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1.
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
2.
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
3.
In this study, ANAMMOX sludge was used as anode microbial catalysts to drive electrocatalytic reduction of nitrate in the SnCu-Pd/CFC catalytic cathode with total nitrogen (TN) removal efficiency of ANAMMOX as well as generate electricity without additional carbon and energy source. The system operation with 1.74 Kg·N/m3·d as nitrogen loading rate (NLR) exhibited a TN removal efficiency of 96.3% and obtained the highest nitrogen removal rate (NRR, 1.69 Kg·N/m3·d), increased by 14.9% and 0.30 Kg·N/m3·d compared with open circuit (control group), respectively. Maximum voltage (39.8 mV) and power density (21.20 ± 0.05 mW/m3, standardized to anode surface area) were also observed. Additionally, microbial community analysis revealed community structure of S2anode had an obvious disparity compared with others as the predominant ANAMMOX bacteria (AnAOB) closed to anode surface was evolved from Candidatus_Kuenenia to Candidatus_Brocadia. 相似文献
4.
Zhaoyong Jin Chuangwei Liu Zaichun Liu Jingrui Han Yanfeng Fang Yaqian Han Yusheng Niu Yuping Wu Chenghua Sun Yuanhong Xu 《Liver Transplantation》2020,10(22)
To enable an efficient and cost‐effective electrocatalytic N2 reduction reaction (NRR) the development of an electrocatalyst with a high NH3 yield and good selectivity is required. In this work, Ti3C2Tx MXene‐derived quantum dots (Ti3C2Tx QDs) with abundant active sites enable the development of efficient NRR electrocatalysts. Given surface functional groups play a key role on the electrocatalytic performance, density functional theory calculations are first conducted, clarifying that hydroxyl groups on Ti3C2Tx offer excellent NRR activity. Accordingly, hydroxyl‐rich Ti3C2Tx QDs (Ti3C2OH QDs) are synthesized as NRR catalysts by alkalization and intercalation. This material offers an NH3 yield and Faradaic efficiency of 62.94 µg h?1 mg?1cat. and 13.30% at ?0.50 V, respectively, remarkably higher than reported MXene catalysts. This work demonstrates that MXene catalysts can be mediated through the optimization of both QDs sizes and functional groups for efficient ammonia production at room temperature. 相似文献
5.
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
6.
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
7.
There is an intensive search for heterogeneous single atom catalysts (SACs) of high activity, efficiency, durability, and selectivity for a wide variety of electrocatalytic conversion and chemical reactions, such as the hydrogen evolution reaction (HER), oxygen evolution/reduction reaction (OER and ORR), CO2 reduction reaction (CO2 RR), and nitrogen reduction reaction (NRR). With the downsizing from nanoparticles and clusters to single atoms, there are steady changes in the bond and coordination environment for each and every atom involved. Indeed, the single atoms in these electrocatalysts are not “singles”; they are “married” to the supporting surfaces, and their performance is controlled by the bonding and coordination with the substrate surfaces. Herein, an overview is presented on the brief history leading to the rapid development of SACs and their current status, by focusing on their synthesis, control of composition, strategies to realize single atoms with the desired bonds and coordination, and targeted performance in selected reactions. Their applications in the selected spectrum of energy conversion and chemical reactions are discussed, in relation to their structures at varying length scales down to the atomic level. A particular emphasis is placed on on‐going research activities, together with the future perspectives and particular challenges for SACs. 相似文献
8.
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
9.
Highly Active and Stable Graphene Tubes Decorated with FeCoNi Alloy Nanoparticles via a Template‐Free Graphitization for Bifunctional Oxygen Reduction and Evolution
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Shiva Gupta Liang Qiao Shuai Zhao Hui Xu Ye Lin Surya V. Devaguptapu Xianliang Wang Mark T. Swihart Gang Wu 《Liver Transplantation》2016,6(22)
Development of highly active and stable bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts from earth‐abundant elements remains a grand challenge for highly demanded reversible fuel cells and metal–air batteries. Carbon catalysts have many advantages over others due to their low cost, excellent electrical conductivity, high surface area, and easy functionalization. However, they typically cannot withstand the highly oxidative OER environment. Here, a new class of bifunctional electrocatalyst is reported, consisting of ultralarge sized nitrogen doped graphene tubes (N‐GTs) (>500 nm) decorated with FeCoNi alloy particles. These tubes are prepared from an inexpensive precursor, dicyandiamide, via a template‐free graphitization process. The ORR/OER activity and the stability of these graphene tube catalysts depend strongly on the transition metal precursors. The best performing FeCoNi‐derived N‐GT catalyst exhibits excellent ORR and OER activity along with adequate electrochemical durability over a wide potential window (0–1.9 V) in alkaline media. The measured OER current is solely due to desirable O2 evolution, rather than carbon oxidation. Extensive electrochemical and physical characterization indicated that high graphitization degree, thicker tube walls, proper nitrogen doping, and presence of FeCoNi alloy particles are vital for high bifunctional activity and electrochemical durability of tubular carbon catalysts. 相似文献
10.
