Research on the Preparation of Graphdiyne and Its Derivatives

As a new 2D carbon material allotrope composed of sp and sp² carbon atoms, graphdiyne (GDY) possesses a highly conjugated porous structure, easily tunable intrinsic bandgap, and various excellent properties. Such properties allowed researchers to develop methods to prepare GDY, so that it can be applied for energy storage and conversion, environmental protection, various electronic devices and so on. In this review, the authors systematically discuss the methods and strategies developed for preparing GDY and its derivatives, including the synthesis of GDY by using liquid-, solid-, and gas-phase methods, the synthesis of heteroatom-doped GDY, the preparation of GDY-based composites, and the synthesis of GDY analogues. All these preparation methods can provide the way to obtain GDY for specific studies and applications.     

Engineering Graphdiyne for Solar Photocatalysis

Graphdiyne (GDY) with a direct band gap, excellent carrier mobility and uniform pores, is regarded as a promising photocatalytic material for solar energy conversion, while the research on GDY in photocatalysis is a less developed field. Herein, the distinctive structure, adjustable band gap, and electronic properties of GDY for photocatalysis is firstly summarized. The construction and progress of GDY-based photocatalysts for solar energy conversion, including H₂ evolution reaction (HER), CO₂ reduction reaction (CO₂RR) and N₂ reduction reaction (NRR) are then elaborated. At last, the challenges and perspectives in developing GDY-based photocatalysts for solar fuel production are discussed. It is anticipated that a timely Minireview will be helpful for rapid progress of GDY in solar energy conversion.     

Porous reduced graphene oxide for ultrasensitive detection of nitrogen dioxide

The defect engineering in graphene plays a significant role for the application of gas sensors. In this work, we proposed an efficient method to prepare ultrasensitive gas sensors based on the porous reduced graphene oxide (PRGO). Photo-Fenton etching was carried out on GO nanosheets in a controlled manner to enrich their vacancy defects. The resulting porous graphene oxide (PGO) was then drop-coated on interdigital electrodes and hydrothermal reduced at 180 °C. Controllable reduction was achieved by varying the water amount. The gas sensor based on PRGO-5 min-6 h exhibited superior sensing and selective performance toward nitrogen dioxide (NO₂), with an exceptional high sensitivity up to 12 ppm^?1. The theoretical limit of detection is down to 0.66 ppb. The excellent performance could be mainly attributed to the typical vacancy defects of PRGO. Some residue carboxylic groups on the edges could also facilitate the adsorption of polar molecules. The process has a great potential for scalable fabrication of high-performance NO₂ gas sensors.     

2D Graphdiyne: A Rising Star on the Horizon of Energy Conversion

Two-dimensional (2D) graphdiyne (GDY), a rapidly rising star on the horizon of carbon materials, is a new carbon allotrope featuring sp- and sp²-cohybridized carbon atoms and 2D one-atom-thick network. Since the first successful synthesis of GDY by Professor Li's group in 2010, GDY has attached great interests from both scientific and industrial viewpoints based on its unique structure and physicochemical properties, which provides a fertile ground for applications in various fields including electrocatalysis, energy conversion, energy storage and optoelectronic devices. In this work, various potential properties of the GDY-based electrocatalysts and their recent advances in energy conversion are reviewed, including atomic catalysts, heterogeneous catalysts, and metal-free catalysts. The critical role of GDY in improving catalytic activity and stability is analyzed. The perspectives of the challenges and opportunities faced by GDY-based materials for energy conversion are also outlined.     

Diffusion Kinetics Study of Lithium Ion in the Graphdiyne Based Electrode

Herein,we report a comparative investigation of the electrochemical lithium diffusion within graphidyne(GDY)based electrodes.The transfer kinetic behaviors of lithium ions during the insertion/extraction process are analyzed through different methods including the galvanostatic intermittent titration technique(GITT)and the electrochemical impedance spectroscopy(EIS).GDY with the morphology of nanosheets(GDY NS)shows lithium diffusion coefficients in the orders range of 10-12-10-13 cm2/s through the GITT method.Meanwhile,EIS indicates quite a lower value of lithium diffusion coefficients between 10-13 and 10-15 cm2/s,which indicates that the analysis technique has an influence on the evaluation of GDY-based electrodes.In addition,under the same measurement condition of GITT,GDY nanoparticles(GDY NP)exhibit a lower value of Li+diffusion coefficient(10-14-10-16 cm2/s)during the charge-discharge process compared to those of GDY NS,which can be ascribed to the wide distributing range of particle size in GDY NP based electrodes.The analysis results in this work reveal that the aggregating forms of GDY electrode material have an important effect on the diffusion process of lithium ions,which provides a pathway to optimize the performance of GDY-based energy storage devices.     

