Formation Of Charge-transfer Complex Research Articles

Photocatalytic Reactions over TiO2-Based Interfacial Charge Transfer Complexes

The present review is related to the novel approach for improvement of the optical properties of wide bandgap metal oxides, in particular TiO2, based on the formation of the inorganic–organic hybrids that display absorption in the visible spectral range due to the formation of interfacial charge transfer (ICT) complexes. We outlined the property requirements of TiO2-based ICT complexes for efficient photo-induced catalytic reactions, emphasizing the simplicity of the synthetic procedure, the possibility of the fine-tuning of the optical properties supported by the density functional theory (DFT) calculations, and the formation of a covalent linkage between the inorganic and organic components of hybrids, i.e., the nature of the interface. In addition, this study provides a comprehensive insight into the potential applications of TiO2-based ICT complexes in photo-driven catalytic reactions (water splitting and degradation of organic molecules), including the identification of the reactive species that participate in photocatalytic reactions by the spin-trapping electron paramagnetic resonance (EPR) technique. Considering the practically limitless number of combinations between the inorganic and organic components capable of forming oxide-based ICT complexes and with the knowledge that this research area is unexplored, we are confident it is worth studying, and we emphasized some further perspectives.

Origin of the intermolecular forces that produce donor–acceptor stacks in π-conjugated charge-transfer complexes

The attraction between π-conjugated planar electron donor and acceptor molecules that form many stable charge-transfer (CT) complexes has been explained by quantum chemical CT interactions, although the fundamental origin remains unclear. Here, we demonstrate the mechanism of CT complex formation by potential energy map analysis for TTF–CA and BTBT–TCNQ, using energy decomposition of intermolecular interaction by symmetry-adapted perturbation theory (SAPT) combined with coupled cluster calculation. We find that the source of attraction between donor and acceptor molecules is ascribed primarily to the dispersion force and also to the electrostatic force. In contrast, the contribution of CT interactions to the attractive forces is minimal. We demonstrate that the highly directional feature of the exchange repulsion force, coupled with the attractive dispersion and electrostatic forces, is crucial in determining the intermolecular arrangements of actual CT crystals. These findings are key for understanding the unique structural and electronic properties of π-conjugated CT complexes.

Determination of Tioconazole via Spectrophotometry Using Charge Transfer Complex Formation

Determination of Tioconazole via Spectrophotometry Using Charge Transfer Complex Formation

Advances of the Holographic Technique to Test the Basic Properties of the Thin-Film Organics: Refractivity Change and Novel Mechanism of the Nonlinear Attenuation Prediction.

A large number of the thin-film organic structures (polyimides, 2-cyclooctylarnino-5-nitropyridine, N-(4-nitrophenyl)-(L)-prolinol, 2-(n-Prolinol)-5-nitropyridine) sensitized with the different types of the nano-objects (fullerenes, carbon nanotubes, quantum dots, shungites, reduced graphene oxides) are presented, which are studied using the holographic technique under the Raman-Nath diffraction conditions. Pulsed laser irradiation testing of these materials predicts a dramatic increase of the laser-induced refractive index, which is in several orders of the magnitude greater compared to pure materials. The estimated nonlinear refraction coefficients and the cubic nonlinearities for the materials studied are close to or larger than those known for volumetric inorganic crystals. The role of the intermolecular charge transfer complex formation is considered as the essential in the refractivity increase in nano-objects-doped organics. As a new idea, the shift of charge from the intramolecular donor fragment to the intermolecular acceptors can be proposed as the development of Janus particles. The energy losses via diffraction are considered as an additional mechanism to explain the nonlinear attenuation of the laser beam.

Tuning (Photo)Electronic Properties of an Electron Deficient Porous Polymer via n-Doping with Tetrathiafulvalene.

Charge-transfer complex formation within the pores of porous polymers is an efficient way to tune their electronical properties. Introduction of electron accepting guests to the electron donating hosts to conduct their p-doping is intensively studied in this context. However, the vice versa scenario, n-doping by treating the electron deficient (i.e., n-type) porous polymers with electron donating dopants, is rare. In this work, synthesis of an n-type phenazine based conjugated microporous polymer and its exposure to strong electron donating tetrathiafulvalene (TTF) dopants are presented. The fundamental physical characterizations (e.g., elemental analysis, gas sorption) showed that the vacuum impregnation technique is a good approach to load the guest molecules inside the pores. Moreover, the formation of charge-transfer complexes between the phenazine building blocks of the polymeric network and TTF dopants are confirmed via spectral techniques such Fourier transform infra-red, UV-vis, steady-state/time-resolved photoluminescence, and transient absorbance spectroscopies. Effect of the doping to the electronical properties is monitored by employing photoelectrochemical measurements, which showed lower charge-transfer resistivity and nearly doubled photocurrents after the doping. The study is, therefore, an important advancement for the applicability of (n-type) porous polymeric materials in the field of photo(electro)catalysis and organic electronics.

