Enhanced Electrochemical N2 Reduction to NH3 on Reduced

Subscriber access provided by Nottingham Trent University

Letter

Enhanced Electrochemical N2 Reduction to NH3 on Reduced Graphene Oxide by Tannic Acid Modification Yanyan Song, Ting Wang, Junwei Sun, Zhichao Wang, Yonglan Luo, Lixue Zhang, Hejiang Ye, and Xuping Sun ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.9b03890 • Publication Date (Web): 15 Aug 2019 Downloaded from pubs.acs.org on August 16, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Sustainable Chemistry & Engineering

Enhanced Electrochemical N2 Reduction to NH3 on Reduced Graphene Oxide by Tannic Acid Modification Yanyan Song,† Ting Wang,‡,║ Junwei Sun,† Zhichao Wang,† Yonglan Luo,‡ Lixue Zhang,†,* Hejiang Ye,∫,* and Xuping Sun║,* †College

of Chemistry and Chemical Engineering, Qingdao University, Qingdao 266071, Shandong, China, ‡Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, College of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637002, Sichuan, China, ║Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan, China, and ∫Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 610072, Sichuan, China *E-mail:

[email protected] (L.Z.); [email protected] (H.Y); [email protected] (X.S.)

ABSTRACT: Developing high-efficiency non-metal electrocatalysts for the electrochemical N2 reduction reaction (NRR) is of great significance for the sustainable development of human society. Here, we demonstrate that surface modification of reduced graphene oxide by tannic acid is a mild and effective strategy to boost its NRR activity. Such electrocatalyst is stable with an NH3 formation rate of 17.02 µg h−1 mg−1cat. in 0.5 M LiClO4, and its Faradaic efficiency can reach 4.83% at an optimized potential. The work would provide an impressive new option to boost the electrocatalytic N2-fixing performances of carbon materials by organic molecules modification.

KEYWORDS: organic molecules modification, N2 reduction reaction, neutral electrolyte, ambient conditions, ammonia

INTRODUCTION In modern agriculture and industry, NH3 not only provides us a basic raw material to make fertilizer production and other chemicals,1,2 but also is a potential hydrogen storage carrier.3 At present time, traditional Haber-Bosch method operated under high temperature and high pressure is dominated in industrial-scale NH3 synthesis, heavily consuming energy and releasing massive amounts of CO2. In this regard, searching an environmental-friendly and sustainable process for NH3 synthesis is in great need. Electrochemical N2 reduction, which can be realized by using electrical energy from solar, wind and other renewable energy resources, is regarded as a promising alternative method, but high-efficiency catalysts for the electrochemical N2 reduction reaction (NRR) are required to overcome the high activation barrier for splitting N≡N triple bonds.4−7 Noble-metal catalysts are efficient for the NRR,8−10 but the scarcity and high cost hinder their wide applications. Considerable recent attentions have thus focused on exploring earth-abundant transition metal-based NRR electrocatalysts.11−25 Great effort is also devoted to developing metal-free alternatives.26−34 Some recent studies suggest that doping of non-metal oxygen heteroatom is effective to improve the NRR performances of nanocarbon.35-37 Introducing C–O groups via acid oxidation is proven as another effective strategy to boost the NRR activity.38 However, all these O-containing carbon catalysts suffer from the involvement of high-temperature thermal annealing process or strong acid for materials preparation and thus are energy-intensive and not green.

Here, we demonstrate that surface modification by oxygenrich tannic acid (TA) is a mild and effective strategy to enhance the NRR performance of reduced graphene oxide (rGO). When operated in 0.5 M LiClO4, the resulting TA-rGO nanohybrid operates stably to electrochemically catalyze the NRR with an NH3 formation rate (RNH3) of 17.02 µg h−1 mg−1cat., and the Faradaic efficiency (FE) can reach 4.83% at – 0.75 V vs. reversible hydrogen electrode (RHE).

Figure 1. (a) TEM image of TA-rGO. (b) SEM image and relevant elemental mapping images of TA-rGO. XPS spectra of TA-rGO in (c) C 1s and (d) O 1s regions.

