A facile one-step method for the fabrication of Pd-AlOOH/Al monolithic catalysts via redox reactions of two galvanic cells

In this work, we report a facile and economic one-step method under atmospheric pressure and 50 °C water bath for the fabrication of a three-dimensional (3D) upright-standing boehmite (AlOOH) nanosheet array film on a structured Al honeycomb substrate, in which zero-valence palladium (Pd0) nanoparticles were well distributed at the same time. Redox reactions of two galvanic cells where the Al honeycomb substrate acted as the common anode, but the palladium precursor (Pd(NH3)42+) and weak base water (H2O + OH−) served as the electrolyte of cathode I and II, respectively, led to simultaneous formation of Pd0 nanoparticles at cathode I and AlOOH nanosheets at cathode II on the surface of Al substrate. The resultant AlOOH nanosheet array was uniform and about 300–400 nm thick, and the highly dispersed Pd0 nanoparticles were also rather small with an average size of 8.4 nm. Hence, the as-obtained Pd-AlOOH/Al monolithic catalysts exhibited high specific surface area and large micro/mesopore structure as compared to pristine Al honeycomb substrate, leading to excellent catalytic activity in total oxidation reaction of toluene.