Rational design of electrocatalysts and photo(electro)catalysts for nitrogen reduction to ammonia (NH<sub>3</sub>) under ambient conditions

Guo, Chunxian; Ran, Jingrun; Vasileff, Anthony; Qiao, Shi Zhang

doi:10.1039/c7ee02220d

Cited by 1,311 publications

(910 citation statements)

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“…under ambient conditions.D ensity functional theory calculations reveal that the active orbital and electrons of zigzag and diff-zigzag type edges of FL-BP NSs enable selective electrocatalysis of N 2 to NH 3 via an alternating hydrogenation pathway.T his work proves the feasibility of using an onmetallic simple substance as an itrogen-fixing catalyst and thus opening an ew avenue towardst he development of more efficient metal-free catalysts. [4][5][6] However,o wing to the strong dipole moment of the N N triple bond and the vigorous competing hydrogen evolution reaction (HER), [7][8][9][10][11] the development of highly effective catalysts with sufficient activity and selectivity is essential. [1] At present, the energyintensive Haber-Bosch process is the main artificial synthesis route for ammonia, and this process uses more than 1% of global annual energy consumption and produces carbon dioxide emissions.…”

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Ammonia Synthesis Under Ambient Conditions: Selective Electroreduction of Dinitrogen to Ammonia on Black Phosphorus Nanosheets

et al. 2019

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Constructing efficient catalysts for the N 2 reduction reaction (NRR) is am ajor challenge for artificial nitrogen fixation under ambient conditions.H erein, inspired by the principle of "like dissolves like", it is demonstrated that am ember of the nitrogen family,w ell-exfoliated few-layer black phosphorus nanosheets (FL-BP NSs), can be used as an efficient nonmetallic catalyst for electrochemical nitrogen reduction. The catalyst can achieve ah igh ammonia yield of 31.37 mgh À1 mg À1cat. under ambient conditions.D ensity functional theory calculations reveal that the active orbital and electrons of zigzag and diff-zigzag type edges of FL-BP NSs enable selective electrocatalysis of N 2 to NH 3 via an alternating hydrogenation pathway.T his work proves the feasibility of using an onmetallic simple substance as an itrogen-fixing catalyst and thus opening an ew avenue towardst he development of more efficient metal-free catalysts. Ammonia (NH 3 )i sabasic raw chemical material used in modern industry and agriculture. [1] At present, the energyintensive Haber-Bosch process is the main artificial synthesis route for ammonia, and this process uses more than 1% of global annual energy consumption and produces carbon dioxide emissions. [2,3] In contrast, electrochemical reduction of nitrogen into ammonia under ambient conditions is ap otential strategy for sustainable ammonia production. [4][5][6] However,o wing to the strong dipole moment of the N N triple bond and the vigorous competing hydrogen evolution reaction (HER), [7][8][9][10][11] the development of highly effective catalysts with sufficient activity and selectivity is essential.According to available experimental and theoretical NRR data, an active center that can easily adsorb nitrogen molecules and sufficiently activate the N Nt riple bond is very desirable. [12][13][14][15] To this end, the search for an electrocatalytic NRR center in recent years has mainly focused on transition-metal-based materials. [8,[14][15][16][17][18][19][20][21][22][23] Specifically,b enefiting from the unoccupied and occupied dorbitals of transition metals,t he electron density from N 2 is synergically accepted with appropriate energy and symmetry,a nd then, the transition metal donates electrons to the p*o rbital of NN, strengthening N 2 adsorption and weakening the NNbond. [7] It is worthwhile to note that although an unoccupied nonbonding orbital and electron donor site with abundant electron cloud density are prerequisites for aN RR catalyst, the do rbital electrons in transition metals also benefit the formation of metal-hydrogen bonds,w hich will exacerbate the competitive hydrogen evolution reaction and limit the nitrogen reduction selectivity and catalytic efficiency. [24] Compared to transition metals,t he weak hydrogen adsorption of nonmetallic elements and their abundant valence electrons should provide am ore ideal nitrogen activation center. [25,26] Some recent studies have shown that the use of nonmetallic components as active centers may be an effective way to obta...

