N-doped graphene quantum dot-decorated N-TiO2/P-doped porous hollow g-C_(3)N_(4) nanotube composite photocatalysts for antibiotic photodegradation and H2 production

Exclusive responsiveness to ultraviolet light (~3.2 eV) and high photogenerated charge recombination rate are the two primary drawbacks of pure TiO_(2). We combined N-doped graphene quantum dots (N-GQDs), morphology regulation, and heterojunction construction strategies to synthesize N-GQD/N-doped TiO_(2)/P-doped porous hollow g-C_(3)N_(4) nanotube (PCN) composite photocatalysts (denoted as G-TPCN). The optimal sample (G-TPCN doped with 0.1wt% N-GQD, denoted as 0.1% G-TPCN) exhibits significantly enhanced photoabsorption, which is attributed to the change in bandgap caused by elemental doping (P and N), the improved light-harvesting resulting from the tube structure, and the upconversion effect of N-GQDs. In addition, the internal charge separation and transfer capability of0.1% G-TPCN are dramatically boosted, and its carrier concentration is 3.7, 2.3, and 1.9 times that of N-TiO_(2), PCN, and N-TiO_(2)/PCN(TPCN-1), respectively. This phenomenon is attributed to the formation of Z-scheme heterojunction between N-TiO_(2) and PCNs, the excellent electron conduction ability of N-GQDs, and the short transfer distance caused by the porous nanotube structure. Compared with those of N-TiO_(2), PCNs, and TPCN-1, the H2 production activity of 0.1%G-TPCN under visible light is enhanced by 12.4, 2.3, and 1.4times, respectively, and its ciprofloxacin (CIP) degradation rate is increased by 7.9, 5.7, and 2.9 times, respectively. The optimized performance benefits from excellent photoresponsiveness and improved carrier separation and migration efficiencies. Finally, the photocatalytic mechanism of 0.1% G-TPCN and five possible degradation pathways of CIP are proposed. This study clarifies the mechanism of multiple modification strategies to synergistically improve the photocatalytic performance of 0.1% G-TPCN and provides a potential strategy for rationally designing novel photocatalysts for environmental remediation and solar energy conversion.

基于MAPbI_(3)/Graphene/Si复合结构的高灵敏宽带太赫兹调制器

高性能硅基太赫兹调制器是构建超宽带太赫兹-光纤混合通信系统的关键器件之一.提出了一种基于钙钛矿/石墨烯/硅(MAPbI_(3)/Graphene/Si)复合结构的近红外光驱动的超宽带大调制深度太赫兹调制器.实验结果表明,石墨烯薄膜和钙钛矿空穴传输层在近红外光驱动下可有效地促进界面电荷分离,增大载流子复合寿命,显著增强器件的表面电导率,进一步调控太赫兹波的传输幅度,实现光控型太赫兹波调制器的功能.通过波长808 nm的近红外调制激励源,对器件在0.2—2.5 THz超宽频率范围的太赫兹透射特性进行表征,实验用6.1 mW/mm^(2)的低功率密度近红外光驱动下实现了高达88.3%的大调制深度,远高于裸硅基底的调制深度(约14.0%),具有高灵敏、宽带和大调制深度等显著优势,并且建立了相应的半解析器件模型,仿真验证了实验结果.所提出的MAPbI_(3)/Graphene复合薄膜在增强硅基调制器性能方面效果显著,为未来实现硅基太赫兹调制器在近红外太赫兹-光纤混合通信系统的集成提供了一种新策略.

A Study on the Efficiency Gain of CsSnGeI3 Solar Cells with Graphene Doping

This paper presents a newly designed ultra-thin, lead-free, and all-inorganic solar cell structure. The structure was optimized using the SCAPS-1D simulator, incorporating solid-state layers arranged as n-graphene/CsSnGeI3/p-graphene. The objective was to investigate the potential of utilizing n-graphene as the electron transport layer and p-graphene as the hole transport layer to achieve maximum power conversion efficiency. Various materials for the electron transport layer were evaluated. The optimized cell structure achieved a maximum power conversion efficiency of 20.97%. The proposed solar cell structure demonstrates promising potential as an efficient, inorganic photovoltaic device. These findings provide important insights for developing and optimizing inorganic photovoltaic cells based on CsSnGeI3, with n-graphene electron transport layers and p-graphene hole transport layers.

