Electroless Deposition of Pb Monolayer: A New Process and Application to Surface Selective Atomic Layer Deposition

Abstract

The present work demonstrates an electroless (e-less) deposition of Pb monolayer on Au and Cu surface whose morphology and properties resemble its underpotentially deposited counterpart. Our results and analysis show that the e-less Pb monolayer deposition is a surface selective, surface controlled, self-terminating process. Results also show that the electroless Pb monolayer deposition is enabling a phenomenon for new deposition method called "electroless atomic layer deposition" (e-less ALD). Here, the e-less Pb monolayer serves as reducing agent and sacrificial material in surface limited redox replacement reaction with noble metal ions such as Pt , i.e., Pt deposition. The e-less ALD is highly selective to the metal substrates at which Pb forms the e-less monolayer. The full e-less ALD cycle leads to an overall deposition of a controlled amount of the noble metal. Repetition of the two-step e-less ALD cycle an arbitrary number of times leads to formation of a highly compact, smooth, and conformal noble metal thin film with applications spanning from catalyst synthesis to semiconductor technology. The process is designed for (but not limited to) aqueous solutions that can be easily scaled up to any size and shape of the substrate, deeming its wide applications.

Electroless Plating of Metal Nanomaterials

“…Self‐limiting reactions like underpotential or atomic layer deposition create ultrathin conformal layers by stalling uncontrolled material accumulation. Considering the synthetic value of this concept, it appears highly worthwhile to deploy self‐terminating strategies in electroless nanoplating as well [41,42] …”

“…Considering the synthetic value of this concept, it appears highly worthwhile to deploy self-terminating strategies in electroless nanoplating as well. [41,42] Electroless plating can be understood as member of a family of solution-based techniques which produce elemental metal by reducing dissolved metal ions (Figure 3). It could be interpreted as a variant of electrodeposition in which the electrons for reduction are not externally supplied, but produced in situ by the catalytic oxidation of the reducing agent.…”

“…These encompass organic compounds (e. g., aldehydes, carbohydrates), salts of inorganic acids (e. g., hypophosphite, sulfite), boron-hydrogen compounds, and compounds with weak nitrogen/oxygen single bonds and a strong tendency to decay into N 2 or O 2 (e. g., hydrazine, hydroxylamine, hydrogen peroxide). Occasionally, reducing metal ions [42,79,83] and sulfur compounds [48] are used as well.…”

Construction of Lattice Strain in Bimetallic Nanostructures and Its Effectiveness in Electrochemical Applications

“…In such a case, the Pb ML deposited on Au or Cu surface can further serve as a reducing agent for generating a Pt layer (Figure 6c). [67] This UPD/galvanic replacement protocol could likewise create the lattice strain although this technique is limited to small-scale production. [11o]…”

Palladium-Coated Platinum Powders with Tunable, Nanostructured Surfaces for Applications in Catalysis

“…Furthermore, in contrast to e-ALD, the substrate does not need to be conductive in the case of electroless deposition. One recent example of this approach involves leveraging the reducing power of solution-phase V 2+ ions to form monolayers of Pb, which are limited to the surface of the metal substrate . These sacrificial Pb layers can then be galvanically replaced with the adlayer element of choice.…”