Surface Reconstruction of Single-Twinned AgPdIr Nanoalloy during the Formate Oxidation and Dehydrogenation Reactions

Formate has emerged as a promising energy carrier to generate electrons via formate oxidation reaction (FOR) and hydrogen via formate dehydrogenation reaction (FDR), and it is desirable but difficult to design a novel bifunctional (electro)catalyst to improve reaction kinetics. Herein, we construct the single-twinned AgPdIr (t-AgPdIr) nanoalloy to improve the catalytic activity and stability for the formate oxidation and dehydrogenation processes. The t-AgPdIr nanoalloy, characterized by a distinctive twinned structure with strains and a downshift of the d-band center, demonstrates an improved peak current density of 4.6 A·mg_Pd^-1, a diminished onset potential of 0.45 V, a superior activity retention of 55.7% after 600 cycles, and a current density of 0.73 A·mg_Pd^-1 following potentiostatic polarization for 3600 s. Additionally, the t-AgPdIr catalyst shows an enhanced turnover frequency value of 407.3 h^-1, a higher volume of generated H₂ gas up to 51.8 mL after 120 min of reaction, and an activity recovery of 90.7% after five reaction cycles. Impressively, compared with the as-prepared nanoalloy, the postreaction catalyst shows a stable strain state along the twin boundaries and a surface segregation of Pd and Ir elements after the formate oxidation and dehydrogenation reactions.