Sb_(2)S_(3)/石墨烯负极材料的制备及其储钠性能研究

钠离子电池(sodium-ion batteries,SIBs)具有成本低的潜在优势,有望成为替代锂离子电池(lithium ion batteries,LIBs)的储能设备。为提升钠离子电池的性能,开发出适应钠离子脱嵌的负极材料尤为重要。硫化锑(Sb_(2)S_(3))因其理论比容量高被认为是较好的钠离子电池负极材料。本文使用简单水热法将Sb_(2)S_(3)与石墨烯复合,制备Sb_(2)S_(3)/石墨烯复合材料(Sb_(2)S_(3)/Gr)。结果表明:Sb_(2)S_(3)/Gr作为钠离子电池负极时,不仅表现出良好的电导率(3.5×10~(-3)S/cm)和钠离子扩散速率(4.853×10~(-13)cm~2/s),而且在0.5 A/g的电流密度下,首圈库伦效率为76.27%,经150次循环后的比容量稳定在488 m A·h/g,表现出较高的比容量。Sb_(2)S_(3)/Gr复合材料表现出了极大的应用潜力,为高性能钠离子电池负极材料的研发提供了一定的参考价值。

0.7BiFeO_(3)-0.3BaTiO_(3)压电陶瓷的工艺优化及其电学性能

基于铁酸铋基陶瓷在压应力作用下产生感应电荷的压电转换特性,通过调控预烧温度、预烧次数和烧结温度3个影响因素,优化陶瓷制备工艺对陶瓷介电损耗和剩余极化强度等的影响,从而改善其压电性能,确定0.7BiFeO_(3)-0.3BaTiO_(3)陶瓷制备工艺的最佳条件:预烧温度730℃,预烧次数2次,预烧时间5 h,烧结温度984℃,制得陶瓷的压电常数为152 pC/N,比优化前提高了15.4%;剩余极化强度为29.16μC/cm 2,比优化前提升了42.3%;优化后的陶瓷样品为三方-四方(R-T)共存的纯钙钛矿相结构,成瓷性好,晶粒大小分布均匀且晶粒尺寸有所增大,介电损耗较优化前降低了14.3%。陶瓷制备工艺的改进显著优化了陶瓷的高温漏导和极化特性,从而提升了其压电性能。

Magnetic Fe_3O_4-Reduced Graphene Oxide Nanocomposites-Based Electrochemical Biosensing

An electrochemical biosensing platform was developed based on glucose oxidase(GOx)/Fe3O4-reduced graphene oxide(Fe3O4-RGO) nanosheets loaded on the magnetic glassy carbon electrode(MGCE).With the advantages of the magnetism, conductivity and biocompatibility of the Fe3O4-RGO nanosheets, the nanocomposites could be facilely adhered to the electrode surface by magnetically controllable assembling and beneficial to achieve the direct redox reactions and electrocatalytic behaviors of GOx immobilized into the nanocomposites. The biosensor exhibited good electrocatalytic activity, high sensitivity and stability. The current response is linear over glucose concentration ranging from 0.05 to 1.5 m M with a low detection limit of0.15 μM. Meanwhile, validation of the applicability of the biosensor was carried out by determining glucose in serum samples. The proposed protocol is simple, inexpensive and convenient, which shows great potential in biosensing application.

Recent advances on 3D printing graphene-based composites

3D printing or additive manufacturing (AM) has revolutionized the way of manufacturing by designing complex structures in a customized feature which cannot be realized by traditional processing methods. Incoming materials are trying to adopt 3D printing techniques which directly fabricate sophisticated entities with multifunctionality like mechanical, electrical, thermal and magnetic properties etc. For the realization of advanced materials, 3D printing techniques are emerging from single material to composite materials manufacturing by simply introducing the nano- and micro-reinforcements with the matrix. In this review, we provide an outline of 3D printing graphene-based composites according to various AM techniques including fused deposition modeling (FDM), direct ink writing (DIW), stereolithography (SLA) and selective laser sintering (SLS). First a brief introduction of various AM techniques is given to get a basic understanding of the principles of 3D printing, and then the fabrication process, structural characteristics and applications of different 3D printing techniques for graphene-based composites are summarized. In addition, some effective simulation and characterization methods are also included. We hope that this review would clarify the potential of AM techniques for composite materials and can open new prospects for designing of novel materials.

