Nonequilibrium Green Function Research Articles

Parametric Analysis of Indium Gallium Arsenide Wafer-based Thin Body (5 nm) Double-gate MOSFETs for Hybrid RF Applications.

The electrical behavior of a high-performance Indium Gallium Arsenide (In- GaAs) wafer-based n-type Double-Gate (DG) MOSFET with a gate length (LG1= LG2) of 2 nm was analyzed. The relationship of channel length, gate length, top and bottom gate oxide layer thickness, a gate oxide material, and the rectangular wafer with upgraded structural characteristics and the parameters, such as switch current ratio (ION/IOFF) and transconductance (Gm) was analyzed for hybrid RF applications. This work was carried out at 300 K utilizing a Non-Equilibrium Green Function (NEGF) mechanism for the proposed DG MOSFET architecture with La2O3 (EOT=1 nm) as gate dielectric oxide and source-drain device length (LSD) of 45 nm. It resulted in a maximum drain current (IDmax) of 4.52 mA, where the drain-source voltage (VDS) varied between 0 V and 0.5 V at the fixed gate to source voltage (VGS) = 0.5 V. The ON current(ION), leakage current (IOFF), and (ION/IOFF) switching current ratios of 1.56 mA, 8.49Í10-6 μA, and 18.3Í107 μA were obtained when the gate to source voltage (VGS) varied between 0 and 0.5 V at fixed drain-source voltage (VDS)=0.5V. The simulated result showed the values of maximum current density (Jmax), one and twodimensional electron density (N1D and N2D), electron mobility (μn), transconductance (Gm), and Subthreshold Slope (SS) are 52.4 μA/m2, 3.6Í107 cm-1, 11.36Í1012 cm-2, 1417 cm2V-1S-1, 3140 μS/μm, and 178 mV/dec, respectively. The Fermi-Dirac statistics were employed to limit the charge distribution of holes and electrons at a semiconductor-insulator interface. The flat-band voltage (VFB) of - 0.45 V for the fixed threshold voltage greatly impacted the breakdown voltage. The results were obtained by applying carriers to the channels with the (001) axis perpendicular to the gate oxide. The sub-band energy profile and electron density were well implemented and derived using the Non-Equilibrium Green's Function (NEGF) formalism. Further, a few advantages of the proposed heterostructure-based DG MOSFET structure over the other structures were observed. This proposed patent design, with a reduction in the leakage current characteristics, is mainly suitable for advanced Silicon-based solid-state CMOS devices, Microelectronics, Nanotechnologies, and future-generation device applications.

Bismuth Oxyiodide as a Highly Efficient Room Temperature NOx Gas Sensor: Role of Surface Orientations on Sensing Performance

In the pursuit of developing fast and reliable gas sensors, a new ternary oxide semiconductor, a bismuth oxyiodide (BiOI)-based sensing material, has been reported with desirable adsorption energy, short recovery time, and high sensitivity and selectivity for detecting nitrogen oxide mixtures (NOx, typically NO and NO2). The structural, electronic, and transport properties of both (001) and (012) planes of BiOI surfaces upon the adsorption of six environmentally relevant gases (NO, NO2, SO2, SO3, O2, and H2O) are systematically explored using a combination of density functional theory (DFT) and non-equilibrium Green’s function (NEGF) methods. The results indicate that BiOI (001) exhibits weak interaction with these gases, with the highest adsorption energy observed for NO. In contrast, the BiOI (012) surface shows enhanced adsorption stability for these gases, particularly acceptable strong adsorption to NO2, indicating its promising capability for detecting these gases with high specificity. Moreover, it demonstrates the most intense chemisorption for SO3, suggesting it to be a reliable SO3 adsorbent/cleaner. The obtained transport characteristics, including current-voltage (I-V) and resistance-voltage (R-V) curves, further highlight the higher selectivity of the BiOI (001) device towards NO and the BiOI (012) device towards NO2 against the other gases. Furthermore, the transmission spectra analyses reveal that the BiOI-based sensor can electrically discriminate the target gas molecules from other considered gas molecules. Besides, the practical application possibilities of both orientations are explored by estimating their recovery time, and the results show that the BiOI sensor has excellent recovery times at room temperature (NO/BiOI (001) = 0.158 ns, and NO2/BiOI (012) = 3.89 s), highlighting its potential as an ideal reversible gas-sensing material for detecting NOx gases.

