Graphdiyne Research Articles

Comparison of developmental toxicity of graphene oxide and graphdiyne to zebrafish larvae

Graphdiyne (GDY) is a new member of family of carbon-based 2D nanomaterials (NMs), but the environmental toxicity is less investigated compared with other 2D NMs, such as graphene oxide (GO). In this study, we compared with developmental toxicity of GO and GDY to zebrafish larvae. It was shown that exposure of zebrafish embryos from 5 h post fertilization to GO and GDY for up to 5 days decreased hatching rate and induced morphological deformity. Behavioral tests indicated that GO and GDY treatment led to hyperactivity of larvae. However, blood flow velocity was not significantly affected by GO or GDY. RNA-sequencing data revealed that both types of NMs altered gene expression profiles as well as gene ontology terms and KEGG pathways related with metabolism. We further confirmed that the NMs altered the expression of genes related with lipid droplets and autophagy, which may be account for the delayed development of zebrafish larvae. At the same mass concentrations, GO induced comparable or even larger toxic effects compared with GDY, indicating that GDY might be more biocompatible compared with GO. These results may provide novel understanding about the environmental toxicity of GO and GDY in vivo.

Graphdiyne chelated iron-based metal–organic frameworks for electrochemical sensing of antibiotic chloramphenicol with ultralow detection limit

Chloramphenicol (CAP), a broad-spectrum antibiotic agent that can inhibit protein synthesis, has caused environmental and human health problems upon excessive usage but to realize its ultrasensitive detection is still a great challenge. We report here the design and fabrication of a nanocomposite comprising graphdiyne (GDY) chelated iron-based metal–organic framework (Fe-MOF@GDY) with strong interfacial interaction to achieve high performance electrochemical sensing of CAP. Fe-MOF@GDY exhibits good selectivity, a linear range of 1 pM − 24 mM and an ultralow detection limit down to 0.54 pM, among the best performance for CAP detection. It displays good reproducibility and storage stability with retained 98.4 % of its initial response after 3 weeks. GDY with unique electronic structure enhances charge transfer of Fe-MOF for improved conductivity, and Fe-MOF nanoparticles are uniformly chelated on GDY for rich active sites towards CAP reduction. Fe-MOF also prevents GDY from being degraded, promoting long-term stability. A portable electrochemical chip is fabricated based on Fe-MOF@GDY, and is successfully used for accurate detection of CAP in lake water with recovery rates of 97.2–104.7 %, demonstrating the practical on-site applications.

Engineering of Thickness Tunable 2D Graphdiyne Film to ZnO Nanowalls via Nanospace‐Confined Synthesis Promotes NO2 Gas Sensing Performance

Achieving rapid response and recovery rates at low operating temperatures for NO2 is desirable for the application of sensors in industrial safety. In this study, we integrate a thickness tunable 2D graphdiyne (GDY) film into ZnO nanowalls (GDY/ZnO) via thermal evaporation of GDY, where ZnO nanowalls are used as the template to confine the growth space of the GDY film. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is used to reveal the transformation process of NO2. Ultraviolet photoemission spectroscopy (UPS) is utilized to analyze changes about the energy band of the materials. Density functional theory (DFT) calculations explain the reason for the selectivity of the samples to NO2. The scanning electron microscopy (SEM) results demonstrate that the thickness of the GDY film with a specific mesoporous structure (25‐53 nm) increases as the thermal evaporation temperature rises from 400 to 800°C.The representative ZG-600, synthesized with a thickness of 46 nm via thermal evaporation at 600°C, exhibits superior NO2 sensing performance. This is evidenced by its ultrahigh response (13.86, at 100 ppm and 150°C) and rapid response/recovery speeds (150 s/198 s), outperforming the ZnO sensor (198 s and 326 s). Moreover, it offers remarkable stability.

