Abstract:In this work, we study the effect of modifying the metal loading (0.5–1.5 wt.% Pd and 0.1–1 wt.% Sn or In), the impregnation order of noble or promoter metal (Pd–Sn or Sn–Pd), and the type of promoter metal (Sn or In) during the preparation process for a Pd bimetallic catalyst, supported on γ-alumina, used in the catalytic reduction of nitrate. The deposition of the noble metal over the promoter metal, especially with Pd:Sn ratios (wt.) of 1:10 and 1:2, favored the hydrogen spillover rate and increased the H c… Show more
Nitrate is one of the most widespread water contaminants globally. Nitrate levels in groundwater and surface water can rise to unhealthy levels as a result of nitrogen fertilizer runoff from lawns and farms. This research aims to selectively convert nitrate to gaseous nitrogen using Palladium‐Tin (Pd‐Sn) bimetallic electrodes electrodeposited on stainless‐steel (SS). Inductively coupled plasma optical emission spectrometry, scanning electron microscope, and X‐ray diffraction are used to analyze the composition, surface morphology, and crystal structure of the electrodes. The XRD analysis reveals that the Pd‐Sn/SS electrode has a crystalline nature when a Pd molar ratio >0.5 while an amorphous phase is detected over a Pd molar ratio (≤0.5). The electrochemical nitrate reduction is carried out in a 0.1 M HClO4 / 8 mM NaNO3 solution for 5 h using electrodes prepared in deep eutectic solvent (DES) system. The Pd0.93Sn0.07/SS electrode shows the best catalytic performance in terms of high nitrate conversion of 97%, N2 selectivity of 88%, and N2 yield of 86% compared to counter electrodes. These findings demonstrate a considerable impact of the electrode preparation process on nitrogen conversion, selectivity, and yield.
Nitrate is one of the most widespread water contaminants globally. Nitrate levels in groundwater and surface water can rise to unhealthy levels as a result of nitrogen fertilizer runoff from lawns and farms. This research aims to selectively convert nitrate to gaseous nitrogen using Palladium‐Tin (Pd‐Sn) bimetallic electrodes electrodeposited on stainless‐steel (SS). Inductively coupled plasma optical emission spectrometry, scanning electron microscope, and X‐ray diffraction are used to analyze the composition, surface morphology, and crystal structure of the electrodes. The XRD analysis reveals that the Pd‐Sn/SS electrode has a crystalline nature when a Pd molar ratio >0.5 while an amorphous phase is detected over a Pd molar ratio (≤0.5). The electrochemical nitrate reduction is carried out in a 0.1 M HClO4 / 8 mM NaNO3 solution for 5 h using electrodes prepared in deep eutectic solvent (DES) system. The Pd0.93Sn0.07/SS electrode shows the best catalytic performance in terms of high nitrate conversion of 97%, N2 selectivity of 88%, and N2 yield of 86% compared to counter electrodes. These findings demonstrate a considerable impact of the electrode preparation process on nitrogen conversion, selectivity, and yield.
Ammonia (NH3) plays an irreplaceable role in human life as a promising energy carrier and indispensable chemical raw material. Nitrate electroreduction to ammonium (NRA) not only removes nitrate pollutants, but also can be used for efficient NH3 production under ambient conditions. However, achieving high efficiency and selectivity of electrocatalysts is still a great challenge. Herein, a complex Cu2(NO3)4(BMMB)·H2O with a bicopper core is assembled by Cu(NO3)2·3H2O and 1,4-bis{[2-(2’-pyridyl)benzimidazolyl]methyl}benzene (BMMB) for NRA under alkaline conditions. The optimal sample showed excellent nitrate reduction performance with the NO3− conversion rate of 70%, Faradaic efficiency of up to 90%, and NH3 selectivity of more than 95%. The high-catalytic activity is mainly due to the ingeniously designed copper cores with strong affinity for NO3−, which accelerates the transferring rate of adsorbed nitrate on the Cu surface and increases the efficiency of rate-determining step (NO3− → NO2−) in the whole catalytic process. Therefore, the transformation of surface-exposed nitrate can be rapidly catalyzed by the Cu active sites, facilitating the conversion efficiency of nitrate.
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