Grain‐Boundary‐Rich Noble Metal Nanoparticle Assemblies: Synthesis, Characterization, and Reactivity

Here, a comprehensive study on the synthesis, characterization, and reactivity of grain-boundary (GB)-rich noble metal nanoparticle (NP) assemblies is presented. A facile scalable synthesis Pt, Pd, Au, Ag, Rh NP developed, in which NPs are predominantly connected via Σ3 (111) twin GBs, forming network. Driven by water electrolysis, random collisions oriented attachment colloidal solution lead to formation boundaries some highly mismatched GBs. This synthetic method also provides convenient control over GB density without altering crystallite size or type varying collision frequency. The structural characterization reveals presence localized tensile strain at sites. ultrahigh activity GB-rich Pt assembly toward catalytic hydrogen oxidation air demonstrated, enabling room-temperature sensing for first time. Finally, functional theory calculations reveal that strained Σ3(111) boundary facilitates oxygen dissociation, drastically enhancing rate dissociative pathway. reported large-scale structures enables development broad range high-performance catalysts.