Surfactant-Free Precious Metal Colloidal Nanoparticles for Catalysis

Jonathan Quinson

doi:10.3389/fnano.2021.770281

Abstract

Colloidal syntheses of nanoparticles (NPs) are one of the preferred approaches to prepare precious metal catalysts. Unfortunately, most colloidal syntheses developed require stabilizing agents to avoid NP agglomeration and/or control NP size and morphology. While these surfactants can bring positive features, they typically block catalytically active sites on the NP surface. As a consequence, these additives often need to be removed by energy and/or time consuming steps, at the risk of complicating the synthesis, introducing irreproducibility and negatively altering the structure and properties of the prepared catalysts. Fortunately, several surfactant-free colloidal syntheses have been reported and are being developed. This Mini Review addresses the challenges in defining a surfactant-free colloidal synthesis of NPs and survey established and emerging strategies to obtain surfactant-free colloidal precious metal NPs. A focus is given to approaches that show promising features to bridge the gap between fundamental and applied research towards industrial applications.

Highlights

Nanoparticles (NPs) have found applications in a vast number of fields, ranging from medicine, imaging, sensing, water/air remediation, energy conversion or catalysis
To advance further the design of NP catalysts, surfactant-free colloidal syntheses are highly desirable, 1) to simplify the synthesis of NPs and make is safer, 2) to simplify the use and processing of the NPs, 3) to develop catalysts readily active without the need for washing and/or activation steps. This reduce production cost and makes it more straightforward to transfer the knowledge gained in fundamental research to industrial applications: With a surfactant-free synthesis, the same production method of the catalyst would be suitable for both the fundamental and applied research involved in a catalyst development (Quinson et al, 2018)
We reported an alternative to the polyol-synthesis where alkaline methanol and ethanol and their mixtures with water were shown to be suitable solvents and reducing agents to develop surfactantfree PM NPs like Pt, Ir, Ru or Os (Quinson et al, 2018) and multi-mettalic

Summary

Jonathan Quinson *

Colloidal syntheses of nanoparticles (NPs) are one of the preferred approaches to prepare precious metal catalysts. Most colloidal syntheses developed require stabilizing agents to avoid NP agglomeration and/or control NP size and morphology. While these surfactants can bring positive features, they typically block catalytically active sites on the NP surface. As a consequence, these additives often need to be removed by energy and/or time consuming steps, at the risk of complicating the synthesis, introducing irreproducibility and negatively altering the structure and properties of the prepared catalysts.

INTRODUCTION

Laser Synthesis and Processing of Colloids

Plasma Synthesis

Polyol Synthesis

DISCUSSION

CONCLUSION