Boosting hydrogen storage capacity in modified-graphdiyne structures: A comprehensive density functional study

Graphdiyne (GDY) is a recently discovered two-dimensional carbon allotrope that holds significant promise for applications in hydrogen adsorption and storage technology. This study investigates the impact of nitrogen doping and sodium decoration on the hydrogen adsorption capacity of GDY nanosheets while examining their influence on electronic and structural properties. Various deliberate impurities are introduced to create modified-GDY structures. Nitrogen doping triggers a transition from a semiconductor to a semi-metallic state, driven by differences in electronegativity and adjustments in bond lengths. Cohesive energy (Ecoh) is found to be −7.231 eV for the most stable N-doped GDY. In contrast, sodium decoration enhances conduction by modifying charge distribution. The other most stable structures are Na-decorated GDY with Eads of −3.804 eV and N, Na-decorated GDY with −3.347 eV. Modified-GDY structures exhibit higher hydrogen adsorption energies compared to pristine GDY, with N-doped GDY displaying the highest energy levels (Eads = −0.455 eV). Maximum hydrogen adsorption capacities are assessed for each structure, and a notable improvement is observed in Na-decorated GDY (19 H2), significantly enhancing the storage capacity to 13.8 wt%, which shows a 10.21 wt% increase in H2 adsorption compared to pure GDY (3.59 wt%). These findings underscore the potential of modified-GDY for hydrogen storage applications, highlighting the effectiveness of structural carbon modification in enhancing hydrogen adsorption capacity.

Computational investigation of charge injection into modified graphdiyne nanosheet via Al doping and Li decoration to improve hydrogen adsorption

The utilization of hydrogen as a clean fuel has been made feasible by the expanding development of cutting-edge materials for hydrogen adsorption and storage. In this study, we thoroughly assessed hydrogen storage capability on both neutral and charge-injected graphdiyne (GDY) nanosheets modified with Al doping and Li decorating (Li.Al-GDY). According to the findings, pure GDY has an adsorption energy of −0.093 eV, while GDY modified with Al and Li atoms has an improved adsorption energy of −0.577 eV. The highest H2 adsorption energy of −0.760 eV was calculated for the applied charge of −2 e to the Li.Al-GDY nanosheet, indicating a significant enhancement in the adsorption energy with the charge injection. While the pristine GDY nanosheet serves as a very poor H2 molecule adsorber and cannot even hold one H2 molecule, the charged Li.Al-GDY nanosheet maintains 13 H2 molecules with an average adsorption energy of −0.287 eV. According to the results, injecting charge into the nanosheet along with modification techniques such as doping and decorating can significantly boost the effectiveness of weak carbon adsorbents in terms of hydrogen adsorption. Such approaches enable the realization of the goal of using carbon adsorbents as H2 green fuel storage.

Theoretical Prediction Leads to Synthesize GDY Supported InOx Quantum Dots for CO2 Reduction

The preparation of formic acid by direct reduction of carbon dioxide is an important basis for the future chemical industry and is of great significance. Due to the serious shortage of highly active and selective electrocatalysts leading to the development of direct reduction of carbon dioxide is limited. Herein the target catalysts with high CO2RR activity and selectivity were identified by integrating DFT calculations and high‐throughput screening and by using graphdiyne (GDY) supported metal oxides quantum dots (QDs) as the ideal model. It is theoretically predicted that GDY supported indium oxide QDs (i.e., InOx/GDY) is a new heterostructure electrocatalyst candidate with optimal CO2RR performance. The interfacial electronic strong interactions effectively regulate the surface charge distribution of QDs and affect the adsorption/desorption behavior of HCOO* intermediate during CO2RR to achieve highly efficient CO2 conversion. Based on the predicted composition and structure, we synthesized the advanced catalytic system, and demonstrates superior CO2‐to‐HCOOH conversion performance. The study presents an effective strategy for rational design of highly efficient heterostructure electrocatalysts to promote green chemical production.

In-situ surface growth strategy to synthesize MXene@graphdiyne heterostructure for achieving high capacity and desirable stability in lithium-ion batteries

Two-dimensional (2D) heterostructured electrodes, combining graphdiyne (GDY) and MXenes, have exhibited substantial promise in augmenting the mobility of both ionic and electron movement. However, the widespread advancement and industrial utilization have been impeded by intricate manufacturing procedures and insufficient stability. This study introduces a more streamlined, in-situ growth approach for preparing MXene@GDY electrodes, presenting a novel heterostructure. The method simplifies the manufacturing process while enhancing the specific capacity of the electrode and the more stable cycle life of lithium-ion batteries (LIBs). The resulting electrode exhibited an impressive initial specific capacity of 464.4 mA h g−1, maintaining a high capacity of 492.9 mA h g−1 after 100 cycles at 100 mA current density. More importantly, after 1200 cycles, MXene@GDY showed a capacity of 340.7 mA h g−1, significantly outperforming pure MXene, which only reached 122.3 mA h g−1 at a current density of 1.0 A g−1. The proposed in-situ construction of heterojunction on the MXene surface has demonstrated immense potential for designing high-performance electrode materials which are applicable to LIBs.