Jiachun Yang Li ZhangDaisuke Hira Yasuhiro FukuzakiKenji Furukawa 《Bioresource technology》2011,102(2):672-676
The purpose of this study is to investigate the nitrogen removal performance of the anaerobic ammonium oxidation (Anammox) process and the microbial community that enables the Anammox system to function well at ambient temperatures. A reactor with a novel spiral structure was used as the gas-solid separator. The reactor was fed with synthetic inorganic wastewater composed mainly of NH4+-N and NO2−-N, and operated for 92 days. Stable nitrogen removal rates (NRR) of 16.3 and 17.5 kg-N m−3 d−1 were obtained at operating temperatures of 33 ± 1 and 23 ± 2 °C, respectively. To our knowledge, such a high NRR at ambient temperatures has not been reported previously. In addition, the experiments presented herein confirm that high influent NO2−-N concentration of 460 mg L−1 did not noticeably inhibit the Anammox activity. Furthermore, the freshwater Anammox bacterium KU2, which was identified as the dominant bacterial species in the consortium by 16S rRNA gene analysis, is considered to be responsible for the stable nitrogen removal performance at ambient temperatures. 相似文献
11.
Laiquan Li Cheng Tang Yao Zheng Bingquan Xia Xianlong Zhou Haolan Xu Shi‐Zhang Qiao 《Liver Transplantation》2020,10(21)
The electrochemical reduction of O2 via a two‐electron reaction pathway to H2O2 provides a possibility for replacing the current anthraquinone process, enabling sustainable and decentralized H2O2 production. Here, a nitrogen‐rich few‐layered graphene (N‐FLG) with a tunable nitrogen configuration is developed for electrochemical H2O2 generation. A positive correlation between the content of pyrrolic‐N and the H2O2 selectivity is experimentally observed. The critical role of pyrrolic‐N is elucidated by the variable intermediate adsorption profiles as well as the dependent negative shifts of the pyrrolic‐N peak on X‐ray adsorption near edge structure spectra. By virtue of the optimized N doping configuration and the unique porous structure, the as‐fabricated N‐FLG electrocatalyst exhibits high selectivity toward electrochemical H2O2 synthesis as well as superior long‐term stability. To achieve high‐value products on both the anode and cathode with optimized energy efficiency, a practical device coupling electrochemical H2O2 generation and furfural oxidation is assembled, simultaneously enabling a high yield rate of H2O2 at the cathode (9.66 mol h?1 gcat?1) and 2‐furoic acid at the anode (2.076 mol m?2 h?1) under a small cell voltage of 1.8 V. 相似文献
12.
Nanoporous Au Thin Films on Si Photoelectrodes for Selective and Efficient Photoelectrochemical CO2 Reduction
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Jun Tae Song Hyewon Ryoo Minhyung Cho Jaehoon Kim Jin‐Gyu Kim Sung‐Yoon Chung Jihun Oh 《Liver Transplantation》2017,7(3)
An Si photoelectrode with a nanoporous Au thin film for highly selective and efficient photoelectrochemical (PEC) CO2 reduction reaction (CO2RR) is presented. The nanoporous Au thin film is formed by electrochemical reduction of an anodized Au thin film. The electrochemical treatments of the Au thin film critically improve CO2 reduction catalytic activity of Au catalysts and exhibit CO Faradaic efficiency of 96% at 480 mV of overpotential. To apply the electrochemical pretreatment of Au films for PEC CO2RR, a new Si photoelectrode design with mesh‐type co‐catalysts independently wired at the front and the back of the photoelectrode is demonstrated. Due to the superior CO2RR activity of the nanoporous Au mesh and high photovoltage from Si, the Si photoelectrode with the nanoporous Au thin film mesh shows conversion of CO2 to CO with 91% Faradaic efficiency at positive potential than the CO2/CO equilibrium potential. 相似文献
13.