RESULTS AND DISCUSSION

ACS Paragon Plus Environment

ACS Sustainable Chemistry & Engineering 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

TA-rGO was prepared by surface modification of rGO with TA (details see the ESI). Figure S1 shows the optical photos of rGO and TA-rGO dispersed in water, indicating the dispersity of the rGO in water can be greatly improved after TA modification. Figure S2 exhibits scanning electron microscopy (SEM) image of TA-rGO with creased texture. Transmission electron microscopy (TEM) image of TA-rGO displays the transparent layered structure and intrinsic folds (Figure 1a), compared to the TEM image of rGO (Figure S3), revealing that TA modification maintains the inherent structure of rGO. The SEM image and the corresponding elemental mapping images of TA-rGO (Figure 1b) indicate that C and O elements are homogeneously distributed in the TA-rGO sample. Raman spectra of TA-rGO and TA are displayed in Figure S4. Compared with rGO, the intensity ratio between D and G bands (Id/Ig) of TA-rGO is not obviously changed, indicating that the inherent structure of rGO is maintained after TA modification. This should be ascribed to the fact that the interaction between TA and rGO is mainly π–π interaction.39 In the Fourier transform infrared (FT-IR) spectra (Figure S5), the broad peak in the region of 3080–3590 cm−1 for TA-rGO can be attributed to the stretching vibration of the abundant aromatic hydroxyls in TA. The other characteristic peaks, such as 1696 cm−1 (conjugated C=O stretching vibration), 1440 cm−1 (aromatic C=C stretching vibration), 1313 cm−1 (C–O stretching), and 752 cm−1 (C–H out-plane bend) appeared in the spectra of TA-rGO, also confirm the successful modification of rGO by TA.40,41 In X-ray photoelectron spectroscopy (XPS) spectra of TA-rGO (Figure 1c), the C 1s binding energies (BEs) at 284.8, 286.3, and 288.7 eV are ascribed to C=C/C–C, C–O, and O–C=O, respectively. In addition, the π–π* transition loss peak is detected at 291.6 eV. In O 1s region (Figure 1d), the BEs at 531.9 and 533.6 eV are ascribed to O–C and O=C, respectively.42,43 In contrast to rGO (Figure S6), the intensities of O=C bonds of TA-rGO are obviously increased, which should be attributed onto the – COOH group of TA attached to rGO.

A three-electrode setup (Figure S7) was used to test NRR performance of TA-rGO in 0.5 M LiClO4 at ambient conditions. NRR electrolysis tests were conducted by using controlled potential from –0.65 to –0.90 V for 2 h, as shown in Figure 2a. After electrolysis, the indophenol blue method was used for spectrophotometrically detecting the target product (NH3),44 while possible by-product (N2H4) was ascertained via the Watt and Chrisp method (Figure S8 and S9).45 The electrolyte was dyed after 2-h electrocatalytic reaction, its absorbance was measured by the UV-vis spectrophotometer (Figure 2b). The RNH3 and corresponding FE at various potential are displayed in Figure 2c and 2d. At –0.75 V, this catalyst electrode is capable of realizing RNH3 of 17.02 μg h–1 mg−1cat and 4.83% FE. Compared with the recently reported other superb metal-free materials, the TA-rGO exhibited considerable performance towards N2 reduction reaction, indicating its advantage (Table S1). Due to the competitive adsorption of hydrogen species and N2 on TA-rGO/CP surface,46 both RNH3 and FE reduce when applied a more negative potential than –0.75 V.

Figure 3. (a) UV-Vis absorption spectra of the electrolytes stained with p-C9H11NO indicator after NRR electrolysis at given potentials. (b) mNH3 of 2 h electrolysis under different conditions. (c) RNH3 and corresponding FEs of TA-rGO/CP at –0.75 V. (d) mNH3 of TA-rGO/CP, rGO/CP, and CP at –0.75 V after 2 h electrolysis.

Figure 2. (a) Chronoamperometry curves of TA-rGO/CP in 0.5 M N2-saturated LiClO4 solution at given potentials. (b) UV-Vis absorption spectra of the electrolytes stained with indophenol indicator after 2-h NRR electrolysis at given potentials. (c) RNH3 and (d) FE of TA-rGO/CP for NRR at given potentials.

