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Rational design of carbon materials for electrochemical devices has attracted great attentions over the past decades. Doping carbon with heteroatoms has been widely proven to be an effective way to improve the physical and electrochemical properties of carbon. The selective types and doping level of heteroatoms, as well as simple and green doping routes, are keys to the development of heteroatoms doped carbon. Due to a strong synergistic effect generated by the co-doping of boron (B) and nitrogen (N), B, N co-doped carbon materials have been demonstrated to be promising catalysts for multiple electrochemical devices. Herein, we report an eco-friendly and one-step approach to synthesis of B, N co-doped graphene (B, N-G) using BN as B and N doping resources. The decomposition of BN under a controlled flow of water steam at high temperature not only enables a high-level B and N co-doping into carbon but also facilitates the formation of highly active catalytic sites. Benefiting from high co-doping level of heteroatoms and highly active catalytic sites (e.g., BC2O), the B, N-G as cathode for rechargeable lithium oxygen batteries displays outstanding lithium storage properties with an ultrahigh specific capacity of 18222 mAh g−1 at 100 mA g−1 and good cycling stability with a limited specific capacity of 1000 mAh g−1 over 120 cycles at 1 A g−1.

The big challenge for practical lithium metal batteries is how to make full and reversible utilization of lithium anode. The preformed three-dimensional (3D) porous framework with numerous lithium nucleation sites is able to guide the lithium deposition in the cavity of 3D framework, suppressing the dendrite growth and dimensional change. Herein, we design a nanocapsule structure for lithium metal anodes consisting of 3D graphene with MgxLiy seeds inside. The 3D composite anode not only can be prepared in a simple and scalable process, but also can meet the requirements for both high energy density and long cycle life in the practical cells. During the observation of lithium deposition by transmission electron microscope, it was found that lithium metal was mainly deposited around the MgxLiy seeds within 3D graphene. Thereafter, when the composite anodes are well paired with the commercial LiFePO4 cathodes in coil cells and NCM811 (LiNi0.8Co0.1Mn0.1O2) cathodes in pouch batteries, they are able to deliver the energy density exceeding 350 ​Wh·kg−1 and long cycle life (>150 cycles) with high energy retention (>85%). The 3D lithium metal/graphene composite anode in the present work provides a promising new avenue for the fabrication of high energy density Li-metal batteries.

Although lithium ion batteries (LIBs) hold great promise as a next generation power supply, the poor rate capability of the graphite that is mainly used as the battery anode limits high-performance LIBs. Compared to other reported carbon-based materials, however, its relatively low average working voltage still makes it attractive. Herein, we were able to introduce carbon disulfide (CS2) at the edges of graphene nanoplatelets (GnPs) with rich –C=S/-C-S bonds via ball-milling graphite in the presence of CS2. The resultant edge-thionic acid-functionalized GnPs (TAGnPs) exhibited a larger accessible surface area and smaller particle size than pristine graphite. Importantly, the TAGnPs retained a long-range-ordered layered structure similar to pristine graphite. When the TAGnPs were used as anode materials for LIBs, they displayed superior rate capability (e.g., high average reversible capacities of 228.3, 208.1, 141.0 and 80.6 mAh g−1 at 0.5, 1, 2 and 5 A g−1, respectively) compared to pristine graphite and the reference edge-hydrogenated GnPs (HGnPs), which mainly have -C-H bonds at their edges. Theoretical calculations also indicated that the presence of –C=S/-C-S bonds at the edges of TAGnPs enabled stronger Li+ adsorption capability.

