Selective Vapor-Phase Doping of Pt Nanoparticles into Phase-Controlled Nanoalloys

Abstract

Bimetallic nanoparticles (BMNPs) are frontrunners in various fields including heterogeneous catalysis, medicinal applications, and medical imaging. Tailoring their properties requires adequate control over their structure and composition, which still presents a non-trivial endeavor. We present a flexible strategy to deposit phase-controlled BMNPs by vapor-phase "titration" of a secondary metal to a pre-deposited monometallic nanoparticle (NP) host. The strategy is exemplified for archetypal Pt−Sn BMNPs but transferrable to other BMNPs which alloy noble and non-noble metals. When exposing Pt NPs on a SiO 2 support to discrete TDMASn (tetrakis(dimethylamino)tin) vapor pulses from 150 to 300 °C, TDMASn selectively decomposes on Pt NPs. This leads to saturated infiltration of Sn into Pt NPs through reactive solid-state diffusion, resulting in the formation of Pt−Sn BMNPs with phase/composition control via the substrate temperature. An additional H 2 pulse after each TDMASn pulse removes the surface ligands and excess Sn on the surface as SnH 4 , preserving the small sizes of the pre-deposited Pt NPs. This approach provides a single-step, selective "vapor-phase conversion" of Pt NPs into Pt x Sn y BMNPs with great potential for catalysis. Hereto, a proof of concept is provided by converting wet impregnated Pt NPs into Pt−Sn BMNPs on high surface area supports.

Dimension Control of Platinum Nanostructures by Atomic Layer Deposition: From Surface Chemical Reactions to Applications

“…The development of diverse precursor chemistries in combination with flexible deposition conditions and surface engineering methods provides numerous ways to control the morphology, dimension, and composition of the materials. Therefore, besides thin Pt films, − a variety of Pt nanostructures have been developed, including percolated structures, , nanoparticles, − nanowires, , core/shell nanoparticles, − and nanocomposites. − For the deposition of thin Pt films, ALD offers the capability of controlling the thickness down to a few nanometers. , Importantly, thin Pt films deposited by ALD can obtain a resistivity close to the bulk value, , showing a great potential for applications in electronic devices. , Nanocomposites of Pt with other metals, such as Ir, Ru, , Pd, Fe, Sn, Ni, and Co , can be achieved by combining Pt ALD with ALD of the other metals. Importantly, by simply varying the number of ALD cycles of each ALD process, the composition of the nanocomposites can be precisely controlled, even at the single-atom level. , This is particularly of great interest for engineering the properties of Pt nanostructures in catalytic applications.…”

Crystalline Tin Disulfide by Low-Temperature Plasma-Enhanced Atomic Layer Deposition as an Electrode Material for Li-Ion Batteries and CO2 Electroreduction

“…The self-limiting characteristics established by the alternate pulsing of well-designed chemical precursors render this vapor phase technique to meet the above requirements . Tin disulfide thin films have previously been deposited by plasma-enhanced ALD (PE-ALD) of bis­(1-dimethylamino-2-methyl-2-propoxy)­tin­(II) [Sn­(dmamp) 2 ] and H 2 S plasma, and thermal ALD of tetrakis­(dimethylamino) tin­(IV) [TDMASn], and tin­(IV) acetate [Sn­(OAc) 4 ] precursors each in combination with H 2 S. Due to its high vapor pressure, the TDMASn precursor has been employed for many Sn-based ALD processes. − Combining the TDMASn precursor with H 2 S gas resulted in the growth of amorphous SnS 2 films below 120 °C and crystalline SnS 2 films in the range of 140–150 °C …”