MoS2/graphdiyne nanotube/MXene 3D-interconnected ternary aerogel: A high-performance electrocatalyst for hydrogen evolution reaction

MoS2 is a promising challenger to Pt for the HER, but we must make it more durable before it can take over the hydrogen production scene. This work fabricated and evaluated a hybrid structure of MXene-graphydine nanotube-MoS2 (MGMX) aerogel toward HER. It showed efficient and stable activity H2 evolution with ƞ10 = 109 mV vs RHE and a Tafel slope of 55 mVdec−1. The catalytic performance results from a synergistic interplay between increased exposed active sites and improved charge transfer within the catalyst. The two-dimensional (2D) islands of double-phase MoS2 are directly deposited onto graphdiyne nanotubes (GDNTs) surface, creating a structurally interesting material with interconnected components. The unique combination of sp and sp2 carbon atoms in the graphdiyne (GDY) makes it an ideal support for catalyst material. The combination of high edge density in metallic MoS2, a conducting MXene framework, and the bridging structure of GDNT significantly enhance the overall HER performance of the ternary aerogel structure.

Preparation and Support Effect of Graphdiyne Nanotubes with Abundant Cu Quantum Dots.

Graphdiyne (GDY) is considered a very attractive support for metal nanocatalysts due to its unique structure and superior properties. The metal-GDY interaction can significantly affect the performance of catalysts. Herein, GDY nanotubes abundant in in situ formed Cu quantum dots (QDs) (Cu-GDYNT) are prepared using the electrospun polyacrylonitrile nanofibers collected on the surface of electrolytic Cu foil as templates. The diameter of the Cu-GDYNT is controllable and the uniform size of the embedded Cu QDs is about 2.2 nm. And then, the uniformly dispersed and highly active supported catalysts of ruthenium nanoparticles (Rux/Cu-GDYNT) are produced using the Cu-GDYNT as the support. Among them, the Ru3/Cu-GDYNT exhibit outstanding HER performance at all pH levels. Only 17, 67 and 83 mV overpotential is required to reach a current density of 10 mA cm-2 in 1.0 M KOH, 0.5 M H2SO4 and 1.0 M neutral PBS solutions, respectively. The sample exhibits 3000 CV cycle stability and 20 h continuous electrolysis without performance degradation in an alkaline medium. This work provides a new idea for constructing the GDY-supported metal nanocatalysts.

Visible‐Light‐Induced Photocatalytic Hydrogen Evolution Performance of Graphdiyne‐Alkyne Phosphating Mo–Metal‐Organic Frameworks Heterojunction

Herein, the application of graphdiyne (GDY) in photocatalytic splitting of water and hydrogen evolution is explored. In this article, GDY is prepared by ball milling using calcium carbide as raw material, and it is compounded with phosphating Mo–metal‐organic frameworks (MOFs), to explore the photocatalytic hydrogen evolution performance and hydrogen evolution mechanism of composite catalysts. In the results, it is shown that the P–Mo–MOFs (PMF)/G‐25 composite photocatalyst has the best hydrogen evolution activity, and the hydrogen evolution rate is highest at pH = 9, reaching 1668.5 μmol g−1 h−1. Through the four‐cycle hydrogen evolution cycle stability test, the PMF/G‐25 composites still has good hydrogen evolution stability. It is shown that the combination of phosphating Mo–MOFs and GDY can enhance the hydrogen evolution activity and has excellent hydrogen evolution performance. In the Mott–Schottky test, it is found that PMF and GDY are n‐type semiconductors. The conduction and valence values are −0.56 and 1.10 eV for GDY, and −0.68 and 0.97 eV for PMF, respectively. The mechanism of photocatalytic hydrogen evolution is analyzed, and it is speculated that S‐Scheme heterojunction is formed between PMF and GDY to further promote photocatalytic hydrogen evolution.