Summary: The 3d transition metals have been investigated as active centers in NiOOH to catalyze oxygen evolution reaction (OER); however, questions about the mechanism remain. Here, we study how cobalt (Co) and iron (Fe) doping and CoFe codoping determine the OER activity of NiOOH via experiments and theoretical calculations. The results show that both Co and Fe, with enhanced density of states near the Fermi level, decrease the overpotential by increasing the binding energy of O∗ and consequently exhibit higher activities than nickel. In particular, Fe, with nearly optimal O∗ binding energy, exhibits the lowest overpotential of 181 mV to reach 50 mA cm−2. In the case of CoFe codoping, Co alters the electronic states of Fe, which weakens the Fe-OOH bond and slightly increases the overpotential. Based on the calculated activities, an overpotential contour plot is constructed, providing guidance for catalyst design via modulating electronic structures and intermediate binding energies.

This paper reports the rational design and synthesis of a novel electron-withdrawing building block, thiazole flanked naphthalene diimide (TzNDI), which offers a coplanar conformation and deep-lying highest-occupied molecular orbitals energy level in resulting conjugated polymers. A series of conjugated polymers (PTzNDI-2FT, PTzNDI-T, PTzNDI-Se, and PTzNDI-2T) consisting of TzNDI and different donor units were synthesized and characterized. The polymers all possess a high molecular weight and excellent thermal property. Their intense light absorption in low energy bands suggests an enhanced intramolecular charge transfer. The organic field-effect transistors (OFETs) based on these polymers exhibit unipolar n-type transport characteristics with low off current and high on–off current ratio. More importantly, all the devices exhibit near ideal transfer curves with kink-free transfer characteristics. Among these polymers, PTzNDI-2FT exhibits the highest electron mobility (μe) of 0.57 cm2 V–1 s–1, outperformi...

A (MoS2/carbon fiber (CF))@MoS2@C hybrid has been prepared by an efficient method combining the electrospinning, hydrothermal and annealing techniques. Coupled with graphite as cathode, the hybrid enables the full cell (i.e., dual ion batteries) to deliver a high initial discharge capacity of 112.3 mAh g−1 at 0.2 A g−1 and maintain a high reversible capacity of 90.5 mAh g−1 at 0.5 A g−1 after 500 cycles. These remarkable sodium storage properties of (MoS2/CF)@MoS2@C are mainly attributed to its three-dimensional framework with its highly conductive, cross-linked structure, which effectively increases the conductivity of the hybrid and the mass loading of MoS2. Moreover, the MoS2 nanoplates embedded inside CF, as well as being sandwiched between the CF/MoS2 and a thin carbon layer, also can effectively buffer the pulverization and aggregation of the electrode, and thus maintain the structural integrity of (MoS2/CF)@MoS2@C during the charge-discharge process.

Heteroatoms doped carbon based materials with enhanced catalytic properties hold great potential in energy storage applications, including rechargeable lithium oxygen batteries (LOBs). However, large-scale production of heteroatoms co-doped carbon with high-level dopants as well as the precise control of uniformly distributed dopant location remain challenges. Holey graphene as an emerging carbon based material has attracted increased attention as cathode for LOBs due to its nanoholes through the graphene nanosheet basal plane. Apart from the given rapid diffusion channels for mass (e.g., O2 and Li+ ), the nanoholes also provide rich egdes for the mass adsorption and storage as well as the heteroatoms doping. Herein, we report an environment-friendly and simple approach to mass production of hG with abundant in-plane nanoholes via direct oxidation of reduced graphene oxides (rG) by a controlled flow gas of H2O. Based on the obtained hG, 3.0 at.% B and 2.1 at.% N atoms are further co-doped into the hG to form B, N-hG. Benefiting from its holey structures and the synergistic effect of B and N, the B, N-hG as cathode for LOBs displays promising properties with a maximum discharge capacity of 15340 mAh g−1 and long cycling stability over 117 cycles.

