatalysts that convert CO₂ and N₂ in flue gas to directly usable urea does not only explore the hidden value of exhaust gas but also alleviates the global environmental issues caused by excessive CO₂ emissions; yet, related research studies are still in their infancy. Herein, multi-porous Cu–W₁₈O₄₉@ZIF-8, composed of ultra-small nanosized ZIF-8 on Cu-doped W₁₈O₄₉ nanowires, was fabricated as a urea-generation electrocatalyst in flue gas. It exhibits an appealing Faraday efficiency of urea up to 16.1% at −0.9 V (vs. RHE) and an outstanding yield of 1.33 mmol g⁻¹ h⁻¹ at −1.0 V (vs. RHE) under the flue gas atmosphere. The catalytic performance was maintained for a wide range of N₂ : CO₂ ratios. Theoretical calculations indicate that the doped copper regulates the electron density around the adjacent W–W, which facilitates N₂ adsorption, partly suppresses the HER side reaction, and decreases the ΔG of the following multi-step hydrogenation after *CO insertion until urea production.