For lithium–sulfur (Li–S) batteries, the problems of polysulfides shuttle effect, slow dynamics of sulfur species and growth of lithium dendrite during charge/discharge processes have greatly impeded its practical development. Of core importance to advance the performances of Li–S batteries lies in the selection and design of novel materials with strong polysulfides adsorption ability and enhanced redox electrocatalytic behavior. Graphene, affording high electrical conductivity, superior carrier mobility, and large surface area, has presented great potentials in improving the performances of Li–S cells. However, the properties of intrinsic graphene are far enough to achieve the multiple management toward electrochemical catalysis of energy storage systems. In addition, a general and objective understanding of its role in Li–S systems is still lacking. Along this line, we summarize the design routes from three aspects, including defect engineering, dimension adjustment, and heterostructure modulation, to perfect the graphene properties. Thus-synthesized graphene materials are explored as multifunctional electrocatalysts targeting high-efficiency and long-lifespan Li–S batteries, based on which the regulating role of graphene is comprehensively analyzed. This project provides a perspective on the effective engineering management of graphene materials to boost Li–S chemistry, meanwhile promote the practical application process for graphene materials.

Gaseous promotors have readily been adopted during the direct synthesis of graphene over insulators to enhance the growth quality and/or boost the growth rate. The understanding of the real functions of carbon-containing promotors has still remained elusive. In this study, we identify the critical roles of a representative CO₂ promotor played in the direct growth of graphene. The comparative experimental trials validate CO₂ as an effective modulator to decrease graphene nucleation density, improve growth kinetics, and mitigate adlayer formation. The first-principles calculations illustrate that the generation of gas-phase OH species in CO₂-assisted system helps decrease the energy barriers of CH₄ decomposition and carbon attachment to the growth front, which might be the key factor to allow high-quality direct growth. Such a CO₂-promoted strategy enables the conformal coating of graphene film over curved insulators, where the sheet resistance of grown graphene on quartz reaches as low as 1.26 kΩ·sq⁻¹ at an optical transmittance of ~ 95.8%. The fabricated endoscope lens based on our conformal graphene harvests an apoptosis of 82.8% for noninvasive thermal therapy. The work presented here is expected to motivate further investigations in the controllable growth of high-quality graphene on insulating substrates.

Direct ink writing (DIW) has recently emerged as an appealing method for designing and fabricating three-dimensional (3D) objects. Complex 3D structures can be built layer-by-layer via digitally controlled extrusion and deposition of aqueous-based colloidal pastes. The formulation of well-dispersed suspensions with specific rheological behaviors is a prerequisite for the use of this route. In this review article, the fundamental concepts of DIW are presented, including the operation principles and basic features. Typical strategies used for ink formulation are discussed with a focus on the most widely used electrode materials, including graphene, Mxenes, and carbon nanotubes. The recent progress in printing design of emerging energy storage systems, encompassing rechargeable batteries, supercapacitors, and hybrid capacitors, is summarized. Challenges and future perspectives are also covered to provide guidance for the future development of DIW.

Attention toward aqueous zinc-ion battery has soared recently due to its operation safety and environmental benignity. Nonetheless, dendrite formation and side reactions occurred at the anode side greatly hinder its practical application. Herein, we adopt direct plasma-enhanced chemical vapor deposition strategy to in situ grow N-doped carbon (NC) over commercial glass fiber separator targeting a highly stabilized Zn anode. The strong zincophilicity of such a new separator would reduce the nucleation overpotential of Zn and enhance the Zn-ion transference number, thereby alleviating side reactions. Symmetric cells equipped with NC-modified separator harvest a stable cycling for more than 1,100 h under 1 mA·cm⁻²/1 mAh·cm⁻². With the assistance of NC, the depth of discharge of Zn anode reaches as high as 42.7%. When assembled into full cells, the zinc-ion battery based on NC-modified separator could maintain 79% of its initial capacity (251 mAh·g⁻¹) at 5 A·g⁻¹ after 1,000 cycles.

Growing high quality graphene films directly on glass by chemical vapor deposition (CVD) meets a growing demand for constructing high-performance electronic and optoelectronic devices. However, the graphene synthesized by prevailing methodologies is normally of polycrystalline nature with high nucleation density and limited domain size, which significantly handicaps its overall properties and device performances. Herein, we report an oxygen-assisted CVD strategy to allow the direct synthesis of 6-inch-scale graphene glass harvesting markedly increased graphene domain size (from 0.2 to 1.8 μm). Significantly, as-produced graphene glass attains record high electrical conductivity (realizing a sheet resistance of 900 Ω·sq^-1 at a visible-light transmittance of 92%) amongst the state-of-the-art counterparts, readily serving as transparent electrodes for fabricating high-performance optical filter devices. This work might open a new avenue for the scalable production and application of emerging graphene glass materials with high quality and low cost.

