Self-aligned synthesis of a NiPt-alloy_core@Pt_shell nanocrystal with contrivable heterojunction structure and oxygen reduction activity

A bimetallic NiPt nanocrystal (NC) has been synthesized using the wet chemical reduction method; it was sequentially designed in the presence of carbon nanotubes. NiPt@Pt NC is a nanocrystal with the configuration of a NiPt alloy core and tuneably thick Pt shell. Under optimum conditions (Pt = 20 at%), the oxygen reduction current of NiPt@Pt NC is 1.08-fold at 0.85 V (vs. RHE), as compared to Pt NC, and the onset voltage (V_OC) is 0.905 V. The results of the atomic and crystal structure analyses show that such an enhancement is largely due to the impact of the local strain and the electronic dipole at the heterogeneous Pt-Ni interface. Most importantly, we have proposed a robust technique for programming the atomic structural configuration and oxygen reduction activity of NC, which shows comparable performance and ~80% less Pt loading than Pt NC.