Biaxial strained dual-phase palladium-copper bimetal boosts formic acid electrooxidation

Surface strain engineering is considered as an effective strategy to promote the electrocatalytic properties of noble metal nanocrystals. Herein, we construct a dual-phase palladium-copper (DP-PdCu) bimetallic electrocatalyst with remarkable biaxial strain via a one-pot wet-chemical approach for formic acid oxidation. The biaxial strain originates from the lattice mismatch between the disordered face-centered cubic (FCC) phase and ordered body-centered cubic (BCC) phase in each of DP-PdCu nanoparticles. The proportion of FCC and BCC phases and size of PdCu nanoparticles are dependent on the addition amount of capping agent, cetyltrimethylammonium bromide (CTAB). Density functional theory calculations reveal the downshift of d-band center of Pd atoms due to the interfacial strain, which weakens the adsorption strength of undesired intermediates. These merit the DP-PdCu catalyst with superior mass activity of 0.55 A·mg_Pd⁻¹ and specific activity of 1.91 mA·cm_Pd⁻² toward formic acid oxidation, outperforming the single FCC/BCC PdCu and commercial Pd/C catalysts. This will provide new insights into the structure design of high-performance electrocatalysts via strain engineering.