Conducting Electrospun Poly(3-hexylthiophene-2,5-diyl) Nanofibers: New Strategies for Effective Chemical Doping and its Assessment Using Infrared Spectroscopy.

Vibrational spectroscopy allows the investigation of structural properties of pristine and doped poly(3-hexylthiophene-2,5-diyl) (P3HT) in highly anisotropic materials, such as electrospun micro- and nanofibers. Here, we compare several approaches for doping P3HT fibers. We have selected two different electron acceptor molecules as dopants, namely iodine and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). In the case of iodine, we have explored the doping of the fibers according to several different procedures, i.e., by sequential doping both in vapors and in solution, and with a novel promising one-step method, which exploits the mixing of the dopant to the electrospinning feed solution. Polarized infrared (IR) spectroscopy experiments prove the orientation of P3HT chains, with the polymer backbone mainly running parallel to the fiber axis. After doping, P3HT fibers show very strong and polarized doping-induced IR active vibrations (IRAVs), which are the spectroscopic signature of the structure relaxation induced by the charged defects (polarons), thus providing an unambiguous proof of the effective doping. Raman spectroscopy complements the IR evidence: The Raman spectrum shows a clearly recognizable shift of the main band, the so-called effective conjugation coordinate band, in the doped samples. A simple protocol, which quantifies the evolution of the IRAV bands with time, allows monitoring of the doping stability over time and confirms that F4TCNQ is by far superior to iodine.

Doping Ferrocene-Based Conjugated Microporous Polymers with 7,7,8,8-Tetracyanoquinodimethane for Efficient Photocatalytic CO2 Reduction.

The design and synthesis of organic photocatalysts remain a great challenge due to their strict structural constraints. However, this could be mitigated by achieving structural flexibility by constructing permanent porosity into the materials. Conjugated microporous polymers (CMPs) are an emerging class of porous materials with an amorphous, three-dimensional network structure, which makes it possible to integrate the elaborate functional groups to enhance photocatalytic performance. Here, we report the synthesis of a novel CMP, named TAPFc-TFPPy-CMP, constructed by 1,1'3,3'-tetra(4-aminophenyl)ferrocene (TAPFc) and 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) monomers. The integration of the p-type dopant 7,7,8,8-tetracyanoquinodimethane (TCNQ) into the TAPFc-TFPPy-CMP improved the light adsorption performance, leading to a decrease in the optical bandgap from 2.00 to 1.43 eV. The doped CMP (TCNQ@TAPFc-TFPPy-CMP) exhibited promising catalytic activity in photocatalytic CO2 reduction under visible light, yielding 546.8 µmol g-1 h-1 of CO with a selectivity of 96% and 5.2 µmol g-1 h-1 of CH4. This represented an 80% increase in the CO yield compared to the maternal TAPFc-TFPPy-CMP. The steady-state photoluminescence (PL) and fluorescence lifetime (FL) measurements reveal faster carrier separation and transport after the doping. This study provides guidance for the development of organic photocatalysts for the utilization of renewable energy.

Enabling Oxidation Protection and Carrier-Type Switching for Bismuth Telluride Nanoribbons via in Situ Organic Molecule Coating.

Thermoelectric materials with high electrical conductivity and low thermal conductivity (e.g., Bi2Te3) can efficiently convert waste heat into electricity; however, in spite of favorable theoretical predictions, individual Bi2Te3 nanostructures tend to perform less efficiently than bulk Bi2Te3. We report a greater-than-order-of-magnitude enhancement in the thermoelectric properties of suspended Bi2Te3 nanoribbons, coated in situ to form a Bi2Te3/F4-TCNQ core-shell nanoribbon without oxidizing the core-shell interface. The shell serves as an oxidation barrier but also directly functions as a strong electron acceptor and p-type carrier donor, switching the majority carriers from a dominant n-type carrier concentration (∼1021 cm-3) to a dominant p-type carrier concentration (∼1020 cm-3). Compared to uncoated Bi2Te3 nanoribbons, our Bi2Te3/F4-TCNQ core-shell nanoribbon demonstrates an effective chemical potential dramatically shifted toward the valence band (by 300-640 meV), robustly increased Seebeck coefficient (∼6× at 250 K), and improved thermoelectric performance (10-20× at 250 K).

