Atmosphere induced amorphous and permeable carbon layer encapsulating PtGa catalyst for selective cinnamaldehyde hydrogenation

•C@PtGa interface structure is constructed by H2/CO2 atmosphere treatment using LDH as precursor.•PtGa alloys were covered by thin carbon layer with the characteristics of defective and permeable.•Preferred conversion compared to oxide layer catalyst is owing to high accessibility of metallic sites.•High selectivity is due to optimized adsorption mode of CAL on C@PtGa interface sites.•Amorphous carbon layer is stable after 5 times cycles under selective cinnamaldehyde hydrogenation reaction.