Selective Electrocatalytic Nitrate Reduction to Ammonia Using Nafion-Covered Cu Electrodeposits

Abstract

Electrocatalytic NH 3 production from NO 3 − reduction is a promising alternative to traditional Haber-Bosch NH 3 synthesis. Although Nafion is commonly employed as a separator in two-compartment electrochemical cells and as a binder in catalyst inks, in this manuscript, we use Nafion as an overlayer on top of Cu electrodeposits to enhance NH 3 selectivity. Faradaic efficiencies for NH 3 and NO 2 − generation were evaluated as a function of electrodeposit morphology with and without the Nafion layer. These studies reveal that the combination of Cu (220) faces in the electrodeposits and activation of a NO intermediate by Nafion enables NH 3 production with a high Faradaic efficiency of (97.0 ± 0.3) %. This optimized architecture also exhibits the fastest rate of NH 3 production among the catalysts studied even after normalizing for its rough electrochemical active surface area. In addition to voltammetry, the electrocatalysts were characterized using a variety of techniques including atomic force microscopy, scanning electron microscopy, X-ray diffraction, and water contact angle measurements. Insights garnered about the parameters needed for selective NH 3 production will inform future research on nonprecious metal NO 3 − reduction catalysts.

Polyaniline/Titania Nanotube-Based Biosensor Strip for Sensitive and Specific Electrochemical Detection of SARS-CoV-2

“…However, it was noticed that a higher redox peak current is observed in the PANi-TNT/SPCE than in the PANi/SPCE. This observation implies the fast electron exchange behavior and electrocatalytic activity , of the sensing platform due to the higher transfer rate in the presence of TNT. , To support this study, an electrochemical impedance spectroscopy experiment and analysis were performed, and modified Randles equivalent circuits for both PANi/SPCE and PANi-TNT/SPCE were fitted, which are shown in Figure b. The Nyquist plots of both the PANi/SPCE and PANi-TNT/SPCE exhibit a semicircle of higher and lower diameters, respectively, in the high-to-medium frequency range, corresponding to the charge transfer resistance ( R ct ) at the electrode/electrolyte interface, followed by a straight line in the low-frequency region, which stands for the Warburg diffusion impedance and relates to the bulk diffusion resistance in the hybrid model. , In addition, the solution resistances for both the PANi/SPCE and PANi-TNT/SPCE are the same ( R 2 = 163.7 and 163.5 Ω, respectively) in the equivalent circuits.…”

An Anti-Scaling Strategy for Electrochemical Wastewater Treatment: Leveraging Tip-Enhanced Electric Fields

“…Comprehensive characterization of the investigated cathodes was performed before and after the reaction to visually inspect scale formation on the electrode surfaces. Figure a illustrates that, aside from minimal intensity changes in the characteristic peaks at 2θ of 43.4, 50.4 and 74° corresponding to (111), (200), and (220) of metallic Cu, respectively, there were no new peaks indicative of scale phase formations in the X-ray diffraction (XRD) patterns of Cu NW/CF after undergoing 5 batched electrolysis cycles. This markedly contrasts with the appearance of two new reflections at 2θ of 18.7 and 38.2° respectively corresponding to (001) and (101) of Mg­(OH) 2 in the postelectrolysis XRD patterns of all three control electrodes (i.e., CF, CM, and Cu NP/CF). , Similarly, new XRD patterns emerged in the CF, CM, and Cu NP/CF cathodes after electrolysis in the presence of Ca 2+ , which were attributed to the formation of CaCO 3 (Figure S16).…”

Correlating Nitrate Adsorption with the Local Environments of FeCoNiCuZn High-Entropy Alloy Catalysts Using Machine Learning

“…The synthesis of ammonia can be accomplished through the Haber–Bosch process, which is however energy intensive and emits abundant greenhouse gases . As a potential alternative strategy for ammonia synthesis, the electrocatalytic reduction of nitrate to ammonia has been attracting increasing attention , as it is a more sustainable and environmentally friendly approach. From the environmental perspective, the nitrate reduction reaction (NO 3 RR) also possesses the benefits of addressing the pollution issues caused by the nitrate, which typically has a concentration of 2000–4000 mg/L in industrial wastewater .…”