In addition, N2H4 was not detected, revealing that TA-rGO has good selectivity toward NH3 synthesis (Figure 3a). Furthermore, some control experiments have been operated to ensure that the N source originates from TA-rGO through N2 electroreduction. As seen in Figure S10 and Figure 3b, there was no appartent NH3 formed when TA-rGO/CP was tested in N2-saturated electrolyte at open circuit voltage, as well as in Ar-saturated electrolyte at –0.75 V. Then, we tested the performance of TA-rGO/CP in N2-saturated and Ar-saturated alternating solutions. As expected, NH3 was only detected in N2-saturated condition (Figure 3c). As shown in Figure S11 and Figure. 3d, TA-rGO/CP shows much higher catalytic activity than rGO/CP. It is reported that oxygen functional groups can alter the electronic distribution of the surrounding carbon atoms, leading to optimized binding energy of reactants and reaction intermediates on carbon.47 Our recent work suggests that oxygen doping is an effective strategy to enhance the NRR performances of graphene and further


Page 2 of 6

Page 3 of 6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


confirms that both the C=O, O–C=O and C–O groups contribute to the NRR.37 For oxygen-doped graphene, the much larger electronegativity of oxygen atom compared to carbon atom endows it stronger manipulate the electronic property of graphene, and such electronic structure accelerates the electrocatalytic NRR. In our present study, the strong π–π stacking interactions between π-rich TA and rGO brings the TA into very close proximity to rGO, leading to intimate contact of the oxygen groups of TA and rGO, which favors the effective manipulation of the electronic property of rGO. As a result, the NRR activity of rGO is greatly enhanced by virtue of the oxygen groups of TA after surface modification. We also investigated the stability of TA-rGO/CP by cycling and long-term tests at –0.75 V. As shown in Figure 4a and S12, both RNH3 and FEs only show minor changes during recycling tests. After 24-h NRR electrolysis (Figure S13), such TA-rGO/CP still keeps initial catalytic activity (Figure 4b). TEM image (Figure S14) and XPS spectra (Figure S15) suggest no obvious structural changes of TA-rGO between before and after stability test. The above results suggest the remarkable electrochemical and structural stability of TArGO.

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China (No. 21775078) and Shandong Provincial Natural Science Foundation of China (No. ZR2016JL007).

REFERENCES (1) (2) (3)

(4)

(5)

(6)

(7)

Figure 4. (a) Stability test for TA-rGO/CP during repeated NRR at –0.75 V. (b) RNH3 and FEs at –0.75 V for 2 h over initial TArGO/CP and post-NRR TA-rGO/CP.

(8)

CONCLUSION In summary, surface modification of rGO by TA is proven as a mild and effective strategy to enhance N2 reduction electrocatalysis. At −0.75 V in 0.5 M LiClO4, such TA-rGO nanohybrid catalyst is stable to attain an NH3 formation rate of 17.02 µg h−1 mg−1cat. with a FE of 4.83%. It not only inspires us a cost-effective non-metal electrocatalyst for electrochemical NH3 synthesis, also would provide an impressive new option to explore the utilization of organic molecules to facilely modulate the catalytic activity of nano carbons for applications.

ASSOCIATED CONTENT

(9)

(10)

(11)

(12)

Supporting Information Experimental Section; Optical photo; SEM and TEM images; Raman spectra, FT-IR spectra, UV-Vis absorption and XPS spectra; calibration and chronoamperometry curves; Table S1. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Author *E-mail:

[email protected] (L.Z.); [email protected] (H.Y); [email protected] (X.S.)

(13)

(14)

