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1.
Ammonia (NH3), an important raw material for chemical industry and agriculture, is also considered to be an intriguing energy storage and transportation media for chemical conversion schemes. The world's primary NH3 supply is based on the natural nitrogen fixation by diazotrophs through an enzymatic nitrogenase process and the industrial nitrogen fixation through a traditional Haber–Bosch process. The natural synthesis of NH3 can hardly meet the rapidly growing global demand. Meanwhile, the industrial NH3 production is still dominated by the high‐temperature and high‐pressure reaction between nitrogen and hydrogen (N2 + 3H2 → 2NH3), requiring intensive energy input and generating massive CO2. Therefore, seeking a breakthrough in the development of catalysts toward efficient ammonia synthesis has become the frontier of energy and chemical conversion schemes. This review summarizes and discusses the recent progress on developing new strategies to optimize the efficiency of NH3 production coupled with renewable energy sources, with a specific focus on electrocatalytic and photoelectrocatalytic conversion of N2 to NH3. The most recent advances in the development of catalytic materials, the design of the reaction systems, and the computational insights for electrochemical and photoelectrochemical ammonia synthesis are covered. 相似文献
2.
Yanyan Liu Miaomiao Han Qizhong Xiong Shengbo Zhang Cuijiao Zhao Wanbing Gong Guozhong Wang Haimin Zhang Huijun Zhao 《Liver Transplantation》2019,9(14)
The Haber‐Bosch process can be replaced by the ambient electrocatalytic N2 reduction reaction (NRR) to produce NH3 if suitable electrocatalysts can be developed. However, to develop high performance N2 fixation electrocatalysts, a key issue to be resolved is to achieve efficient hydrogenation of N2 without interference by the thermodynamically favored hydrogen evolution reaction (HER). Herein, in‐operando created strong Li–S interactions are reported to empower the S‐rich MoS2 nanosheets with superior NRR catalytic activity and HER suppression ability. The Li+ interactions with S‐edge sites of MoS2 can effectively suppress hydrogen evolution reaction by reducing H* adsorption free energy from 0.03 to 0.47 eV, facilitate N2 adsorption by increasing N2 adsorption free energy from –0.32 to –0.70 eV and enhance electrocatalytic N2 reduction activity by decreasing the activation energy barrier of the reaction control step (*N2 → *N2H) from 0.84 to 0.42 eV. A NH3 yield rate of 43.4 μg h?1 mg?1 MoS2 with a faradaic efficiency (FE) of 9.81% can be achieved in presence of strong Li–S interactions, more than 8 and 18 times by the same electrocatalyst in the absence of Li–S interactions. This report opens a new way to design and develop catalysts and catalysis systems. 相似文献
3.
Dazhi Yao Cheng Tang Laiquan Li Bingquan Xia Anthony Vasileff Huanyu Jin Yanzhao Zhang Shi‐Zhang Qiao 《Liver Transplantation》2020,10(33)
The electrochemical nitrogen reduction reaction (NRR) is a promising alternative to the energy‐intensive Haber–Bosch process for ammonia synthesis. Among the possible electrocatalysts, bismuth‐based materials have shown unique NRR properties due to their electronic structures and poor hydrogen evolution activity. However, identification of the active sites and reaction mechanism is still difficult due to structural and chemical changes under reaction potentials. Herein, in situ Raman spectroscopy, complemented by electron microscopy, is employed to investigate the structural and chemical transformation of the Bi species during the NRR. Nanorod‐like bismuth‐based metal–organic frameworks are reduced in situ and fragment into densely contacted Bi0 nanoparticles under the applied potentials. The fragmented Bi0 nanoparticles exhibit excellent NRR performance in both neutral and acidic electrolytes, with an ammonia yield of 3.25 ± 0 .08 µg cm?2 h?1 at ?0.7 V versus reversible hydrogen electrode and a Faradaic efficiency of 12.11 ± 0.84% at ?0.6 V in 0.10 m Na2SO4. Online differential electrochemical mass spectrometry detects the production of NH3 and N2H2 during NRR, suggesting a possible pathway through two‐step reduction and decomposition. This work highlights the importance of monitoring and optimizing the electronic and geometric structures of the electrocatalysts under NRR conditions. 相似文献
4.
