A Strategy for the Formation of Gold-Palladium Supra-Nanoparticles from Gold Nanoparticles of Various Shapes and Their Application to High-Performance H2O2 Sensing

We present a new approach for the synthesis of gold (Au)-palladium (Pd) bimetallic supra-nanoparticles in which densely packed anisotropic Pd nanostructures surround a central Au nanoparticle (rod, sphere, cubic shape). They were obtained by means of Pd crystal growth on Au nanoparticle surfaces which are modified with a mixture of cetyltrimethylammonium bromide (CTAB) and 5-bromosalicylic acid (5-BrSA). From a comparative study with a Au nanorod (NR) as a seed, the use of the CTAB/5-BrSA mixture plays a pivotal role in obtaining such unique supra-structures; the Au NR capped with only CTAB resulted in Au corecontinuous Pd shell nanoparticles instead. The AuPd supra-nanoparticles provide active surface area for electrocatalytic activities higher than that of the Au@Pd continuous shell nanoparticles, displaying outstanding performance for mediator-free electrochemical detection of H2O2 .Y.H. acknowledges grants from the Natural Science Foundation of China (21404110 and 51473179). Y.H, A.R.F., A.D., and D.H.K. gratefully acknowledge financial support from the Ministry of Science, ICT & Future Planning of Korea (NRF-2013M3C8A3078512). J.E.S. and E.C.C. acknowledge a grant from the NRF (2015R1A2A2A01007003) and a KETEP grant funded by the Ministry of Trade, Industry, and Energy of the Korean government (20133030000300)