Smil, V. Detonator of the Population Explosion. Nature 1999, 400, 415, DOI 10.1038/22672. Schlögl, R. Catalytic Synthesis of Ammonia—A “NeverEnding Story”? Angew. Chem. Int. Ed. 2003, 42, 2004–2008, DOI 10.1002/anie.200301553. Lan, R.; Irvine, J. T. S.; Tao, S. Ammonia and Related Chemicals as Potential Indirect Hydrogen Storage Materials. J. Hydrogen Energy 2012, 37, 1482–1494, DOI 10.1016/j.ijhydene.2011.10.004. Guo, C.; Ran, J.; Vasileff, A.; Qiao, S. Rational Design of Electrocatalysts and Photo(electro)catalysts for Nitrogen Reduction to Ammonia (NH3) under Ambient Conditions. Energy Environ. Sci. 2018, 11, 45–56, DOI 10.1039/c7ee02220d. Shipman, M. A.; Symes, M. D. Recent Progress towards the Electrosynthesis of Ammonia from Sustainable Resources. Catal. Today 2017, 286, 57–68, DOI 10.1016/j.cattod.2016.05.008. Wang, Q.; Lei, Y.; Wang, D.; Li, Y. Defect Engineering in Earth-abundant Electrocatalysts for CO2 and N2 Reduction. Energy Environ. Sci. 2019, 12, 1730–1750, DOI 10.1039/c8ee03781g. Zhao, R.; Xie, H.; Chang, L.; Zhang, X.; Zhu, X.; Tong, X.; Wang, T.; Luo, Y.; Wei, P.; Wang, Z.; Sun, X. Recent Progress in the Electrochemical Ammonia Synthesis under ambient Conditions. EnergyChem 2019, DOI 10.1016/j.enchem.2019.100011. Bao, D.; Zhang, Q.; Meng, F.; Zhong, H.; Shi, M.; Zhang, Y.; Yan, J.; Jiang, Q.; Zhang, X. Electrochemical Reduction of N2 under Ambient Conditions for Artificial N2 Fixation and Renewable Energy Storage Using N2/NH3 Cycle. Adv. Mater. 2017, 29, 1604799, DOI 10.1002/adma.201604799. Huang, H.; Xia, L.; Shi, X.; Asiri, A. M.; Sun, X. Ag Nanosheets for Efficient Electrocatalytic N2 Fixation to NH3 under Ambient Conditions. Chem. Commun. 2018, 54, 11427– 11430, DOI 10.1039/c8cc06365f. Wang, J.; Yu, L.; Hu, L.; Chen, G.; Xin, H.; Feng, X. Ambient Ammonia Synthesis via Palladium-catalyzed Electrohydrogenation of Dinitrogen at Low Overpotential. Nat. Commun. 2018, 9, 1795, DOI 10.1038/s41467-018-04213-9. Lv, C.; Yan, C.; Chen, G.; Ding, Y.; Sun, J.; Zhou, Y.; Yu, G. An Amorphous Noble-Metal-Free Electrocatalyst that Enables Nitrogen Fixation under Ambient Conditions. Angew. Chem. Int. Ed. 2018, 57, 6073–6076, DOI 10.1002/anie.201801538. Zhang, L.; Xie, X.; Wang, H.; Ji, L.; Zhang, Y.; Chen, H.; Li, T.; Luo, Y.; Cui, G.; Sun, X. Boosting Electrocatalytic N2 Reduction by MnO2 with Oxygen Vacancies. Chem. Commun. 2019, 55, 4627–4630, DOI 10.1039/c9cc00936a. Zhu, X.; Liu, Z.; Wang, H.; Zhao, R.; Chen, H.; Wang, T.; Wang, F.; Luo, Y.; Wu, Y.; Sun, X. Boosting Electrocatalytic N2 Reduction to NH3 on β-FeOOH by Fluorine Doping. Chem. Commun. 2019, 55, 3987–3990, DOI 10.1039/c9cc00647h. Kong, J.; Lim, A.; Yoon, C.; Jang, J. H.; Ham, H. C.; Han, J.; Nam, S.; Kim, D.; Sung, Y.; Choi, J.; Park, H. S. Electrochemical Synthesis of NH3 at Low Temperature and Atmospheric Pressure Using a γ-Fe2O3 Catalyst. ACS Sustainable Chem. Eng. 2017, 5, 10986–10995, DOI 10.1021/acssuschemeng.7b02890.



(15)

(16)

(17)

(18)

(19)

(20)

(21)

(22)

(23)

(24)

(25)

(26)

(27)

(28)

