Strain effects on catalytic activity and stability of PdM nanoalloys with grain boundaries.

Formate has emerged as a promising liquid hydrogen carrier for fuel cell applications, yet the kinetic limitations and stability issues of catalysts for formate dehydrogenation (FDH) and oxidation (FOR) remain challenging. Through systematic density functional theory (DFT) calculations, we computationally investigated how strain engineering modulates the electronic structure and catalytic behavior of PdM and PdM nanoalloys (M = Ir/Ag). Our theoretical models revealed that Ir atoms exhibit surface segregation driven by hydrogen/oxygen adsorption, effectively alleviating core lattice strain. Compressive strain was computationally observed to induce a negative shift in the d-band center of surface Pd sites. First-principles calculations identified core-shell PdIr and Janus-type PdAg configurations as optimal candidates, demonstrating enhanced theoretical activity for both FDH and FOR. This improvement was attributed to the elevated hydrogen adsorption free energy at Ir-enriched surfaces. By establishing a correlation between atomic strain, electronic structure, and catalytic descriptors, this computational study provides a theoretical framework for designing strain-engineered Pd-based catalysts, highlighting the critical role of element-specific segregation patterns in optimizing formate-based hydrogen storage systems as a hydrogen carrier and fuel.