Template-free synthesize of PANI nanostructures: Modulating structure for enhanced dielectric characteristics and superior electromagnetic wave absorption

To provide electromagnetic protection for intelligent equipment, advanced electromagnetic wave absorption (EWA) materials are highly desired. To reveal the interaction mechanism of structure and electromagnetic waves, polyaniline (PANI) with various structures, including nanosheets, clusters, and nanofibers, is synthesized via a template-free approach. The self-assembly process of PANI can be regulated by camphor sulfonic acid due to the formation and guidance of charge transfer complexes. A comprehensive analysis of structure, chemical constitution, and electromagnetic characteristics is conducted. Clusters with three-dimensional micro-nano structure exhibit superior microwave absorption, achieving a minimum reflection loss of −52.22 dB at 9.84 GHz with a 3.2 mm thickness and an absorption bandwidth of 6.12 GHz at 2.3 mm thickness. The outstanding EWA performance is attributed to the unique architecture, strong dielectric loss capabilities, and effective impedance matching. Moreover, the fabrication process is cost-effective and scalable, making it conducive to practical applicability.

Chromoionophoric probe decorated porous polymer monolithic scaffold as solid-state colorimetric sensor and concentrator for target specific capturing of ultra-trace copper and cobalt ions

The present work reports on the development of an affordable aqueous-compatible two-in-one solid-state sensor engineered through the systematic suffusion of a chromoionophoric probe onto the porous poly(BTM-co-EGD) monolithic scaffolds for the selective colorimetric sensing of ultra-trace Cu2+ and Co2+ that are of industrial importance and environmental nuisance. The structurally regulated dual pore poly(BTM-co-EGD) template offers a high surface area for voluminous/homogenous imbuement of the probe molecules in a frozen geometrical alignment. The intriguing properties such as surface morphology, pore dimensions, structural network, phase identification, purity/elemental composition and thermal stability of the polymer monolith and probe-inoculated sensor were studied using XPS, BET/BJH, HR-TEM-SAED, FE-SEM-EDAX, XRD, FT-IR and DTG analysis. The ion recognition efficacy of the sensor material is evaluated through naked-eye color transformations and UV-Vis-DRS-based analysis. The sensor imposes a vibrant color transitional from pale yellow (blank) to intense olive brown and dark reddish brown for Cu2+ and Co2+, respectively, due to stable ligand-to-metal charge transfer complex formation. The sensor imposes high sensitivity with a response linear range of 0–200 and 0–150 ppb, with a detection limit of 0.13 and 0.16 ppb for Cu2+ and Co2+, respectively. The sensor exhibits impressive workability in the pH range of 7.0–8.0, with 0.05 mmol/g probe coating onto the poly(BTM-co-EGD) template, with an enriched response of ≤50 s, using 4 mg of the sensor material. Upon practical testing with natural/synthetic samples, the sensor executes stable characteristics with reliable and reproducible data (RSD ≤1.98 %). The proposed sensing methodology is simple, cost-effective and can be reused over eight sensing trails for the ultra-trace detection of Cu2+ and Co2+. The portable sensor has the potential for commercialization based on its effortlessness in real-time utility.

Remotely Modulating the Optical Properties of Organic Charge-Transfer Crystallites via Molecular Packing.

Organic charge-transfer complex (CTC) formation has emerged as an effective molecular engineering strategy for achieving the desired optical properties via intermolecular interactions. By synthesizing organic CTCs with carbazole-based electron donors and a 7,7,8,8-tetracyanoquinodimethane acceptor and adopting a molecular linker located remotely from the charge-transfer interface within the donors, we were able to modulate near-infrared absorptive and short-wavelength infrared emissive properties. Structural characterizations performed by using single-crystal X-ray diffraction confirmed that the unique molecular arrangements induced by the steric hindrance from the remotely located linker significantly influence the electronic interactions between the donor and acceptor molecules, resulting in different photophysical properties. Our findings offer an improved understanding of the interplay between molecular packing and optoelectronic properties, providing a foundation for designing advanced materials for optoelectronic applications.