Charge Transfer and Orbital Reconstruction at an Organic-Oxide Interface.

The two-dimensional electron system (2DES) located at the surface of strontium titanate (STO) and at several other STO-based interfaces has been an established platform for the study of novel physical phenomena since its discovery. Here we report how the interfacing of STO and tetracyanoquinodimethane (TCNQ) results in a charge transfer that depletes the number of free carriers at the STO surface, with a strong impact on its electronic structure. Our study paves the way for efficient tuning of the electronic properties, which promises novel applications in the framework of oxide/organic-based electronics.

Tetraphenylethene Derivatives Bearing Alkylammonium Substituents: Synthesis, Chemical Properties, and Application as BSA, Telomere DNA, and Hydroxyl Radical Sensors.

Tetraphenylethene derivatives (TPEs) are used as luminescence probes for the detection of metal ions and biomolecules. These sensors function by monitoring the increase in the photoluminescence (PL) intensity of the TPEs resulting from aggregation-induced emission (AIE) upon interaction with the analytes. The AIE behavior of the sensors was investigated by measuring their PL. In this study, PL, PL lifetime, and confocal laser scanning microscopy measurements were carried out as part of our in-depth investigation of AIE behavior of TPEs for the detection of biomolecules and radical species. We used 1,1,2,2-tetrakis(4-((trimethylammonium)alkoxy)phenyl)tetraphenylethene tetrabromide (TPE-C(m)N+Me3Br-, m = 2, 4, and 6, where m denotes the number of methylene groups in the alkyl chain) and TPE-C(m)N+Me3TCNQ-• (TCNQ-• is the 7,7',8,8'-tetracyanoquinodimethane anion radical) as luminescent probes for the detection of bovine serum albumin (BSA), DNA, and the hydroxyl radical (•OH) generated from Fenton's reagent. The sensing performance of TPE-C(m)N+Me3Br- for BSA and DNA was found to depend on the length of the alkyl chains (m). UV-vis and PL measurements revealed that the responses of TPE-C(m)N+Me3Br- and TPE-C(4)N+TCNQ-• to Fenton's reagent depended on the solvent. The electrochemical properties of the TPE derivatives prepared in this study were additionally investigated via cyclic voltammetry.

Effect of Fluoride Atoms on the Electrochemical Performance of Tetracyanoquinodimethane(TCNQ) Electrodes in Zinc-ion Batteries.

Tetracyanoquinodimethane (TCNQ) electrode material has achieved excellent performance in aqueous zinc-ion batteries (AZIBs). However, fundamental understanding about effect of substitutes on electrochemical performance of TCNQ remain unknown. In this work, the effects of fluorine (F) as an electron-absorbing group on the structure, morphology and electrochemical performance of TCNQ and storage mechanism of TCNQ in AZIBs are discussed. Theoretical calculation proves that the introduction of fluorine atoms decreases lowest unoccupied molecular orbital (LUMO) energy of TCNQ thus affect the redox potential. Electrochemical performance of TCNQ/Fluoro-7,7,8,8-tetracyanoquinodimethane (FTCNQ)/2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4 TCNQ) is evaluated from 25 °C to -20 °C in AZIBs. Results tend out that with the increasing substituents of F on TCNQ molecular, their stability in AZIBs decrease. Dipole moment calculation further shows that the introduction of fluorine atoms is inconducive to the stability of the electrode material in aqueous solution. Ex-situ characterization demonstrate that electron withdrawing groups do not change the REDOX center of TCNQ electrode materials. Our work provides a new thought for the selection of the electrode material in AZIBs.

Preparation of g-C3N4/TCNQ Composite and Photocatalytic Degradation of Pefloxacin.

g-C3N4 and g-C3N4/TCNQ composites with different doping levels were prepared using the copolymerization thermal method with melamine as a precursor. XRD, FT-IR, SEM, TEM, DRS, PL, and I-T characterized them. The composites were successfully prepared in this study. The photocatalytic degradation of pefloxacin (PEF), enrofloxacin (ciprofloxacin), and ciprofloxacin (ciprofloxacin) under visible light (λ > 550 nm) showed that the composite material had the best degradation effect on PEF. When TCNQ doping is 20 mg and catalyst dosage is 50 mg, the catalytic effect is the best, and the degradation rate reaches 91.6%, k = 0.0111 min-1, which is four times that of g-C3N4. Repeated experiments found that the cyclic stability of the g-C3N4/TCNQ composite was good. The XRD images were almost unchanged after five reactions. The radical capture experiments revealed that ·O2- was the main active species in the g-C3N4/TCNQ catalytic system, and h+ also played a role in PEF degradation. And the possible mechanism for PEF degradation was speculated.