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Ammonia Synthesis Under Ambient Conditions: Selective Electroreduction of Dinitrogen to Ammonia on Black Phosphorus Nanosheets

et al. 2019

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“…One of the cheapest and most abundant metals on earth, iron, is an effective dopant for greatly improving the nitrogen reduction reaction (NRR) performance of TiO 2 nanoparticles in ambient N 2 -to-NH 3 conversion. [5][6][7][8] Noble metals perform the NRR efficiently;however, their scarcity and high cost limits their application in large-scale N 2 reduction. The catalytic mechanism is further probed with theoretical calculations.…”

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Greatly Improving Electrochemical N₂ Reduction over TiO₂ Nanoparticles by Iron Doping

Zhu

Xing

et al. 2019

Angewandte Chemie

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Titanium-based catalysts are needed to achieve electrocatalytic N 2 reduction to NH 3 with alarge NH 3 yield and ahigh Faradaic efficiency (FE). One of the cheapest and most abundant metals on earth, iron, is an effective dopant for greatly improving the nitrogen reduction reaction (NRR) performance of TiO 2 nanoparticles in ambient N 2 -to-NH 3 conversion. In 0.5 m LiClO 4 ,F e-doped TiO 2 catalyst attains ah igh FE of 25.6 %a nd al arge NH 3 yield of 25.47 mgh À1 mg cat À1 at À0.40 Vv ersus ar eversible hydrogen electrode.This performance compares favorably to those of all previously reported titanium-and iron-based NRR electrocatalysts in aqueous media. The catalytic mechanism is further probed with theoretical calculations.Asanessential activated nitrogen source,NH 3 is extensively used to manufacture dyes,p olymers,f ertilizers,a nd explosives,and it also serves as carbon-neutral energy carrier with high energy density. [1][2][3] To date,the dominant industrial route for NH 3 synthesis is the Haber-Bosch process using N 2 and H 2 as the feeding gases,b ut this process operates at high temperature and high pressure,a nd consumes al arge amount of energy while emitting CO 2 . [4] Electrochemical N 2 reduction offers an attractive alternative in an environmentally benign and sustainable manner,b ut the strong N N bond is fairly inert and thus difficult to break in ac hemical reaction, underlying the need for electrocatalysts with high activity in the nitrogen reduction reaction (NRR). [5][6][7][8] Noble metals perform the NRR efficiently;however, their scarcity and high cost limits their application in large-scale N 2 reduction. [8][9][10][11] NRR research has thus shifted to development of noble-metal-free alternatives. [12][13][14][15][16][17][18][19][20][21][22][23][24] TiO 2 is highly adaptable as asemiconductor catalyst because of its long-term thermodynamic stability,n atural abundance,a nd nontoxicity. [25] Recent studies have demonstrated that TiO 2 with oxygen defects has good electrocatalytic activity for the NRR, [26,27] and heteroatoms (B, [28] C, [29] V, [30] and Zr, [31] )a re effective dopants to enhance the NRR performances of TiO 2 catalysts. However,T i-based catalysts that simultaneously achieve al arge NH 3 yield with ah igh Faradaic efficiency (FE) are not available thus far.As one of the cheapest and most abundant metals on the earth, [32] Fe also exists in biological nitrogenases for natural N 2 fixation. [33] Fe compounds have been widely utilized as catalysts for artificial N 2 fixation in the Haber-Bosch [4] and electrochemical [34][35][36][37][38][39] processes.I ti st hus natural for us to explore use of Fe as ad opant for TiO 2 ,w hich has not been reported before.Herein, we report on our recent experimental results that Fe-doped TiO 2 is superior in performances for electrocatalytic N 2 reduction under ambient conditions.I n 0.5 m LiClO 4 ,t his catalyst achieves ah igh FE of 25.6 %a nd al arge NH 3 yield of 25.47 mgh À1 mg cat À1 at À0.40 Vv ersus ar eversible hydrogen electrode (...

