Underpotential electroless deposition of metals on polyaniline

TL;DR

This paper introduces a new method for underpotential electroless metal deposition on polyaniline films, enabling the deposition of metals like Mn and Cu, which are difficult to deposit by other methods, potentially enhancing catalytic activity.

Contribution

The study presents a novel technique combining polyaniline reduction with formic acid and metal salt dipping for underpotential deposition of metals on conducting polymers.

Findings

Successfully deposited Mn and Cu metals on polyaniline.

Metals are likely coordinated with amine nitrogen, enhancing catalytic properties.

Method overcomes hydrogen evolution issues in metal electrodeposition.

Abstract

A novel technique to deposit metals on highly conjugated polyaniline films has been developed. In general, electrodeposition of metals, having low reduction potential, from aqueous solution, is difficult due to disruptive effect of hydrogen which evolves during the process. This difficulty is avoided using conducting polymers films with high surface mass density. The polymer chains of these films possess a high degree of conjugation. Such a polymer produces highly stable polarons and therefore has the ability to perform underpotential deposition. Our method involves reduction of polyaniline film with formic acid followed by dipping the coated electrode in the metal salt solution. Deposition of the metal is monitored by rise in the open circuit potential of the electrode. Deposition of metals with high surface mass density has been achieved. The metal is most likely present in the polymer as a coordination complex with amine nitrogen. Such form of metal is expected to have higher catalytic activity than the zero-valent metal. We have been able to deposit metals such as Mn and Cu. Among these, Mn cannot be deposited on polymer by any other method.