Electronic modulation and structural engineering of tetracyanoquinodimethane with enhanced reaction kinetics for aqueous NH4+ storage.

Lithium-ion batteries (LIBs) have received much attention because of their environmental, financial, and safety concerns. The advantages of aqueous electrochemical energy storage include environmental friendliness and safety, and the development of prepared electrode materials is predicted to alleviate these issues. A redox-active organic compound, 7,7,8,8­tetracyanoquinodimethane (TCNQ), is a suitable electrode for aqueous batteries. In this work, the porous and electronic interconnected structure of TCNQ is designed by electronic modulation and structure engineering. With the reduced graphene oxide (rGO) in situ homogeneous loading TCNQ by a one-step facile approach, the exquisite architecture has enhanced conductivity and connected conductive networks, favoring the storage and transportation of NH4+ or electrons in aqueous electrolytes. As a cathode, the obtained TCNQ-rGO exhibits superior performance for NH4+ batteries with an improved reversible capacity of 92.7 mAh/g at 1 A/g of quadruple capacity boosting to pure TCNQ and stable cycle life (5000 cycles at 10 A/g). The adjustment of the loading ratio of TCNQ and rGO for the cycling performance has been studied in detail. Furthermore, the superior ammonium storage mechanism of the TCNQ-rGO hybrid is thoroughly discussed by in situ Raman or ex situ measurements, which also determine the redox activity center groups of the TCNQ-rGO hybrid. Energy level calculations are conducted to help illustrate its potential as an electrode material. Our work demonstrates that electronic modulation and structural engineering of TCNQ can improve the electrochemical performance of molecular organic compound-based electrodes for aqueous rechargeable batteries in a simple and effective way.

CuO Modified by 7,7,8,8-Tetracyanoquinodimethane and Its Application to CO2 Separation.

7,7,8,8-Tetracyanoquinomethane (TCNQ) was added to polyvinylpyrrolidone (PVP)/CuO composites to modify and prevent agglomeration of the particles, and thus the CuO particles were well dispersed to a small size, thereby increasing CO2 solubility and separation performance. When the separation performance of the PVP/CuO/TCNQ composite membrane was measured for CO2/N2 gases, a CO2 separation of about 174 was measured. This improvement in performance was attributed to the fact that TCNQ was applied to PVP and CuO to prevent agglomeration between particles with surface modification. Due to TCNQ, CuO could be dispersed to a small size in PVP; the bonds between chains in PVP weakened; the interaction between molecules weakened; and the free volume increased, as confirmed by FT-IR, TGA, and UV-Vis spectroscopy.

Application of Plackett-Burman Design for Spectrochemical Determination of the Last-Resort Antibiotic, Tigecycline, in Pure Form and in Pharmaceuticals: Investigation of Thermodynamics and Kinetics.

Tigecycline (TIGC) reacts with 7,7,8,8-tetracyanoquinodimethane (TCNQ) to form a bright green charge transfer complex (CTC). The spectrum of the CTC showed multiple charge transfer bands with a major peak at 843 nm. The Plackett-Burman design (PBD) was used to investigate the process variables with the objective being set to obtaining the maximum absorbance and thus sensitivity. Four variables, three of which were numerical (temperature-Temp; reagent volume-RV; reaction time-RT) and one non-numerical (diluting solvent-DS), were studied. The maximum absorbance was achieved using a factorial blend of Temp: 25 °C, RV: 0.50 mL, RT: 60 min, and acetonitrile (ACN) as a DS. The molecular composition that was investigated using Job's method showed a 1:1 CTC. The method's validation was performed following the International Conference of Harmonization (ICH) guidelines. The linearity was achieved over a range of 0.5-10 µg mL-1 with the limits of detection (LOD) and quantification (LOQ) of 166 and 504 ng mL-1, respectively. The method was applicable to TIGC per se and in formulations without interferences from common additives. The application of the Benesi-Hildebrand equation revealed the formation of a stable complex with a standard Gibbs free energy change (∆G°) value of -26.42 to -27.95 kJ/mol. A study of the reaction kinetics revealed that the CTC formation could be best described using a pseudo-first-order reaction.