Huang, H.; Gong, F.; Wang, Y.; Wang, H.; Wu, X.; Lu, W.; Zhao, R.; Chen, H.; Shi, X.; Asiri, A. M.; Li, T.; Liu, Q.; Sun, X. Mn3O4 Nanoparticles@Reduced Graphene Oxide Composite: An Efficient Electrocatalyst for Artificial N2 Fixation to NH3 at Ambient Conditions. Nano Res. 2019, 12, 1093–1098, DOI 10.1007/s12274-019-2352-5. Liu, Y.; Han, M.; Xiong, Q.; Zhang, S.; Zhao, C.; Gong, W.; Wang, G.; Zhang, H.; Zhao, H. Dramatically Enhanced Ambient Ammonia Electrosynthesis Performance by Inoperando Created Li-S Interactions on MoS2 Electrocatalyst. Adv. Energy Mater. 2019, 9, 1803935, DOI 10.1002/aenm.201803935. Yu, J.; Li, C.; Li, B.; Zhu, X.; Zhang, R.; Ji, L.; Tang, D.; Asiri, A. M.; Sun, X.; Li, Q.; Liu, S.; Luo, Y. A Perovskite La2Ti2O7 Nanosheet as an Efficient Electrocatalyst for Artificial N2 Fixation to NH3 in Acidic Media. Chem. Commun. 2019, 55, 6401–6404, DOI 10.1039/c9cc02310k. Wang, Z.; Gong, F.; Zhang, L.; Wang, R.; Ji, L.; Liu, Q.; Luo, Y.; Guo, H.; Li, Y.; Gao, P.; Shi, X.; Li, B.; Tang, B.; Sun, X. Electrocatalytic Hydrogenation of N2 to NH3 by MnO: Experimental and Theoretical Investigations. Adv. Sci. 2019, 6, 1801182, DOI 10.1002/advs.201801182. Zhang, X.; Kong, R.; Du, H.; Xia, L.; Qu, F. Highly Efficient Electrochemical Ammonia Synthesis via Nitrogen Reduction Reactions on a VN Nanowire Array under Ambient Conditions. Chem. Commun. 2018, 54, 5323–5325, DOI 10.1039/C8CC00459E. Du, H.; Guo, X.; Kong, R.; Qu, F. Cr2O3 Nanofiber: a Highperformance Electrocatalyst toward Artificial N2 Fixation to NH3 under Ambient Conditions. Chem. Commun. 2018, 54, 12848–12851, DOI 10.1039/C8CC07186A. Yang, L.; Wu, T.; Zhang, R.; Zhou, H.; Xia, L.; Shi, X.; Zheng, H.; Zhang, Y.; Sun, X. Insights into Defective TiO2 in Electrocatalytic N2 Reduction: Combining Theoretical and Experimental Studies. Nanoscale 2019, 11, 1555–1562, DOI 10.1039/C8NR09564G. Cheng, H.; Ding, L.; Chen, G.; Zhang, L.; Xue, J.; Wang, H. Molybdenum Carbide Nanodots Enable Efficient Electrocatalytic Nitrogen Fixation under Ambient Conditions. Adv. Mater. 2018, 30, 1803694, DOI: 10.1002/adma.201803694. Zhang, R.; Ji, L.; Kong, W.; Wang, H.; Zhao, R.; Chen, H.; Li, T.; Li, B.; Luo, Y.; Sun, X. Electrocatalytic N2-to-NH3 Conversion with High Faradaic Efficiency Enabled by Bi Nanosheet Array. Chem. Commun. 2019, 55, 5263–5266, DOI 10.1039/c9cc01703h. Luo, Y.; Chen, G.; Ding, L.; Chen, X.; Ding, L.; Wang, H. Efficient Electrocatalytic N2 Fixation with MXene under Ambient Conditions. Joule 2019, 3, 279–289, DOI 10.1016/j.joule.2018.09.011. Zhao, J.; Zhang, L.; Xie, X.; Li, X.; Ma, Y.; Liu, Q.; Fang, Wei-Hai; Shi, X.; Cui, G.; Sun, X. Ti3C2Tx (T= F, OH) MXene Nanosheets: Conductive 2D Catalysts for Ambient Electrohydrogenation of N2 to NH3. J. Mater. Chem. A 2018, 6, 24031–24035, DOI 10.1039/c8ta09840a. Zhao, J.; Yang, J.; Ji, L.; Wang, H.; Chen, H.; Niu, Z.; Liu, Q.; Li, T.; Cui, G.; Sun, X. Defect-Rich Fluorographene Nanosheet for Artificial N2 Fixation under Ambient Conditions. Chem. Commun. 2019, 55, 4266–4269, DOI 10.1039/C9CC01920K. Chen, H.; Zhu, X.; Huang, H.; Wang, H.; Wang, T.; Zhao,R.; Zheng, H.; Asiri, A. M..; Luo, Y.; Sun, X. Sulfur Dots– graphene Nanohybrid: a Metal-free Electrocatalyst for Efficient N2-to-NH3 Fixation under Ambient Conditions. Chem. Commun. 2019, 55, 3152–3155, DOI 10.1039/C9CC00461K. Zhu, X.; Wu, T.; Ji, L.; Li, C.; Wang, T.; Wen, S.; Gao, S.; Shi, X.; Luo, Y.; Sun, X. Ambient Electrohydrogenation of N2 for NH3 Synthesis on Non-Metal Boron Phosphide