Sodium ion batteries (SIBs) have attracted increasing attention as one of the most promising candidates for cost-effective, high-energy rechargeable batteries. Owing to their high theoretical capacity and energy density, and rich electrochemical interaction with Na+ (V2+–V5+), a large number of vanadium(V)-based cathode materials, including vanadium oxides (e.g., V2O5 and VO2), vanadium bronzes (e.g., NaxVO2, NaV3O8, NaV6O15 and δ-NH4V4O10), V-based phosphates (e.g., Na3V2(PO4)3, VOPO4, NaVOPO4, Na7V3(P2O7)4 and Na2(VO)P2O7) and F-containing V-based polyanions (e.g., NaVPO4F, Na3V2(PO4)2F3 and Na3(VOx)2(PO4)2F3−2x), have been explored for SIBs. In this review, we mainly summarize the basic structures, modified/optimized structures, synthetic methods and morphology control of V-based cathode materials for SIBs. Additionally, major drawbacks, emerging challenges and some perspectives on the development of V-based cathode materials for SIBs are also discussed.

Lithium iodide (LiI) as cathode for lithium-iodine (Li-I 2 ) batteries hold great promise compared to I 2 mainly owing to its greater merits, including its potential pairing with a lithium-metal-free anode and only ~5% decrease in theoretical capacity. LiI confined within the meso-micro porous carbon polyhedrons (LiI@MCP) as cathode for Li-I 2 batteries has been studied for the first time. Benefiting from the rich meso-/micro-porous structures and highly conductive frameworks of MCP, the LiI@MCP with uniform distribution of LiI displays high reversible capacity, good rate abilities and superior long cycling life at 2C over 800 cycles with a low capacity decaying rate (0.021% per cycle). This work will open a new paradigm for the use of LiI as cathode for high-performance Li-I 2 batteries.

Solar-driven photoelectrochemical (PEC) water splitting is a clean and powerful approach for renewable hydrogen production. The PEC performance of hematite (α-Fe 2 O 3 ) is largely limited by its short hole diffusion length, which imposes restrictions on increasing the thickness for enough light absorption. In this work, we report a well-engineered three-dimensional (3D) Fe 2 O 3 /NTO (Nb-doped SnO 2 ) nanobowl heterojunction for PEC electrode, driven by a high-photovoltage perovskite solar cell (PSC), has boosted the efficiency greatly. The 3D heterojunction is made of an ultrathin Ti-doped hematite layer deposited on a periodic NTO nanobowl array. This PEC electrode, not only significantly improves the light absorption of the ultrathin hematite, but also enhances the interface contact. As a result, it exhibits ∼3.16 mA cm −2 photocurrent at 1.23 V vs the reversible hydrogen electrode with the Co–Pi cocatalyst. The tandem cell self-biased with a high-photovoltage PSC delivers up to 3.25% solar-to-hydrogen conversion efficiency, higher than those of state-of-the-art hematite-based PEC cells.

Metal-air batteries, especially Li-air batteries, have attracted significant research attention in the past decade. However, the electrochemical reactions between CO2 (0.04 % in ambient air) with Li anode may lead to the irreversible formation of insulating Li2CO3, making the battery less rechargeable. To make the Li-CO2 batteries usable under ambient conditions, it is critical to develop highly efficient catalysts for the CO2 reduction and evolution reactions and investigate the electrochemical behavior of Li-CO2 batteries. Here, we demonstrate a rechargeable Li-CO2 battery with a high reversibility by using B,N-codoped holey graphene as a highly efficient catalyst for CO2 reduction and evolution reactions. Benefiting from the unique porous holey nanostructure and high catalytic activity of the cathode, the as-prepared Li-CO2 batteries exhibit high reversibility, low polarization, excellent rate performance, and superior long-term cycling stability over 200 cycles at a high current density of 1.0 A g−1. Our results open up new possibilities for the development of long-term Li-air batteries reusable under ambient conditions, and the utilization and storage of CO2.