Highly concentrated graphene oxide ink for facile 3D printing of supercapacitors

3D printing of functional energy storage devices is receiving escalating attention over the years due to the customizable manufacturing flexibility and imparted high areal and gravimetric energy density of three-dimensional structured devices, which contribute to the creation of numerous new opportunities for futuristic electronics. Graphene-based inks are ideal elements for the realization of 3D printed energy storage devices if the attractive intrinsic physiochemical properties of graphene could be preserved. However, it is still a great challenge to prepare uniformly dispersed graphene-based materials with desired rheological properties for 3D printing. Here we report a facile strategy for 3D printing of supercapacitors from a highly concentrated graphene oxide (GO) ink. The GO is properly dispersed and the ink fulfills the stringent rheological specifications for 3D printing. The printed GO electrode is functionalized with enhanced structural stability for proper reduction to graphene. The printed supercapacitors deliver the potential to linearly scale up in areal capacitance without jeopardizing the gravimetric capacitance when increasing printed layers. The results hold great promise for the construction of 3D structured energy storage devices that cater to the challenges from next-generation electronics.

Graphene-immobilized flower-like Ni3S2 nanoflakes as a stable binder-free anode material for sodium-ion batteries

A binder-free Ni3S2 electrode was prepared directly on a graphene-coated Ni foam （G/Ni） substrate through surface sulfiding of substrate using thiourea as the sulfur source in this work. The Ni3S2 showed a flower-like morphology and was uniformly distributed on the G/Ni surface. The flower-like Ni3S2 was composed of cross-arrayed nanoflakes with a diameter and a thickness of 1-2 μm and -50 nm, re- spectively. The free space in the flowers and the thin feature of Ni3S2 buffered the volume changes and relieved mechanical strain during re- peated cycling. The intimate contact with the Ni substrate and the fixing effect of graphene maintained the structural stability of the Ni3S2 electrode during cycling. The G/Ni-supported Ni3S2 maintained a reversible capacity of 250 mAh·g^-1 after 100 cycles at 50 mA·g^-1, demon- strating the good cycling stability as a result of the unique microstructure of this electrode material.

Ge nanoparticles uniformly immobilized on 3D interconnected porous graphene frameworks as anodes for high-performance lithium-ion batteries

Germanium(Ge), an alloy-type anode material for lithium-ion batteries(LIBs), possesses many advantages such as high theoretical capacity and decent electrical conductivity. Nevertheless, its application is restricted by tremendous volume variation and tardy reaction kinetic during discharge/charge process.In this paper, the Ge/3DPG composites with Ge nanoparticles uniformly dispersed in 3D interconnected porous graphene(3DPG) skeleton are successfully prepared using a template-assisted in-situ reduction method. The unique 3D interconnected porous graphene can not only enhance the electronic conductivity and reaction kinetics of the materials, but also provide sufficient buffer space to effectively mitigate the volume expansion during cycling and strengthen the structural integrity. Moreover, the small-sized Ge nanoparticles in close conjunction with the 3D graphene can boost the surface-controlled reaction of the electrode, which contributes to a fast charge–discharge rate capability. The Ge/3DPG composite with optimized Ge/graphene mass ratio delivers high reversible specific capacity(1102 mAh g^(-1) after 100 cycles at 0.2 C), outstanding rate capability(494 mAh g^(-1) at 5 C), and admirable cycling stability(85.3% of capacity retention after 250 cycles at 0.5 C). This work provides a significant inspiration for the design and fabrication of advanced Ge-based anode materials for next-generation highperformance LIBs.

