Fabrication of 3D hollow acorn-shell-like PtBi intermetallics via a surfactant-free pathway for efficient ethylene glycol electrooxidation

The synthesis of atomically ordered Pt-based intermetallic electrocatalysts for the direct alcohol fuel cells generally requires the addition of surfactants or the high-temperature annealing. However, some residual surfactants on the surface of the as-synthesized catalysts would prevent the exposure of catalytic active sites, and the high-temperature annealing process is easy to accelerate the sintering of the metal, which both lead to the decline of electrocatalytic performance. Herein, we construct the atomically ordered bimetallic PtBi intermetallics with clean surfaces and unique three-dimensional hollow acorn-shell-like structure (3D PtBi HASL) by a simple, low-temperature, and surfactant-free one-pot synthetic approach. Benefiting from the special hollow structures, the obtained 3D PtBi HASL intermetallics expose abundant accessible active sites. Moreover, the introduction of oxophilic metal Bi can enhance adsorption of OH_ads, thereby significantly facilitating removal of poisoned intermediates. Density functional theory (DFT) simulations further indicate that formation of the PtBi intermetallic phase with the downshift of the Pt d-band center endows 3D Pt_49.4Bi_50.6 HASL intermetallics with significantly attenuated CO_ads and enhanced OH_ads adsorption, bringing about the boosting electrocatalytic property. The mass activity of the 3D Pt_49.4Bi_50.6 HASL intermetallics for ethylene glycol oxidation reaction is as high as 24.67 A·mg_Pt⁻¹, which is 12.98 times higher than that of commercial Pt/C (1.90 A·mg_Pt⁻¹). This work may inspire the design of Pt-based intermetallics as high-efficiency anode electrocatalysts for fuel cell applications.