Institute of Metallurgy & Metals, Chinese Academy of Sciences, Tsinghua-Berkeley Shenzhen Institute AFM Review: Chemistry and Application Prospects of Graphene and Porous Graphene Materials

【Background Introduction】

Graphene is a two-dimensional carbon nanomaterial composed of carbon atoms and sp ² hybrid orbitals forming a hexagonal honeycomb lattice with high specific surface area, high Young‘s modulus, high electron mobility, and excellent thermal conductivity. . Graphene is one of the key new materials for China‘s "13th Five-Year Plan". It is listed as advanced basic materials, key strategic materials and cutting-edge new materials. It has important application prospects in the fields of new energy, national security, aerospace and information technology . Among them, graphene oxide and reduced graphene oxide are two typical single-layer graphene derivatives containing oxidized groups and defects, which can be bonded to many different atoms through sp, sp ² and sp ³ hybrid orbitals, thus Graphene materials with different pore structures are obtained. In particular, porous graphene materials can effectively combine the advantages of porous materials and graphene. They not only have high specific surface area and rich pores, but also can realize rapid ion transmission. They are widely concerned in the fields of energy, catalysis and separation. Therefore, understand the chemical intrinsic properties of graphene and porous graphene materials, the internal mechanism of pore formation and their functional application roles, and design and construct new graphene and porous graphene materials for future applications in catalysis, energy, and environment It has important scientific significance and application value.

【Achievement Introduction】

Based on this, researcher Wu Zhongshuai from Dalian Institute of Chemical Physics , Chinese Academy of Sciences and his team collaborated with Academician Cheng Huiming from Institute of Metal Research, Chinese Academy of Sciences and Tsinghua-Berkeley Shenzhen University to systematically review the chemistry and application prospects of graphene and porous graphene materials. This paper systematically reviews the chemistry and application prospects of graphene and porous graphene materials. The paper first introduces the surface interface chemistry, assembly chemistry and functional chemistry of graphene in detail, focusing on the construction methods of different porous (in-plane pores, two-dimensional layered pores, three-dimensional pores) graphene materials, revealing different pore structures The regulatory mechanism and the importance of surface chemical modification. Secondly, the in-depth discussion of the chemical action and structure-activity relationship of different graphene and porous graphene materials in important applications such as supercapacitors, secondary batteries, electrocatalysis, seawater desalination, gas separation, and the emphasis on porous graphene materials with graphene And the double advantage of porous materials. Finally, the challenges faced by graphene and porous graphene materials are discussed, and possible solutions and development strategies are proposed from the perspectives of bionic chemistry, assembly chemistry, and surface interface chemistry (Figure 1). This review paper can provide scientific guidance for in-depth understanding of the chemical properties of graphene and porous graphene, and provide new inspiration for its controllable preparation, rational construction, and important applications. The research result "The Chemistry and Promising Applications of Graphene and Porous Graphene Materials" was published in Advanced Functional Materials (DOI: 10.1002 / adfm.201909035).

【Graphic Interpretation】

Figure 1. Chemistry and important applications of graphene and porous graphene materials

Figure 2. Schematic diagram of GO‘s OCFG molecular structure

Figure 3. Graphene boundary structure, preparation and characterization
(a) The jagged and armchair edges of single-layer graphene nanoribbons (GNR);

(B) Energy level;

(C) Kohn-Sham spin orbit with the closest edge positioning state and the block state with the closest energy;

(Df) The method used to undo the doped nanotubes to form the GNR: a schematic diagram of the chemical route, the embedding-exfoliation of the MWCNT, and the catalytic method;

(G, h) TEM images show irregular edges, as well as zigzag and armchair edges;

(I) High-resolution TEM (HRTEM) images show clear jagged and armchair edges.

Figure IV. Preparation and morphological characterization of in-plane pore graphene
(a) Preparation of porous graphene from the bottom-up through the surface-promoted aryl-aryl coupling reaction and the three porous graphene structures obtained;

(B) Scanning tunnel microscope (STM) image of the polyphenylene supercellular network edge;

(C) Schematic diagram of preparing graphene nano-network;

(D) TEM image of graphene nanosieve;

(E) Schematic diagram of the preparation process of HGFs and HGF films;

(F) SEM picture of HGF;

(G) TEM image of porous graphene in HGFs.