A highly efficient and continuous high-pressure homogenization (HPH) approach is developed for scalable production of graphene sheets and sandwich-structured α-Fe2O3/graphene hybrids by liquid-phase exfoliation of stage-1 FeCl3-based graphite intercalation compounds (GICs). The enlarged interlayer spacing of FeCl3-GICs facilitates their efficient exfoliation to produce high-quality graphene sheets. Moreover, sandwich-structured α-Fe2O3/few-layer graphene (FLG) hybrids are readily fabricated by thermally annealing the FeCl3 intercalated FLG sheets. As an anode material of Li-ion battery, α-Fe2O3/FLG hybrid shows a satisfactory long-term cycling performance with an excellent specific capacity of 1100.5 mA h g–1 after 350 cycles at 200 mA g–1. A high reversible capacity of 658.5 mA h g–1 is achieved after 200 cycles at 1 A g–1 and maintained without notable decay. The satisfactory cycling stability and the outstanding capability of α-Fe2O3/FLG hybrid are attributed to its unique sandwiched structure consisti...

Phosphorus has recently received extensive attention as a promising anode for lithium ion batteries (LIBs) due to its high theoretical capacity of 2,596 mAh·g–1. To develop high-performance phosphorus anodes for LIBs, carbon materials have been hybridized with phosphorus (P-C) to improve dispersion and conductivity. However, the specific capacity, rate capability, and cycling stability of P-C anodes are still less than satisfactory for practical applications. Furthermore, the exact effects of the carbon support on the electrochemical performance of the P-C anodes are not fully understood. Herein, a series of xP-yC anode materials for LIBs were prepared by a simple and efficient ball-milling method. 6P-4C and 3P-7C were found to be optimum mass ratios of x/y, and delivered initial discharge capacities of 1,803.5 and 1,585.3·mAh·g–1, respectively, at 0.1 C in the voltage range 0.02–2 V, with an initial capacity retention of 68.3% over 200 cycles (more than 4 months cycling life) and 40.8% over 450 cycles. The excellent electrochemical performance of the 6P-4C and 3P-7C samples was attributed to a synergistic effect from both the adsorbed P and carbon.

Li–air batteries represent cutting edge electrochemical energy storage devices, but their practical applications have been precluded by the high cathode cost, the low discharge/charge efficiency, and/or the short battery lifetime. Here, we developed a low-cost, but very efficient, air electrode from porous nitrogen-doped holey graphene for rechargeable nonaqueous Li–O2 cells. The resultant Li–O2 cell can deliver a high round-trip efficiency (85%) and a long cycling life (>100 cycles) under controlled discharge/charge depths or a high capacity of 17 000 mAh/g under the full discharge/charge condition, superior to most other carbonaceous air cathodes. The observed superb performance for the air electrode based on the nitrogen-doped holey graphene can be attributed to its efficient metal-free catalytic activity and three-dimensional mass transport pathway. Therefore, this work represents a new approach to low-cost, efficient, metal-free, binder-free, and hierarchically porous air electrodes useful for energy...

Three-dimensional heterostructured NiCo2O4@MnMoO4 nanocolumn arrays (NCAs) on Ni foam were first fabricated through an improved two-step hydrothermal process associated with a successive annealing treatment. The hybrid NiCo2O4@MnMoO4 electrode exhibited remarkable pseudocapacitor property with high initial mass specific capacitance of 1705.3 F g(-1) at 5 mA cm(-2), and retained 92.6% after 5000 cycles, compared to the bare NiCo2O4 electrode with 839.1 F g(-1) and 90.9%. The excellent capacitive property of the NiCo2O4@MnMoO4 hydrid was attributed to its high-electron/ion-transfer rate, large electrolyte infiltrate area, and more electroactive reaction sites.

Electrocatalysts for the oxygen reduction reaction (ORR) play a crucial role in renewable-energy technologies, including metal-air batteries and fuel cells. However, development of novel catalysts with high activity and low cost remains a great challenge. Here, we present hierarchical MnO 2 /reduced graphene oxide (MnO 2 /rGO) hybrid nanosheets by using a facile method and study its electrocatalytic performance. Cyclic voltammograms, and rotating disk electrode and rotating ring/disk electrode measurements demonstrate that the hierarchical MnO 2 /rGO hybrid nanosheets exhibit excellent electrocatalytic activity for the ORR in an alkaline medium, as evidenced by their higher cathodic current density, more positive onset potential, lower H 2 O 2 yield, and higher electron transfer number compared to pure rGO. The excellent catalytic activity of the MnO 2 /rGO hybrid nanosheets highlights the importance of the synergetic chemical coupling effect between the ultrathin MnO 2 nanosheets and the graphene layer.

