Oxidation-State Control of Nanoparticles Synthesized via Chemical Reduction Using Potential Diagrams

Abstract

A general concept for oxidation-state control of nanoparticles synthesized via chemical reduction has been developed. By comparing kinetically determined mixed potential measured in reaction solution and thermodynamically drawn potential diagrams, e.g., potential–pH diagram, it is possible to know “what chemical species is stable in the reaction solution?.” It is predicted from potential diagrams that nanoparticles in different oxidation states can be selectively synthesized by controlling mixed potential. This concept is verified by selectively synthesizing Cu and Cu2O nanoparticles from CuO aqueous suspension via chemical reduction using the concept as an example. The dependency of mixed potential on pH and temperature is discussed in detail for the selective synthesis of nanoparticles.