Anchoring PdCu Amorphous Nanocluster on Graphene for Electrochemical Reduction of N2 to NH3 under Ambient Conditions in Aqueous Solution
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As an alternative approach for N2 fixation under milder conditions, electrocatalytic nitrogen reduction reaction (NRR) represents a very attractive strategy for sustainable development and N2 cycle to store and utilize energy from renewable sources. However, the research on NRR electrocatalysts still mainly focuses on noble metals, while, high costs and limited resources greatly restrict their large‐scale applications. Herein, as a proof‐of‐concept experiment, taking PdCu amorphous nanocluster anchored on reduced graphene oxide (rGO) as NRR catalysts, the optimum Pd0.2Cu0.8/rGO composite presents a synergistic effect and shows superior electrocatalytic performance toward NRR under ambient conditions (yield: 2.80 µg h?1 mgcat.?1 at ?0.2 V vs reversible hydrogen electrode), which is much higher than that of monometallic, especially noble metal, counterparts. The superior catalytic performance of alloy catalysts with low noble metal loading would strongly spur interest toward more researches on NRR catalysts in the future. 相似文献
5.
W. T. De Nobel Jacky L. Snoep Hans V. Westerhoff Luuc R. Mur 《Journal of phycology》1997,33(5):794-799
The effect of simultaneous nitrogen fixation and phosphorus limitation on the physiological adaptation and growth performance of Aphanizomenon flos-aquae (L.) Ralfs PCC 7905 was studied in continuous culture. In the absence of ammonia, N2 fixation occurred and the maximum growth rate (as determined in diluted batch cultures) was lower. However, no distinction could be made between the steady-state N uptake rates (based on cellular N contents) of N2-fixing cells and cells grown with ammonia. At the higher dilution rates, the residual P concentration increased with increasing dilution rate, more so under N2-fixing conditions, compared to the cultures grown in the presence of ammonia. More generally, the yield of biomass per consumed P, as the biomass concentration itself, decreased with increasing dilution rate, and both were lower under N2-fixing conditions. The restricted biomass production under N2-fixing conditions suggests that reduction of N loading may benefit lake restoration projects. The influence of N2-fixation on the severity of P limitation is discussed in terms of metabolic control analysis. From the increase of the residual P concentration on switching from ammonium to N2-fixing conditions, it is deduced that under N2-fixing and P-limited conditions, control of growth is shared by N and P metabolism. 相似文献
6.
Kayaramkodath C. Ranjeesh Sukhjot Kaur Abdul K. Mohammed Safa Gaber Divyani Gupta Khaled Badawy Mohamed Aslam Nirpendra Singh Tina Skorjanc Matjaž Finšgar Jésus Raya Tharamani C. Nagaiah Dinesh Shetty 《Liver Transplantation》2024,14(5):2303068
The electrocatalytic nitrogen reduction reaction (NRR) driven by renewable electricity provides a green synthesis route for ammonia (NH3) production under ambient conditions but suffers from a low conversion yield and poor Faradaic efficiency (F.E.) because of strong competition from hydrogen evolution reaction (HER) and the poor solubility of N2 in aqueous systems. Herein, an in situ proton filter covalent organic framework catalyst ( Ru-Tta-Dfp ) is reported with inherent Ruthenium (Ru) sites where the framework controls reactant diffusion by suppressing proton supply and enhancing N2 flux, causing highly selective and efficient catalysis. The smart catalyst design results in a remarkable ammonia production yield rate of 2.03 mg h−1 mgcat−1 with an excellent F.E. of ≈52.9%. The findings are further endorsed with the help of molecular dynamics simulations and control COF systems without in situ proton filter feasibility. The results point to a paradigm shift in engineering high-performance NRR electrocatalysts for more feasible green NH3 production. 相似文献
7.