Tetrametallic mastery: Cluster-doped graphdiyne as a superior electrocatalyst for hydrogen evolution

Hydrogen evolution reaction (HER) is a promising route for sustainable hydrogen production. However, its efficiency is limited by kinetic barriers. Herein, we employ density functional theory (DFT) calculations to demonstrate a new strategy of embedding tetrametallic transition metal clusters (3TM1-TM2) into the pores of graphdiyne (GDY) to effectively optimize its HER performance. By screening 900 configurations, 10 prototypes displayed near-ideal hydrogen adsorption free energies. Among them, 3W–Hg@GDY with a ΔGH of −0.00035 eV was identified as the optimal candidate. Analysis of the electronic structure reveals hybridization between the metal d orbitals and GDY p orbitals near the Fermi level, creating partially filled impurity states to promote hydrogen adsorption. Additionally, coordination between the three TM1 atoms and active TM2 atom in the cluster enables precise tuning of TM2's electron density to achieve a moderate interaction with the adsorbed H, facilitating superior HER catalysis. Our findings showcase a new paradigm of cluster engineering for modulating GDY's reactivity that holds great promise as a universal approach for the design of high-performance GDY-based electrocatalysts beyond HER.

Exploring the impact of stress on the electronic structure and optical properties of graphdiyne nanoribbons for advanced optoelectronic applications

Graphdiyne (GDY), a two-dimensional carbon material with sp- and sp2-hybridization, is recognized for its unique electronic properties and well-dispersed porosity. Its versatility has led to its use in a variety of applications. The precise control of this material's properties is paramount for its effective utilization in nano-optical devices. One effective method of regulation, which circumvents the need for additional disturbances, involves the application of external stress. This technique provides a direct means of eliciting changes in the electronic characteristics of the material. For instance, when subjected to uniaxial stress, electron transfer occurs at the triple bond. This results in an armchair-edged graphdiyne nanoribbon (A(3)-GDYNR) with a planar width of 2.07 nm, which exhibits a subtle plasmon effect at 500 nm. Conversely, a zigzag-edged graphdiyne nanoribbon (Z(3)-GDYNR) with a planar width of 2.86 nm demonstrates a pronounced plasmon effect within the 250–1200 nm range. This finding suggests that the zigzag nanoribbon surpasses the armchair nanoribbon in terms of its plasmon effect. First principles calculations and ab initio molecular dynamics further confirmed that under applied stress Z(3)-GDYNR exhibits less deformation than A(3)-GDYNR, indicating superior stability. This work provides the necessary theoretical basis for understanding graphene nanoribbons (GDYNRs).

Theoretical study of NO/CO/O2 gas separation using graphdiyne and boron-doped graphdiyne membranes – A new corresponding state principle

The adsorption and permeance of O2, NO and CO gases on graphdiyne (GDY) and boron-doped graphdiyne (B-doped GDY) surfaces are modeled and studied. Dispersion-corrected density functional theory (DFT) calculation combined with the Climbing Image Nudged Elastic Band (CI-NEB) method was used to elucidate the gas/membrane adsorption energy, equilibrium distance and energy barrier of the studied gases passing through the membranes. It is revealed that the selectivity of B-doped GDY to NO is much greater than that of GDY. Based on selectivity and permeability values, high separation efficiency of NO can be achieved by lowering B-doped GDY temperature below 100 K. In addition, using the corresponding principle, a general expression for the dimensionless permeance of gases in terms of reduced temperature is introduced, which helps us to find an industrially acceptable value of permeance for each gas at a given pressure.

Graphdiyne Preparation and Application in Photocatalytic Hydrogen Evolution.

Graphdiyne (GDY) is a new two-dimensional carbon network material composed of sp2 hybrid carbon and sp hybrid carbon conjugation. It has unique physical and chemical properties, such as high porosity, good electrical conductivity, high carrier mobility, adjustable band gap, and so on. The preparation of GDY and GDY derivatives by adjusting physical and chemical methods and changing monomers has become the key material in the fields of photocatalysis, energy storage, life science, and so on. In this paper, new methods for controllable growth of GDY are reviewed, including liquid phase chemical classical total synthesis, chemical vapor deposition, the interface method, the explosion method, and the mechanically driven ball milling method. FT-IR, Raman, NMR, and XAS are the main means to characterize the structure of GDY. Finally, the representative application of GDY in the field of photocatalytic hydrogen evolution is summarized, and its future development has been explored.

