Enhanced electrocatalytic effects of Pd particles immobilized on GC surface on the nitrite oxidation reactions

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2019-04, Vol.839, p.1-8
• Main Authors: Alam, Md. Saiful, Shabik, Md. Fazle, Rahman, Mohammed M., del Valle, Manel, Hasnat, Mohammad A.
• Format: Article
• Language: English
• Subjects: Activation energy; Catalysis; Charge transfer; Electrodes; Electron transfer; Free energy; Glassy carbon; Kinetics; Nanoparticles; Nitrogen dioxide; Oxidation; Oxidation reactions; Pd-Pt catalyst; Reaction kinetics; Single electrons; X ray photoelectron spectroscopy
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2019.02.058

Nitrite (NO2−) oxidation reactions (NOR) have been performed using a pristine glassy carbon (GC) electrode and Pd modified GC electrode to investigate catalysis and kinetics of oxidation reaction. The XPS analysis revealed that Pd nanoparticles (NPs) on GC is differed electronically from Pd particles alone. Electrochemical observations entailed that the Pd-GC electrode improved the catalytic efficiency by lowering peak potential and improving peak current compared to those obtained by GC or Pd electrode alone. Additionally, the onset potential (Ei) of kinetic process concerning NOR was appeared at 0.63V for Pd-GC electrode which is smaller than 0.81V and 0.75V observed by GC and Pd electrodes, respectively. These observations suggest that the Pd–GC electrode can obtain faster electron transfer and maximum catalytic sites. The validation of Pd-GC as noble catalyst is also supported by observing least free energy of activation at peak (ΔGp‡=0.461 eV). The nitrite ions involve a single electron transfer reaction with NO2 molecules being the product, which later undergoes through a dispropornation reaction yielding NO2− and NO3− as final products. The precise observations by RDE experiments revealed that the charge transfer reaction followed by an irreversible first order kinetics with standard rate constant (k0) of 1.98×10−4cm/s and formal potential (Eo′) of 0.03V. Efficient electrocatalytic oxidation of nitrite (NO2−) is attained while a Pd modified glassy carbon (GC) electrode. Nitrite undergoes one electron transfer oxidation reaction on a Pd-GC surface to yield nitrogen dioxide gas which undergoes disproportionation reaction to yield NO2− and NO3−. [Display omitted] •Pd-GC electrode is more effective than GC towards the Nitrite oxidation reaction (NOR).•One electron transfer involves in NOR.•First order irreversible process of NOR•Concerted mechanism followed by NOR•Low onset potential Pd-GC electrode