Printed Platinum Nanoparticle Thin-Film Structures for Use in Biology and Catalysis: Synthesis, Printing, and Application Demonstration

This work describes the formulation of a stable platinum nanoparticle-based ink for drop-on-demand inkjet printing and fabrication of metallic platinum thin films. A highly conductive functional nanoink was formulated based on dodecanethiol platinum nanoparticles (3–5 nm) dispersed in a toluene–terpineol mixture with a loading of 15 wt %, compatible with inkjet printing. The reduced sintering temperatures (200 °C) make them interesting for integration in devices using flexible substrates and substrates that cannot tolerate high-temperature exposures. A resistive platinum heater was successfully printed as a demonstrator for integration of the platinum ink. The platinum nanoink developed herein will be, therefore, attractive for a range of applications in biology, chemistry, and printed electronics

Structural Investigation of the Ligand Exchange Reaction with Rigid Dithiol on Doped (Pt, Pd) Au₂₅ Clusters

The ligand exchange reaction between heteroatom doped (Pd, Pt) Au₂₅(2-PET)₁₈ (2-PET = 2-phenylethylthiolate) clusters and enantiopure 1,1′-binaphthyl-2,2′-dithiol (BINAS) was monitored in situ using chiral high-performance liquid chromatography (HPLC). During the ligand exchange reactions, replacement of two protecting thiols (2-PET) with one new entering BINAS ligand on the cluster surface occurs. The rigid dithiol BINAS adsorbs in a specific mode that bridges the apex and one core site of two adjacent S­(R)–Au–S­(R)–Au–S­(R) units. This is the most favorable binding mode and theoretically preserves the original structure. A kinetic investigation on these in situ ligand exchange reactions revealed a decrease in reactivity after multiple exchange. A comparison of relative rate constants demonstrates a similar exchange rate toward BINAS for both (Pd, Pt) systems. The possible structural deformation after incorporation of BINAS was investigated by X-ray absorption spectroscopy (XAS) at the S K-edge and Au L₃-edge. First, a thorough assignment of all sulfur contributions to the XANES spectrum was performed, distinguishing for the first time long and short staple motifs. Following that, a structural comparison of doped systems using XANES and EXAFS confirmed the unaltered Au₂₅ structure, except for some slight influence on the Au–S bonds. Additionally, an intact staple motif was confirmed after incorporation of rigid dithiol BINAS by both XANES and EXAFS. This finding agrees with a BINAS interstaple binding mode predicted by calculation, which does not perturb the cluster structure