Reinforced photogenerated electron convergence on graphdiyne(g-CnH2n-2) “as an active site and substrate” for enhance photocatalytic hydrogen production

Graphdiyne(GDY), as a carbon-based catalyst with tunable electronic structure, has a significant impact on the advancement of sustainable photocatalytic technology. Its tunable electronic structure can effectively regulate the activity and selectivity of photocatalytic reaction. In this paper, GDY was prepared by a new method of ball milling HEB-TMS, and CoWO4 nanoparticles were uniformly loaded on the surface of GDY to construct a Type-II heterojunction. GDY provides a dispersed and effective substrate for CoWO4, forming a closer contact interface. Based on GDY's unique electronic structure and the formation of Type-II heterojunction, GDY/CoWO4 enhances the separation of photoexcited electrons and holes, thus increasing the electron cloud density on GDY. As an electron acceptor and active site for hydrogen production, GDY promotes the proton reduction reaction. In addition, the charge transfer process of GDY/CW-15 was demonstrated by in-situ XPS and UPS, and the corresponding hydrogen production mechanism was proposed. This study provides a facile and efficient method for preparing GDY and a new idea for heterojunction photocatalyst based on GDY substrate.

Stimuli-responsive graphdiyne-silver nanozymes for catalytic ion therapy of dental caries through targeted biofilms removal and remineralization

Clinical mechanical decontamination and irrigants are not consistently effective in preventing intractable biofilm-induced dental caries, especially when biofilms have caused demineralization. Constructing stimuli-responsive nanocatalysts with improved catalytic activity for plaque biofilm removal and remineralization enhancement remains challenging. Herein, a coordination-reduction strategy driven by L-cysteine and graphdiyne (GDY) is employed to anchor low-dose Ag nanoparticles/Ag+ to GDY nanosheets to obtain GDY/L-cys/Ag (GLA) nanozymes. Subsequently, biomimetic approach is used to encapsulate GLA into a GS ointment composed of gelatin methacryloyl and sodium alginate to form biodegradable and adhesive GLA/GS. GLA demonstrates acidic plaque biofilm-activated peroxidase-like activity, surpassing affinity toward H2O2 than natural horseradish peroxidase, effectively catalyzing low-dose H2O2 into highly toxic hydroxyl radicals (•OH). This catalytic activity simultaneously enhances Ag+ release triggered by acidic plaque biofilms, generating additional reactive oxygen species that can suppress plaque biofilms on ex vivo human teeth by the synergistic effect of catalysis and released ions. Importantly, GLA/GS serves as template nucleation sites crosslinked to rich Ca2+, thereby attracting PO43- from saliva, prompting growth into hydroxyapatite on tooth enamel, facilitating rapid remineralization. Due to the safe nanocatalytic ion therapy, in an in vivo rodent model, GLA/GS + H2O2 effectively prevents dental caries without influencing surrounding oral tissues.

Interconversion of sp-hybridized chemical bonds induces piezoelectric enhanced photocatalysis

The synergism of piezoelectric catalysis and plasmonic photocatalysis is an effective approach for enhancing the catalytic performance. Nevertheless, challenges remain in addressing the slow interfacial charge transfer rate and the high recombination of energetic hot electrons. In this study, we constructed a heterostructure comprising barium titanate/graphdiyne/gold nanofibers (BTO/GDY/Au NFs). The incorporation of a graphdiyne (GDY) layer serves as an electron sponge, significantly boosting the piezo-photocatalytic activity, with a degradation rate constant 3.3-fold higher than that of BTO/Au. Theoretical calculations indicated that BTO could undergo elastic deformation under ultrasound irradiation, resulting in the stretching and compression of GDY within a lattice constant range of 7.1–10.4 Å. This deformation induced the reversible conversion of sp-hybridized CC to CC, releasing electrons that could recombine with hot holes generated by the Au nanoparticles (Au NPs). Consequently, more hot electrons were able to participate in the catalytic reaction process. Furthermore, BTO/GDY/Au NFs demonstrated excellent catalytic performance in the rapid degradation of organic dyes and antibiotics in wastewater, while also inhibiting bacterial propagation. The above-mentioned results validated the feasibility of this heterostructure for practical applications. Overall, this study presents a novel piezo-photocatalysts, where the interconversion of sp-hybridized chemical bonds in GDY can serve as electron donor, thus significantly enhancing piezo-photocatalysis.

