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Focusing on the simultaneous enhancement of activity and selectivity in α, β‐unsaturated aldehyde hydrogenation, we designed and prepared an ultrathin CoAl‐LDH supported Pt catalyst. A series of technologies revealed the ultrathin CoAl‐LDH support possesses the characteristic of dual defects, oxygen vacancy (VO) and cobalt vacancy (VCo). Then, two kinds of vacancy related interface sites were identified, namely Pt−VO−Coδ+ and Pt−VCo−OHδ−. Compared with the bulk catalyst, the ultrathin catalyst exhibits both enhanced intrinsic activity and C=O bond selectivity under the synergistic effect of the dual interface sites. Specifically, the Pt−VO−Coδ+ interface site changes the adsorption mode of cinnamaldehyde and promotes the activation of C=O bonds, thus leading to the improved cinnamyl alcohol selectivity. The H atoms of the Pt−VCo−OHδ− interface site participate in the hydrogenation process, which facilitates the mobility of active hydrogen and therefore promotes the intrinsic activity. More importantly, the ultrathin catalyst shows good reusability.

Cinnamaldehyde (CAL) is a typical sustainable biomass molecule which is classified as α, β-unsaturated aldehydes. Selective hydrogenation of CAL to produce high-value and fine chemical cinnamylalcohol (COL) is an attractive catalytic transformation process. However, the hydrogenation of C=O bond in CAL is more unfavorable than C=C bond in thermodynamics and kinetics, leading to great challenge on achieving high yield of unsaturated alcohol. In this work, a Pt/CoAl-LDHs catalyst was prepared for hydrogenation of CAL to COL, showing outstanding intrinsic activity (TOF as high as 4.93 s À 1 ) and finally achieving 93.6 % selectivity at 95.4 % conversion. In contrast, the yields of COL over Pt/Co(OH) 2 and Pt/Al(OH) 3 were only 73 % and 34 % respectively. Characterizations including Raman, O-XAFS, XPS revealed that the Co 2 + À O 2À À Al 3 + structure in CoAl-LDHs contributed to strengthened metal-support interactions, and resulted in electron-rich and geometric decoration Pt δÀ sites. The electron-rich Pt δÀ provided preferable H 2 activation capability, and also exposed abundant unsaturated sites which optimized the adsorption mode of cinnamaldehyde favorable for C=O hydrogenation. However, in Pt/Co(OH) 2 and Pt/Al(OH) 3 catalysts, the Pt 0 without electron-rich and unsaturated property cannot improve the H 2 activation capability as well as electronic repellency to C=C bond. In addition, a possible catalytic mechanism was proposed to illustrate the role of Pt δÀ À Co 2 + À O 2À À Al 3 + interfacial structure on enhancing activity and selectivity.

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