Graphene-wrapped Ag3PO4/LaCO3OH heterostructures for water purification under visible light

We demonstrated a unique synthesis approach of graphene（GR）-wrapped AgPO/LaCOOH（APO/LCO）heterostructures by an in-situ wet chemical method. FESEM analysis reveals the formation of rhombic dodecahedrons of APO decorated with LCO and later wrapped with GR flakes. Optical studies shows two absorption edges corresponding to the band gap energies of APO（2.41 eV） and LCO（4.1 eV）. Considering the absorption edge of the heterostructures in the visible region, the photocatalytic activities of photocatalysts containing different APO/LCO mass ratios were evaluated by the degradation of MB. GR-decorated composite with 20% LCO（APO/LCO20/GR） exhibited the highest photocatalytic activity for MB degradation, with a rate constant, k of 0.541 min. The photocatalytic activity of APO/LCO20/GR more greatly enhanced than those of the individual constituents（APO, LCO, APO/LCO20）. The enhanced photocatalytic activity of the heterostructure can be attributed to the co-catalytic effect of LCO as well as intriguing physicochemical properties of GR. To understand the enhanced photocatalytic activity of the heterostructures the photocatalytic reaction mechanism is proposed in detail. The recyclability of the APO/LCO/GR composite photocatalyst is further evaluated by reusing the catalyst in replicate photocatalytic experiments which shows consistent photocatalytic activity thereby confirms the stability and reusability of heterostructure photocatalyst.

Porous monoliths of 3D graphene for electric double-layer supercapacitors

For delivering the nanoscaled extraordinary characteristics in macroscopical bulk,it is essential to integrate two-dimensional nanosheets into threedimensional(3D)porous monoliths,alternatively called as 3D architectures,3D networks,or aerogels.The intersupported structure of porous monolithic 3D graphene(3DG)can prevent aggregation or restacking of graphene individuals,and the interconnected sp^(2) network of 3DG not only can provide the highway for the transport of electron/phonon but also can present continual cavities/channels for mass transfer.This review summarizes the synthesis methodology of 3DG porous monoliths and highlights the application for electric double-layer capacitors.Present challenges and future prospects about the manufacture and application of 3DG are also discussed.

MOF-Like 3D Graphene-Based Catalytic Membrane Fabricated by One-Step Laser Scribing for Robust Water Purification and Green Energy Production

Increasing both clean water and green energy demands for survival and development are the grand challenges of our age.Here,we successfully fabricate a novel multifunctional 3D graphene-based catalytic membrane(3D-GCM)with active metal nanoparticles(AMNs)loading for simultaneously obtaining the water purification and clean energy generation,via a“green”one-step laser scribing technology.The as-prepared 3D-GCM shows high porosity and uniform distribution with AMNs,which exhibits high permeated fluxes(over 100 L m^(−2) h^(−1))and versatile super-adsorption capacities for the removal of tricky organic pollutants from wastewater under ultra-low pressure-driving(0.1 bar).After adsorption saturating,the AMNs in 3D-GCM actuates the advanced oxidization process to self-clean the fouled membrane via the catalysis,and restores the adsorption capacity well for the next time membrane separation.Most importantly,the 3D-GCM with the welding of laser scribing overcomes the lateral shear force damaging during the long-term separation.Moreover,the 3D-GCM could emit plentiful of hot electrons from AMNs under light irradiation,realizing the membrane catalytic hydrolysis reactions for hydrogen energy generation.This“green”precision manufacturing with laser scribing technology provides a feasible technology to fabricate high-efficient and robust 3D-GCM microreactor in the tricky wastewater purification and sustainable clean energy production as well.

Sn_(4)P_(3)nanoparticles confined in multilayer graphene sheets as a high-performance anode material for potassium-ion batteries

Phosphorus-based anodes are highly promising for potassium-ion batteries(PIBs)because of their large theoretical capacities.Nevertheless,the inferior potassium storage properties caused by the poor electronic conductivity,easy self-aggregation,and huge volumetric changes upon cycling process restrain their practical applications.Now we impregnate Sn_(4)P_(3)nanoparticles within multilayer graphene sheets(Sn_(4)P_(3)/MGS)as the anode material for PIBs,greatly improving its potassium storage performance.Specifically,the graphene sheets can efficiently suppress the aggregation of Sn_(4)P_(3)nanoparticles,enhance the electronic conductivity,and sustain the structural integrity.In addition,plenty of Sn_(4)P_(3)nanoparticles impregnated in MGS offer a large accessible area for the electrolyte,which decreases the diffusion distance for K^(+)and electrons upon K^(+)insertion/extraction,resulting in an improved rate capability.Consequently,the optimized Sn_(4)P_(3)/MGS containing 80 wt%Sn_(4)P_(3)(Sn_(4)P_(3)/MGS-80)exhibits a high reversible capacity of 378.2 and 260.2 m Ah g;at 0.1 and 1 A g^(-1),respectively,and still delivers a large capacity retention of 76.6%after the 1000th cycle at 0.5 A g^(-1).