Carbon materials as promising anodes for lithium ion batteries (LIBs) have attracted great attentions owing to their high theoretical capacities and rich natural resources. To improve anode performance of carbon, several common strategies have been developed, such as the fabrication of carbon with various nanostructures and modification of carbon frameworks by heteroatoms doping. Besides, the introduction of transition metal single atom or atom clusters embedded in nitrogen-doped carbon frameworks is also a feasible route. Herein, we report a simple and effective approach for synthesis of Con@N-C hybrids (i.e., Co@N-C-0, Con@N-C-1 and Con@N-C-2) with interconnected porous carbon nanostructures and numerous active sites (e.g., Co-N-C). When it was measured as anode for LIBs, the Con@N-C-1 hybrid displayed outstanding lithium storage properties with a high initial reversible capacity of 1587 mAh g−1 at 0.1 C and maintained a high reversible capacity of 1000 mAh g−1 at 5 C after 800 cycles. Both experimental and theoretical results reveal that Co-N-C with high specific activity along with interconnected porous carbon nanostructures synergistically promote the transportation and storage of Li+.

Antimony- (Sb) based materials have been considered as one of promising anodes for sodium ion batteries (SIBs) owing to their high theoretical capacities and appropriate sodium inserting potentials. So far, the reported energy density and cycling stability of the Sb-based anodes for SIBs are quite limited and need to be significantly improved. Here, we develop a novel Sb/C hybrid encapsulating the Sb nanorods into highly conductive N and S codoped carbon (Sb@(N, S–C)) frameworks. As an anode for SIBs, the Sb@(N, S–C) hybrid maintains high reversible capacities of 621.1 mAh g–1 at 100 mA g–1 after 150 cycles, and 390.8 mAh g–1 at 1 A g–1 after 1000 cycles. At higher current densities of 2, 5, and 10 A g–1, the Sb@(N, S–C) hybrid also can display high reversible capacities of 534.4, 430.8, and 374.7 mAh g–1, respectively. Such impressive sodium storage properties are mainly attributed to the unique cross-linked carbon networks providing highly conductive frameworks for fast transfer of ions and electrons, a...

Amorphous nitrogen-doped carbon nanosheets was synthesized through thermal decomposition of ethylenediaminetetraacetic acid manganese disodium salt hydrate (C 10 H 12 N 2 O 8 MnNa 2 ⿿2H 2 O). The as-synthesized nitrogen-doped carbon nanosheets were characterized by X-ray diffraction, scanning electron microscopy, transition electron microscopy and X-ray photoelectron spectroscopy. The N content of the as-synthesized carbon nanosheets could reach as high as 11.77 at.%, with an especially high total of 7.94 at.% pyridinic N pluspyrrolic N. When tested as anode material for lithium ion batteries, the optimized carbon nanosheets exhibited high capacity, excellent rate capability, and stable cyclability over 600 cycles. The specific capacity was still as high as 465.8 mAh g ⿿1 at 0.5 C after 600 cycles,with a capacity decay from the 2nd cycle of 0.05% per cycle over 599 cycles. The excellent performance of C-600 is attributed to a synergistic effect of high surface area, numerous nanopores, high thermal stability, and low charge transfer resistance.

Sb/Cu2Sb/C composites are synthesized via a thermolysis approach with copper citrate and antimony acetate as precursors, respectively. The as-synthesized composites display an initial reversible capacity of 602 mA h g−1 and maintain 461 mA h g−1 after 60 cycles. The excellent electrochemical performance of the Sb/Cu2Sb/C composites can be ascribed to the presence of Sb/Cu2Sb and amorphous carbon layers. The amorphous carbon layers could prevent the damage of electrodes that resulted from large volume expansion. The Sb/Cu2Sb improves their electronic conductivity.

