Graphynes: Electronic Properties, Synthesis, and Applications in Catalysis

A dual-mode strategy for early detection of sugarcane pokkah boeng disease pathogen: A portable sensing device based on Cross-N DNA framework and MoS2@GDY

Sucrose, a common sugar primarily derived from sugarcane, is a crucial national strategic resource. However, its yield is significantly affected by various serious diseases, with pokkah boeng disease being one of the most damaging. Therefore, developing a sensitive method for the accurate detection of the pokkah boeng disease pathogen is crucial for ensuring the safety of sugar. This work presents a portable dual-modal detection device, assisted by a smartphone, which is based on MoS2@GDY, Mn3O4@Au nanomenzyme, cross-N DNA framework and Exo III exonuclease-assisted CHA signal amplification technology. The cross-N DNA framework provides many binding sites and is not restricted by AuNPs scattering positions, enhancing the signal output strength of the sensor. Additionally, the detection system incorporates a high-power-density capacitor to further amplify the electrochemical detection signal, increasing sensitivity by 9.1 times. Moreover, the use of electrochemical and colorimetric dual-mode detection effectively avoids mutual interference, reducing the likelihood of false positives from a single signal. Under optimized conditions, the proposed method has a linear range of 0.0001-10,000 pM, and with a detection limit of 6.1 aM (S/N=3). This high-sensitivity, high-reliability portable sensing method shows significant potential for the early detection and real-time on-site monitoring of the pokkah boeng disease pathogen.

B-Doped Graphdiynes and Several of Their Corresponding Oxides: A Theoretical Study by X-ray Spectra

Boron doping can significantly improve the electronic structure and physical and chemical properties of graphdiyne (GDY), which also expands its application prospects in photoelectricity, catalysis, and biology. The accurate configurations characterization of B-doped graphdiyne (B-GDY) has not been achieved due to insufficient experimental and theoretical research. The current work involves the simulation of the geometries of 11 typical B-GDY and B-doped graphdiyne oxides [B(O)-GDY] as well as a pristine GDY, along with their X-ray photoelectron (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectra at the density functional theory (DFT) level. The boron and carbon spectra for various bonding types were theoretically imitated to assess the spectral contributions. Calculated outcomes indicate that there is a noticeable dependence of the NEXAFS spectra on the local structure. The simulated XPS spectra provide precise assignments and an extra supplement to the spectra peaks, in addition to the position and general peak forms of simulated spectral peaks matching the experimental spectra fairly well. The combination of XPS and NEXAFS spectra can give useful information for identifying typical B-GDY and B(O)-GDY molecules. This paper offers a comprehensive structure-spectrum relationship of B-GDY and its oxides as well as a further theoretical prediction and guidance for experimental synthesis, which is helpful to solve the challenging issue of identification of B-doped carbon-based materials.

A Smartphone-Mediated "All-In-One" Biosensing Chip for Visual and Value-Assisted Detection

A smartphone-mediated self-powered biosensor is fabricated for miRNA-141 detection based on the CRISPR/Cas12a cross-cutting technique and a highly efficient nanozyme. As a novel nanozyme and a signal-amplified coreaction accelerator, the AuPtPd@GDY nanozyme exhibits an excellent ability to catalyze cascade color reactions and high conductivity to enhance the electrochemical signal for miRNA-141 assays. After CRISPR/Cas12a cross-cutting of S2-glucose oxidase (S2-GOD), the electrochemical signal is weakened, and miRNA-141 is detected by monitoring the decrease in the signal. On the other hand, a cascade reaction among glucose, H2O2, and TMB is catalyzed by GOD and AuPtPd@GDY, respectively, resulting in a color change of the solution, which senses miRNA-141. The self-powered biosensor enables value-assisted and visual detection of miRNA-141 with limits of detection of 3.1 and 15 aM, respectively. Based on the dual-modal self-powered sensing system, a smartphone-mediated "all-in-one" biosensing chip is designed to achieve the real-time and intelligent monitoring of miRNA-141. This work provides a new approach to design multifunctional biosensors to realize the visualization and portable detection of tumor biomarkers.

Structural identification of single boron-doped graphdiynes by computational XPS and NEXAFS spectroscopy

Boron-doped graphdiyne (B-GDY) material exhibits an excellent performance in electrocatalysis, ion transport, and energy storage. However, accurately identifying the structures of B-GDY in experiments remains a challenge, hindering further selection of suitable structures with the most ideal performance for various practical applications. In the present work, we employed density functional theory (DFT) to simulate the X-ray photoelectron spectra (XPS) and near-edge X-ray absorption fine-structure (NEXAFS) spectra of pristine graphdiyne (GDY) and six representative single boron-doped graphdiynes at the B and C K-edges to establish the structure-spectroscopy relationship. A notable disparity in the C 1s ionization potentials (IPs) between substituted and adsorbed structures is observed upon doping with a boron atom. By analyzing the C and B 1s NEXAFS spectra on energy positions, spectral widths, spectral intensities, and different spectral profiles, we found that the six single boron-doped graphdiyne configurations can be sensitively identified. Moreover, this study provides a reliable theoretical reference for distinguishing different single boron-doped graphdiyne structures, enabling accurate selection of B-GDY structures for diverse practical applications.

