Breaking activity-selectivity trade-off: Synergistic catalysis over electron enriched Ru single-atoms and oxygen vacancies for cinnamaldehyde hydrogenation

Anion etching strategy has been developed to fabricate dual-function active site catalysts with a clear division of labour. • The Ru O /TiO 2 catalyst breaking the activity-selectivity trade-off of cinnamaldehyde hydrogenation. • The high electron density of Ru active sites effectively lowers the reaction barrier for isopropanol activation. • The oxygen vacancies dominate the product selectivity, as they promote the preferential activation of -C=O groups. • Revealed the promotional effect of the carbon radical-mediated pathway on cinnamaldehyde hydrogenation. The activity-selectivity trade-off is a longstanding challenge for the selective hydrogenation of α,β-unsaturated aldehydes/ketones, and conventional single-atom or defective catalysts often fail to simultaneously increase the conversion and selectivity via a single active site. Herein, we develop a one-step anion etching strategy to synchronously fabricate electron-enriched Ru single-atoms and high-density oxygen vacancies on the anatase TiO 2 support, realizing spatially adjacent yet functionally divided dual active sites. The optimal Ru O /TiO 2 catalyst breaks the activity-selectivity trade-off, achieving 99% cinnamaldehyde conversion with 95% selectivity for cinnamyl alcohol under visible light, and has excellent structural stability and substrate universality. Combined characterizations and density functional theory (DFT) calculations reveal that oxygen vacancies modulate the electronic metal-support interaction (EMSI) between Ru single-atom and the TiO 2 support and suppress electron transfer from Ru to TiO 2 , thereby forming electron-rich Ru centres that efficiently activate isopropanol for a continuous hydrogen supply. Moreover, oxygen vacancies exclusively anchor the -C O group of cinnamaldehyde in an end-on adsorption mode and inhibit -C C hydrogenation. Thus, the synergistic effect between the dual-function active sites enables the high-efficiency and high-selectivity hydrogenation of cinnamaldehyde. This work clarifies the synergistic mechanism of single-atoms and vacancies at the atomic level and provides a facile, universal strategy for designing high-performance catalysts for the selective transformation of unsaturated organics. Download: Download high-res image (147KB) Download: Download full-size image The electron-enriched Ru active centers and oxygen vacancies form dual functional active sites with clear division of labor through anion etching strategy, and this dual functional sites breaking activity-selectivity trade-off of cinnamaldehyde hydrogenation.