Charge-transfer chemistry of two corticosteroids used adjunctively to treat COVID-19. Part II: The CT reaction of hydrocortisone and dexamethasone donors with TCNQ and fluoranil acceptors in five organic solvents.

Hydrocortisone (termed as D1) and dexamethasone (termed as D2) are corticosteroids currently used to treat COVID-19. COVID-19 is a disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Exploring additional chemical properties of drugs used in the treatment protocols for COVID-19 could help scientists alike improve these treatment protocols and potentially even the vaccines (i.e., Janssen, Moderna, AstraZeneca, Pfizer-BioNTech). In this work, the charge-transfer (CT) properties of these two corticosteroids (D1 and D2) with two universal acceptors: 7,8,8-tetracyanoquinodimethane (termed as TCNQ) and fluoranil (termed as TFQ) in five different solvents were investigated. The examined solvents were MeOH, EtOH, MeCN, CH2Cl2, and CHCl3. The CT interactions formed stable corticosteroid CT complexes in all examined solvents. Several spectroscopic parameters were derived, and the oscillator strength (f) and transition dipole moment (µe.g. ) values revealed that the interaction between the investigated corticosteroids with TCNQ acceptor is much stronger than their interaction with TFQ acceptor. The CT interactions were proposed to process via n â†’ π* transition.

Interactions of Ag Particles Stabilized by 7,7,8,8-Tetracyanoquinodimethane with Olefin Molecules in Poly(ether-block-amide).

In this study, to use a stabilized carrier, silver nanoparticles (AgNPs) were used as carriers and electron acceptors were added to activate the surface of AgNPs as olefin carriers. In addition, poly(ether-block-amide) (PEBAX), consisting of polyamide (hard segments) and polyether (soft segments), was investigated for the correlation of the between-segments ratio related to the stability of AgNPs and separation performance. As a result, contrary to the expectation that high permeance would be observed in PEBAX-1657/AgNPs/7,7,8,8-tetracyanoquinodimethane (TCNQ) membrane, which had a higher ratio of polyether soft segment, the PEBAX-5513/AgNPs/TCNQ membrane, which had a relatively high proportion of polyamide, showed a higher permeance without difference in selectivity. These unexpected data were attributable to the fact that the relatively abundant amount of PA groups in PEBAX-5513 was able to stabilize and positively polarize the surface of AgNPs, resulting in the stabilized and high performance of olefin separation.

Semiconductive 2D arrays of pancake-bonded oligomers of partially charged TCNQ radicals.

Multicentre two-electron (mc/2e or 'pancake bonding') bonding between 7,7,8,8-tetra-cyano-quinodi-methane (TCNQ) radical anions was studied on its 14 novel salts with planar organic cations. The formal charges of the TCNQδ- moieties are -1/2 and -2/3, and they form mc/2e bonded dimers, trimers and tetramers which are further stacked into extended arrays. Multicentre bonding within these oligomers is characterized by short interplanar separations of 2.9-3.2 Å; distances between the oligomers are larger, typically >3.3 Å. The stacks are laterally connected by C-H⋯N hydrogen bonding, forming 2D arrays. The nature of mc/2e bonding is characterized by structural, magnetic and electrical data. The compounds are found to be semiconductors, and high conductivity [10-2 (Ω cm)-1] correlates with short interplanar distances between pancake-bonded oligomers.

Transition Metals Embedded Two-Dimensional Square Tetrafluorotetracyanoquinodimethane Monolayers as a Class of Novel Electrocatalysts for Nitrogen Reduction Reaction.

The combination of transition metal (TM) atoms and high electron affinity organic framework tetrafluorotetracyanoquinodimethanes (F4TCNQs) makes the TM-embedded two-dimensional (2D) square F4TCNQ monolayers (TM-sF4TCNQ) possible to have excellent characteristics of single-atom catalysts and 2D materials. For the first time, the TM-sF4TCNQ monolayers have been considered for application in the electrocatalytic nitrogen reduction reaction (eNRR) field. Through high-throughput screening, the catalytic performance of 30 TM-sF4TCNQ (TM = 3d∼5d TMs) monolayers for eNRR was comprehensively evaluated. The Mo-, Nb-, and Tc-sF4TCNQ catalysts stand out with the onset potentials of -0.18, -0.44, and -0.54 V, respectively, through the optimal reaction paths. Our work will provide guidance for the green and sustainable development of electrocatalytic nitrogen fixation.