3D hierarchically porous NiO/Graphene hybrid paper anode for long-life and high rate cycling flexible Li-ion batteries

With the rapid emergence of wearable devices, flexible lithium-ion batteries(LIBs) are much more needed than ever. Free-standing graphene-based composite paper electrodes with various active materials have appealed wide applications in flexible LIBs. However, due to the prone-to-restacking feature of graphene layers, a long cycle life at high current densities is rather difficult to be achieved. Herein, a unique threedimensional(3D) hierarchically porous NiO micro-flowers/graphene paper(fNiO/GP) electrode is successfully fabricated. The resulting fNiO/GP electrode shows superior long-term cycling stability at high rates(e.g., storage capacity of 359 mAh/g after 600 cycles at a high current density of 1 A/g). The facile 3D porous structure combines both the advantages of the graphene that is highly conductive and flexible to ensure rapid electrons/ions transfer and buffer the volume expansion of NiO during charge/discharge,and of the micro-sized NiO flowers that induces hierarchical between-layer pores ranging from nanomicro meters to promote the penetration of the electrolyte and prevent the re-stacking of graphene layers. Such structural design will inspire future manufacture of a wide range of active materials/graphene composite electrodes for high performance flexible LIBs.

Coupling Co_(3)[Co(CN)_(6)]_(2) nanocubes with reduced graphene oxide for high-rate and long-cycle-life potassium storage

As one of prussian blue analogues,Co_(3)[Co(CN)_(6)]_(2) has been explored as a promising anode material for potassium-ion batteries(PIBs) owing to its high potassium storage capacity.Unfortunately,Co_(3)[Co(CN)_(6)]_(2) possesses low electronic conductivity and its structure collapses easily during potassiation and depotassiation,resulting in poor rate performance and cyclic stability.To solve these problems,we develop a facile multi-step method to successfully combine uniformCo_(3)[Co(CN)_(6)]_(2) nanocubes with rGO by C-O-Co bonds.As expected,these chemcial bonds shorten the distance betweenCo_(3)[Co(CN)_(6)]_(2) and rGO to the angstrom meter level,which significantly improve the electronic conductivity ofCo_(3)[Co(CN)_(6)]_(2).Besides,the complete encapsulation ofCo_(3)[Co(CN)_(6)]_(2) nanocubes by rGO endows the structure ofCo_(3)[Co(CN)_(6)]_(2) with high stability,thus withstanding repeated insertion/extraction of potassium-ions without visible morphological and structural changes.Benefiting from the abovementioned structural advantages,the CO3 [Co(CN)6]2/rGO nanocomposite exhibits a high reversible capacity of 400.8 mAh g^(-1) at a current density of 0.1 A g^(-1),an exceptional rate capability of 115.5 mAh g^(-1) at 5 A g^(-1), and an ultralong cycle life of 231.9 mAh g^(-1) at 0.1 A g^(-1) after 1000 cycles.Additionally,the effects of different amounts of rGO and different sizes ofCo_(3)[Co(CN)_(6)]_(2) nanocubes on the potassium storage performance are also studied.This work offers an ideal route to significantly enhance the electrochemical properties of prussian blue analogues.

