Preparation and Characterization of Rhodium Nanostructures through the Evolution of Microgalvanic Cells and Their Enhanced Electrocatalytic Activity for Formaldehyde Oxidation

Abstract

Shape-controlled morphological evolution of nanostructured Rh has been demonstrated with the help of a galvanic displacement reaction using Al in 1 mM aqueous Rh(III) chloride at an open circuit potential 0.99 V and at a temperature of 273 K (room temperature). Nanospheres composed of small nanoparticles of size around 2.9 ± 0.4 nm having uniform distribution with a FCC pattern have been evolved during the course of the reaction. Electrochemical results coupled with structural and morphological characterization data from transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and cyclic voltammetry (CV) suggested the formation of Rh nanostructures. Considering the role of the potential of substrate Al and Rh and diffusion of reactant and product species toward and from the surface of the Al, we proposed the tentative mechanism for the formation of microgalvanic cell. Significantly, these rhodium nanostructures exhibit enhanced electrocatalytic activity toward many fuel cell reactions as demonstrated by formaldehyde oxidation in 0.5 M NaOH. The present strategy is expected to be valid for preparing many other similar electrocatalysts (Pt, Au, and Pd) capable of exhibiting such a remarkable size- and shape-dependent reactivity.

Electrooxidation of Formaldehyde on Silver/Ordered Mesoporous Carbon Composite Electrode in Alkaline Solutions

“…The electrooxidation of formaldehyde on metal, such as Pt, Cu, Rh et al, has been widely reported [1]- [5]. In aqueous solutiongs, formaldehyde exists mainly in its hydrated form, methylene glycol (H 2 C(OH) 2 ), and the following electrochemical oxidation maybe occur on Ag surface: …”

“…Formaldehyde is also one of the initial products of methanol oxidation which has its fundamental and technological importance in industrial catalytic processes [2]. The electrooxidation mechanism of formaldehyde has been widely investigated on Pt [3], Pd [4], and Rh [5] electrodes which are mostly in connection with fuel cells and sensors. Whereas, these anodic materials are the noble metal with their scarcity, and can't lower the commercial cost.…”

Size and shape controlled synthesis of rhodium nanoparticles

“…Recently, significant progresses have been made for the size- and shape-control of NMNPs by tuning the crystal growth kinetics in numerous wet-chemistry approaches. Among various NMNPs, rhodium (Rh) is particularly known for its critical role in diverse catalytic reactions, such as CO oxidation [22, 23, 24, 25], NO reduction [26, 27, 28], hydrogenation [29, 30, 31, 32, 33], hydroformylation [34, 35, 36], and electro-oxidation [37, 38, 39, 40]. Moreover, Rh-based catalysts are especially stable for use under harsh reaction conditions because of its strong resistance to the etching of acid/base and heat.…”

Electrochemical Design of Ultrathin Palladium Coated Gold Nanoparticles as Nanostructured Catalyst for Amperometric Detection of Formaldehyde

“…Sathe et al. prepared rhodium nanostructures through the evolution of microgalvanic cells 11. These rhodium nanostructures exhibit enhanced electrocatalytic activity toward many fuel cell reactions as demonstrated by formaldehyde oxidation in 0.5 M NaOH.…”