From Molecular Design to Practical Applications: Strategies for Enhancing the Optical and Thermal Performance of Polyimide Films.

Polyimide (PI) films are well recognized for their outstanding chemical resistance, radiation resistance, thermal properties, and mechanical strength, rendering them highly valuable in advanced fields such as aerospace, sophisticated electronic components, and semiconductors. However, improving their optical transparency while maintaining excellent thermal properties remains a significant challenge. This review systematically checks over recent advancements in enhancing the optical and thermal performance of PI films, focusing on various strategies through molecular design. These strategies include optimizing the main chain, side chain, non-coplanar structures, and endcap groups. Rigid and flexible structural characteristics in the proper combination can contribute to the balance thermal stability and optical transparency. Introducing fluorinated substituents and bulky side groups significantly reduces the formation of charge transfer complexes, enhancing both transparency and thermal properties. Non-coplanar structures, such as spiro and cardo configurations, further improve the optical properties while maintaining thermal stability. Future research trends include nanoparticle doping, intrinsic microporous PI polymers, photosensitive polyimides, machine learning-assisted molecular design, and metal coating techniques, which are expected to further enhance the comprehensive optical and thermal performance of PI films and expand their applications in flexible displays, solar cells, and high-performance electronic devices. Overall, systematic molecular design and optimization have significantly improved the optical and thermal performance of PI films, showing broad application prospects. This review aims to provide researchers with valuable references, stimulate more innovative research and applications, and promote the deep integration of PI films into modern technology and industry.

Regulation of Dihedral Angle on Molecular Engineering for Enhancing Triboelectric Performance

AbstractThe performance of triboelectric polymers relies on their molecular structure. Therefore, investigating how to construct high‐performance molecular structures of triboelectric polymers becomes imperative, yet the relationship between microscopic structural parameters and triboelectric performance remains unclear. In this study, the relationship is studied between dihedral angles of adjacent conjugated planes and triboelectric performance. Various polyimide monomers are synthesized to manipulate the conjugated dihedral angles within the molecular chains. Introducing larger dihedral angles in polyimides (PIs) reduces the conjugation between molecular chains, suppressing the formation of charge transfer complexes (CTCs), and widening the energy gap between molecular orbitals. With the increase in dihedral angles, the output performance improved by 100%. The surface charge density of 335 µC·m−2 is achieved through the synergistic effect of the high charge retention capability of the PI film and the high triboelectric properties of the corona‐polarized fluorinated ethylene propylene (FEP). A large dihedral angle can form numerous deep traps and effectively prevent charge escaping while ensuring stable output. This study provides a feasible strategy for investigating the construction of high triboelectric performance molecular structures, enriching the understanding of how molecular structures influence the triboelectric properties of polymer materials and promote high‐performance fluorine‐free and environmentally friendly polymers.

Charge transfer interaction dynamics between 6-Aminoindole and picric acid: Synthesis, spectrophotometric, characterization, computational, DNA binding, and anticancer properties

The charge transfer complex (CT) chemistry is studied between electron donor 6-Aminoindole (AMI) and electron acceptor Picric acid (PA) at 25 °C, in an acetonitrile medium by using UV–Visible absorption spectroscopy. The molecular ratio of the CT complex was determined to be 1:1 by using jobs variation and spectrophotometric titration processes. To assess the stability constant (KCT), and molar extinction coefficient (ƐCT) by using the Benesi-Hildebrand equation. These outcomes reveal that the synthesized CT complex is highly stable. The thermodynamic study is carried out in different temperatures (20-45 °C), and these results indicate increases the stability with increasing temperature. The CT complex structure was analyzed by FT-IR, 1H NMR, and 13C NMR. The surface morphology and elemental composition were identified by the SEM-EDX technique. The crystalline nature was analyzed by powdered XRD investigation. The CT complex has been screened for DNA binding and invitro cytotoxicity. The DNA binding constant value (2.3 × 105 M−1) and in vitro cytotoxicity test results on HeLa, suggest that it could be used as a potential medicinal drug in the future. Finally, the geometry optimizations were carried out by the DFT with the wB97XD method and 6-31+G(d,p) basis set. Here we investigated different parameters like bond parameters, NBO analysis, FMO analysis, DOS, PDOS, and computed electronic spectra. The computational analysis provided additional support for the experimental CT complex formation.