Graphene-like nanomaterials have received tremendous research interest due to their atomic thickness and fascinating properties. Previous studies mainly focus on the modulation of their electronic structures, which undoubtedly optimizes the electronic properties, but is not the only determinant of performance in practical applications. Herein, we propose a generalized strategy to incrementally manipulate the architectures of several atomically thin transition metal (hydr)oxides, and study their effects on catalytic water oxidation. The results demonstrate the obvious superiority of a wrinkled nanosheet architecture in both catalytic activity and durability. For instance, wrinkled Ni(OH)2 nanosheets display a low overpotential of 358.2 mV at 10 mA cm–2, a high current density of 187.2 mA cm–2 at 500 mV, a small Tafel slope of 54.4 mV dec–1, and excellent long-term durability with gradually optimized performance, significantly outperforming other nanosheet architectures and previously reported catalysts. Th...

Novel layered 2D frameworks (C3N and C2N-450) with well-defined crystal structures are explored for use as anode materials in lithium-ion batteries (LIBs) for the first time. As anode materials for LIBs, C3N and C2N-450 exhibit unusual electrochemical characteristics. For example, C2N-450 (and C3N) display high reversible capacities of 933.2 (383.3) and 40.1 (179.5) mAh g−1 at 0.1 and 10 C, respectively. Furthermore, C3N shows a low hypothetical voltage (≈0.15 V), efficient operating voltage window with ≈85% of full discharge capacity secured at >0.45 V, and excellent cycling stability for more than 500 cycles. The excellent electrochemical performance (especially of C3N) can be attributed to their inherent 2D polyaniline frameworks, which provide large net positive charge densities, excellent structural stability, and enhanced electronic/ionic conductivity. Stable solid state interface films also form on the surfaces of the 2D materials during the charge/discharge process. These 2D materials with promising electrochemical performance should provide insights to guide the design and development of their analogues for future energy applications.

Lithium‐ion batteries (LIBs) with higher energy density are very necessary to meet the increasing demand for devices with better performance. With the commercial success of lithiated graphite, other graphite intercalation compounds (GICs) have also been intensively reported, not only for LIBs, but also for other metal (Na, K, Al) ion batteries. In this Progress Report, we briefly review the application of GICs as anodes and cathodes in metal (Li, Na, K, Al) ion batteries. After a brief introduction on the development history of GICs, the electrochemistry of cationic GICs and anionic GICs is summarized. We further briefly summarize the use of cationic GICs and anionic GICs in alkali ion batteries and the use of anionic GICs in aluminium‐ion batteries. Finally, we reach some conclusions on the drawbacks, major progress, emerging challenges, and some perspectives on the development of GICs for metal (Li, Na, K, Al) ion batteries. Further development of GICs for metal (Li, Na, K, Al) ion batteries is not only a strong supplement to the commercialized success of lithiated‐graphite for LIBs, but also an effective strategy to develop diverse high‐energy batteries for stationary energy storage in the future.