The production of ammonia (NH3) from molecular dinitrogen (N2) under mild conditions is one of the most attractive topics in the field of chemistry. Electrochemical reduction of N2 is promising for achieving clean and sustainable NH3 production with lower energy consumption using renewable energy sources. To date, emerging electrocatalysts for the electrochemical reduction of N2 to NH3 at room temperature and atmospheric pressure remain largely underexplored. The major challenge is to achieve both high catalytic activity and high selectivity. Here, the recent progress on the electrochemical nitrogen reduction reaction (NRR) at ambient temperature and pressure from both theoretical and experimental aspects is summarized, aiming at extracting instructive perceptions for future NRR research activities. The prevailing theories and mechanisms for NRR as well as computational screening of promising materials are presented. State‐of‐the‐art heterogeneous electrocatalysts as well as rational design of the whole electrochemical systems for NRR are involved. Importantly, promising strategies to enhance the activity, selectivity, efficiency, and stability of electrocatalysts toward NRR are proposed. Moreover, ammonia determination methods are compared and problems relating to possible ammonia contamination of the system are mentioned so as to shed fresh light on possible standard protocols for NRR measurements. 相似文献
8.
Michael F. Piehler Julianne Dyble Pia H. Moisander James L. Pinckney Hans W. Paerl 《Aquatic Ecology》2002,36(3):371-385
A variety of analyses were used to assess the structure (community composition) and function (assimilation number, nitrogen fixation) of phytoplankton in the Neuse River Estuary (NRE), NC under ambient and modified nutrient concentrations. Dilution bioassays were employed to reduce the concentration of nitrogen (N) or both N and phosphorus (P) and thus compare varied DIN:DIP ratios. Experimental manipulations created conditions that may result from mandated N load reductions to the estuary. We hypothesized that unilateral reduction of N loading to the NRE would increase the activity, abundance and diversity of N2 fixing cyanobacteria. Changes in phytoplankton primary productivity, N2 fixation (nitrogenase activity), genetic potential for N2 fixation (presence of nifH), phytoplankton taxonomic composition (diagnostic photopigment concentration) and abundances of N2 fixing cyanobacteria (microscopy) were determined. Decreasing ambient DIN:DIP ratios in NRE samples resulted in increased rates of N2 fixation when seed populations were present and environmental conditions were amenable. Decreasing the DIN:DIP ratio did not lead to an increase in the abundance or diversity of N2 fixing cyanobacteria. Because N2 fixing cyanobacteria were only actively fixing nitrogen during periods of low riverine N discharge (summer and early autumn), lowering nutrient ratios may not have a major impact on the NRE. However, the maximum potential amount of N from N2 fixation was calculated using rates from this study and was found to be approximately 3% of total riverine loading of N to the NRE. Because N2 fixation occurs farther downstream and later in the year than riverine N loading to the NRE, there is potential for N2 fixation to modify N dynamics. Analyses of the phytoplankton community as a whole in these relatively short term experiments indicated that reduced DIN:DIP may not have a major impact on their structure and function. 相似文献
9.
A. G. Zhivotchenko E. S. Nikonova M. H. Jørgensen 《Bioprocess and biosystems engineering》1995,14(1):9-15
Nitrogen fixation has been investigated during chemostat fermentations with a culture of Methylococcus capsulatus with natural gas. It is demonstrated that nitrogen fixation occurs under conditions when either nitrate or ammonia as nitrogen source is insufficient for the growth on fixed supply of methane and oxygen. The fixation occurs contrary to expectations within a wide range of dilution rates and with variation of concentration of liquid source of nitrogen. An O2 optimum is determined for the nitrogenase system of the culture in an assay. During fermentation a complete abolishment of nitrogenase reaction is attained at 15% air saturation (dissolved oxygen). Conditions for N2 fixation is unaltered with change of pH from 6.8 to 5.7. 相似文献
10.