Figure 5. Preparation and characterization of two-dimensional layered mesoporous graphene
(a) Schematic diagram of the preparation process of GOM-silica nanosheets.

(Bd) Schematic diagram of preparation process, SEM and TEM images of mPPy @ GO nanosheets.

Figure 6. Preparation and characterization of three-dimensional porous graphene materials
(a) Preparation process of three-dimensional Fe ₃ O ₄ / N-GAs catalyst;

(B) Schematic diagram of the preparation method of three-dimensional graphene (ERGO) -based composite materials;

(C) Synthesis of 3D GF and integration with PDMS;

(D) Schematic diagram of the procedure for preparing a three-dimensional macroporous MnO ₂ / e-CMG thin film;

(E) A schematic diagram showing the preparation process of LSG-based supercapacitors.

Figure 7. Preparation of different doped graphene
(a) N 1s XPS spectrum of N-doped graphene;

(Bc) Schematic diagram and Raman spectrum of N-doped graphene;

(D) Transfer characteristics of original graphene and N-doped graphene;

(Ef) I _ds / V _ds characteristics of original graphene and N-doped graphene field effect transistor (FET) devices at various V _g values .

Figure 8. Preparation of doped graphene aerogel film
(a) Schematic diagram of the preparation process of N-doped graphene aerogel film;

(B) Schematic diagram of all-solid supercapacitor based on B and N co-doped graphene aerogel (BN-GA);

(C) N 1s and B 1s XPS spectra of BN-GAs;

(D) The preparation process of N-S co-doped reduced pore graphene oxide / carbonized cellulose paper (NS-RHGO-CCP) intermediate layer;

(E) Schematic diagram of the synthesis of I-doped porous graphene (INPG).

Figure 9.
Schematic diagram of supercapacitors (a) HGFs used in electrochemical capacitors;

(B) Schematic diagram of chemical activation of microwave peeled graphene (MEGO) with KOH to form pores;

(C) The CV curve of a-MEGO at different scan rates in BMIMBF ₄ / AN electrolyte;

(D) Under different constant currents, the constant current charge / discharge curve of super capacitors based on a-MEGO;

(Ef) Volume modulation and energy density of electrolyte modulation-chemical conversion graphene (EM-CCG) film and dried CCG film;

(G) Schematic diagram of the formation of Ni (OH) ₂ / graphene sheet;

(H) Ni (OH) ₂ and Ni (OH) ₂ / graphene specific capacitance at various scan rates ;

(I) Schematic diagram of an asymmetric supercapacitor with porous graphene as the negative electrode and Ni (OH) ₂ / graphene as the positive electrode;

(J) The specific capacitance of porous graphene and chemically reduced graphene at different current densities;

(K) Schematic diagram of the assembly process of interdigitated lithography graphene-micro supercapacitor (LSG-MSC), and more than 100 photos of LSG-MSC are displayed on a single disk;

(Lm) Constant current charge / discharge curves of four LSG-MSCs connected in series and parallel.

Figure 10. Lithium ion battery
(a) Schematic diagram of preparation of porous three-dimensional Nb ₂ O ₅ / HGF composite material;

(B) Cross-sectional SEM image of the three-dimensional porous structure of Nb ₂ O ₅ / HGF composite material;

(C) TEM image of graphene sheet with customized holes;

(D) The rate performance of the electrode under different mass loads;

(E) at C of Nb 10 ₂ O _{. 5} /HGF-2.0,Nb ₂ O _{. 5} / GF and of Nb ₂ O _{. 5} the specific capacity / G electrode.

Figure 11. Lithium-air battery
(a) Synthesis diagram of porous graphene and Ru-functional nanoporous graphene structure;

(Bc) SEM pictures of PGE-2 and Ru @ PGE-2;

(D) The first cycle charge / discharge curve of LOBs within the range of 200 mA g ^-1 and 2.0-4.0 V;

(Eg) Charging / discharging characteristics of Li-O ₂ battery using Ru @ PGE-2 catalyst under different cycles at 200 mA g ^-1 , and comparison of specific energy and cycle number.