A One-Step Green Microwell Spectrophotometric Assay for the Determination of Certain New Chemotherapeutic Drug Formulations.

The formation of charge-transfer complexes (CTCs) of iodine with five chemotherapeutic drugs used for the treatment of different types of cancer has not been investigated. These drugs are olaparib, seliciclib, vandetanib, dasatinib, and tozasertib. Additionally, these drugs need an appropriate general spectrophotometric assay for their analysis in the dosage forms regardless of the differences in their chemical structures. The aim of this study was the development of a novel microwell spectrophotometric assay (MW-SPA) for one-step determination of these drugs via their interactions with iodine, which resulted in instantaneous production of bright lemon-yellow CTCs. A spectrophotometric study of the CTCs was conducted, and all CTCs were characterized. Site(s) of interaction on each drug were assigned, and the MW-SPA was developed and applied to the analysis of dosage forms. The findings confirmed that the reactions proceeded via CTC formation. Beer's law was obeyed over a general concentration range of 1-6 µg/mL. The LODs and LOQs were in the ranges of 0.5-2.1 and 1.5-6.4 µg/mL, respectively. The proposed MW-SPA demonstrated excellent precisions as the relative standard deviations were < 2.24 and 2.23% for the intra- and inter-assay precision, respectively. Recovery studies demonstrated the accuracy of MW-SPA. Successful determination of all drugs in bulk and tablet forms was achieved using the MW-SPA. The environmental sustainability of the proposed methodology was determined, providing evidence of the assay's alignment with the basis of green analytical chemistry. The high throughput of the assay was documented. In contrast to other existing methods, the MW-SPA described herein was valid for analyzing all drugs at the same wavelength. The assay is useful for routine analysis of drugs in their formulations in QC laboratories.

Photochromic ionogel with a wide temperature range and fatigue resistance for high-resolution rewritable information record

Recently, photochromic hydrogels have received significant attention and hold substantial promise for rewritable information record. However, the intrinsic instability of hydrogels has restricted their applications. Herein, a photochromic ionogel aiming at extending service life for long-term use is presented by embedding photochromic ammonium molybdate tetrahydrate [(NH4)6Mo7O24·4H2O] (Mo7) in engineered double networks. Covalently cross-linked 2-hydroxyethyl acrylate (HEA) and self-assembled cationic cellulose (JR-400) constitute the networks, and a protic ionic liquid of ethylammonium nitrate (EAN) is immobilized therein. Such a design affords the ionogel comprehensive properties, including high optical transparency (>97%), good adhesion, anti-dehydration, wide operating temperature range (–60 to 150 °C) as well as the sensitive and stable UV-light responsiveness (within 30 s). Besides, the ionogel exhibits admirable mechanical properties of high toughness (over 180 kJ/m3), excellent resilience and a high fatigue threshold (over 1000 cycles with negligible hysteresis). The photochromic process is typically accomplished by photoreduction of Mo7, which is combined with network through electrostatic interaction with quaternized JR-400. The distinctive feature is that EAN serving as both proton donor and electron donor, plays a dominant role in coloration process and formation of charge-transfer complex. The photochromic mechanism which is less well understood in ionic liquid medium, has been revealed. Remarkably, the ionogel used as an information carrier exhibits outstanding stability in a wide operating temperature range. The superiorities of the photochromic ionogel including accurate information recording capacity and application in harsh environments have greatly boosted the high-quality information dissemination and expanded applications of photochromic soft materials.

Cationic manganese(II)-based metal-organic framework constructed from viologen derivative with multifunctional properties

Utilizing the rigid and linear viologen carboxylic ligand as an organic linker, we have successfully synthesized and structurally characterized a multifunctional Mn-based cationic metal-organic framework (1). Compound 1 features a three-dimensional framework structure with a positively charged skeleton, wherein triangular pores accommodate [MnCl4]2− anions to preserve charge neutrality. Notably, compound 1 demonstrates a chemical chromism phenomenon, transitioning from yellow-brown to deep green upon exposure to ammonia. This color change is attributed to the nucleophilic attack of electron-rich ammonia molecules on the electron-deficient viologen moiety of viologen carboxylic ligand, leading to the formation of viologen radicals and charge transfer complexes. Moreover, compound 1 exhibits rapid and selective detection of antibiotics like metronidazole (MDZ) and dimetridazole (DTZ) via a competitive absorption-induced luminescence quenching process, featuring high quenching coefficients and low detection limits. Additionally, magnetic property investigations reveal predominant antiferromagnetic coupling between Mn(II) ions within compound 1.

