In SituShell‐Isolated Nanoparticle‐Enhanced Raman Spectroscopy of Nickel‐Catalyzed Hydrogenation Reactions

Abstract

Synthesis methods to prepare lower transition metal catalysts and specifically Ni for Shell‐Isolated Nanoparticle‐Enhanced Raman Spectroscopy (SHINERS) are explored. Impregnation, colloidal deposition, and spark ablation have been investigated as suitable synthesis routes to prepare SHINERS‐active Ni/Au@SiO2 catalyst/Shell‐Isolated Nanoparticles (SHINs). Ni precursors are confirmed to be notoriously difficult to reduce and the temperatures required are generally harsh enough to destroy SHINs, rendering SHINERS experiments on Ni infeasible using this approach. For colloidally synthesized Ni nanoparticles deposited on Au@SiO2 SHINs, stabilizing ligands first need to be removed before application is possible in catalysis. The required procedure results in transformation of the metallic Ni core to a fully oxidized metal nanoparticle, again too challenging to reduce at temperatures still compatible with SHINs. Finally, by use of spark ablation we were able to prepare metallic Ni catalysts directly on Au@SiO2 SHINs deposited on a Si wafer. These Ni/Au@SiO2 catalyst/SHINs were subsequently successfully probed with several molecules (i. e. CO and acetylene) of interest for heterogeneous catalysis, and we show that they could be used to study the in situ hydrogenation of acetylene. We observe the interaction of acetylene with the Ni surface. This study further illustrates the true potential of SHINERS by opening the door to studying industrially relevant reactions under in situ or operando reaction conditions.

Ultrafast Photoinduced Heat Generation by Plasmonic HfN Nanoparticles

“…Overall, these properties are highly attractive for plasmonic heat generation with broadband light sources, such as in photothermal catalysis or photothermal therapy, [ 25,26 ] or Raman applications where material robustness and resistance to thermal deformation is required. [ 27,28 ]…”

“…Overall, these properties are highly attractive for plasmonic heat generation with broadband light sources, such as in photothermal catalysis or photothermal therapy, [25,26] or Raman applications where material robustness and resist ance to thermal deformation is required. [27,28] Presently, the photodynamics of HfN is not well understood, with a discrepancy in the literature. On the one hand, experi mental work on HfN thin films has ascribed a longlived (ns) signal to the slow decay of hot carriers, [29][30][31][32][33] whereas on the other hand, theoretical work has predicted a maximum hot car rier lifetime of only 10 fs.…”

π-Adsorption promoted electrocatalytic acetylene semihydrogenation on single-atom Ni dispersed N-doped carbon

“…33,34 When the potential increased from 0 to À0.6 V, the n(C]C) stretching vibration of p-bound ethylene gradually emerged at 1546 cm À1 . [34][35][36][37] Weak p-adsorption of ethylene is benecial for ethylene desorption, eventually facilitating acetylene semi- hydrogenation kinetics. As illustrated by the DFT simulations in Fig.…”

Operando Shell‐Isolated Nanoparticle‐Enhanced Raman Spectroscopy of the NO Reduction Reaction over Rhodium‐Based Catalysts

“…The enhancement factor was calculated according to a previous study by Le Ru et al [21] . Based on the Raman intensity of the peak at 1362 cm −1 of the xanthene ring stretch of Rhodamine 6G, [25] we calculated the analytical enhancement factor of the bare Au NPs and the SHINS to be approximately 5×10 5 and 5×10 4 , respectively (Figure S1b) [26] …”