Ni2+-Directed Anisotropic Growth of PtCu Nested Skeleton Cubes Boosting Electroreduction of Oxygen

Structure-controlled Pt-based nanocrystals have the great potential to provide a flexible strategy for improving the catalysis of the oxygen reduction reaction (ORR). Here, a new synthetic approach is developed to tune the 3D structure of Pt-based alloys, and switch a synthetic reaction which produces solid PtCu octahedral stars (OSs) to produce PtCu nested skeleton cubes (NSCs) by simple addition of Ni(acac)(2). In particular, Ni2+-guided anisotropic growth is observed to generate the nested skeleton structure in PtCu NSCs. Ni2+, though absent from the nanoalloys, not only endows faster Cu reduction kinetics but also acts as a structure-directing agent. Moreover, it is shown that acetic acid treatment of PtCu NSCs/C exposes Pt-rich surface with a fine-tuned Pt d-band center energy and the reduced Cu leaching, resulting in strikingly high activity and stability. Acid-treated PtCu NSCs/C shows a remarkable ORR mass activity of 5.13 A mg(Pt)(-1), about 26 times higher than commercial Pt/C catalyst. This catalyst also exhibits excellent stability with a lower activity decay of 11.5% and the negligible variation in structure after 10 000 cycles.

Automated summary

A new synthetic approach to tune the 3D structure of PtCu alloys has been developed, resulting in the synthesis of PtCu nested skeleton cubes (NSCs) with high activity and stability for oxygen reduction reaction (ORR) catalysis. The PtCu NSCs exhibit remarkable mass activity and excellent stability compared to commercial Pt/C catalysts.