(29)

(30)

(31)

(32)

(33)

(34)

(35)

(36)

(37)

(38)

(39)

(40) (41)

(42)

Page 4 of 6

Nanoparticles: the Critical Role of P to Boost the Catalytic Activity. J. Mater. Chem. A 2019, 7, 16117–16121, DOI 10.1039/C9TA05016G. Li, W.; Wu, T.; Zhang, S.; Liu, Y.; Zhao, C.; Liu, G.; Wang, G.; Zhang, H.; Zhao, H. Nitrogen-Free Commercial Carbon Cloth with Rich Defects for Electrocatalytic Ammonia Synthesis under Ambient Conditions. Chem. Commun. 2018, 54, 11188−11191, DOI 10.1039/c8cc06000b. Zhao, C.; Zhang, S.; Han, M.; Zhang, X.; Liu, Y.; Li, W.; Chen, C.; Wang, G.; Zhang, H.; Zhao, H. Ambient Electrosynthesis of Ammonia on a Biomass-Derived Nitrogen-Doped Porous Carbon Electrocatalyst: Contribution of Pyridinic Nitrogen. ACS Energy Lett. 2019, 4, 377–383, DOI 10.1021/acsenergylett.8b02138. Lv, C.; Qian, Y.; Yan, C.; Ding, Y.; Liu, Y.; Chen, G.; Yu, G. Defect Engineering Metal-Free Polymeric Carbon Nitride Electrocatalyst for Effective Nitrogen Fixation under Ambient Conditions. Angew. Chem. Int. Ed. 2018, 57, 10246−10250, DOI 10.1002/anie.201806386. Zhang, Y.; Du, H.; Ma, Y.; Ji, L.; Guo, H.; Tian, Z.; Chen, H.; Huang, H.; Cui, G.; Asiri, A. M.; Qu, F.; Chen, L.; Sun, X. Hexagonal Boron Nitride Nanosheet for Effective Ambient N2 Fixation to NH3. Nano Res. 2019, 12, 919–924, DOI 10.1007/s12274-019-2323-x. Yu, X.; Han, P.; Wei, Z.; Huang, L.; Gu, Z.; Peng, S.; Ma, J.; Zheng, G. Boron-Doped Graphene for Electrocatalytic N2 Reduction. Joule 2018, 2, 1610−1622, DOI 10.1016/j.joule.2018.06.007. Zhang, X.; Wu, T.; Wang, H.; Zhao, R.; Chen, H.; Wang, T.; Wei, P.; Luo, Y.; Zhang, Y.; Sun, X. Boron Nanosheet: an Elemental 2D Material for Ambient Electrocatalytic N2-toNH3 Fixation in Neutral Media. ACS Catal. 2019, 9, 4609– 4615, DOI 10.1021/acscatal.8b05134. Huang, H.; Xia, L.; Cao, R.; Niu, Z.; Chen, H.; Liu, Q.; Li, T.; Shi, X.; Asiri, A. M.; Sun, X. A Biomass-derived Carbonbased Electrocatalyst for Efficient N2 Fixation to NH3 at Ambient Conditions. Chem. Eur. J. 2019, 25, 1914–1917, DOI 10.1002/chem.201805523. Wu, T.; Li, P.; Wang, H.; Zhao, R.; Zhou, Q.; Kong, W.; Liu, M.; Zhang, Y.; Sun, X.; Gong, F. Biomass-derived Oxygendoped Hollow Carbon Microtubes for Electrocatalytic N2-toNH3 Fixation under Ambient Conditions. Chem. Commun. 2019, 55, 2684–2687, DOI 10.1039/c8cc09867k. Wang, T.; Xia, L.; Yang, J.; Wang, H.; Fang, W.; Chen, H.; Tang, D.; Asiri, A. M.; Luo, Y.; Cui, G.; Sun, X. Electrocatalytic N2-to-NH3 Conversion by Oxygen-Doped Graphene: Experimental and Theoretical Studies. Chem. Commun. 2019, 55, 7502–7505, DOI 10.1039/C9CC01999E. Zhao, J.; Wang, B.; Zhou, Q.; Wang, H.; Li, X.; Chen, H.; Wei, Q.; Wu, D.; Luo, Y.; You, J.; Gong, F.; Sun, X. Efficient Electrohydrogenation of N2 to NH3 by Oxidized Carbon Nanotube under Ambient Conditions. Chem. Commun. 2019, 55, 4997–5000, DOI 10.1039/c9cc00726a. Lei, Y.; Tang, Z.; Liao, B. Hydrolysable Tannin as Environmentally Friendly Reducer and Stabilizer for Graphene Oxide. Green Chem. 2011, 13, 1655–1658, 10.1039/C1GC15081B. Zhang, J.; Yang, H.; Shen, G.; Cheng, P.; Zhang, J.; Guo, S. Reduction of Graphene Oxide via L-ascorbic Acid. Chem. Commun. 2010, 46, 1112–1114, DOI 10.1039/B917705A. Wang, Z.; Kang, H.; Zhang, W.; Zhang, S.; Li, J. Improvement of Interfacial Interactions Using Natural Polyphenol-inspired Tannic Acid-coated Nanoclay Enhancement of Soy Protein Isolate Biofilms. Appl. Surf. Sci. 2017, 401, 271–282, DOI 10.1016/j.apsusc.2017.01.015. Datsyuk, V.; Kalyva, M.; Papagelis, K.; Parthenios, J.; Tasis, D.; Siokou, A.; Kallitsis, I.; Galiotis, C. Chemical Oxidation of Multiwalled Carbon Nanotubes. Carbon 2008, 46, 833–840, DOI 10.1016/j.carbon.2008.02.012.


