Dinitrogen reduction on a polypyrrole coated Pt electrode under high-pressure conditions: electrochemical impedance spectroscopy studies

Abstract

Abstract:The electrochemical impedance spectroscopy (EIS) responses of a polypyrrole (PPy)-coated platinum electrode were investigated during N 2 -reduction to ammonia in aqueous medium. Kinetic parameters such as film resistance, pore resistance, and double layer capacitance were analyzed as a function of applied potential and polymer film thickness.The relation between kinetic parameters was discussed by combining electrolysis results. It was found that the optimum film thickness of polypyrrole was 0.73 µ m and optimum potential for ammonia synthesis was -0.150 V under 60 bar α -transfer coefficient of 0.49 and an exchange current density with a value of 3.17 10 −3 A cm −2 were characteristic for H ad formation in acidic aqueous medium.

Nitrogenase Bioelectrocatalysis: ATP-Independent Ammonia Production Using a Redox Polymer/MoFe Protein System

“…In the low-frequency region, the process is controlled by reactant diffusion to the reaction site contributing to the linear part (i.e., Warburg impedance). 36,37 The R ct for MoFe/Cc-PAA and MoFe electrode were 25 and 150 Ω, respectively. The relationship between reactant concentration and charge-transfer resistance is characterized by the equation…”

“…In the high-frequency region, the semicircle diameter is a measure of the charge-transfer resistance, which is affected by the electron transfer crossing the electrode surface. In the low-frequency region, the process is controlled by reactant diffusion to the reaction site contributing to the linear part (i.e., Warburg impedance). , The R ct for MoFe/Cc-PAA and MoFe electrode were 25 and 150 Ω, respectively. The relationship between reactant concentration and charge-transfer resistance is characterized by the equation where R is the ideal gas constant, T is the temperature, n is the number of electrons involved in the redox process, F is Faraday’s constant, K et is the potential-dependent charge transfer, [S] is the concentration of redox molecules, and A is the geometric surface area of the electrode in cm 2 .…”

Bio‐reduced GO /Pd nanocomposite as an efficient and green synthesized catalyst for hydrogen evolution reaction

“…One semicircle was observed in the Nyquist plots for the three electrode surface, indicates to the interfacial electron transfer resistance ( R ct ), which characterizes the kinetics of the HER process 53 . The obtained impedance spectra are fitted by the classical Randles equivalent circuit model based on the only one constant phase element (CPE) as presented in Figure 9, 11,54 where R e stands for the electrolyte resistance.…”

Recent Advances and Challenges of Electrocatalytic N2Reduction to Ammonia

“…304 This mechanism was similar to the one the authors suggested for N 2 reduction in the aqueous solution. 235 N 2 electroreduction in 2-propanol 305 and ethylenediamine 306 was examined by Kim et al In the first case, 305 the electrolyte was a mixture of 2propanol and deionized water (9:1, v/v) with 10 mM H 2 SO 4 as a supporting electrolyte, and a porous nickel electrode was used as the cathode (Figure 39d). As shown in Figure 39e, a significantly higher ammonia formation rate and Faradaic efficiency were obtained in the mixed solvent compared to those in water.…”

“…The low activity of Pt catalysts toward N 2 reduction is partially due to the endothermic nature of the binding energy of N adatoms on Pt surfaces (Figure ); therefore N 2 molecules are hardly adsorbed on the catalyst surface. To solve this problem, Köleli and Kayan , used a Pt plate coated with a polypyrrole film as an electrode material for N 2 reduction in an aqueous solution containing 0.1 M Li 2 SO 4 and 0.03 M H + . A N 2 pressure of 6 MPa was used in order to improve the solubility of N 2 in the reaction medium.…”