Prognostication of two-dimensional transition-metal atoms embedded rectangular tetrafluorotetracyanoquinodimethane single-atom catalysts for high-efficiency electrochemical nitrogen reduction.

Extensive investigations on the electrocatalytic nitrogen reduction reactions (eNRR) and the high-efficiency single-atom catalysts (SACs) have increasingly given us confidence in intensive arrival of nitrogen (N2) fixation into ammonia (NH3) under ambient conditions in the future, which prompts us to speed up the exploration for highly active SACs for eNRR. Excellent SACs in eNRR should have three advantages: high selectivity, low overpotential, and high stability. Based on these aspects, we employed high-throughput screening method and first-principles calculations to study the catalytic performance of 30 transition-metal atoms (TMs) embedded rectangular tetrafluorotetracyanoquinodimethane (denoted as TM-rF4TCNQ) monolayers (TM = 3d, 4d, and 5d series transition metal atoms) for the eNRR process, and four potential catalysts, i.e., Ti-, Mo-, Nb-, and Tc-rF4TCNQ, were obtained. Among them, Ti-rF4TCNQ catalyzing the N2 reduction to NH3 through an enzymatic mechanism needs a theoretical onset potential of only -0.41 V. When Mo-rF4TCNQ catalyzes eNRR through a distal mechanism, the theoretical onset potential is as low as -0.43 V. The band structures show that these materials are all metallic, ensuring good charge transport during the eNRR process. Analyzing the projected density of states (PDOSs) before and after N2 adsorption, the differential charge density, and the spin density reveals that the Ti-, Mo-, Nb-, and Tc-rF4TCNQ monolayers all can effectively adsorb and activate inert N2, which may be mainly attributed to the "acceptance-donation" interaction between TM and N2.

Tamoxifen charge transfer complexes with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and 7,7,8,8-tetracyanoquinodimethan: Synthesis, spectroscopic characterization and theoretical study.

To understand bioactive molecule-receptor interactions it is important to understand the molecular complexation and structural recognition properties of the materials in question. To this aim, the electron donating bioactive molecule tamoxifen (TAM) was combined with the electron accepting molecules 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) to form TAM-DDQ and TAM-TCNQ charge transfer (CT) complexes. The properties of the complexes in solution and solid, their donor-acceptor interactions were investigated, and their stability was assessed in acetonitrile. Solid complexes of TAM-DDQ and TAM-TCNQ were characterized using nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopies to confirm their formation. Job's and modified Benesi-Hildebrand methods were used to study the stoichiometries and association constants of TAM-DDQ and TAM-TCNQ, from which their stoichiometries were found to be 1:1. The physical parameters of the CT complexes in terms of their molar extension constants, dipole moments, and formation constants were determined to study their stability in solution. The results obtained in this study indicate that the complexes are suitable for assessing TAM in pharmaceutical preparations. The experimental results were complemented by density functional theory (geometry optimization, energy transition, and molecular electrostatic potential maps) at DFT/B3LYPlevel of theory.

Structure, optical and electro-physical properties of tetramerized anion-radical salt (N-Xy-Qn)(TCNQ)2.

The (N-Xy-Qn)(TCNQ)2 anion-radical salt characterized by tetramerized stacks of the TCNQ acceptor molecules has been synthesized and characterized using vibrational spectroscopy and electrical resistivity measurements. The bond lengths analysis based on the crystal structure data, indicates that the TCNQ molecules are non-uniformly charged with -0.83 e localized on the inner B molecules and -0.33 e on the outer A molecules within ABBA tetramers. Both infrared and Raman spectra of (N-Xy-Qn)(TCNQ)2 are dominated by vibrational modes of TCNQ and display splitting related to the tetramerized structure. Many of these features are affected by the strong electron-molecular vibration (EMV) coupling. Other charge-sensitive modes allowed estimation of charge localized on TCNQ, with the results that confirm the charges estimated on basis of the crystal data. Electrical measurements revealed the low-conducting behavior with room temperature conductivity value of 2.6 mS cm-1 and temperature dependence of resistivity that can be explained within the band conduction model. The calculated activation energies range from 0.169 eV to 0.187 eV, depending on the crystallographic direction and thermal history of the sample.

