Platinum–palladium alloy nanotetrahedra with tuneable lattice-strain for enhanced intrinsic activity

Abstract

Understanding how to modify the intrinsic physical or chemical properties of precious metals to improve their electrocatalytic performance is crucial to the design of active and robust catalysts with high catalytic performance and low quantities. This report describes how to modify the intrinsic physical properties (lattice strain, high active facets and d-band center) of platinum–palladium alloy nanotetrahedra (Pt_nPd_100−n NTDs) through simple tuning of the alloy composition, resulting in a higher electrocatalytic performance than pure platinum. The results show that Pt_nPd_100−n NTDs possess dominant (111) facets and have a tuneable composition and reveal that lattice shrinking and expansion are tuned by the alloy composition, which is confirmed by TEM and X-ray diffraction, and also change the activity of methanol and ethanol electrooxidation. Interestingly, Pt₆₂Pd₃₈/C NTDs with lattice shrinking have the optimal composition with maximum mass activity (1.21 A mg_Pt+Pd⁻¹ and 0.66 A mg_Pt+Pd⁻¹) toward the MOR and EOR, respectively, which is also supported by DFT. XPS analysis and electrocatalytic experiments reveal that the combination of alloy-induced band structure engineering and lattice strain modulation weakens the adsorption of poisoning species and fundamentally improves the catalytic activity. The Pt_nPd_100−n/C NTDs exhibit high catalytic activity and stability for the methanol and ethanol electrooxidation reaction. These findings will provide a new path for designing robust and active nanoalloy catalysts with lattice mismatch and dominant active facets for direct alcohol fuel cell applications.