Porous metal oxide architectures coated with a thin layer of carbon are attractive materials for energy storage applications. Here, a series of porous metal oxide (e.g., vanadium oxides, molybdenum oxides, manganese oxides) foams with/without nitrogen-doped carbon (N-C) coating have been synthesized via a general surfactant-assisted template method, involving the formation of porous metal oxides coated with 1-hexadecylamine (HDA) and a subsequent thermal treatment. The presence of HDA is of importance for the formation of a porous structure, and the successive pyrolysis of such a nitrogen-containing surfactant generates nitrogen-doped carbon (N-C) coated on the surface of metal oxides, which also provides a facile way to adjust the valence states of metal oxides via the carbothermal reduction reaction. When used as electrode materials, the highly porous metal oxides with N-C coating exhibited enhanced performance for lithium ion storage, thanks to the unique 3D structures associated with highly porous structure and thin N-C coating. Typically, the porous metal oxides (V2O5, MoO3, MnO2) exhibited discharge capacities of 286, 303, and 463 mAh g(-1) at current densities of 30 and 100 mA g(-1), respectively. In contrast, the metal oxides with low valences and carbon coating (VO2@N-C, MoO2@N-C, and MnO@N-C) exhibited improved capacities of 461, 613, and 892 mAh g(-1). The capacity retentions of about 87.5, 80.2, and 85.0% for VO2@N-C, MoO2@N-C, and MnO@N-C were achieved after 600 cycles, suggesting the acceptable cycling stability. The present strategy would provide general guidance for preparing porous metal oxide foams with enhanced lithium storage performances.

Since the discovery of graphene in 2004, research on 2D materials has grown rapidly. Compared to their bulk counterparts, 2D atomically thin, layered transition-metal dichalcogenides (TMDCs or MX2) nanosheets exhibit excellent electronic and optical properties, outstanding mechanical flexibility, and exceptional catalytic performance. As a representative of 2D materials, MX2 holds great promise in many potential applications, especially in energy-related applications. Here, a brief overview of atomically thin layered MX2 nanosheets applied in energy storage and conversion systems is presented. Firstly, the crystal structures and phases, morphologies, and synthesis methods of MX2 are discussed. Sequentially, the achieved progress on atomically thin MX2 in energy-related applications (i.e., the hydrogen-evolution reaction, oxygen-evolution reaction, CO2 electrochemical reduction, electrochemical capacitors, lithium-ion batteries, sodium-ion batteries, and lithium–sulfur batteries) is systematically discussed. Finally, the conclusions and some prospects regarding atomically thin MX2 for applications in the field of energy-storage systems are provided.

The rapid increase of the CO2 concentration in the Earth's atmosphere has resulted in numerous environmental issues, such as global warming, ocean acidification, melting of the polar ice, rising sea level, and extinction of species. To search for suitable and capable catalytic systems for CO2 conversion, electrochemical reduction of CO2 (CO2 RR) holds great promise. Emerging heterogeneous carbon materials have been considered as promising metal-free electrocatalysts for the CO2 RR, owing to their abundant natural resources, tailorable porous structures, resistance to acids and bases, high-temperature stability, and environmental friendliness. They exhibit remarkable CO2 RR properties, including catalytic activity, long durability, and high selectivity. Here, various carbon materials (e.g., carbon fibers, carbon nanotubes, graphene, diamond, nanoporous carbon, and graphene dots) with heteroatom doping (e.g., N, S, and B) that can be used as metal-free catalysts for the CO2 RR are highlighted. Recent advances regarding the identification of active sites for the CO2 RR and the pathway of reduction of CO2 to the final product are comprehensively reviewed. Additionally, the emerging challenges and some perspectives on the development of heteroatom-doped carbon materials as metal-free electrocatalysts for the CO2 RR are included.

With the large-scale applications of electric vehicles in recent years, future batteries are required to be higher in power and possess higher energy densities, be more environmental friendly, and have longer cycling life, lower cost, and greater safety than current batteries. Therefore, to develop alternative electrode materials for advanced batteries is an important research direction. Recently, the Chevrel phase Mo6 T8 (T = S, Se) has attracted increasing attention as electrode candidate for advanced batteries, including monovalent (e.g., lithium and sodium) and multivalent (e.g., magnesium, zinc and aluminum) ion batteries. Benefiting from its unique open crystal structure, the Chevrel phase Mo6 T8 cannot only ensure rapid ion transport, but also retain the structure stability during electrochemical reactions. Although the history of the research on Mo6 T8 as electrodes for advanced batteries is short, there has been significant progress on the design and fabrication of Mo6 T8 for various advanced batteries as above mentioned. An overview of the recent progress on Mo6 T8 electrodes applied in advanced batteries is provided, including synthesis methods and diverse structures for Mo6 T8 , and electrochemical mechanism and performance of Mo6 T8 . Additionally, a briefly conclusion on the significant progress, obvious drawbacks, emerging challenges and some perspectives on the research of Mo6 T8 for advanced batteries in the near future is provided.