Figure 12. Cathode materials for lithium metal / sulfur batteries

(A) Schematic diagram of the synthesis of the space-constrained GS hybrid nanosheets in the "sauna" reaction system and their interfacial bonding;

(B) Schematic diagram of preparing an independent rGO-S composite film by depositing S nanoparticles on the surface of the Zn foil of the GO sheet, self-assembling the S nanoparticles into thin sheets and peeling off the rGO-S thin film from it;

(C) The formation process of GS hybrids and the preparation of self-supporting electrodes;

(D) Schematic diagram of VN / G composite materials and battery components.

Figure 13. Lithium-sulfur battery intermediate layer and separator
(a) Schematic diagram of conventional PP separator and Janus separator with CGF layer;

(Bc) SEM image of the cross-section of CGF diaphragm and CGF diaphragm;

(D) Optical pictures of PP diaphragm and CGF diaphragm after circulation;

(E) Raman spectra of PP diaphragm and CGF diaphragm after circulation;

(F) Schematic diagram of the mechanism of action between the dense PP membrane and the CGF membrane with non-blocking ion channels;

(Gh) The SEM image of the CGF separator after cycling in the charged state;

(Ij) SEM image of the CGF separator after cycling in the discharged state.

Figure 14. Lithium anode
(a) Schematic diagram of Li deposition / stripping process on graphene sheet;

(B) SEM image of the graphene-based negative electrode after Li deposition and Li stripping;

(C) Schematic diagram of Li plating without dendrite growth on CGB;

(D) SEM image of CGB;

(E) TEM image during the lithiation of CGB;

(F) Reduce GO paper by thermal shock to produce independent PGN;

(G) Capacity and coulombic efficiency of PGN negative electrode;

(H) Schematic diagram of Li nucleation and electroplating on N-doped graphene electrode and Cu foil electrode;

(I) The morphology of NG electrode and Cu foil electrode under the condition of Li plating 0.50 mAh cm ^-2

Figure 15. Monovalent non-lithium metal battery
(a) Schematic diagram of the three-dimensional mesopore and macropore NVP @ C @ rGO positive electrode with electron and sodium ion transmission paths;

(B) Schematic diagram of synthesizing C @ P / GA composite material and C @ P / GA electrode;

(Cd) Schematic diagram of the electrochemical embedding of K ions in graphite and rGO, and the different stages of K embedding in graphite.

Figure 16.
Multivalent metal ion battery (a) Schematic diagram of the "three high three connections (3H3C)" graphene positive electrode;

(B) HRTEM image of 3H3C graphene film (GF-HC);

(C) Thermal expansion and electrochemical hydrogen production to produce three-dimensional graphite foam (3DGF);

(D) SEM image of 3DGF;

(E) GA thin film battery components;

(F) Schematic diagram of GNR on the surface of highly porous three-dimensional graphene;

(G) SEM image of GNR formed on 3DGF.

Figure 17. Electrocatalysis of doped graphene
(a) SEM image of chemically doped nanoporous graphene with different pore sizes;

(B) Possible defect structure of nanopore graphene doped with nitrogen, sulfur and phosphorus;

(C) Highly curved graphene increases the amount of chemical doping;

(D) CV curves of samples with different chemical dopants;

(E) DFT calculation of Gibbs free energy distribution for chemically doped highly curved graphene with topological defects.

Figure 18. Electrocatalysis of defective graphene
(a) shows the synthesis diagram of DG;

(B) N 1s XPS spectra of NG and DG;

(C) DG‘s high-angle annular dark field (HAADF) diagram;

(D) Evaluate the ORR performance of samples prepared in 0.1 M KOH solution saturated with oxygen;

(E) OER activity of prepared samples tested in 1 M KOH;

(Fg) HER performance of the prepared samples tested in 0.5 MH ₂ SO ₄ and 1 M KOH;

(H) Side pentagon;

(I) 5-8-5 defects;

(J) 7-55-7 defects;

(K) In the alkaline solution, the calculated energy distribution of the ORR path on the DG.