Recent progress in applications of graphene oxide for gas sensing: A review

This paper is a review of the recent progress on gas sensors using graphene oxide (GO). GO is not a new material but its unique features have recently been of interest for gas sensing applications, and not just as an intermediate for reduced graphene oxide (RGO). Graphene and RGO have been well known gas-sensing materials, but GO is also an attractive sensing material that has been well studied these last few years. The functional groups on GO nanosheets play important roles in adsorbing gas molecules, and the electric or optical properties of GO materials change with exposure to certain gases. Addition of metal nanoparticles and metal oxide nanocomposites is an effective way to make GO materials selective and sensitive to analyte gases. In this paper, several applications of GO based sensors are summarized for detection of water vapor, NO₂, H₂, NH₃, H₂S, and organic vapors. Also binding energies of gas molecules onto graphene and the oxygenous functional groups are summarized, and problems and possible solutions are discussed for the GO-based gas sensors.     

A Low-Strain Cathode by sp-Carbon Induced Conversion in Multi-Level Structure of Graphdiyne

A multi-level architecture formed alternatively by the conformal graphdiyne (GDY) and CuS is well engineered for Li-free cathode. Such a proof-of-concept architecture efficiently integrates the advantages of GDY and produces new functional heterojunctions (sp−C−S−Cu hybridization bond). The layer-by-layer 2D confinement effect successfully avoids structural collapse, the selective transport inhibits the shuttling of active components, and the interfacial sp−C−S−Cu hybridization bond significantly regulates the phase conversion reaction. Such new sp−C−S−Cu hybridization of GDY greatly improves the reaction dynamics and reversibility, and the cathode delivers an energy density of 934 Wh kg⁻¹ and an unattenuated lifespan of 3000 cycles at 1 C. Our results indicate that the GDY-based interface strategy will greatly promote the efficient utilization of the conversion-type cathodes.     

A Photoelectrochemical Immunosensor for Prostate Specific Antigen Detection Based on Graphdiyne Oxide Conjugated with Horseradish Peroxidase

Graphdiyne (GDY) was a novel flat material with sp and sp² hybridized carbon atoms. It exhibited good biocompatibility. The application of GDY in PEC immunosensor was very limited. Thus, a novel photoelectrochemical sensor for the sensitive detection of prostate specific antigen (PSA) was proposed by using GDY oxide (GDYO) conjugated with horseradish peroxidase (HRP) and secondary antibody for photocurrent signal inhibition. GDYO was prepared by oxidation of honeycomb-like nanotubes composed of numerous GDY nanosheets. It showed high loading capacity for HRP and the catalytic activity of HRP could be remained. With reduced graphene oxide-CdS (rGO-CdS) as photoelectrochemical sensing platform, a sandwich-type photoelectrochemical (PEC) immunosensor was thus fabricated. The immunosensor presented a wide linear concentration range of 10 fg mL⁻¹–20.0 ng mL⁻¹ with a detection limit (LOD) of 3.5 fg mL⁻¹. Moreover, the PEC immunosensor displayed ideal reproducibility, stability, and selectivity, which was a promising platform for the detection of other important tumor targets.     

Enhancing Electrochemical Nitrate Reduction to Ammonia over Cu Nanosheets via Facet Tandem Catalysis

Electrochemical conversion of nitrate (NO₃⁻) into ammonia (NH₃) represents a potential way for achieving carbon-free NH₃ production while balancing the nitrogen cycle. Herein we report a high-performance Cu nanosheets catalyst which delivers a NH₃ partial current density of 665 mA cm⁻² and NH₃ yield rate of 1.41 mmol h⁻¹ cm⁻² in a flow cell at −0.59 V vs. reversible hydrogen electrode. The catalyst showed a high stability for 700 h with NH₃ Faradaic efficiency of ≈88 % at 365 mA cm⁻². In situ spectroscopy results verify that Cu nanosheets are in situ derived from the as-prepared CuO nanosheets under electrochemical NO₃⁻ reduction reaction conditions. Electrochemical measurements and density functional theory calculations indicate that the high performance is attributed to the tandem interaction of Cu(100) and Cu(111) facets. The NO₂⁻ generated on the Cu(100) facets is subsequently hydrogenated on the Cu(111) facets, thus the tandem catalysis promotes the crucial hydrogenation of *NO to *NOH for NH₃ production.     

