Search

Growing Pt on Ag nanoparticles is a promising approach to forming catalysts that present active sites with both Pt and Ag available to improve the activity for the hydrogen evolution reaction (HER). By carefully controlling the concentration of a Pt precursor, the amount of Pt-decorated particles onto the Ag nanoparticles could be controlled to grow Pt islands between 0.6 and 1.5 nm. As a result, the relative amounts of the Ag-Pt active sites could be tuned. The smallest, 0.6 nm Pt islands on the Ag nanoparticle, with the highest ratio of Ag-Pt to Pt-Pt sites was found to have the highest activity and an accelerated Volmer step. DFT modeling showed that the improved performance was due to increased electron density on Pt from electron donation from neighboring Ag that leads to weaker Pt-H binding and the presence of more oxophilic Ag that can bind −OH on the active site that accelerates the water splitting.

Creating high surface area nanocatalysts that contain stacking faults is a promising strategy to improve catalytic activity. Stacking faults can tune the reactivity of the active sites, leading to improved catalytic performance. The formation of branched metal nanoparticles with control of the stacking fault density is synthetically challenging. In this work, we demonstrate that varying the branch width by altering the size of the seed that the branch grows off is an effective method to precisely tune the stacking fault density in branched Ni nanoparticles. A high density of stacking faults across the Ni branches was found to lower the energy barrier for Ni2+/Ni3+ oxidation and result in enhanced activity for electrocatalytic oxidation of 5-hydroxylmethylfurfural. These results show the ability to synthetically control the stacking fault density in branched nanoparticles as a basis for enhanced catalytic activity.

Creating high surface area nanocatalysts that contain stacking faults is a promising strategy to improve catalytic activity. Stacking faults can tune the reactivity of the active sites, leading to improved catalytic performance. The formation of branched metal nanoparticles with control of the stacking fault density is synthetically challenging. In this work, we demonstrate that varying the branch width by altering the size of the seed that the branch grows off is an effective method to precisely tune the stacking fault density in branched Ni nanoparticles. A high density of stacking faults across the Ni branches was found to lower the energy barrier for Ni2+/Ni3+ oxidation and result in enhanced activity for electrocatalytic oxidation of 5-hydroxylmethylfurfural. These results show the ability to synthetically control the stacking fault density in branched nanoparticles as a basis for enhanced catalytic activity.

Diamine functionalization of GO continues to draw significant research attention because of the ability to manipulate the interlayer spacing between GO sheets. Control over the GO interlayer spacing has resulted in profound improvements in the capacitance and cyclic stability in lithium-ion batteries. The reaction of ethylene diamine (EDA) with GO has previously been reported to cause simultaneous "stitching/crosslinking", "reduction", and "functionalization"of GO. However, detailed understanding of "stitching"and "reduction"is still lacking. In the present work, we have used combinatorial experimental and computational approaches to determine the reactivity of EDA toward main oxygen-containing functional groups of GO (epoxy, hydroxyl, and carboxylic acid). Using excess EDA, we observed experimental predominant evidence of "stitching", which was further corroborated with DFT calculations. However, no clear experimental evidence of "reduction"of GO as a result of reaction of EDA with GO was observed. DFT calculations revealed that the first step of EDA functionalization exhibits similar reaction energies for hydroxyl and epoxy groups. However, in regard to "stitching", hydroxyl and carboxyl groups were energetically comparable. The present results have implications in regard to energy storage applications of these materials.

Almost difference sets have interesting applications in cryptography and coding theory. In this paper, we give a well-rounded treatment of known families of almost difference sets, establish relations between some difference sets and some almost difference sets, and determine the numerical multiplier group of some families of almost difference sets. We also construct six new classes of almost difference sets, and four classes of binary sequences of period n equivalent to 0 (mod 4) with optimal autocorrelation. We have also obtained two classes of relative difference sets and four classes of divisible difference sets (DDSs). We also point out that a result due to Jungnickel can be used to construct almost difference sets and sequences of period 4l with optimal autocorrelation.

Almost difference sets have interesting applications in cryptography and coding theory. In this paper, we give a well-rounded treatment of known families of almost difference sets, establish relations between some difference sets and some almost difference sets, and determine the numerical multiplier group of some families of almost difference sets. We also construct six new classes of almost difference sets, and four classes of binary sequences of period n equivalent to 0 (mod 4) with optimal autocorrelation. We have also obtained two classes of relative difference sets and four classes of divisible difference sets (DDSs). We also point out that a result due to Jungnickel can be used to construct almost difference sets and sequences of period 4l with optimal autocorrelation.

Almost difference sets have interesting applications in cryptography and coding theory. In this paper, we give a well-rounded treatment of known families of almost difference sets, establish relations between some difference sets and some almost difference sets, and determine the numerical multiplier group of some families of almost difference sets. We also construct six new classes of almost difference sets, and four classes of binary sequences of period n equivalent to 0 (mod 4) with optimal autocorrelation. We have also obtained two classes of relative difference sets and four classes of divisible difference sets (DDSs). We also point out that a result due to Jungnickel can be used to construct almost difference sets and sequences of period 4l with optimal autocorrelation.