Efficient Ammonia Synthesis from Nitrate Catalyzed by Au/Cu with Enhanced Adsorption Ability

Abstract

The traditional method for synthesizing NH3 is the Haber–Bosch process which results in high‐fuel consumption and environmental pollution. Therefore, ecofriendly electrochemical synthesis of NH3 through nitrate (NO3−) reduction is a good choice. Herein, an integral Au/Cu electrode to catalyze NO3− reduction to NH3 is introduced. The catalyst exhibits not only the highest NH3 yield rate (73.4 mg h−1 cm−2) up to now but also a very high Faradaic efficiency of 98.02% at −0.7 V at room temperature. It is commonly believed that the transformation of NO3− to nitrite (NO2−) is an obstacle to the NH3 generation from NO3− reduction. Surprisingly, unlike most of the other catalysts, Au/Cu exhibits better activity for NO3− reduction than that for NO2− reduction. Based on the detailed experimental and density functional theory calculations, the excellent performance of Au/Cu for selective NO3− reduction lies in the enhanced adsorption capabilities of Au/Cu to NO3− in the alkaline environment and the lower energy barriers of the electrochemical reduction reaction.

The interface-mediated electron structure tuning of RuOx–Co3O4 nano-particles for efficient electrocatalytic nitrate reduction

“…Additionally, at room temperature and pressure, nitrogen gas (N 2 ) has a low solubility in electrolytes due to its non-polar characteristics and the reaction kinetics at the gas-liquid-solid interface are slow. 1,[10][11][12][13][14] In contrast, the electrocatalytic nitrate reduction reaction (NO 3 RR) for ammonia production is thermodynamically more viable. This is because NO 3 RR involves a higher theoretical electrode potential (NO 3…”

“…Moreover, ammonia has the potential to be a promising carrier for hydrogen energy in the future. 1 As both a fertilizer and neutralizer, ammonia has been widely used in various industries, including wastewater treatment, leather, paper, food, and beverage. Currently, the main method for the industrial production of ammonia is the Haber–Bosch process (H 2 + N 2 → NH 3 ).…”

“…Additionally, at room temperature and pressure, nitrogen gas (N 2 ) has a low solubility in electrolytes due to its non-polar characteristics and the reaction kinetics at the gas–liquid–solid interface are slow. 1,10–14…”

“…This can lead to the occurrence of the competing hydrogen evolution reaction (HER), resulting in a reduced faradaic efficiency of ammonia synthesis. 1,15,[28][29][30][31] Hence, the development of NO 3 RR catalysts that demonstrate both high activity and faradaic efficiency towards ammonia is a significant challenge. 32,33 Co-based materials have been widely applied as catalysts for electrocatalytic reactions such as NO 3 RR.…”

Investigating the role of oxygen vacancies in metal oxide for enhanced electrochemical reduction of NO3− to NH3: mechanistic insights

“…Considerable endeavors have been directed toward creating advanced metal electrode materials by incorporating heteroatoms/heterojunctions, [41][42][43] and introducing noble metals. 7,44,45 Recent investigations have demonstrated that the inclusion of vacancy sites, such as selenium-vacancy, S-vacancy, and oxygen vacancy (OV), within materials based on metal oxides presents a straightforward and efficient approach for boosting their catalytic effectiveness. [46][47][48][49][50][51] The incorporation of OVs as a strategy has found extensive application in diverse fields, including the OER, 52,53 ORR, 54,55 CO 2 RR, 56,57 HER 58,59 and NRR, 60,61 supercapacitors, 62 and batteries, 63,64 with impressive results showcasing their remarkable ability to adsorb and activate various molecules like O 2 , H 2 O, and H 2 , among others.…”