Detection of nitrogen dioxide using mixed tungsten oxide-based thick film semiconductor sensor

The thick film semiconductor sensor for NO₂ gas detection was fabricated by screen-printing method using a mixed WO₃-based as sensing material. The sensing characteristics, such as response time, response linearity, sensitivity, working range, cross sensitivity, and long-term stability were further studied by using a WO₃-based mixed with different metal oxides (SnO₂, TiO₂ and In₂O₃) and doped with noble metals (Au, Pd and Pt) as sensing materials was observed. The highest sensitivity for low concentrations (<16 mg l⁻¹) was observed using WO₃-based mixed with In₂O₃ or TiO₂. The NO₂ gas sensor showing the fastest response and recovery time (both within 2 min), good linearity (Y=0.606X+0.788 R²=0.991) for gas concentrations from 3 to 310 mg l⁻¹, low resistance (3 MΩ), high sensitivity, undesirable cross sensitivity effect and good long-term stability (at least 120 days) using WO₃-SnO₂-Au as sensing material.     

Rational construction and triethylamine sensing performance of foam shaped α-MoO3@SnS2 nanosheets

Owing to their high surface area, stable structure and easy fabrication, composite nanomaterials with encapsulation structures have attracted considerable research interest as sensing materials to detect volatile organic compounds. Herein, a hydrothermal route is designed to prepare foam shaped α-MoO₃@SnS₂ nanosheets that exhibit excellent sensing performance for triethylamine（TEA）. The developed sensor,based on α-MoO₃@SnS₂ nanosheets, displays a high ...     

Novel NO2 Gas Sensor Based on Cr(III) Complex Thin Film

The results concerning the gas‐sensing characteristics of novel NO₂ gas sensors, fabricated from complex [Cr(bipyO₂)Cl₂]Cl thin films, were first presented. The sensors exhibited high response to NO₂ gas in the concentration range from 1.97% to 6.67% at relative low temperatures (from room temperature to 348 K). No response to H₂S and SO₂ was observed. The maximum response for 6.03% NO₂ was approximately 11.7 at 338 K and 10 V operating voltage. The response time of the sensors was about 4.5 min for NO₂ and the recovery time about 40 s. The effect of the electrical resistance change of the sensors in the presence of NO₂ could be used for gas sensing measurements. The performance and reliability of the sensors showed their potential applications for monitoring and controlling NO₂ component continuously in chemical production.     

Graphdiyne:A Versatile Material in Electrochemical Energy Conversion and Storage

Graphdiyne(GDY),which is composed of sp2-/sp-hybridized carbon atoms,has attracted increasing attention.In the structure of GDY,the existence of large triangular-like pores,well dispersed electron-rich cavities as well as a large π-conjugated structure endows GDY with a natural bandgap,fast electron/ion transport,and tunable electronic properties.These unique features make GDY competitive in areas of gas separation and capture,electronics,detectors,catalysts,biomedicine and therapy,and energy-related fields.Benefiting from the facile synthesis method,various GDY structures and GDY-based composites have been successfully prepared and show great potential in the practical application of energy storage and catalysis areas.Here,this review aims at providing a timely and comprehensive update on the preparation and application of GDY materials.The current development of GDY materials in various electrochemical fields especially in energy conversion,energy storage,and catalysis is mainly summarized.Moreover,the potential development prospects are also discussed.     

Coordination of Actinide Single Ions to Deformed Graphdiyne: Strategy on Essential Separation Processes in Nuclear Fuel Cycle

The coordination of actinides and lanthanides, as well as strontium and cesium with graphdiyne (GDY) was studied experimentally and theoretically. On the basis of experimental results and/or theoretical calculations, it was suggested that Th⁴⁺, Pu⁴⁺, Am³⁺, Cm³⁺, and Cs⁺ exist in single‐ion states on the special triangular structure of GDY with various coordination patterns, wherein GDY itself is deformed in different ways. Both experiment and theoretical calculations strongly indicate that UO₂²⁺, La³⁺, Eu³⁺, Tm³⁺ and Sr²⁺ are not adsorbed by GDY at all. The distinguished adsorption behaviors of GDY afford an important strategy for highly selective separation of actinides and lanthanides, Th⁴⁺ and UO₂²⁺, and Cs⁺ and Sr²⁺, in the nuclear fuel cycle. Also, the present work sheds light on an approach to explore the unique functions and physicochemical properties of actinides in single‐ion states.     