Hydrogen inhibition of nitrogen reduction by nitrogenase in isolated soybean nodule bacteroids
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Dihydrogen, a by-product of biological nitrogen fixation, is a competitive inhibitor of N2 reduction by nitrogenase. To evaluate the significance of H2 inhibition in vivo, we have measured the apparent inhibition constant for H2 inhibition of N2 reduction in Bradyrhizobium japonicum bacteroids isolated from soybean nodules. The rate of N2 reduction was measured as ammonia production by bacteroids incubated in a buffer containing 200 micromolar leghemoglobin and 10 millimolar succinate under 0.02 atmosphere O2 and various concentrations of N2 and H2. The apparent inhibition constant for H2 under these conditions was determined to be approximately 0.03 atmosphere. This relatively low value strengthens the proposal that H2 inhibition of N2 reduction may be a significant factor in lowering the efficiency of nitrogen fixation in legume nodules. 相似文献
11.
Wei Peng Min Luo Xiandong Xu Kang Jiang Ming Peng Dechao Chen Ting‐Shan Chan Yongwen Tan 《Liver Transplantation》2020,10(25)
The electrochemical nitrogen reduction reaction (NRR) process usually suffers extremely low Faradaic efficiency and ammonia yields due to sluggish N?N dissociation. Herein, single‐atomic ruthenium modified Mo2CTX MXene nanosheets as an efficient electrocatalyst for nitrogen fixation at ambient conditions are reported. The catalyst achieves a Faradaic efficiency of 25.77% and ammonia yield rate of 40.57 µg h?1 mg?1 at ‐0.3 V versus the reversible hydrogen electrode in 0.5 m K2SO4 solution. Operando X‐ray absorption spectroscopy studies and density functional theory calculations reveal that single‐atomic Ru anchored on MXene nanosheets act as important electron back‐donation centers for N2 activation, which can not only promote nitrogen adsorption and activation behavior of the catalyst, but also lower the thermodynamic energy barrier of the first hydrogenation step. This work opens up a promising avenue to manipulate catalytic performance of electrocatalysts utilizing an atomic‐level engineering strategy. 相似文献
12.
13.
Nitrogen Fixation by the Photosynthetic Sulfur Bacterium Chlorobium phaeobacteroides from Lake Kinneret 总被引:1,自引:1,他引:0
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N2 fixation by Chlorobium phaeobacteroides from Lake Kinneret was dependent on ammonia concentration and light intensity. In the thermocline of Lake Kinneret, N2 fixation and photosynthesis were low. It was concluded that the bacteria do not contribute significantly to the organic nitrogen load of the lake. 相似文献
14.
Soybean nodulation and N2 fixation response to drought under carbon dioxide enrichment 总被引:1,自引:1,他引:0
The combined effects of carbon dioxide (CO2) enrichment and water deficits on nodulation and N2 fixation were analysed in soybean [Glycine max (L.) Merr.]. Two short-term experiments were conducted in greenhouses with plants subjected to soil drying, while exposed to CO2 atmospheres of either 360 or 700 μmol CO2 mol–1. Under drought-stressed conditions, elevated [CO2] resulted in a delay in the decrease in N2 fixation rates associated with drying of the soil used in these experiments. The elevated [CO2] also allowed the plants under drought to sustain significant increases in nodule number and mass relative to those under ambient [CO2]. The total non-structural carbohydrate (TNC) concentration was lower in the shoots of the plants exposed to drought; however, plants under elevated CO2 had much higher TNC levels than those under ambient CO2. For both [CO2] treatments, drought stress induced a substantial accumulation of TNC in the nodules that paralleled N2 fixation decline, which indicates that nodule activity under drought may not be carbon limited. Under drought stress, ureide concentration increased in all plant tissues. However, exposure to elevated [CO2] resulted in substantially less drought-induced ureide accumulation in leaf and petiole tissues. A strong negative correlation was found between ureide accumulation and TNC levels in the leaves. This relationship, together with the large effect of elevated [CO2] on the decrease of ureide accumulation in the leaves, indicated the importance of ureide breakdown in the response of N2 fixation to drought and of feedback inhibition by ureides on nodule activity. It is concluded that an important effect of CO2 enrichment on soybean under drought conditions is an enhancement of photoassimilation, an increased partitioning of carbon to nodules and a decrease of leaf ureide levels, which is associated with sustained nodule growth and N2 rates under soil water deficits. We suggest that future [CO2] increases are likely to benefit soybean production by increasing the drought tolerance of N2 fixation. 相似文献
15.