Nitrogen doped carbon is a burgeoning anode candidate for potassium-ion battery (PIBs) owing to its outstanding attributes. It is imperative to grasp further insight into specific effects of different nitrogen dopants in carbon anode toward advanced K-ion storage. However, the prevailing fabrication method is plagued by the fact that considerable variations in the total N-doping concentration occur in the course of regulating the type of nitrogen dopants, incapable of distinguishing the certain roles of them under similar conditions. Herein, throughout the precise preparation of high edge-N doped carbon (HENC) and high graphitic-N doped carbon (HGNC) harnessing basically identical N-doping levels (5.78 at.% for HENC; 5.07 at.% for HGNC) via chemical vapor deposition route, the effects of edge-N and graphitic-N in the carbon anode on K-ion storage are revisited, offering guidance into the design of low-cost and high-performance PIB systems.

Scalable synthesis of transfer-free graphene over insulators offers exciting opportunity for next-generation electronics and optoelectronics. However, rational design of synthetic protocols to harvest wafer-scale production of directly grown graphene still remains a daunting challenge. Herein we explore a batch synthesis of large-area graphene with wafer-scale uniformity by virtue of direct chemical vapor deposition (CVD) on quartz. Such a controllable CVD approach allows to synthesize 30 pieces of 4-inch graphene wafers in one batch, affording a low fluctuation of optical and electrical properties. Computational fluid dynamics simulations reveal the mechanism of uniform growth, indicating thermal field and confined flow field play leading roles in attaining the batch uniformity. The resulting wafer-scale graphene enables the direct utilization as key components in optical elements. Our method is applicable to other types of insulating substrates (e.g., sapphire, SiO₂/Si, Si₃N₄), which may open a new avenue for direct manufacture of graphene wafers in an economic fashion.

Tin-based compounds are deemed as suitable anode candidates affording promising sodium-ion storages for rechargeable batteries and hybrid capacitors. However, synergistically tailoring the electrical conductivity and structural stability of tin-based anodes to attain durable sodium-ion storages remains challenging to date for its practical applications. Herein, metal-organic framework (MOF) derived SnSe/C wrapped within nitrogen-doped graphene (NG@SnSe/C) is designed targeting durable sodium-ion storage. NG@SnSe/C possesses favorable electrical conductivity and structure stability due to the "inner" carbon framework from the MOF thermal treatment and "outer" graphitic cage from the direct chemical vapor deposition synthesis. Consequently, NG@SnSe/C electrode can obtain a high reversible capacity of 650 mAh·g^-1 at 0.05 A·g^-1, a favorable rate performance of 287.8 mAh·g^-1 at 5 A·g^-1 and a superior cycle stability with a negligible capacity decay of 0.016% per cycle over 3, 200 cycles at 0.4 A·g^-1. Theoretical calculations reveal that the nitrogen-doping in graphene can stabilize the NG@SnSe/C structure and improve the electrical conductivity. The reversible Na-ion storage mechanism of SnSe is further investigated by in-situ X-ray diffraction/ex-situ transmission electron microscopy. Furthermore, assembled sodium-ion hybrid capacitor full-cells comprising our NG@SnSe/C anode and an active carbon cathode harvest a high energy/power density of 115.5 Wh·kg^-1/5, 742 W·kg^-1, holding promise for next-generation energy storages.

The booming of wearable electronics has nourished the progress on developing multifunctional energy storage systems with versatile flexibility, which enable the continuous and steady power supply even under various deformed states. In this sense, the synergy of flexible energy and electronic devices to construct integrative wearable microsystems is meaningful but remains quite challenging by far. Herein, we devise an innovative supercapacitor/sensor integrative wearable device that is based upon our designed vanadium nitride-graphene (VN-G) architectures. Flexible quasi-solid-state VN-G supercapacitor with ultralight and binder-free features deliver a specific capacitance of ~ 53 F·g^-1 with good cycle stability. On the other hand, VN-G derived pressure sensors fabricated throughout a spray-printing process also manifest favorably high sensitivity (40 kPa^-1 at the range of 2–10 kPa), fast response time (~ 130 ms), perfect skin conformability, and outstanding stability under static and dynamic pressure conditions. In turn, their complementary unity into a self-powered wearable sensor enables the precise detection of physiological motions ranging from pulse rate to phonetic recognition, holding promise for in-practical health monitoring applications.

Sodium-ion batteries (SIBs) have been increasingly attracting attention as a sustainable alternative to lithium-ion batteries for scalable energy storage. The key to advanced SIBs relies heavily upon the development of reliable anodes. In this respect, Bi₂S₃ has been extensively investigated because of its high capacity, tailorable morphology, and low cost. However, the common practices of incorporating carbon species to enhance the electrical conductivity and accommodate the volume change of Bi₂S₃ anodes so as to boost their durability for Na storage have met with limited success. Herein, we report a simple method to realize the encapsulation of Bi₂S₃ nanorods within three-dimensional, nitrogen-doped graphene (3DNG) frameworks, targeting flexible and active composite anodes for SIBs. The Bi₂S₃/3DNG composites displayed outstanding Na storage behavior with a high reversible capacity (649 mAh·g^–1 at 62.5 mA·g^–1) and favorable durability (307 and 200 mAh·g^–1 after 100 cycles at 125 and 312.5 mA·g^–1, respectively). In-depth characterization by in situ X-ray diffraction revealed that the intriguing Na storage process of Bi₂S₃ was based upon a reversible reaction. Furthermore, a full, flexible SIB cell with Na_0.4MnO₂ cathode and as-prepared composite anode was successfully assembled, and holds a great promise for next-generation, wearable energy storage applications.