Fabrication,characterization and exploration of cobalt (II) ion doped,modified zinc oxide thick film sensor for gas sensing characteristics of some pernicious gases

The present research deals with the synthesis of zinc oxide (ZnO) nanoparticles by the co-precipitation (CPT) method. The CPT method was successfully utilized for the synthesis of ZnO nanoparticles. The structural properties of undoped ZnO and cobalt doped ZnO were confirmed by employing an X-ray diffraction (XRD) study, from which the average particle size for each prepared material was calculated from the Debye Scherer formula. The average particle size confirms the nano range fabrication of undoped and cobalt doped ZnO material. The surface characteristics, morphology, texture, and porosity properties of undoped ZnO and cobalt doped ZnO were investigated from scanning electron microscopy (SEM). The elemental composition was investigated from energy dispersive spectroscopy (EDS). The High-resolution transmission electron microscopy (HRTEM) results revealed the hexagonal phase of prepared material. Furthermore, the undoped ZnO and 5% cobalt doped ZnO gas sensors prepared by screen printing technology were utilized for gas sensing purposes for testing the gases like H₂S, NO₂, SO₂, and methanol. For the gases examined, the cobalt modified ZnO sensor proved to be quite effective, especially for H₂S and NO₂ gas vapors. The Co²⁺ doped ZnO sensor showed 70.12% sensitivity for H₂S gas at 150 ⁰C and 68.75% gas response for NO₂ gas vapors at 120 ⁰C. In addition, the cobalt modified sensor was also investigated for reusability test to get concrete gas response results with the time interval of 15 days. In conclusion, it can be mentioned that the cobalt doped ZnO thick film sensor is a promising sensor for H₂S and NO₂ gas vapors.     

Regulating Efficient and Selective Single-atom Catalysts for Electrocatalytic CO2 Reduction

Anchoring transition metal (TM) atoms on suitable substrates to form single-atom catalysts (SACs) is a novel approach to constructing electrocatalysts. Graphdiyne with sp−sp² hybridized carbon atoms and uniformly distributed pores have been considered as a potential carbon material for supporting metal atoms in a variety of catalytic processes. Herein, density functional theory (DFT) calculations were performed to study the single TM atom anchoring on graphdiyne (TM₁−GDY, TM=Sc, Ti, V, Cr, Mn, Co and Cu) as the catalysts for CO₂ reduction. After anchoring metal atoms on GDY, the catalytic activity of TM₁−GDY (TM=Mn, Co and Cu) for CO₂ reduction reaction (CO₂RR) are significantly improved comparing with the pristine GDY. Among the studied TM₁−GDY, Cu₁−GDY shows excellent electrocatalytic activity for CO₂ reduction for which the product is HCOOH and the limiting potential (U_L) is −0.16 V. Mn₁−GDY and Co₁−GDY exhibit superior catalytic selectivity for CO₂ reduction to CH₄ with U_L of −0.62 and −0.34 V, respectively. The hydrogen evolution reaction (HER) by TM₁−GDY (TM=Mn, Co and Cu) occurs on carbon atoms, while the active sites of CO₂RR are the transition metal atoms . The present work is expected to provide a solid theoretical basis for CO₂ conversion into valuable hydrocarbons.     

Graphdiyne-Based Single-Atom Catalysts with Different Coordination Environments

As a special carbon material, graphdiyne (GDY) features the superiorities of incomplete charge transfer effect on the atomic level, tunable electronic structure and anchoring metal atoms directly with organometallic coordination bonds M (metal)-C (alkynyl carbon in GDY), providing it an ideal platform to construct single-atom catalysts (ACs). The coordination environment of single atoms anchored on GDY plays a key role in their catalytic performance. The mini-review highlights state-of-the-art progress in the rational design of GDY-based ACs and their applications, and mainly reveals the relationship between the coordination engineering of the GDY-based ACs and corresponding catalytic performance. Finally, some prospects concerning the future development of GDY-based ACs in energy conversion are also discussed.     