One-pot synthesis of gamma-graphyne supported Pd nanoparticles with high catalytic activity

As a unique member of the graphyne family, gamma-graphyne (γ-graphyne) is a novel kind of 2D carbon allotrope with potential high carrier mobility and large surface area. It remains a great challenge to synthesize graphynes with targeted topologies and good performance. Herein, a novel one-pot method was applied to the synthesis of γ-graphyne using hexabromobenzene and acetylenedicarboxylic acid via a Pd-catalyzed decarboxylative coupling reaction, which is easy to perform with mild reaction conditions, facilitating the possibility of mass production. As a result, the synthesized γ-graphyne reveals a two-dimensional γ-graphyne structure consisting of 1 : 1 sp/sp² hybridized carbon atoms. Furthermore, γ-graphyne as a carrier for Pd (Pd/γ-graphyne) displayed a superior catalytic activity for the reduction of 4-nitrophenol with a short reaction time and high yields, even in aqueous media under aerobic conditions. Compared with Pd/GO, Pd/HGO, Pd/CNT, and commercial Pd/C, Pd/γ-graphyne showed more excellent catalytic performance with lower palladium loadings. Thus we expect that the novel approach for the synthesis of γ-graphyne will boost research on the design and application of graphyne-type functional materials for catalysis.

Real-Time Biosensor Platform Based on Novel Sandwich Graphdiyne for Ultrasensitive Detection of Tumor Marker

Realization of a highly sensitive analysis and sensing platform is important for early-stage tumor diagnosis. In this work, a self-powered biosensor with a novel sandwich graphdiyne (SGDY) combined with an aptamer-specific recognition function was developed to sensitively and accurately detect tumor markers. Results indicated that the detection limits of microRNA (miRNA)-21 and miRNA-141 were 0.15 and 0.30 fM (S/N = 3) in the linear range of 0.05-10000 and 1-10000 fM, respectively. The newly designed platform has great promise for early-stage tumor diagnosis.

Influence of Alkali Metal Doping and BN Substitution on the Second-Order Nonlinear Optical Properties of Graphyne: A Theoretical Perspective

The electronic and nonlinear optical (NLO) properties of BN-substituted graphynes and the corresponding alkali-doped hybrid systems have been determined using density functional theory. When the carbon atoms in the graphyne are replaced by BN pairs, the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap (E_gap) increases to some extent, and the static first hyperpolarizabilities (β₀) of the novel systems hardly increase. However, when an alkali atom is introduced on the surface of BN-substituted graphyne, the doping effect can effectively modulate the electronic and NLO properties. Doping the alkali atom can significantly narrow the wide E_gap of BN-substituted graphynes in the range of 1.03-2.03 eV. Furthermore, the doping effect brings considerable β₀ values to these alkali-doped systems, which are 52-3609 au for Li-doped systems and 3258-211 053 au for Na/K-doped ones. The result reveals that the β₀ values of alkali-doped complexes are influenced by the atomic number of alkali metals and the proportion of BN pairs. The nature of the excellent NLO responses of alkali-doped complexes can be understood by the low excitation energy of the crucial excited state and the analysis of the first hyperpolarizability density. Besides, these alkali-doped complexes have a deep-ultraviolet working region. Therefore, the combined effect of alkali metal doping and BN substitution can be an excellent strategy to design novel high-performance NLO materials based on graphyne.

Modeling the Adsorption of Polycyclic Aromatic Hydrocarbons on Graphynes: An Improved Lennard-Jones Formulation

Research on the development of theoretical methodologies for modeling noncovalent interactions governing the adsorption of polycyclic aromatic hydrocarbons (PAHs) on graphene and other two-dimensional materials is being intensely pursued in recent times. Highly accurate empirical potentials have emerged as a viable alternative to first-principles calculations for performing large-scale simulations. Herein, we report exploration of the potential energy surfaces for the adsorption of cata-condensed and peri-condensed PAHs on graphynes (GYs) using the improved Lennard-Jones (ILJ) potential. Initially, the ILJ potential is parametrized against benchmark electronic structure calculations performed on a selected set of PAH-GY complexes using dispersion-corrected density functional theory. The accuracy of the parametrization scheme is then assessed by a comparison of the adsorption features predicted from the ILJ potential with those computed using electronic structure calculations. The potential energy profiles as well as the single point energy calculations and geometry reoptimizations performed on the minimum-energy configurations predicted by the ILJ potential for a broader range of PAH-GY complexes provided a validation of the parametrization scheme. Finally, by an extrapolation of the PAH adsorption energies on various GYs, we estimated the interlayer cohesion energies for the van der Waals bilayer heterostructures of GYs with graphene to be in the range of 25-50 meV/atom.