Electrochemical ammonia synthesis: fundamental practices and recent developments in transition metal boride, carbide and nitride-class of catalysts

Abstract

Ammonia, the value-added chemical, major fertilizer and future transportation fuel is conventionally and synthetically produced by the energy intensive Haber-Bosch process. For the conversion of nitrogen to ammonia, more energy...

Revisiting the Electrochemical Nitrogen Reduction on Molybdenum and Iron Carbides: Promising Catalysts or False Positives?

“…Here, we critically assess the electrocatalytic NRR activity of molybdenum and iron carbides, where more than 10 independent literature reports claim to observe superior or excellent catalytic performance. 23 , 24 , 31 − 38 In the present work, α-Mo 2 C nanodots from Cheng et al (reported as the most promising carbide catalyst) are reproduced and compared with α-Mo 2 C nanoparticles as a benchmark. 23 Additionally, nanostructured θ-Fe 3 C and χ-Fe 5 C 2 are synthesized and examined for their NRR activity.…”

“…As a consequence, a handful of research groups have tried to reproduce electrocatalysts initially labeled as promising, such as Fe, Bi, Au, VN, CoMo, Mo 2 N, and MoS 2 , ,,− but discovered that the quantified ammonia must originate from sources other than the NRR. Here, we critically assess the electrocatalytic NRR activity of molybdenum and iron carbides, where more than 10 independent literature reports claim to observe superior or excellent catalytic performance. ,,− In the present work, α-Mo 2 C nanodots from Cheng et al (reported as the most promising carbide catalyst) are reproduced and compared with α-Mo 2 C nanoparticles as a benchmark . Additionally, nanostructured θ-Fe 3 C and χ-Fe 5 C 2 are synthesized and examined for their NRR activity.…”

The journey of iron-based electrocatalytic materials for nitrogen reduction reaction: from current status to future prospects

“…Transition metal borides, also known as MBenes, are an emergent class of catalysts that are still in their infancy in the electrochemical NRR eld. [187][188][189] MBenes as NRR electrocatalysts have the advantage of dual active edges from both the exposed metal end and the exposed boride end. 190 In the previous section, we have elaborated on how the electrons and orbitals of iron activate nitrogen bonds.…”

A High-Throughput Screening toward Efficient Nitrogen Fixation: Transition Metal Single-Atom Catalysts Anchored on an Emerging π–π Conjugated Graphitic Carbon Nitride (g-C10N3) Substrate with Dirac Dispersion

“…Currently, extensive efforts have been contributed to design high-efficient NRR catalysts to achieve high-efficiency-NRR performance . To date, many metal-based catalysts have been designed theoretically or prepared experimentally, including noble-metals (Ru, Rh, Pt, Au, and Ag), transition metal sulfides (CoS 2 and MoS 2 ), nitrides (VN, Mo 2 N), phosphides (δ-AlP 3 ), carbides (Mo 2 C), and oxides (Mo-doped W 18 O 49 and Fe 2 O 3 –CNT).…”

“…17−19 Currently, extensive efforts have been contributed to design high-efficient NRR catalysts to achieve high-efficiency-NRR performance. 20 To date, many metal-based catalysts have been designed theoretically or prepared experimentally, including noble-metals (Ru, 21 Rh, 22 Pt, 23 Au, 24 and Ag 25 ), transition metal sulfides (CoS 2 26 and MoS 2 27 ), nitrides (VN, 28 Mo 2 N 29 ), phosphides (δ-AlP 3 30 ), carbides (Mo 2 C 31 ), and oxides (Modoped W 18 O 49 32 and Fe 2 O 3 −CNT 33 ). It is generally recognized that the coexistent occupied and empty d orbitals can back-donate π-electrons to and accept lone-pair electrons from N 2 , which determines the origin of the NRR activity for these transition metal (TM) containing catalysts.…”