Enhancing bioavailability of resveratrol through complexation with π-acceptors: A spectroscopic investigation

Polyphenols, including the highly effective resveratrol, have garnered attention due to their potential as drug candidates for COVID-19 prevention and treatment, as well as their diverse biological activities. However, clinical application is hindered by limited bioavailability. To address this, complexation of resveratrol (RES) with electron-accepting compounds, such as TCNE and DDQ, was investigated. A spectroscopic and thermodynamic study of these charge transfer complexes was conducted in methanol and ethanol using UV-visible spectrophotometry. The composition of the charge transfer complexes (CTC) were determined using molar ratio method and Job's continuous variation method. Benesi–Hildbrand equation was used to calculate the formation constants KCT and the molar extinction coefficient ɛCT of the formed complexes. Thermodynamic parameters (∆G°), (∆H°), (∆S°) and other physical factors, transition energy (ECT), ionization potential (IP), resonance energy (RN), oscillator strength (ƒ) and dipole moment (μ) were determined too.Solid CTC were characterized by FT-IR and NMR spectroscopy. CTC formed in the reaction of resveratrol with both π -acceptors have high formation constants KCT indicating the high stability of these complexes. The solvent nature was identified as a factor influencing KCT values. Specifically, the KCT values for [RES-DDQ] CTC formed in ethanol surpassed those of the same complex formed in methanol. Conversely, the KCT values of [RES-TCNE] CTC formed in methanol were higher than those of the same complex formed in ethanol.This research offers insights into enhancing the properties of resveratrol through charge transfer complex formation, paving the way for potential applications in anticancer therapeutics.

Unveiling the enhanced optical limiting of polyaniline – Fullerene composite investigated by z-scan

The reverse saturable absorption (RSA) and optical limiting (OL) mechanisms of polyaniline (PANI) and fullerene doped PANI (PANI-C60) solutions were investigated by open-aperture z-scan studies, using a nanosecond pulsed Nd:YAG laser operating at 532 nm wavelength as the excitation source. The nonlinear absorption coefficient (β), OL threshold, and imaginary part of nonlinear susceptibility (χi(3)) of PANI and PANI-C60 solutions were determined for three different laser input pulse energies and are found to be in the order of 10−9 cm/W, 106 W/cm2, and 10−10 esu respectively. The results showed enhanced OL efficiency for the PANI-C60 solution, making it a promising candidate for applications in optoelectronics and optical limiting. The transmission electron microscope (TEM) images revealed the uniform distribution of C60 of particle size in the range of 5–10 nm in the PANI matrix. The composite formation of PANI-C60 was confirmed by Fourier transform infrared spectroscopy (FTIR). The presence of C60 and its charge transfer complex (CTC) formation with PANI are responsible for the enhanced OL efficiency. The linear refractive index values were measured using UV–Visible absorption spectra and compared with the theoretical values. The investigation of the OL mechanism and the calculation of its associated NLO parameters for PANI and PANI-C60 solutions are reported for the first time.

Study on An Interaction between Titan Yellow and Orange S Indicators in Water and Ethanol by using Spectroscopy Technique

Charge transfer complex (CTC) of Orange S (donor) and Titan Yellow (acceptor) has been studied in ethanol, and water solvents at room temperature (20°C) using absorption spectrophotometer. The results indicate that formation of CTC in high polar solvent is high. The stoichiometry of the complex was found to be 1:1 ratio by straight-line method between donor and acceptor with maximum absorption bands and present of isosbestic point suggest this fact. The data are discussed in terms of formation constant (KCT), molar extinction coefficient (εCT), standard free energy (ΔGo), transition energy (ECT), and ionization potential (IP). The formation constant (KCT) for the complex was shown to be dependent upon the polarity of solvents that were used. Electronic absorption spectra, which indicate the CT interaction, associated with proton migration from the acceptor to the donor followed by hydrogen bonding.

