Hydrogen Peroxide Oxidation Reaction on a 4-Mercaptopyridine Self-Assembled Monolayer on Au(111) Metallized by Platinum Nanoislands

Abstract

A systematic investigation of the hydrogen peroxide oxidation reaction (HPOR) in phosphate buffer (pH = 7.3) on an Au(111) single crystal modified with a 4-mercaptopyridine self-assembled monolayer (SAM) has been conducted before and after metallization with Pt. While bare Au(111) shows considerable electrocatalytic activity towards the HPOR, the inhibition of the oxidation reaction after modification with the SAM implies that adsorbed 4-mercaptopyridine molecules do not catalyze the HPOR. However, SAM-modified Au(111) recovers catalytic activity for the HPOR already after a single metallization step fabricating Pt islands on-top. Hydrogen peroxide (HP) may then either react at the (non-metallic) Pt nanoislands or on reactivated Au sites, made accessible by structural changes of the SAM induced by the metallization. The shape of the voltammetric profiles for the HPOR on repeatedly metallized SAMs suggests that the contribution of Au to the total current density gradually diminishes with increasing Pt coverage while the contribution of the Pt islands increases. The electrochemical behavior is dominated by the Pt islands at a coverage of 0.5 ML obtained by three subsequent metallization steps. Graphical abstract

Coordination-Controlled Electrodeposition of Palladium/Copper Thin Films onto a Pyridine-Terminated Self-Assembled Monolayer

“…Compared to the well-established approach using chemically inert SAMs, [1][2][3][4][5][6][7] functionalised layers bearing metal coordinating moieties change the paradigm from defect-based electrodeposition to deposition controlled by molecular properties. The different mechanism not only confines deposition to on top of the SAM as first reported by Kolb et al [8][9][10] but the level of control over the deposition process offers new prospects for the design of materials as illustrated by the tuning of electronic properties, [11][12][13][14][15][16] generation of SAM/metal hybrid structures, 17 control of catalytic activity, 12,18,19 the epitaxial growth of Cu films on a cysteine modified Au surface, 20 or the generation of bimetallic nanostructures. 21 Coordination-controlled electrodeposition (CCED) can be accomplished in different ways and the ones employed in the work presented here are illustrated in Fig.…”