In Situ Fabrication of Graphdiyne Nanoisland Anchored Ti3C2Tx Film to Accelerate Intercalation Pseudocapacitance Kinetics

AbstractA key challenge in flexible supercapacitor is balancing the trade‐off between high capacity and fast charging ability caused by dense structure‐induced sluggish ionic diffusion and storage dynamics. Herein, a hydrogen‐rich graphdiyne (GDY)–Ti3C2Tx electrode is reported with tunable interlayer spacing, abundant active sites, and extensive charge storage nanochannels. In particular, the GDY–Ti3C2Tx (12.6 wt.%) electrode has a remarkable volumetric capacitance (2296 F cm−3 at 1 A cm−3) and fast charging behavior (1262 F cm−3 at 50 A cm−3) resulting from the shortened transport pathways, enhanced ionic diffusion rate, and facilitated electrolyte mass transport. Moreover, an all‐solid‐state supercapacitor (ASSC) delivers a high volumetric energy density of 65.6 mWh cm−3, as well as long‐term deformable cyclic stability and high capacitance retention properties under harsh conditions. Density functional theory calculations and molecular dynamic simulation demonstrate the fast electronic responsiveness of the GDY–Ti3C2Tx heterostructure owning to the stronger H+ electrostatic attraction, lower migration resistance, and accelerated intercalation pseudocapacitance kinetics. In situ X‐ray diffraction reveals that a stable Ti─O─C bond bridged organic–inorganic heterostructure can tolerate the repeated high‐current charge/discharge cycling process. The state‐of‐the‐art ASSC delivers multiple functional outputs and shows great potential for efficient energy supply in practical applications.

Multiscale modification of graphdiyne-based electrodes and diffusion kinetics analysis of lithium ions

The diffusion of lithium ions is highly related to the chemical structure, packing mode, and pore size distribution of the electrode materials. In this paper, a multiscale modification strategy is performed to investigate the correlation between the chemical structure and diffusion kinetics of lithium ions in graphdiyne (GDY) based electrodes. Various electrochemical tests show consistent results that hydrogen-substituted GDY has the fastest lithium-ion diffusion rate, and the doping of Cl and F atoms with large atomic radii leads to slower lithium-ion diffusion in the system. The functional groups (H, Cl, F) introduced in the GDY-based electrodes not only regulate the pore size of the materials but also modulate the binding energy with lithium ions. chlorine-substituted GDY shows a higher diffusion coefficient than that of fluorine-substituted GDY for proper affinity to lithium. In addition, the specific surface area and the pore size distribution also collectively contribute to the differences in lithium-ion diffusion. Finally, the lithium storage mechanism of substituted GDY electrodes is explored. Our strategy sheds some light on the design and fabrication of anode materials for lithium-ion batteries.

Self-Assembly of Wheel-Shaped Nanographdiynes and Self-Template Growth of Graphdiyne.

Graphdiyne (GDY) multilayers show stacking-style-dependent physical properties; thus, controlling the stacking style of nanostructures is crucial for utilizing their electrical, optical, and transport properties in electro-optical devices. Herein, we report the assemblies of nanographdiynes decorated with substituents with different steric hindrances to adjust the stacking style. We show that the π-stacked aggregates were influenced by peripheral substituents and the substrate. Steric hexaterphenyl-substituted nanoGDY scaffolds led to dimer structures stacked in the AB-3 configuration with a twist angle of 26.01° or the AB-1 configuration with an in-plane shift along one diyne link. With the interval replacement of steric substituents with long C12 alkyl chains, nanoGDYs were stacked in the AB-2 configuration to decrease the steric congestion, eventually leading to one-dimensional (1D) nanofibrous aggregates. Self-assembly in the presence of substrates can result in ABC-stacked nanoGDYs, which endowed us with the possibility of using nanoGDY as the template for GDY growth in a homogeneous reaction. High-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and near-infrared-ultraviolet-visible (NIR-UV-vis) absorption spectroscopy indicate that the crystalline GDY prepared in this way is a 1.18 eV bandgap semiconductor.