Enhanced CO₂ Activation Through Spin States Engineering Boosting Urea Electrosynthesis From Co-Reduction of CO₂ and...

Electrocatalytic urea synthesis through co-reduction of CO₂ and NO₃ ^-/NO₂ ^- has been considered as a sustainable alternative for urea production. However, the challenge for inert CO₂ activation results in inefficient C-containing species coverage, leading to low urea yield and dominant NH₃ production. Herein, we design a Cu-Mn dual-site catalyst by co-embedding CuO_x clusters and single-atomic Mn sites on C₃N₄-coated carbon nanotubes (CuO_x/Mn₁-C₃N₄@CNT) for urea electrosynthesis through co-reduction of CO₂ and NO₂ ^-. Experimental and theoretical results show that the electron transfer from CuO_x clusters to single-atomic Mn sites induces Mn 3d electron delocalization and further spin configuration transformation from low spin states to high spin states. The electronic states regulation improves electron-donation ability of Mn sites to substrates and enables the enhanced CO₂ activation and C-containing intermediates adsorption behavior, facilitating coupling with N-intermediates. Consequently, the CuO_x/Mn₁-C₃N₄@CNT catalyst achieves 60.2% urea Faradaic efficiency at -0.4 V (vs. RHE), 100% carbon selectivity over a record-wide potential range of 300 mV, and exceptional 336 h cycling stability with 202.4 mg urea production. This work reveals a clear mechanism for performance enhancement through electronic interactions of dual sites and provides a dual-substrate conversion catalyst design strategy.