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.

The work reporting a detailed and comparative study of Pb UPD and Pb e-less ML deposition on Ru(0001) substrate is presented. The electrochemical results are analyzed through the scope of the adsorption isotherm formalism where parameters describing the thermodynamics of deposited Pb monolayer obtained by each process are compared. In addition to these results, the in situ STM and electrochemical quartz micro balance data are presented for each process identifying the mutual mechanistic similarities and differences between electroless Pb and underpotential Pb monolayer. Considerable applications of Ru metal in microelectronics and catalysis rise significance of these results for variety of future developments in these areas.

We present results exploring different concepts for Pb monolayer mediated thin film growth of Cu on Ru(0001) and Co on polycrystalline Cu substrates. Both systems are of considerable importance in microchip fabrication technology and they exhibit a three dimensional growth at room temperature which somewhat limits their application. The Pb monolayer mediation of the growth process is explored by having its role as a surfactant, flux mediator or as a sacrificial layer in deposition via surface limited redox replacement protocol. Electrochemical and STM results suggest that Pb monolayer induces 2D Cu growth on Ru(0001) and the growth mechanism is very dependent on the Pb mediation role. The surfactant properties of electrolessly deposited Pb monolayer are also studied during electroless deposition of Co on polycrystalline Cu. The benefit of Pb monolayer mediation of the Co growth process was manifested by 2D Co thin film morphology, high quality of the grain boundaries, and improved magnetic properties.

Presented work studies the relation between kinetics of metal deposition via surface limited redox replacement (SLRR) of underpotentially deposited (UPD) monolayer (ML) and experimental parameters of reaction solution such as meal ions concentrations and supporting electrolyte concentration. The model system is Au deposition on Au(111) via SLRR of Pb UPD ML. The rate constant of the SLRR reaction for different solution designs is determined from temporal change of electrode surface reflectivity and from the open circuit potential transients' analysis. The obtained results show clearly that reaction kinetics of metal deposition via SLRR of UPD ML is significantly affected by the design of the reaction solution i.e. the UPD metal ion, depositing metal ion, and supporting electrolyte concentrations. The ten-fold change of concentration of either solution parameter produces approximately the same change in the value of the rate constants. The presented results have fundamental importance for the future development and application of the metal deposition via SLRR of UPD ML. They offer a link between the reaction solution design and expected trend in SLRR reaction rate, which transposes to successful control of deposition flux, nucleation density and resulting morphology of the deposit. Deposition via Surface Limited Redox Replacement (SLRR) of underpotentially deposited (UPD) monolayer (ML)1 has gained a lot of attention and applications in last two decades.2-4 The main idea is to use an UPD ML as sacrificial material to reduce/deposit a more noble metal (SLRR reaction i.e. galvanic displacement). The basic stoichiometry of the SLRR reaction and deposition process is shown by Equation 1.Here, M and P and S(h,k,l) stand for UPD metal/ion, depositing metal/ion and substrate, while m + /m and p + /p represent the oxidation state of M and P metal ions and corresponding stoichiometry coefficients. Over the years, several experimental protocols for deposition via SLRR of UPD ML have been developed. The first and the basic one, 1,6 involves formation of the UPD ML of M on the substrate S(h,k,l), (potential controlled step) and then subsequent immersion of M UPD /S(h,k,l) into a separate reaction solution where SLRR occurs and deposition of P takes place at open circuit (sample shuffling approach). The second protocol involves the stagnant substrate but sequential application of potential control in solution for UPD ML formation and then application of solution for SLRR reaction and deposition of P at open circuit (solution shuffling approach 7 ). The most recent development has introduced a "one-solution, one-cell" experimental design. 8,9 In this case, the same solution serves for UPD ML formation and subsequent SLRR reaction at open circuit potential. This protocol assumes a sequence of potential controlled step, where co-deposition of UPD ML of M with small amount of P occurs, and the open circuit step, where SLRR reaction and deposition of P proceeds. The very details of these three protocols and their applications hav...

We present a combined experimental and theoretical study of CO ads on Pt 147 dendrimer-encapsulated nanoparticles (DENs). In-situ electrochemical IR spectroscopy reveals an 8 cm −1 redshift of the CO ads stretching frequency on Pt 147 DENs relative to a Pt (111) crystal. This value is in good agreement with the shift calculated by density functional theory. Importantly, the wavenumber shift observed in this study is significantly smaller than has been found previously. We attribute this primarily to the absence of support effects and the narrow size distribution of DENs. The agreement between experiment and theory validates the model nanoparticle system used for the calculations, and this will make it possible to use the CO ads frequency as a probe to study more complex DEN structures and as a descriptor of the catalytic activity of DENs toward reactions such as formic acid oxidation and methanol oxidation.We are interested in developing a better understanding of how small changes in the structure of nanoparticles in the 1-2 nm size range impact important electrocatalytic reactions like oxygen reduction and CO oxidation. We approach this problem by directly comparing theory and experiments. 1 This is important, because previous results from our groups and others have shown that nanoparticle structures in this size range are dynamic. For example, core@shell nanoparticles are able to invert, 2,3 ligands can drive shape changes, 4 and interactions with a substrate can result in major electronic and shape changes. [5][6][7] One effective method for gaining insight into nanoparticle surface structure is to measure changes in the vibrational frequency of adsorbed CO (CO ads ) using infrared (IR) spectroscopy. 8,9 Spectroscopic results from single-crystal surface models are relevant for understanding the structure of Pt nanoparticles (PtNPs) having size >4 nm, but for smaller nanoparticles the connection to bulk surfaces is more tenuous. 8 This is because the dominance of discrete facets is reduced, while the contribution of edge and corner sites increases. These latter sites can be identified because they bind CO more strongly, thereby decreasing its stretching frequencies. 8,10 It has previously been shown that the CO ads frequency decreases as the size of PtNPs supported on carbon (C/PtNP) decreases. 8,11,12 For example, frequency shifts on the order of 20 cm −1 have been reported as nanoparticle size decreases from ∼4 nm to ∼2 nm. 8 However, these studies have been carried out on commercial C/PtNP catalysts, which exhibit wide variations in the size and shape of the PtNPs and also effects exerted by the support. 12,13 This in turn makes it difficult to precisely correlate IR spectra to particular nanoparticle structures.We sought to better understand the interaction between CO and PtNPs by developing a more refined model system that could be directly compared to first principles theory. The model we chose are dendrimer-encapsulated nanoparticles (DENs), which are welldefined materials in the size range of 1-2 nm. 1,...