Figure 19. Electrocatalysis of single atoms of graphene
(a) HAADF-STEM diagram of Ni-graphene doped;

(B) Hydrogen adsorption sites and structure of Nisub / G model with ΔGH * =-0.10 eV;

(C) Polarization curves of Ni-doped graphene samples with different Ni dissolution times;

(D) The Gibbs free energy diagram of HER at equilibrium potential of platinum catalyst and Ni-doped graphene sample;

(E) Schematic diagram of preparation of A-Ni @ DG;

(F) LCF analysis of XANES theoretical model;

(G) HAADF-STEM diagram of A-Ni @ DG double-vacancy atomic resolution;

(H) OER polarization curves of DG, Ni @ DG, A-Ni @ DG and Ir / C in 1 M KOH electrolyte;

(I) The energy distribution of the three configurations of OER.

Figure 20. Gas adsorption separation
(a) Schematic diagram of the formation process of porous graphene;

(B) Photograph and SEM of membrane structure;

(C) N ₂ permeability of each hole through holes of different diameters ;

(D) Permeability is normalized to Knudsen number by free molecular flow;

(E) Normalize the gas permeability by the N ₂ permeability of graphene films with different pore sizes ;

(F) Relationship between H ₂ / CO ₂ gas separation factor and pore size.

Figure 21. Bioseparation
(a) Schematic diagram of a typical graphene nanopore device;

(B) The current measured in the graphene nanopore system with or without dsDNA in the buffer;

(C) Schematic diagram of the graphene-dielectric graphene film that studies the 850 bp dsDNA translocation;

(D) Translocation histogram of dsDNA translocation at transmembrane voltages of 300 and 500 mV, respectively.

【Summary and Outlook】

This paper introduces the surface interface chemistry, assembly chemistry and functional chemistry of graphene in detail; it focuses on the construction methods, control mechanisms and surface chemistry of different porous graphene, including in-plane pores, 2D layered pores and 3D assembly pore materials The importance of grooming. And in-depth discussion of the role of porous graphene materials in applications such as supercapacitors, lithium-ion / lithium-sulfur / lithium batteries, non-lithium batteries (sodium / potassium / aluminum, etc.), electrocatalysis (HER, OER, ORR), and molecular separation To the role. Although graphene and porous graphene have made significant progress in preparation methods and applications, there are still key issues to be resolved. Based on this, the paper proposes some possible solutions, including bionic construction strategies, design of graded graphene, construction of new porous graphene composites, development of in-situ characterization technology, pre-lithiation to improve the first coulomb efficiency, balance weight and Volumetric energy density, as well as equilibrium conductivity and electrocatalytic active sites. It is worth noting that the combination of multiple methods can more effectively solve the scientific problems of porous graphene in specific applications. In summary, this review paper provides scientific guidance for in-depth understanding of the chemical properties of graphene and porous graphene, and provides new inspiration for its controllable preparation, rational construction, and important applications.

The first author of the paper is Dr. Huang Haibo, and the corresponding authors are researcher Wu Zhongshuai and academician Cheng Huiming .

Literature link: The Chemistry and Promising Applications of Graphene and Porous Graphene Materials ( Adv. Funct. Mater. , 2020 , DOI: 10.1002 / adfm.201909035)

Corresponding author

Wu Zhongshuai, Chief Researcher, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 2D Materials and Energy Device Research Team Leader (PI), PhD Supervisor, Fellow of the Royal Society of Chemistry, Distinguished Expert of High-level Talents of the Central Organization Department (2015) , 2018 and 2019, "Cravion" global highly cited scientist, academic leader of Dalian city key field innovation team support plan project; won the second prize of National Natural Science Award (2017, the fourth finisher), Liaoning Province Natural First prize of Science Award (2015, fourth finisher). He has long been engaged in basic research on the application of two-dimensional energy materials and high-efficiency electrochemical energy innovation systems, including flexible / miniature energy storage devices, metal / solid-state batteries, and supercapacitors. Academic papers 130 have been developed in journals such as Energy Environ. Sci., Adv. Mater., Nat. Commun., J. Am. Chem. Soc., Angew. Chem. Int. Ed., Adv. Energy Mater., ACS Nano, etc. More than 70 papers with an impact factor greater than 10 have been cited by SCI more than 20,000 times. He has served as academic editor of Applied Surface Science, executive editor of Journal of Energy Chemistry, international editorial board member and guest editor of Energy Storage Materials, and guest editor of Advanced Materials.

