Cation-mediated Pt Site-Selective Trimetallic Nanostructures for High-Performance Electrocatalysis

Precisely structure-controlled Pt-based multimetallic nanocrystals represent one of most promising candidates in the realm of electrocatalysis, but their rational design and engineering have been restricted. Herein, a cationmediated strategy is reported for exquisitely manipulating Pt sites on Pd hexagonal nanosheets by regulating the reduction kinetics of the Pt precursor. The key is to introduce metal cations (Co3+, Ni2+, Fe3+), which not only coordinate the relationship between the deposition rate and diffusion rate of Pt atoms but also act as dopants to optimize the electronic structure of nanomaterials. As a result, a series of PdPtM (M = Co, Ni, Fe) nanostructures, including alloy nanorings (PdPtCo NRs), core-shell nanosheets with Pt-rich shells (PdPtNi CSNSs), and Pt-rich nanoparticle-decorated nanosheets (PdPtFe NP-D NSs), are successfully constructed. Impressively, these Pt site-selective nanocrystals remarkably boost the oxygen reduction reaction (ORR), ethylene glycol oxidation reaction, and glycerol oxidation reaction performance. In particular, the optimal PdPtCo NRs deliver the highest ORR mass and specific activities of 2.18 A mg(-1)Pd(+ Pt)(-1) and 3.23 mA cm(-2) at 0.9 V vs. RHE, enhanced by 21.8 and 20.2 times, respectively, compared to those of commercial Pt/C. The excellent ORR stability of this catalyst is corroborated by the negligible changes after 15,000 cycles. This cation-mediated strategy may pave a new avenue to develop high-efficiency catalysts for energy-related applications.