Synthesis and high-temperature energy storage performances of fluorinated polyimides

In light of the increasingly stringent requirements for the applications of light-weight flexible high-temperature-resistant dielectric materials in the fields of aerospace, electronics, and electric vehicles, the imperative lies in the development of dielectric materials with high discharged energy density, enduring temperature resistance and high reliability. This work introduced side-chain trifluoromethyl (–CF3) groups into high-temperature engineering polymer polyimides and conducted comprehensive studies on the breakdown and energy storage capabilities. The introduction of bulky –CF3 substituents reduces the intermolecular interactions, increases the free volume, and suppresses the high-temperature leakage conductance loss by decreasing the formation of intermolecular charge transfer complexes between polymer chains. As a result, the fluorinated polyimides (PFI) with lower dielectric constant exhibit enhanced breakdown strengths (730 MV m−1 at 25 °C; 630 MV m−1 at 150 °C), leading to a high discharged energy density of 3.6 J cm−3 (∼1.7 times of pristine polyimides), alongside a charge-discharge energy efficiency of ∼80% at 150 °C. These findings underscore the great potential of PFI for applications in the field of high-temperature energy storage.

Development of Two Eco-Friendly and High-Throughput Microwell Spectrophotometric Methods for Analysis of an Antibacterial Drug Tulathromycin in Pharmaceutical Bulk Form.

Tulathromycin (TUL) is a triamilide antibacterial drug which has been approved for use in the European Union and the United States for the treatment and prevention of bovine respiratory diseases. The existing methods for determination of TUL in its pharmaceutical bulk form are very limited and suffer from major drawbacks. The aim of this study was the development of two innovative microwell spectrophotometric methods (MW-SPMs) for determination of TUL in its pharmaceutical bulk form. The formation of charge-transfer complexes (CTCs) of TUL, as an electron donor, was investigated with 2,5-dihydroxy-3,6-dichlorocyclohexa-2,5-diene-1,4-dione (HCD) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (CBQ), as π-electron acceptors. The CTCs were characterized using UV-Vis spectrophotometry and computational calculations. The reactions were employed for the development of two MW-SPMs with one step for the quantitative analysis of TUL. The formation of CTCs was confirmed via the formation of characteristic absorption bands with maximum absorption at 520 and 460 nm for CTCs with HCD and CBQ, respectively. The stoichiometry of both CTCs was found to be 1:1, and the values of different spectroscopic and electronic constants confirmed the stability of the CTCs. The mechanisms of the reactions were postulated. The linear range of both MW-SPMs was 10-500 µg/mL. The LOQs were 13.5 and 26.4 µg/mL for methods involving reactions with HCD and CBQ, respectively. Both methods were successfully applied to the quantitation of TUL in pharmaceutical bulk form with acceptable accuracy and precision. The results of eco-friendliness/greenness assessment proved that both MW-SPMs fulfill the requirements of green analytical approaches. In addition, the one-step reactions and simultaneous handling of a large number of samples with micro-volumes in the proposed methods gave them the advantage of high-throughput analysis. This study described two new MW-SPMs as valuable analytical tools for the determination of TUL. The proposed methods are valuable analytical tool for the analysis of bulk form of TUL.

Nanoscale mapping of relativistic photocarrier transports in epitaxial graphene surface and edge states

We report the direct mapping of photo-transport properties of relativistic carriers generated on terrace-surface and terrace-edge structures of epitaxial graphene grown on silicon carbide. In this method, a conductive probe made a direct contact with epitaxial graphene and scanned the surface, allowing us to map the topography, current, and noise of graphene with nanoscale resolutions via a scanning noise microscopy. The maps were further analyzed by a two-dimensional network model to obtain the sheet-conductance (S□) and noise-source density (neff) distributions of epitaxial graphene. The topography image showed the formation of terraces, which could be attributed to the different decomposition rate of silicon atoms during the graphene growth. The terraces of graphene exhibited uniform S□, being separated by one-dimensional terrace-edges. Interestingly, terrace-edges exhibited a rather large neff with a power-law relationship of S□ ∝ neff−0.5, indicating a typical hopping conduction. However, in terrace-surfaces, sheet-conductance was nearly independent on neff, which was attributed to the relativistic nature of charge carriers unaffected by charge-trapping potential. Notably, under illumination, we observed the relativistic behavior of photocarriers in overall graphene terraces, presumably because photocarriers were generated through charge-transfer complexes formation at epitaxial graphene/substrate interface without the participation of noise-sources. Interestingly, we observed nearly homogeneous photoconductance and neff, which could be possibly due to the merger of one-dimensional edge-states into two-dimensional surface-states. The mapping of photoconductance and photo-traps provides valuable insights into the generation of relativistic photocarriers in epitaxial graphene.