Single-atom catalysts boost nitrogen electroreduction reaction

Abstract

Ammonia (NH3) is mainly produced through the traditional Haber-Bosch process under harsh conditions with huge energy consumption and massive carbon dioxide (CO2) emission. The nitrogen electroreduction reaction (NERR), as an energy-efficient and environment-friendly process of converting nitrogen (N2) to NH3 under ambient conditions, has been regarded as a promising alternative to the Haber-Bosch process and has received enormous interest in recent years. Although some exciting progress has been made, considerable scientific and technical challenges still exist in improving the NH3 yield rate and Faradic efficiency, understanding the mechanism of the reaction and promoting the wide commercialization of NERR. Single-atom catalysts (SACs) have emerged as promising catalysts because of its atomically dispersed activity sites and maximized atom efficiency, unsaturated coordination environment, and its unique electronic structure, which could significantly improve the rate of reaction and yield rate of NH3. In this review we briefly introduce the unique structural and electronic features of SACs, which contributes to comprehensively understand the reaction mechanism owing to their structural simplicity and diversity, and in turn expedite the rational design of fantastic catalysts at the atomic scale. Then, we summarize the most recent experimental and computational efforts on developing novel SACs with excellent NERR performance, including precious metal-, nonprecious metal-and nonmetal-based SACs. Finally, we present challenges and perspectives of SACs on NERR, as well as some potential means for advanced NERR catalyst.

Two-dimensional metal–organic framework Mo3(C2O)12 as a promising single-atom catalyst for selective nitrogen-to-ammonia conversion

“…12–14 Recently, there have been great efforts to design NRR SACs based on 2D materials. 15 For example, single metal atoms anchored on graphene-based systems, 16–18 defective h -BN nanosheets, 19,20 graphdiyne (graphyne), 21–24 CN (CN, C 2 N, and C 3 N 4 ) materials, 25–27 two-dimensional transition metal dichalcogenides, 28 and so on. Therefore, the best platform usually possesses a defective vacancy or sufficient large holes, which could capture the metal atom effectively.…”

Recent Advances on Dual‐Band Electrochromic Materials and Devices

“…The following strategies are helpful to improve the performance of the dual‐band EC device and to meet real applications ( Figure ). (1) Novel dual‐band EC materials with multi‐doping, diverse particle sizes, [ 53 ] low dimensional nanostructures, [ 132 ] porous property, various morphologies [ 29 ] and compositions, crystalline structures [ 133 ] are encouraged to be synthesized, supplemented by different types of electrolytes [ 134 ] and elaborate in‐situ characterizations [ 135–137 ] to demonstrate high‐performance dual‐band EC devices with selective and independent optical modulation and improved ion transport rate, and further help to fully understand the mechanism of dual‐band EC progress as well. (2) The composition and pattern of the ion‐storage layer should be optimized to ensure high optical contrast, accelerate the switching process, and fabricate large‐area devices.…”

Single-atom catalysts for thermal- and electro-catalytic hydrogenation reactions

“…The compounds are not only limited to organic ones (such as alkynes, aldehydes, alkenes, ketones, nitroarenes, and so on), but also span a variety of inorganic ones (such as metal carbonates, nitrates, carbon dioxide, nitrogen, and so on). [6][7][8][9][10] The thermal-catalytic hydrogenation reaction, in most cases, uses gaseous hydrogen (H 2 ) as the hydrogen source to reduce unsaturated compounds with a suitable catalyst capable of dissociating hydrogen gas. For example, in the thermal-catalytic hydrogenation of alkynes under reaction conditions of 175 C and 0.1 MPa H 2 , ethylene could be obtained at 94% conversion over the Au/SiO 2 catalyst.…”