Breaking scaling relations to achieve low-temperature ammonia synthesis through LiH-mediated nitrogen transfer and hydrogenation

Wang, Peikun; Chang, Fei; Gao, Wenbo; Guo, Jianping; Wu, Guotao; He, Teng; Chen, Ping

doi:10.1038/nchem.2595

Cited by 539 publications

(479 citation statements)

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“…It should be highlighted that TM(N)s–LiH composites has recently been reported for ammonia synthesis by our coauthors, Chen et al . TM(N)s–LiH composites show high catalytic activities in the temperature range of 150–327 °C.…”

Section: Figurementioning

confidence: 77%

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Transition and Alkali Metal Complex Ternary Amides for Ammonia Synthesis and Decomposition

Cao

Guo

Chang

et al. 2017

Chemistry A European J

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A new complex ternary amide, Rb [Mn(NH ) ], which simultaneously contains both transition and alkali metal catalytic sites, is developed. This is in line with the recently reported TM-LiH composite catalysts, which have been shown to effectively break the scaling relations and achieve ammonia synthesis under mild conditions. Rb [Mn(NH ) ] can be facilely synthesized by mechanochemical reaction at room temperature. It exhibits two temperature-dependent polymorphs, that is, a low-temperature orthorhombic and a high-temperature monoclinic structure. Rb [Mn(NH ) ] decomposes to N , H , NH , Mn N , and RbNH under inert atmosphere; whereas it releases NH at a temperature as low as 80 °C under H atmosphere. Those unique behaviors enable Rb [Mn(NH ) ], and its analogue K [Mn(NH ) ], to be excellent catalytic materials for ammonia decomposition and synthesis. Experimental results show both ammonia decomposition onset temperatures and conversion rates over Rb [Mn(NH ) ] and K [Mn(NH ) ] are similar to those of noble metal Ru-based catalysts. More importantly, these ternary amides exhibit superior capabilities in catalyzing NH synthesis, which are more than 3 orders of magnitude higher than that of Mn nitride and twice of that of Ru/MgO. The in situ SR-PXD measurement shows that manganese nitride, synergistic with Rb/KH or Rb/K(NH ) H , are likely the active sites. The chemistry of Rb /K [Mn(NH ) ] and Rb/K(NH ) H with H /N and NH correlates closely with the catalytic performance.

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Section: Figurementioning

confidence: 77%

“…The production of NH 3 in the TM(N)s–LiH composites can be divided into 3 different steps [Reactions 4–7, Eqs. ]:

true normalN_{2} \to normalN_{ad}

true LiH + normalN_{ad} \to [LiNH]

true [LiNH] + normalH_{2} \to NH_{3} + LiH

true Overall reaction : normalN_{2} + 3 H_{2} \to 2 NH_{3}

…”

Section: Figurementioning

confidence: 99%

Transition and Alkali Metal Complex Ternary Amides for Ammonia Synthesis and Decomposition

Cao

Guo

Chang

et al. 2017

Chemistry A European J

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“…Molecular hydrides have been studied in great detail in homogeneous catalysis because they are involved in several important hydrogen‐involved reactions, such as hydrogenation, hydroformylation, and hydrosilylation. In heterogeneous catalysis, hydrides on the surface or in the bulk also play a critical role as either active components or reaction intermediates from H 2 storage to catalytic processes, including hydrogenation/dehydrogenation, hydrodesulfurization, ammonia synthesis, hydrogenolysis (cracking), reforming, electrocatalysis, and photocatalysis . However, hydrides in heterogeneous catalysis are much less understood, regarding their structure and catalytic functions, compared with the molecular counterparts in homogeneous catalysis, mostly due to difficulties in revealing the molecular structure of hydrides on/in solid catalysts, the structures of which are complex.…”

Section: Introductionmentioning

confidence: 99%

Neutron Scattering Investigations of Hydride Species in Heterogeneous Catalysis

et al. 2018

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In heterogeneous catalysis, hydrides on the surface or in the bulk play a critical role as either active components or reaction intermediates in many hydrogen‐involving reactions, but characterization of the nature and structure of these hydride species remains challenging. Neutron scattering, which is extremely sensitive to light elements, such as hydrogen, has shown great potential in meeting this challenge. In this Minireview, recent advances in neutron studies of hydride species, mainly over the two most typical classes of catalysts—metals and oxides—are surveyed. Findings on catalysts outside these categories are raised if they are considered to be relevant for contextualization in the present Minireview. The adsorption, dissociation, spillover, and reactivity of hydrogen, especially hydride species over supported metal and oxide catalysts, have been successfully investigated, mostly by means of neutron vibrational spectroscopy. Insights from these neutron studies, which are otherwise not possible with other techniques, shed light on the interaction mechanism of hydrogen with solid surfaces and reaction mechanisms in which hydrogen is involved. Future research challenges on neutron scattering studies of hydrides, as well as catalysis in general, are also highlighted, and more operando‐type neutron studies need be conducted to advance the field.

