A new design and synthesis approach of supported metal catalysts via interfacial hydrothermal-oxidation/reductive- exolution chemistry of Al metal substrate

Supported metal catalysts of high intrinsic catalytic activities with significant mass and heat-transport properties are constructed via in situ synthesis based on the interfacial hydrothermal-oxidation/reductive-exolution (HO/RE) chemistry of Al metal substrates. The hydrothermal reaction of Al metal particles in an aqueous solution of Ni salt gives rise to the formation of NiAl-LDH@Al core-shell microstructure consisting of an Al core and a NiAl layered double hydroxide (LDH) shell with petal-like surface morphology. A reduction of the NiAl-LDH@Al leads to exolution of Ni atoms from the NiAl-LDH shell, developing fine Ni metal nanoparticles (NPs) with high surface dispersion and size uniformity. The mechanism of heterogeneous formation of MeAl-LDH (Me = hetero-metals) structures from Al metal substrate is suggested in detail. For CO₂ methanation, the Ni/Al₂O₃@Al exhibits a three-fold greater turnover frequency (TOF) than the Ni/Al₂O₃ catalyst prepared by the conventional impregnation method, indicating the marked intrinsic catalytic properties of the Ni/Al₂O₃@Al catalyst.