Heng‐guo Wang Qiong Wu Yinghui Wang Xiao Wang Lanlan Wu Shuyan Song Hongjie Zhang 《Liver Transplantation》2019,9(3)
The fabrication of ultrasmall and high‐content SnO2 nanocrystals anchored on doped graphene can endow SnO2 with superior electrochemical properties. Herein, an effective strategy, involving molecular engineering of a layer‐by‐layer assembly technique, is proposed to homogeneously anchor SnO2 nanocrystals on nitrogen/sulfur codoped graphene (NSGS), which serves as an advanced anode material in lithium/sodium‐ion batteries (LIBs/SIBs). Benefiting from novel design and specific structure, the optimized NSGS for LIBs displays high initial capacity (2123.9 mAh g?1 at 0.1 A g?1), long‐term cycling performance (only 0.8% loss after 500 cycles), and good rate capability (477.4 mAh g?1 at 5 A g?1). In addition, the optimized NSGS for SIBs also delivers high initial capacity (791.7 mAh g?1 at 0.1 A g?1) and high reversible capacity (180.2 mAh g?1 after 500 cycles at 0.5 A g?1). Meanwhile, based on the detailed analysis of phase transition and electrochemical reaction kinetics, the reaction mechanisms of NSGS in LIBs and SIBs as well as the distinction in LIBs/SIBs are clearly articulated. Notably, to further explore the practical application, Li/Na+ full cells are also assembled by coupling the optimized NSGS anode with LiCoO2 and Na3V2(PO4)3/C cathodes, respectively. 相似文献
14.
15.
Tunable and Efficient Tin Modified Nitrogen‐Doped Carbon Nanofibers for Electrochemical Reduction of Aqueous Carbon Dioxide
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Efficient and selective earth‐abundant catalysts are highly desirable to drive the electrochemical conversion of CO2 into value‐added chemicals. In this work, a low‐cost Sn modified N‐doped carbon nanofiber hybrid catalyst is developed for switchable CO2 electroreduction in aqueous medium via a straightforward electrospinning technique coupled with a pyrolysis process. The electrocatalytic performance can be tuned by the structure of Sn species on the N‐doped carbon nanofibers. Sn nanoparticles drive efficient formate formation with a high current density of 11 mA cm?2 and a faradaic efficiency of 62% at a moderate overpotential of 690 mV. Atomically dispersed Sn species promote conversion of CO2 to CO with a high faradaic efficiency of 91% at a low overpotential of 490 mV. The interaction between Sn species and pyridinic‐N may play an important role in tuning the catalytic activity and selectivity of these two materials. 相似文献
16.
The objective was to compare the reproductive performance of a new PGF2α-based timed artificial insemination (TAI) protocol in sheep (Synchrovine®: two doses of PGF2α, 7 d apart) to a traditional progesterone-eCG (P4-eCG) protocol, considering the effects of seminal state, AI-times, and AI-pathway. Three experiments involving 1297 multiparous Australian Merino ewes were done during the physiologic breeding season (location 32 °S-57 °W). Reproductive performance was assessed as non-return rate to service 21 d after AI (NRR21d), based on detection with androgenized wethers, as well as Fertility (pregnant/inseminated ewes), Prolificacy (fetuses/pregnant ewe), and Fecundity (fetuses/inseminated ewe), which were based on transabdominal ultrasonography 50 d after TAI. In Experiment 1, Synchrovine® treated ewes TAI cervically with fresh semen at 42, 48, or 54 h had similar NRR21d (0.51, 0.46, 0.57), Fertility (0.27, 0.31, 0.26), and Fecundity (0.29, 0.32, 0.27), all of which were lower (P < 0.05) than in a control P4-eCG group inseminated at 54 h (0.61, 0.48, 0.52, NRR21d, Fertility and Fecundity respectively). In Experiment 2, using chilled semen and cervical TAI, Synchrovine® treated ewes inseminated at 42 h yielded lower (P < 0.05) NRR21d, Fertility and Fecundity (0.28, 0.06, 0.06) compared to 48 (0.43, 0.24, 0.24) and 54 h (0.44, 0.22, 0.23). In Experiment 3 with chilled semen, Synchrovine® treated ewes TAI into the cervix at 51 or 57 h were similar in NRR21d (0.16 vs 0.20), Fertility (0.12 vs 0.14), and Fecundity (0.12 vs 0.15), respectively; but lower (P < 0.05) than P4-eCG treated ewes TAI at 54 h (0.34, 0.28, and 0.33 for NRR21d, Fertility and Fecundity respectively). Synchrovine® treated ewes intrauterine TAI at 51 or 57 h yielded similar NRR21d (0.51 vs 0.58), Fertility (0.43 vs 0.51), and Fecundity (0.45 vs 0.56) respectively, but lower (P < 0.05) results compared to P4-eCG treated ewes (0.75, 0.71, and 0.88 for NRR21d, Fertility and Fecundity respectively). In conclusion, AI-time in Synchrovine® treated ewes with fresh semen might be extended (42 to 54 h after the second PGF2α), but should be delayed to 48-54 h with chilled semen and cervical AI. Independent of the seminal state, AI-time or AI-pathway, Synchrovine® yielded lower reproductive results than a conventional P4-eCG protocol. 相似文献
17.