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“…

performance and low price for working in alkaline solution.

Ruthenium, as a member of platinumgroup metals with 1/30 price of Pt, [14] has been proved to be a promising catalyst for HER in alkaline solution due to its high efficiency on water dissociation, [15][16][17][18] however, the strong interaction between Ru and H atoms impedes the subsequent hydrogen evolution because of the well-known scaling relationship for heterogeneous catalysts. [17,[19][20][21] Many efforts had been devoted to constructing Rubased heterostructures (e.g., Ru/carbon quantum dots, [22] Ru/C 2 N, [18] RuCo/ nitrogen-doped graphene, [23] fcc-Ru/ C 3 N 4 /C, [17] Ru/nitrogen-doped carbon, [24] Ru/graphene [25] ), which show great advantages on promoting water dissociation by synergistic effect. Nevertheless, less attention was paid on the improvement of hydrogen adsorption.

…”

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Ruthenium‐Based Single‐Atom Alloy with High Electrocatalytic Activity for Hydrogen Evolution

Chen

et al. 2019

Advanced Energy Materials

305

217

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performance and low price for working in alkaline solution.Ruthenium, as a member of platinumgroup metals with 1/30 price of Pt, [14] has been proved to be a promising catalyst for HER in alkaline solution due to its high efficiency on water dissociation, [15][16][17][18] however, the strong interaction between Ru and H atoms impedes the subsequent hydrogen evolution because of the well-known scaling relationship for heterogeneous catalysts. [17,[19][20][21] Many efforts had been devoted to constructing Rubased heterostructures (e.g., Ru/carbon quantum dots, [22] Ru/C 2 N, [18] RuCo/ nitrogen-doped graphene, [23] fcc-Ru/ C 3 N 4 /C, [17] Ru/nitrogen-doped carbon, [24] Ru/graphene [25] ), which show great advantages on promoting water dissociation by synergistic effect. Nevertheless, less attention was paid on the improvement of hydrogen adsorption. Recently, singleatom alloys (SAAs), which comprise separated solute atoms in metallic matrix, show great potential on circumventing scaling relationships. [23,26,27] meanwhile, the interaction between the solute atoms and matrix can modify their electronic structure, [26,28,29] leading to a suitable adsorption energy for hydrogen. Consequently, constructing Ru-based SAAs opens a new avenue toward high HER performance.Herein, we reported the synthesis of RuAu SAAs through a laser ablation in liquid (LAL) technique, which possesses strong quenching effect so as to fabricate metastable nanostructures with novel properties. [30,31] We choose Au as the alloying element on the basis of the following considerations: First, Au is known as an inert metal with weak hydrogen adsorption thus can counteract the strong hydrogen adsorption of Ru matrix. Second, the immiscibility between Au and Ru may create a unique geometric and electronic structure in RuAu SAAs. [32,33] Finally, chemically inert Au favors long-term durability during the reaction. As such, the as-prepared RuAu catalyst exhibits a low overpotential, 24 mV@10 mA cm −2 , which is much lower than Pt/C (46 mV@10 mA cm −2 ) in alkaline media. Moreover, the turnover frequency (TOF) of RuAu SAAs is three times that of the Pt/C catalyst. Density functional theory (DFT) computation reveals that the high performance originates from the relay catalysis of Ru host (for water dissociation) and Au dopant (for hydrogen evolution). To the best of our knowledge, this is the first report on the synthesis of RuAu SAAs with outstanding HER performance in alkaline media. Furthermore, the idea of the mixing immiscible metallic elements by LAL can be facilely Highly efficient and stable catalysts for the hydrogen evolution reaction, especially in alkaline conditions are crucial for the practical demands of electrochemical water splitting. Here, the synthesis of a novel RuAu single-atom alloy (SAA) by laser ablation in liquid is reported. The SAA exhibits a high stability and a low overpotential, 24 mV@10 mA cm −2 , which is much lower than that of a Pt/C catalyst (46 mV) in alkaline media. Moreover, the turnover frequency of RuAu SAA is th...

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Breaking scaling relations to achieve low-temperature ammonia synthesis through LiH-mediated nitrogen transfer and hydrogenation

Cited by 539 publications

References 49 publications

Transition and Alkali Metal Complex Ternary Amides for Ammonia Synthesis and Decomposition

Transition and Alkali Metal Complex Ternary Amides for Ammonia Synthesis and Decomposition

Neutron Scattering Investigations of Hydride Species in Heterogeneous Catalysis

Ruthenium‐Based Single‐Atom Alloy with High Electrocatalytic Activity for Hydrogen Evolution

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