Page 5 of 6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(43)

(44)

(45) (46)

(47)


Lu , Z.; Chen, G.; Siahrostami, S.; Chen, Z.; Liu, K.; Xie, J.; Liao, L.; Wu, T.; Lin, D.; Liu , Y.; Jaramillo, T. F.; Nørskov, J. K.; Cui, Y. High-Efficiency Oxygen Reduction to Hydrogen Peroxide Catalysed by Oxidized Carbon Materials. Nat. Catal. 2018, 1, 156−162, DOI 10.1038/s41929-017-0017-x. Zhu, D.; Zhang, L.; Ruther, R. E.; Hamers, R. J. Photoilluminated Diamond as a Solid-state Source of Solvated Electrons in Water for Nitrogen Reduction. Nat. Mater. 2013, 12, 836–841, DOI 10.1038/nmat3696. Watt, G. W.; Chrisp, J. D. Spectrophotometric Method for the Determination of Hydrazine. Anal. Chem. 1952, 24, 2006– 2008, DOI 10.1021/ac60072a044. Ren, X.; Zhao, J.; Wei, Q.; Ma, Y.; Guo, H.; Liu, Q.; Wang, Y.; Cui, G.; Asiri, A. M.; Li, B.; Tang, B.; Sun, X. HighPerformance N2-to-NH3 Conversion Electrocatalyzed by Mo2C Nanorod. ACS Central Sci. 2019, 5, 116–121, DOI 10.1021/acscentsci.8b00734. Lu, X.; Yim. W-L.; Suryanto. B. H. R.; Zhao. C. Electrocatalytic Oxygen Evolution at Surface-Oxidized Multiwall Carbon Nanotubes. J. Am. Chem. Soc. 2015, 137, 2901–2907, DOI 10.1021/ja509879r.



Page 6 of 6

For Table of Contents Use Only

Tannic acid modified reduced graphene oxide acts an efficient electrocatalyst for conversion of N2 to NH3 in 0.5 M LiClO4, achieving a large NH3 yield of 17.02 µg h–1 mg–1cat. and a high Faradaic efficiency of 4.83%.


6

Enhanced Electrochemical N2 Reduction to NH3 on Reduced

Recommend Documents