7,7-bis(N, N-diethylethylenediamino)-8,8-dicyanoquinodimethane: Effect of Ethyl Moiety on the Photophysical Property besides Thermal Stability.

Tetracyanoquinodimethane (TCNQ) on reaction with primary/secondary amines sequels in mono/di-substituted TCNQ adducts known as diaminodicyanoquinodimethanes (DADQ's) possessing astounding optical or non-linear optical characteristics. Crucially, the subtle choice of amine contributes to the outcome of molecular material aspects. Herein, we present a comprehensive investigation of 7,7-bis(N,N-diethylethylenediamino)-8,8-dicyanoquinodimethane (BDEDDQ); manifesting the impact of ethyl group (existing on the di-substituted nitrogen of N,N-diethylethylenediamine (DEED)); on the crystal structure, optical property and thermal stability. Crystallography study revealed supramolecular self-assemblies among molecular dipoles emanating fluorescence enhancement in the solid state compared to solutions. Quantum yields were primarily ~0.2 to 0.4% in solutions and ~56% in the solid. Stokes shift was noticed to be more in solutions (~90 nm) than solid (~67 nm), suggesting excess vibrational relaxations in solutions. Differential scanning calorimetry revealed ~182 °C as the melting temperature. The heat capacity of solid was found to be 5.03 mJs-1. Thermogravimetric analysis conveyed single stage decomposition process initiated by the two amine side chains. Scanning electron microscopy of films prepared by drop casting solutions imparted divergent morphological features, due to different rates of evaporation accompanied by varied growth kinetics. Accordingly, in this paper we have demonstrated the utilization of simple N,N-diethylethylenediamine (DEED) to successfully generate a noteworthy blue emissive molecular material exhibiting semiconducting feature besides reasonable thermal stability.

Structural investigations into a new polymorph of F4TCNQ: towards enhanced semiconductor properties.

During the course of research into the structure of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), C12F4N4, an important compound in charge-transfer and organic semiconductor research, a previously unreported polymorph of F4TCNQ was grown concomitantly with the known polymorph from a saturated solution of dichloromethane. The structure was elucidated using single-crystal X-ray diffraction and it was found that the new polymorph packs with molecules in parallel layers, in a similar manner to the layered structure of F2TCNQ. The structure was analysed using Hirshfeld surface analysis, fingerprint plots and pairwise interaction energies, and compared to existing data. The structure of a toluene solvate of F4TCNQ is also reported.

Electrocatalytic Mechanism of N2 Reduction Reaction by Single-Atom Catalyst Rectangular TM-TCNQ Monolayers.

Herein, the catalytic properties and reaction mechanisms of the 3d, 4d, and 5d transition metals embedded in 2D rectangular tetracyanoquinodimethane (TM-rTCNQ) monolayers as single-atom catalysts (SACs) for the electrocatalytic N2 reduction reaction (NRR) were systematically investigated, using first-principles calculations. A series of high-throughput screenings were carried out on 30 TM-rTCNQ monolayers, and all possible NRR pathways were explored. Three TM-rTCNQ (TM = Mo, Tc, and W) SACs were selected as promising new NRR catalyst candidates because of their high structural stability and good catalytic performance (low onset potential and high selectivity). Our results show that the Mo-rTCNQ monolayer can catalyze NRR through a distal mechanism with an onset potential of -0.48 V. Surprisingly, the NH3 desorption energy on the Mo-rTCNQ monolayer is only 0.29 eV, the lowest one reported in the literature so far, which makes the Mo-rTCNQ monolayer a good NRR catalyst candidate. In-depth research studies on the structures of N2-TM-rTCNQ (TM = Mo, Tc, and W) found that strong adsorption and activation performance of TM-rTCNQ for N2 may be due to the strong charge transfer and orbital hybridization between the TM-rTCNQ catalyst and the N2 molecules. Our work provides new ideas for achieving N2 fixation under environmental conditions.