Crystalline core–amorphous shell heterostructures: epitaxial assembly of NiB nanosheets onto PtPd mesoporous hollow nanopolyhedra for enhanced hydrogen evolution electrocatalysis

Abstract

Engineering the composition and structure of hybrid electrocatalysts based on precious Pt and non-precious metals is of paramount importance for increasing the utilization efficiency of Pt and enhancing their electrocatalytic performance. Here we report the construction of novel crystalline PtPd @ amorphous NiB core–shell heterostructures (c-PtPd@a-NiB CSHs) with crystalline PtPd mesoporous truncated octahedral nanocages (c-PtPd MTONs) as the cores and amorphous NiB (a-NiB) nanosheets as the shells via a three-step strategy. This hybridization, between c-PtPd MTONs and a-NiB nanosheets, leads to increased catalytically active sites, a modulated surface electronic structure, and enhanced hydrophilic properties. With these properties, the as-obtained c-PtPd@a-NiB CSHs exhibit enhanced electrocatalytic activity toward the hydrogen evolution reaction (HER) in an alkaline medium, with a small required overpotential of 31 mV (@-10 mA cm⁻²), a low Tafel slope of 40.9 mV dec⁻¹, and excellent long-term catalytic durability.