18.
Md Delowar Hossain Zhenjing Liu Minghao Zhuang Xingxu Yan Gui‐Liang Xu Chaitanya Avinash Gadre Abhishek Tyagi Irfan Haider Abidi Cheng‐Jun Sun Hoilun Wong Alexander Guda Yufeng Hao Xiaoqing Pan Khalil Amine Zhengtang Luo 《Liver Transplantation》2019,9(10)
The proper choice of nonprecious transition metals as single atom catalysts (SACs) remains unclear for designing highly efficient electrocatalysts for hydrogen evolution reaction (HER). Herein, reported is an activity correlation with catalysts, electronic structure, in order to clarify the origin of reactivity for a series of transition metals supported on nitrogen‐doped graphene as SACs for HER by a combination of density functional theory calculations and electrochemical measurements. Only few of the transition metals (e.g., Co, Cr, Fe, Rh, and V) as SACs show good catalytic activity toward HER as their Gibbs free energies are varied between the range of –0.20 to 0.30 eV but among which Co‐SAC exhibits the highest electrochemical activity at 0.13 eV. Electronic structure studies show that the energy states of active valence dz2 orbitals and their resulting antibonding state determine the catalytic activity for HER. The fact that the antibonding state orbital is neither completely empty nor fully filled in the case of Co‐SAC is the main reason for its ideal hydrogen adsorption energy. Moreover, the electrochemical measurement shows that Co‐SAC exhibits a superior hydrogen evolution activity over Ni‐SAC and W‐SAC, confirming the theoretical calculation. This systematic study gives a fundamental understanding about the design of highly efficient SACs for HER. 相似文献
19.
Fine Tuning Electronic Structure of Catalysts through Atomic Engineering for Enhanced Hydrogen Evolution
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Yichao Huang Jun Hu Haoxiang Xu Wei Bian Jingxuan Ge Dejin Zang Daojian Cheng Yaokang Lv Cheng Zhang Jing Gu Yongge Wei 《Liver Transplantation》2018,8(24)
An efficient, durable, and low‐cost hydrogen evolution reaction (HER) catalyst is an essential requirement for practical hydrogen production. Herein, an effective approach to facilitate the HER kinetics of molybdenum carbide (Mo2C) electrocatalysts is presented by tuning its electronic structure through atomic engineering of nitrogen implantation. Starting from the organoimido‐derivatized polyoxometalate nanoclusters with inherent Mo? N bonds, the formation of N‐implanted Mo2C (N@Mo2C) nanocrystals with perfectly adjustable amounts of N atoms is demonstrated. The optimized N@Mo2C electrocatalyst exhibits remarkable HER performance and good stability over 20 h in both acid and basic electrolytes. Further density functional theory calculations show that engineering suitable nitrogen atoms into Mo2C can regulate its electronic structure well and decrease Mo? H strength, leading to a great enhancement of the HER activity. It could be believed that this ligand‐controlled atomic engineering strategy might influence the overall catalyst design strategy for engineering the activation sites of nonprecious metal catalysts for energy conversions. 相似文献
20.
In this study, effluent sludge from a high-rate Anammox reactor was used to re-start new Anammox reactors for the reactivation of Anammox granular sludge. Different start-up strategies were evaluated in six upflow anaerobic sludge blanket (UASB) reactors (R1–R6) for their effect on nitrogen removal performance. Maximal nitrogen removal rates (NRRs) greater than 20 kg N/m3/day were obtained in reactors R3–R5, which were seeded with mixed Anammox sludge previously stored for approximately 6 months and 1 month. A modified Boltzmann model describing the evolution of the NRR fit the experimental data well. An amount of sludge added to the UASB reactor or decreasing the loading rate proved effective in relieving the substrate inhibition and increasing the NRR. The modified Stover–Kincannon model fit the nitrogen removal data in the Anammox reactors well, and the simulation results showed that the Anammox process has great nitrogen removal potential. The observed inhibition in the Anammox reactors may have been caused by high levels of free ammonia. The sludge used to seed the reactors did not settle well; sludge flotation was observed even after the reactors were operated for a long time at a floating upward velocity (Fs) of greater than 100 m/h. The settling sludge, however, exhibited good settling properties. Scanning electron microscopy showed that the Anammox granules consisted mainly of spherical and elliptical bacteria with abundant filaments on their surface. Hollows in the granules were also present, which may have contributed to sludge floatation. 相似文献