1. In situ measurements of nitrogen fixation rates for Aphanizomenon in fertile Colorado lakes with low inorganic nitrogen concentrations demonstrated high efficiency of nitrogen fixation at low irradiance. 2. For study populations, rates of N2 fixation in darkness and with alternating exposure to light and darkness were a higher percentage of light‐saturated rates for Aphanizomenon than for Anabaena, suggesting storage of reduced metabolites at high irradiance that are used subsequently by Aphanizomenon when cells are forced by mixing into zones of low irradiance. Also, saturation of N2 fixation occurred over a lower range of irradiance for Aphanizomenon than for Anabaena. 3. High efficiency of N2 fixation in Aphanizomenon at low or fluctuating irradiance is complementary to its previously demonstrated high efficiency of photosynthesis at low irradiance. Nitrogen fixation rate was also strongly related to DIN concentration; fixation was highest at low DIN (maximum < 5 μg L?1) but was also most vulnerable to photoinhibition under such conditions. 4. The fixation capabilities of Aphanizomenon under weak or varying irradiance could explain its commonly observed domination over Anabaena when transparency is low and available nitrogen is scarce. 相似文献
16.
Nutrient biogeochemistry associated with the early stages of soil development in deltaic floodplains has not been well defined. Such a model should follow classic patterns of soil nutrient pools described for alluvial ecosystems that are dominated by mineral matter high in phosphorus and low in carbon and nitrogen. A contrast with classic models of soil development is the anthropogenically enriched high nitrate conditions due to agricultural fertilization in upstream watersheds. Here we determine if short-term patterns of soil chemistry and dissolved inorganic nutrient fluxes along the emerging Wax Lake delta (WLD) chronosequence are consistent with conceptual models of long-term nutrient availability described for other ecosystems. We add a low nitrate treatment more typical of historic delta development to evaluate the role of nitrate enrichment in determining the net dinitrogen (N2) flux. Throughout the 35-year chronosequence, soil nitrogen and organic matter content significantly increased by an order of magnitude, whereas phosphorus exhibited a less pronounced increase. Under ambient nitrate concentrations (>60 μM), mean net N2 fluxes (157.5 μmol N m?2 h?1) indicated greater rates of gross denitrification than gross nitrogen fixation; however, under low nitrate concentrations (<2 μM), soils switched from net denitrification to net nitrogen fixation (?74.5 μmol N m?2 h?1). As soils in the WLD aged, the subsequent increase in organic matter stimulated net N2, oxygen, nitrate, and nitrite fluxes producing greater fluxes in more mature soils. In conclusion, soil nitrogen and carbon accumulation along an emerging delta chronosequence largely coincide with classic patterns of soil development described for alluvial floodplains, and substrate age together with ambient nitrogen availability can be used to predict net N2 fluxes during early delta evolution. 相似文献
17.
Nitrogen fixation is a critical part of the global nitrogen cycle, replacing biologically available reduced nitrogen lost by denitrification. The redox‐sensitive trace metals Fe and Mo are key components of the primary nitrogenase enzyme used by cyanobacteria (and other prokaryotes) to fix atmospheric N2 into bioessential compounds. Progressive oxygenation of the Earth's atmosphere has forced changes in the redox state of the oceans through geologic time, from anoxic Fe‐enriched waters in the Archean to partially sulfidic deep waters by the mid‐Proterozoic. This development of ocean redox chemistry during the Precambrian led to fluctuations in Fe and Mo availability that could have significantly impacted the ability of prokaryotes to fix nitrogen. It has been suggested that metal limitation of nitrogen fixation and nitrate assimilation, along with increased rates of denitrification, could have resulted in globally reduced rates of primary production and nitrogen‐starved oceans through much of the Proterozoic. To test the first part of this hypothesis, we grew N2‐fixing cyanobacteria in cultures with metal concentrations reflecting an anoxic Archean ocean (high Fe, low Mo), a sulfidic Proterozoic ocean (low Fe, moderate Mo), and an oxic Phanerozoic ocean (low Fe, high Mo). We measured low rates of cellular N2 fixation under [Fe] and [Mo] estimated for the Archean ocean. With decreased [Fe] and higher [Mo] representing sulfidic Proterozoic conditions, N2 fixation, growth, and biomass C:N were similar to those observed with metal concentrations of the fully oxygenated oceans that likely developed in the Phanerozoic. Our results raise the possibility that an initial rise in atmospheric oxygen could actually have enhanced nitrogen fixation rates to near modern marine levels, providing that phosphate was available and rising O2 levels did not markedly inhibit nitrogenase activity. 相似文献
18.
