Bimetallic palladium-supported halloysite nanotubes for low temperature CO oxidation: Experimental and DFT insights

Abstract

The design and fabrication of novel metal-supported catalysts for energy conversion and heterogeneous catalysis is a pivotal theme. Herein, we present the synthesis of bimetallic palladium nanoalloys supported on halloysite nanotubes, PdM@HNTs, where M = Co, Cu, and Ni and their catalytic performance towards CO oxidation. The synthesis procedure involves simple co-reduction of the metals precursors using NaBH4 on halloysite nanotubes support. The synthesized catalysts retain the tubular morphology of halloysite support with surface area of 90–107 m2 g−1. Transmission electron microscopy (TEM) revealed smaller size for bimetallic nanoparticles (6–8 nm) compared to Pd (14 nm). PdNi displayed the highest catalytic activity towards CO oxidation. Moreover, PdCo and PdNi demonstrated enhanced CO oxidation kinetics compared to PdCu and PdNi as revealed from the calculated activation energies. DFT calculations revealed that the order of catalytic activity is PdNi > PdCo > PdCu > Pd which is in agreement with the experimental results and that the adsorption energy of CO2 on the different catalysts has no apparent role in the whole activity of the catalyst.

In conclusion, PdM@HNTs catalysts expressed homogeneous distribution for metallic nanoparticles as well as high dispersion and expressed promising potential to be applied in real flare control processes.