Strain effect of PtCu alloy aerogel nanocatalysts on the oxygen reduction reaction enhancement

• PtCu alloy aerogels (AAs) with variable Cu/Pt atomic ratio were successfully synthesized by a simple NaBH 4 reduction strategy. • The surface detects induced by electrochemical dealloying along the PtCu AAs architecture provide abundant available active sites. • PtCu AAs with connected pore structure and self-supporting architecture as efficient electrocatalysts accelerate ORR kinetic process. • Pt 1 Cu 2 AAs delivers a high mass activity (1.7 A/mg Pt ) and specific activity (4.0 mA/cm 2 ) and remarkable stability compare to commercial Pt/C and Pt 1 Cu 1 AAs and Pt 1 Cu 3 AAs catalysts. • This work offers a new strategy to design the efficient ORR electrocatalyst for PEMFCs. Tuning their strain effect of Pt based alloy electrocatalysts is an efficient strategy to enhance the electrocatalytic performance toward oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs). Herein, an efficient PtCu alloy aerogels (PtCu AAs) with adjustable Pt/Cu atomic ratio form a subtle lattice contraction, as well as the electrochemical dealloying process created surface defects with abundant active sites. The prepared Pt 1 Cu 2 AAs catalysts with optimal strain effects and accessible surface sites displayed much-enhanced mass activity and specific activity of 1.65 A/mg Pt and 3.96 mA/cm 2 , which are higher than those of the Pt 1 Cu 1 AAs, Pt 1 Cu 3 AAs and commercial Pt/C catalysts, respectively, originating from the optimal strain effect with the moderate degree of lattice shrinkage. Meanwhile, Pt 1 Cu 2 AAs displayed a remarkable stability. This work offers a new strategy to design an efficient ORR electrocatalyst with surface strain and defects by controlling atomic compositions and electrochemical dealloying process for PEMFCs. PtCu alloy aerogels with a subtle strain effect, abundant surface active sites, connected pore structure and self-supporting architecture as efficient oxygen reduction reaction electrocatalysts for proton exchange membrane fuel cells.