H. -J. Schick 《Archives of microbiology》1971,75(2):89-101
Summary Whole cells of Rhodospirillum rubrum were cultivated in a malate medium lacking bound nitrogen under N2 and tested for their nitrogenase activity by measuring the disappearance of nitrogen manometrically.Several experimental conditions were relevant in maintaining consistently high activities. These included: a) light intensity, b) substrate concentration, c) concentration of the cell suspension, d) buffer molarity, pH, and e) temperature.Under our optimal experimental conditions about 6 moles of either l-malate, fumarate, succinate or 10 moles of pyruvate were consumed per 1 mole of molecular nitrogen.The amount of gas taken up by the cells agreed quantitatively with the increase of bound nitrogen found in the cells by microkjeldahl determinations.The fixation of molecular nitrogen is suppresed quickly and specifically by very small amounts of ammonia (<5 g ammonia N/ml). The duration of this inhibition depends on the amount of ammonia available to the cells. 相似文献
19.
Probably the first nitrogen fixers were anaerobic, non-photosynthetic, bacteria, i.e. fermenters. During the evolution of N2 fixation they still needed nitrogen on the oxidation level of ammonia. Because of the complexities in structure and function of nitrogenase this evolution must have required a long time. The photosynthetic and later the respiring bacteria inherited the capacity for N2 fixation from the fermenters, but the process did not change a great deal when it was taken over.Because of the long need for NH3, which is unstable in a redoxneutral atmosphere, a long-persisting reducing atmosphere was needed. The transition to a redoxneutral atmosphere, dominated by CO2, H2O and N2, cannot have been rapid, and the NH3 in it was recycled. Probably the atmosphere contained for a long time, as was suggested by Urey but is often denied now, a great deal of methane as a reductant. The recycling occurred with participation of intermediates like cyanide, through energy input as UV radiation or as electric discharges. A stationary state was set up.The hypothesis is recalled that coloured, photosynthetic, NH3 bacteria, analogous to coloured sulphur bacteria, may have existed, or may still exist, in reducing conditions. A few remarks are made about the origin of nitrification in the later, oxidizing atmosphere. 相似文献
20.
N. Burias C. Planchon 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1992,83(5):543-548
Summary Nitrogen fixation is generally considered to be a major parameter of productivity in soybean (Glycine max). The aim of the investigations reported here was to analyse the genetic behaviour of this trait in view of its possible use as an indirect criterion of selection for productivity. Divergent selection for nitrogen fixation rate was carried out on F2 populations obtained from crosses between high-yielding cultivars that are well adapted to French climatic conditions. The genetic component of nitrogen fixation and yield was isolated through the analysis of (1) the nitrogen fixation potentials of the genotypes under controlled conditions and (2) the field yields under favourable conditions. Divergent selection resulted in two groups of genotypes whose nitrogen fixation abilities are significantly different. The F6 filial progeny obtained by single seed descent from the two groups displayed significantly different abilities for nitrogen fixation and for field productivity. The gain achieved for the nitrogen fixation activity with respect to the mean value of the parents ranged from 20% to 33% for the positive selection, depending on the crosses. The occurrence of positive and significant correlations between the level of nitrogen fixation activity in F2 plants and N2 fixation or yield in the F6 generation corroborates the relatively high heritability of this trait and suggests its possible use as an indirect selection criterion for yield. 相似文献