Enhanced electrocatalytic performance of interconnected Rh nano-chains towards formic acid oxidation

Abstract

A chain-like assembly of rhodium nanoparticles (5-7 nm mean diameter) has been synthesized from rhodium chloride with the help of polydentate molecules like tartaric and ascorbic acids (1 : 3 in mM scale) as capping agents at room temperature. Subsequent characterization using transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy reveals a unique inter-connected network like features, while their electrochemical behavior using cyclic voltammetry and current-time transient suggests potential applications as electrocatalysts in fuel cells. A significant negative shift in the onset potential as well as higher anodic peak current density for formic acid oxidation on Rhtartaric acid (Rh-TA) as compared to that of bulk Rh metal confirms their higher electrocatalytic activity. Interestingly, the enhancement factor (R) with respect to that of bulk metallic Rh towards formic acid oxidation ranges up to 2000% for Rh-TA and 1200% for Rh-AA (Rh-ascorbic acid) respectively. The composition of Rh nano-chains has been further analyzed with thermogravimetry and Fourier transform infra-red spectroscopy to demonstrate the importance of controlling the chain topology using polyfunctional organic molecules. These findings open up new possibilities for tailoring nanostructured electrodes with potential benefits since the development of a better electrocatalysts for many fuel cell reactions continues to be an important challenge.

Coverage-Dependent Formic Acid Oxidation Reaction Kinetics Determined by Oscillating Potentials

“…For carbon-based electrodes, the CV peaks are less easily discernable but similar peak shapes to Pt plates have been reported before. [21][22][23][24] The effect of oscillating potentials on the FA oxidation reaction on Pt plate electrodes has been investigated and we identified a frequency of 100 Hz at a duty cycle of 50% between OCP and 0.8 V to yield the largest FA oxidation enhancement ( Figure S4) in accordance to a previous study. 14 In the following, we further elucidated the transient current responses upon potential switches and we explored the capability of oscillating potentials in illuminating reaction kinetics.…”

Electrically conducting osmium nano-chain networks with superior catalytic and SERS performance

“…Similar types of mechanism have previously been proposed for rhodium nano-chains, using tartaric acid as the reducing agent and ascorbic acid as the capping agent. 37 Wire-like Au NP assemblies were also reported recently by Yin et al in the presence of ethanol. 38 They claimed that PAD acts as a capping agent, and the uncapped faces of the Au NPs could orient one another through dipole-dipole interactions, resulting in the formation of an organized 1D assembly.…”

Stable and Efficient PtRu Electrocatalysts Supported on Zn-BTC MOF Derived Microporous Carbon for Formic Acid Fuel Cells Application

“…Further, Rh interconnected networks, Rh nanoneedles, and Rh nanorods were synthesized at room temperature using RhCl 3 salt as a precursor and tartaric acid (TA), ascorbic acid (AA), hexamethylene tetraamine, and tridecylamine as capping agents. The nanostructured Rh-catalysts have demonstrated high catalytic activity toward FAOR in comparison to bulk Rh in terms of more negative onset potential and high anodic peak current density (Sathe et al, 2011;Sathe, 2013). Herein, we uncover that catalysts with a PtRu atomic ratio of 1:2 follow a direct oxidation pathway of FAOR and presented high specific, mass activities and stability.…”