Synergetic Ruthenium Clusters and Ligand Motifs in Insoluble Polyoxometalates for Efficient Urea Electrosynthesis

Abstract

The electrocatalytic co‐reduction of CO 2 and nitrate () to synthesize urea presents a sustainable alternative to traditional industrial processes, yet its efficiency is fundamentally limited by the kinetically mismatched activation and coupling of CO 2 and . To address this, we designed and synthesized two insoluble trinuclear ruthenium (Ru) cluster‐anchored polyoxometalate (POM) catalysts, Ru 3 SiW 12 and Ru 3 PW 12 , in which the central heteroatom of the Keggin‐type framework (Si vs. P) serves as a key structural variable. This work reveals that the central heteroatom critically modulates the synergy within the Ru‐cluster‐ligand ensemble, which in turn governs the catalytic interface. The optimized Ru 3 SiW 12 delivers a remarkable urea yield rate of 81.6 mmol h −1  g cat. −1 with a Faradaic efficiency of 56.3% at −0.30 V versus RHE, substantially outperforming its P‐centered analog. In situ spectroscopic studies combined with electrochemical analysis demonstrate that the Si‐centered framework promotes a more effective activation of interfacial water, establishing an extensive hydrogen‐bonding network that facilitates proton transfer and hydrogenation of key C‐ and N‐intermediates, thereby boosting C–N coupling. This study highlights the pivotal role of engineering synergistic metal cluster‐ligand motifs via secondary coordination sphere tuning in insoluble matrices, offering a new design strategy for advanced electrocatalysts in sustainable chemical synthesis.