Lattice engineering route for self-assembled nanohybrids of 2D layered double hydroxide with 0D isopolyoxovanadate: chemiresistive SO2 sensor

Tuning the interior chemical composition of layered double hydroxides (LDHs) via lattice engineering route is a unique approach to enable multifunctional applications of LDHs. In this regard, the exfoliated 2D LDH nanosheets coupled with various guest species lead to the lattice-engineered LDH-based multifunctional self-assembly with precisely tuned chemical composition. This article reports the synthesis and characterization of mesoporous zinc–chromium-LDH (ZC-LDH) hybridized with isopolyoxovanadate nanohybrids (ZCiV) via lattice-engineered self-assembly between delaminated ZC-LDH nanosheets and isopolyoxovanadate (iPOV) anions. Electrostatic self-assembly between 2D ZC-LDH monolayers and 0D iPOV significantly altered structural, morphological, and surface properties of ZC-LDH. The structural and morphological study demonstrated the formation of mesoporous interconnected sheet-like architectures composed of restacked ZCiV nanosheets with expanded surface area and interlayer spacing. In addition, the ZCiV nanohybrid resistive elements were used as a room-temperature gas sensor. The selectivity of ZCiV nanohybrid was tested for various oxidizing (SO₂, Cl₂, and NO₂) gases and reducing (LPG, CO, H₂, H₂S, and NH₃) gases. The optimized ZCiV nanohybrid demonstrated highly selective SO₂ detection with the maximum SO₂ response (72%), the fast response time (20 s), low detection limit (0.1 ppm), and long-term stability at room temperature (27 ± 2 °C). Of prime importance, ZCiV nanohybrids exhibited moderately affected SO₂ sensing responses with high relative humidity conditions (80%–95%). The outstanding SO₂ sensing performance of ZCiV is attributed to the active surface gas adsorptive sites via plenty of mesopores induced by a unique lattice-engineered interconnected sheet-like microstructure and expanded interlayer spacing.     

Nanofibrous polyaniline thin film prepared by plasma‐induced polymerization technique for detection of NO2 gas

A nanofibrous polyaniline (PANI) thin film was fabricated using plasma‐induced polymerization method and explored its application in the fabrication of NO₂ gas sensor. The effects of substrate position, pressure, and the number of plasma pulses on the PANI film growth rate were monitored and an optimum condition for the PANI thin film preparation was established. The resulting PANI film was characterized with UV–visible spectrophotometer, FTIR, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The PANI thin film possessed nanofibers with a diameter ranging from 15 to 20 nm. The NO₂ gas sensing behavior was studied by measuring the change in electrical conductivity of PANI film with respect to NO₂ gas concentration and exposure time. The optimized sensor exhibited a sensitivity factor of 206 with a response time of 23 sec. The NO₂ gas sensor using nanofibrous PANI thin film as sensing probe showed a linear current response to the NO₂ gas concentration in the range of 10–100 ppm. Copyright © 2009 John Wiley & Sons, Ltd.     

Nitrite and Nitrate Production by NO and NO2 Dissolution in Water Utilizing Plasma Jet Resembling Gas Flow Pattern

This study investigated the reactive dissolution of nitric oxide (NO) and nitrogen dioxide (NO₂) mixtures in deionized water. The dissolution study was carried out in a flat surface type gas–liquid reaction chamber utilizing a gas flow-pattern resembling plasma jets which are often used in biomedical applications. The concentration of NO and NO₂ in the gas mixtures was varied in a broad range by oxidizing up to 800 ppm of nitric oxide in Ar carrier gas with variable amount of ozone. The production of nitrite (NO₂^?) and nitrate (NO₃^?) in the water was proportional to treatment time up to 50 min. The concentration of NO₃^? was a power function of gas phase NO₂ while the concentration of NO₂^? increased approximately linearly with gas phase NO₂. The formation of NO₂^? and NO₃^? could be described by reactions between dissolved NO₂ and NO in the water while the production rate was determined by diffusion-limited mass transport of nitrogen oxides to the bulk of the liquid. At higher NO₂ concentrations, the formation of dinitrogen tetraoxide (N₂O₄) increased the formation rate of NO₂^? and NO₃^?. The identified mass transport limitation by diffusion suggests that convection of water created by the gas jet is insufficient and dissolution of nitrogen oxides can be increased by additional mixing. In respect of practical applications, the ratio of NO₂^? /NO₃^? in water could be varied from 0.8 to 5.3 with treatment time and gas phase NO₂ and NO concentrations.