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“…[6,[9][10][11] This traditional process is not only energy-intensive, but the H 2 used as the feeding gas often comes from fossil fuels leading to serious greenhouse gas emission. [14,15] Efficient catalysts based on noble metals have been designed to perform NRR with remarkable catalytic NH 3 is a valuable chemical with a wide range of applications, but the conventional Haber-Bosch process for industrial-scale NH 3 production is highly energy-intensive with serious greenhouse gas emission. [12,13] Although tackling the energy-and H 2 -intensive operations by the Haber-Bosch process, it is still challenged with N 2 activation and electrocatalysts for N 2 reduction reaction (NRR) are a prerequisite.…”

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Electrocatalytic Hydrogenation of N₂to NH₃by MnO: Experimental and Theoretical Investigations

et al. 2018

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NH3 is a valuable chemical with a wide range of applications, but the conventional Haber–Bosch process for industrial‐scale NH3 production is highly energy‐intensive with serious greenhouse gas emission. Electrochemical reduction offers an environmentally benign and sustainable route to convert N2 to NH3 at ambient conditions, but its efficiency depends greatly on identifying earth‐abundant catalysts with high activity for the N2 reduction reaction. Here, it is reported that MnO particles act as a highly active catalyst for electrocatalytic hydrogenation of N2 to NH3 with excellent selectivity. In 0.1 m Na2SO4, this catalyst achieves a high Faradaic efficiency up to 8.02% and a NH3 yield of 1.11 × 10−10 mol s−1 cm−2 at −0.39 V versus reversible hydrogen electrode, with great electrochemical and structural stability. On the basis of density functional theory calculations, MnO (200) surface has a smaller adsorption energy toward N than that of H with the *N2 → *N2H transformation being the potential‐determining step in the nitrogen reduction reaction.

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Rational design of electrocatalysts and photo(electro)catalysts for nitrogen reduction to ammonia (NH₃) under ambient conditions

Abstract: This perspective highlights the rational design of efficient electrocatalysts and photo(electro)catalysts for N2 reduction to ammonia (NH3) under ambient conditions.

Cited by 1,311 publications

References 82 publications

Ammonia Synthesis Under Ambient Conditions: Selective Electroreduction of Dinitrogen to Ammonia on Black Phosphorus Nanosheets

Ammonia Synthesis Under Ambient Conditions: Selective Electroreduction of Dinitrogen to Ammonia on Black Phosphorus Nanosheets

Greatly Improving Electrochemical N₂ Reduction over TiO₂ Nanoparticles by Iron Doping

Electrocatalytic Hydrogenation of N₂to NH₃by MnO: Experimental and Theoretical Investigations

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Rational design of electrocatalysts and photo(electro)catalysts for nitrogen reduction to ammonia (NH3) under ambient conditions

Abstract: This perspective highlights the rational design of efficient electrocatalysts and photo(electro)catalysts for N2 reduction to ammonia (NH3) under ambient conditions.

Cited by 1,311 publications

References 82 publications

Ammonia Synthesis Under Ambient Conditions: Selective Electroreduction of Dinitrogen to Ammonia on Black Phosphorus Nanosheets

Ammonia Synthesis Under Ambient Conditions: Selective Electroreduction of Dinitrogen to Ammonia on Black Phosphorus Nanosheets

Greatly Improving Electrochemical N2 Reduction over TiO2 Nanoparticles by Iron Doping

Electrocatalytic Hydrogenation of N2to NH3by MnO: Experimental and Theoretical Investigations

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Rational design of electrocatalysts and photo(electro)catalysts for nitrogen reduction to ammonia (NH₃) under ambient conditions

Greatly Improving Electrochemical N₂ Reduction over TiO₂ Nanoparticles by Iron Doping

Electrocatalytic Hydrogenation of N₂to NH₃by MnO: Experimental and Theoretical Investigations