Recent advances and achievements in emerging Li-X (X = O2 , S, Se, Te, I2 , Br2 ) batteries with promising cathode materials open up new opportunities for the development of high-performance lithium-ion battery alternatives. In this review, we focus on an overview of recent important progress in the design of advanced cathode materials and battery models for developing high-performance Li-X (X = O2 , S, Se, Te, I2 , Br2 ) batteries. We start with a brief introduction to explain why Li-X batteries are important for future renewable energy devices. Then, we summarize the existing drawbacks, major progress and emerging challenges in the development of cathode materials for Li-O2 (S) batteries. In terms of the emerging Li-X (Se, Te, I2 , Br2 ) batteries, we systematically summarize their advantages/disadvantages and recent progress. Specifically, we review the electrochemical performance of Li-Se (Te) batteries using carbonate-/ether-based electrolytes, made with different electrode fabrication techniques, and of Li-I2 (Br2 ) batteries with various cell designs (e.g., dual electrolyte, all-organic electrolyte, with/without cathode-flow mode, and fuel cell/solar cell integration). Finally, the perspective on and challenges for the development of cathode materials for the promising Li-X (X = O2 , S, Se, Te, I2 , Br2 ) batteries is presented.

Kish graphite, a waste (called dust) from a steelmaking process, can be simultaneously purified and functionalized by mechanochemical ball-milling in the presence of iodine. The resultant iodinated Kish graphite (I-Kish-G) contains low content of impurities and high iodine content (1.83 at%, 16.17 wt%, energy dispersive X-ray spectroscopy) with high crystallinity. It has high specific surface area (924.3 m2 g−1), indicating that I-Kish-G is significantly purified, functionalized, and exfoliated into a few graphitic layers. More importantly, I-Kish-G displays outstanding electrocatalytic activity for oxygen reduction reaction with long-term durability and robustness against methanol crossover and CO poisoning effects in alkaline media.

A series of post-transition metals and semimetals in groups IIIA (Al, Ga, In), IVA (Ge, Sn, Pb) and VA (As, Sb, Bi) were introduced onto graphene nanoplatelets (GnPs) by mechanochemical reaction. The selected metals have a lower electronegativity (χ, 1.61 ≤ χ M ≤ 2.18) but a much larger covalent atomic radius (d M = 120–175 pm) than carbon (χ C = 2.55, d C = 77 pm). The effect of the electronegativity and atomic radius of the metalated GnPs (MGnPs, M = Al, Ga, In, Ge, Sn, Pb, As, Sb, or Bi) on the anode performance of lithium-ion batteries was evalusted. Among the series of prepared MGnPs, GaGnP (χ Ga = 1.81, d Ga = 135 pm) in group IIIA, SnGnP (χ Sn = 1.96, d Sn = 140 pm) in group IVA and SbGnP (χ Sb = 2.05, d Sb = 141 pm) in group VA exhibited significantly enhanced performance, including higher capacity, rate capability and initial Coulombic efficiency. Both the experimental results and theoretical calculations indicated that the optimum atomic size (d M ~ 140 pm) was more significant to the anode performance than electronegativity, allowing not only efficient electrolyte penetration but also fast electron and ion transport across the graphitic layers.

An "atomic layer-by-layer" structure of Co3O4/graphene is developed as an anode material for lithium-ion batteries. Due to the atomic thickness of both the Co3O4 nanosheets and the graphene, the composite exhibits an ultrahigh specific capacity of 1134.4 mAh g-1 and an ultralong life up to 2000 cycles at 2.25 C, far beyond the performances of previously reported Co3O4/C composites.