Pd/MgAl-LDH nanocatalyst with vacancy-rich sandwich structure: Insight into interfacial effect for selective hydrogenation

•Pd/MgAl-LDH catalyst with sandwich interface is fabricated by a two-step method.•This new approach leads to more Pd-LDH interface sites with boosted oxygen vacancy.•The catalyst with sandwich interface exhibits both high activity and selectivity.•Preferred activity is attributed to the improved hydrogen spillover ability.•High selectivity is owing to special adsorption mode of CO on the interface sites.