Cheng Huiming, Director of Advanced Carbon Materials Research Department, Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, and Director of Low-Dimensional Materials and Devices Laboratory, Tsinghua-Berkeley Shenzhen University. Carbon materials scientist, academician of the Chinese Academy of Sciences, academician of the Academy of Developing Countries, and chief editor of Energy Storage Materials magazine . Won the second prize of National Natural Science Award, American Charles E. Pettinos Award, He Liang He Li Science and Technology Progress Award and other awards. Mainly engaged in the preparation, performance and application of low-dimensional materials such as carbon nanotubes, graphene, and other two-dimensional materials. He has published more than 600 academic papers in international journals such as Nature Mater., Adv. Mater., APL, CPL, JMR, Carbon, etc., and has been cited by SCI nearly 60,000 times. One of the highly cited scholars in the two fields of chemistry and materials science, he has compiled and published 4 monographs and translations, and obtained more than 100 invention patents.

Relevant high-quality literature recommendation:

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2. XY Shi, SF Pei, F. Zhou, WC Ren *, H.-M. Cheng, Z.-S. Wu *, XH Bao, Ultrahigh-Voltage Integrated Micro-Supercapacitors with Designable Shapes and Superior Flexibility , E nergy & Environmental Science , 2019 , 12, 1534-1541.

3. SH Zheng, JM Ma, Z.-S. Wu *, F. Zhou, YB He *, FY Kang, H.-M. Cheng and XH Bao, All-Solid-State Flexible Planar Lithium Ion Micro-Capacitors, Energy & Environmental Science , 2018 , 11, 2001-2009.

4. SH Zheng, XY Shi, P. Das, Z.-S. Wu *, XH Bao, The Road Towards Planar Microbatteries and Micro-Supercapacitors: From 2D To 3D Device Geometries, Advanced Materials , 2019 , 1900583.

5. Y. Wu, HB Huang, Z.-S. Wu * and Y. Yu *, The Promise and Challenge of Phosphorus-Based Composites as Anode Materials for Potassium-Ion Batteries, Advanced Materials , 2019 , 31, 1901414.

6. XY Shi, Z.-S. Wu *, JQ Qin, SH Zheng, S. Wang, F. Zhou, CL Sun and XH Bao, Graphene Based Linear Tandem Micro-Supercapacitors with Metal-Free Current Collectors and High-Voltage Output, Advanced Materials , 2017 , 29, 1703034.

7. Y. Yao, Z. Wei, H. Wang, H. Huang, Y. Jiang, X. Wu, X. Yao *, Z.-S. Wu * and Y. Yu *, Toward High Energy Density All Solid -State Sodium Batteries with Excellent Flexibility, Advanced Energy Materials , 2020 , 1903698.

8. X. Wang, S. Zheng, F. Zhou, J. Qin, X. Shi, S. Wang, CL Sun, X. Bao and Z.-S. Wu *, Scalable Fabrication of Printed Zn // MnO ₂ Planar Micro-Batteries with High Volumetric Energy Density and Exceptional Safety, National Science Review , 2020 , 7, 64-72.

9. H. Tian, J. Qin, D. Hou, Q. Li, C. Li, Z.-S. Wu * and Y. Mai *, A General Interfacial Self-Assembly Engineering for Patterning Two-dimensional Polymers with Cylindrical Mesopores on Graphene, Angewandte Chemie International Edition , 2019 , 58, 10173-10178.

10. F. Zhou, HB Huang, CH Xiao, SH Zheng, XY Shi, JQ Qin, Q. Fu, XH Bao, XL Feng *, K. Müllen * and Z.-S. Wu *, Electrochemically Scalable Production of Fluorine Modified Graphene for Flexible and High-Energy Ionogel-Based Micro-supercapacitors, Journal of the American Chemical Society , 2018 , 140, 8198-8205.

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