Atomic Layer Coated Al_(2)O_(3) on Nitrogen Doped Vertical Graphene Nanosheets for High Performance Sodium Ion Batteries

Heteroatom doped graphene materials are considered as promising anode for high-performance sodium-ion batteries(SIBs).Defective and porous structure especially with large specific surface area is generally considered as a feasible strategy to boost reaction kinetics;however,the unwanted side reaction at the anode hinders the practical application of SIBs.In this work,a precisely controlled Al_(2)O_(3)coated nitrogen doped vertical graphene nanosheets(NVG)anode material has been proposed,which exhibits excellent sodium storage capacity and cycling stability.The ultrathin Al_(2)O_(3)coating on the NVG is considered to help construct an advantageous interface between electrode and electrolyte,both alleviating the electrolyte decomposition and enhancing sodium adsorption ability.As a result,the optimal Al_(2)O_(3)coated NVG materials delivers a high reversible capacity(835.0 mAh g^(-1))and superior cycling stability(retention of 92.3%after 5000 cycles).This work demonstrates a new way to design graphene-based anode materials for highperformance sodium-ion batteries.

Preparation and Characterization of Co_(3)O_(4)/Graphene/Cellulose Nanofiber Composite Films

Nanocellulose has served as an eye-catching nanomaterial for constructing advanced functional devices with renewability,light weight,flexibility,and environmental friendliness.In this study,Co_(3)O_(4)/graphene/cellulose nanofiber(CNF)flexible composite films,in which the CNF acted as a spacer for the graphene,were prepared via a facile and scalable vacuum filtration method.The effects of the CNF on the microstructure,hydrophilicity,thermal stability,tensile strength,surface resistance,and electrochemical performance of the Co_(3)O_(4)/graphene/CNF composite films were systematically investigated.The results showed that the synergistic interaction of the CNF and graphene substantially improved the overall properties of the Co_(3)O_(4)/graphene/CNF composite films,particularly their hydrophilicity and tensile strength.Meanwhile,Co_(3)O_(4)/graphene/CNF composite films with a CNF content of 4%appeared to have the optimal electrochemical performance,with an area specific capacitance of 56 mF/cm^(2) and prominent capacitance retention of 95.6%at a current density of 1 A/g after 1000 cycles.This work demonstrated that the prepared Co_(3)O_(4)/graphene/CNF flexible composite films have great application potential in the field of flexible energy storage devices.

A 1.7-ps pulse mode-locked Yb^(3+):Sc_2SiO_5 laser with a reflective graphene oxide saturable absorber

By using a reflective graphene oxide as saturable absorber, a diode-pumped passively mode-locked Yb^3＋：Sc2Si O5（Yb：SSO） laser has been demonstrated for the first time. Without extra negative dispersion compensation, the minimum pulse duration of 1.7 ps with a repetition rate of 94 MHz was obtained at the central wavelength of 1062.6 nm. The average output power amounts to 355 m W under the absorbed pump power of 15 W. The maximum peak power of the mode-locking laser is up to 2.2 k W, and the single pulse energy is 3.8nJ.

Superior Pseudocapacitive Storage of a Novel Ni3Si2/ NiOOH/Graphene Nanostructure for an All‑Solid‑State Supercapacitor

Recent developments in the synthesis of graphene-based structures focus on continuous improvement of porous nanostructures,doping of thin films,and mechanisms for the construction of threedimensional architectures.Herein,we synthesize creeper-like Ni3Si2/NiOOH/graphene nanostructures via low-pressure all-solid meltingreconstruction chemical vapor deposition.In a carbon-rich atmosphere,high-energy atoms bombard the Ni and Si surface,and reduce the free energy in the thermodynamic equilibrium of solid Ni–Si particles,considerably catalyzing the growth of Ni–Si nanocrystals.By controlling the carbon source content,a Ni3Si2 single crystal with high crystallinity and good homogeneity is stably synthesized.Electrochemical measurements indicate that the nanostructures exhibit an ultrahigh specific capacity of 835.3 C g^−1(1193.28 F g^−1)at 1 A g^−1;when integrated as an all-solidstate supercapacitor,it provides a remarkable energy density as high as 25.9 Wh kg^−1 at 750 W kg^−1,which can be attributed to the freestanding Ni3Si2/graphene skeleton providing a large specific area and NiOOH inhibits insulation on the electrode surface in an alkaline solution,thereby accelerating the electron exchange rate.The growth of the high-performance composite nanostructure is simple and controllable,enabling the large-scale production and application of microenergy storage devices.