Electrocatalytic nitrate/nitrite reduction to ammonia synthesis using metal nanocatalysts and bio-inspired metalloenzymes

Elucidating the activity, mechanism and application of selective electrosynthesis of ammonia from nitrate on cobalt phosphide

“…As a consequence, about 150 million tons of NH 3 being produced by the Haber–Bosch process per year results in large amounts of energy usage and also contributes to the environmental crisis. 6–9 Electrochemical synthesis of ammonia without the use of H 2 provides a sustainable alternative for ammonia synthesis.…”

“…During the past few years, aqueous-based electrochemical reduction of N 2 to NH 3 (nitrogen reduction reaction, NRR) has received some attention, but the highly stable and apolar NN bond (bond energy of 941 kJ mol −1 ), as well as the competing hydrogen evolution reaction (HER) and limited N 2 solubility result in ultra-low reactive rates (<10 mmol g cat −1 h −1 ), selectivity and faradaic efficiency. 6,7,10,11 In contrast, the electrochemical reduction of nitrate to NH 3 (nitrate reduction reaction, NO 3 − RR, NO 3 − + 6H 2 O + 8e − → NH 3 + 9OH − ) is an alternative and attractive route for low-temperature ammonia synthesis due to the following advantages: (1) deoxygenation of NO 3 − requires a much lower energy of 204 kJ mol −1 , 12 thus the NO 3 − RR is energy-efficient compared to the Haber–Bosch process and NRR; (2) the source of nitrate is widespread. Nitrate-rich wastewater streams are available for the NO 3 − RR since nitrate is extensively found in industrial and agricultural runoff.…”

“…Nitrate-rich wastewater streams are available for the NO 3 − RR since nitrate is extensively found in industrial and agricultural runoff. 6,7,10,11 Moreover, given the wide distribution of niter ore (mainly in Chile and China's Turpan Basin), it is also available for the NO 3 − RR. Extensive and abundant nitrate reserves make the NO 3 − RR available for large-scale ammonia production; (3) nitrate release pollutes ground and surface waters thereby disturbing ecosystems.…”

Flexible 2D Cu Metal: Organic Framework@MXene Film Electrode with Excellent Durability for Highly Selective Electrocatalytic NH 3 Synthesis

“…In addition, the NO 3 − is one of the most difficult N-pollutants to remove [ 8 – 10 ], which induces global eutrophication and does damage to the human health [ 11 , 12 ]. Therefore, electrocatalytic NO 3 − reduction to NH 3 (ENRA) is one of the most promising strategy for producing NH 3 under ambient conditions and solving global NO 3 − contamination and energy crisis [ 13 , 14 ]. However, owing to the fragile nature of a traditional electrode, the practical application of ENRA is limited by poor stability and lossy and even disappeared activity after omnidirectional deformability in a fluid environment [ 14 ].…”

“…Therefore, electrocatalytic NO 3 − reduction to NH 3 (ENRA) is one of the most promising strategy for producing NH 3 under ambient conditions and solving global NO 3 − contamination and energy crisis [ 13 , 14 ]. However, owing to the fragile nature of a traditional electrode, the practical application of ENRA is limited by poor stability and lossy and even disappeared activity after omnidirectional deformability in a fluid environment [ 14 ]. Thus, the electrocatalytic NH 3 synthesis using flexible electrode with effective electrocatalytic activity, high Faradaic efficiency, robust mechanical stability, and low environmental impacts would be a promising strategy to solve the abovementioned problem.…”