The thermal transport properties of Boron-doped C2N nanoribbons

In this paper, we focus on the thermal spin transport properties of hydrogen-saturated graphene-like nanoribbons substituted for doped nonmetallic B by using density functional theory combined with non-equilibrium Green's function approach. We find that AC2NNR-H(B) is a distinctly narrow bandgap semiconductor material and exhibits significant spin Seebeck effect, temperature switching effect, and giant magnetoresistance. Surprisingly, the spin Seebeck coefficients can reach 1.16 mV/K and the magnetoresistance value not only reaches 108% at low temperature, but also 104% near room temperature. These unique transport properties can be explained using spin-dependent transmission spectra combined with energy band structure. The current work further extends the theoretical study of graphene-like derivatives and provides new ideas for the construction of spintronic devices.

A Mechanism of Resistance Switching in CNT Based Memory Devices

Carbon nanotubes (CNTs) show promise for high energy efficiency electronic devices due to their high electrical conductivity. One possible application is in the fabrication of resistance-change computer memory, where the application of an external electrical bias can use a CNT layer as the switching element in a RAM cell. Memory cells of this type have been extensively demonstrated, where the electrical resistance of a switching layer of CNTs can be reversibly controlled by the application of external bias [1].To better understand these devices, we have developed a nanoscale model of their electrical switching. Towards this end, first-principles calculations of the electrical conductivity of CNT-CNT junctions were performed using the Density Functional Tight Binding (DFTB) in combination with the Non-Equilibrium Greens functions (NEGF) approach, enabling an improved understanding of the tunnelling of electrons across a range of CNT junctions [2]. These results demonstrate that the conductivity of CNT contacts depends on the overlap area between nanotubes and exponentially on the distances between the carbon atoms of the interacting CNTs. Secondly, we employed coarse-grained molecular dynamics [3,4] to produce nanoscale dense CNT film models like those used in the devices. We devise a set of metrics for characterising the structural properties of CNT films, and apply them to a set of model films designed to mimic those used in microelectronics devices. In order to understand how the geometrical properties of CNTs affect the film structure, we analyse films with different CNT chirality and length distributions. Unlike previous studies that focused on relatively low-density systems below ∼0.4 g/cm3, we also consider films with density of ∼0.6 g/cm3, as employed in experimentally fabricated CNT-based NRAM devices. By adding amorphous carbon to the film models, in varying amounts, we are then able to assess its effects. Finally, these two elements were combined to produce electrical simulations of the conductivity of the CNT films connected to TiN electrodes. These electrodes are shown to be partially oxidized during the device fabrication. The electrical conductivity in a device is characterized by formation of conduction paths formed by CNTs between the electrodes and connected via the CNT junctions. The conductivity is modulated by charging of CNTs and amorphous carbon present in the film.Using these simulations, we propose a resistance switching mechanism in TiN/CNT/TiN devices based on the physical movement of CNTs. During the initial operation of the device, oxygen is released from the oxidized bottom electrode and this readily reacts with individual CNTs to form charge trapping sites. Once these sites have become charged, they enable controllable movement of CNTs at the bottom electrode under the application of electric field. By reversibly connecting and disconnecting such CNTs from the bottom electrode, the electrical conductivity through the CNT film as a whole can be controlled.

Enhanced thermoelectric properties in hybrid graphane/graphene nanoribbons

The thermoelectric properties of hybrid graphane and graphene nanoribbons (GGNRs) are studied by the Landauer formula within the atomistic non-equilibrium Green's function. It is shown that hybrid GGNRs present the tunable band gap depending upon the width ratio of their components. Modulation of hybrid GGNRs can give rise to the lower thermal conductance of phonons and the better thermoelectric properties compared to pure graphene nanoribbons and graphane nanoribbons. Introducing the hydrogen defects can enhance the maximum of ZT (ZTmax) in both armchair GGNRs (AGGNRs) and zigzag GGNRs (ZGGNRs). Such the enhancement of ZTmax sensitively depends upon the defect concentrations. Among different defect concentrations, ZTmax for the 20 % defect concentration has the highest value, which can be enhanced to 0.42 and 0.24 at T = 300 K in AGGNRs and ZGGNRs, respectively. A laconic analysis of these results is given.

Electron Transport through Linear-, Broken-, and Cross-Conjugated Polycyclic Compounds.

Quantum interference (QI) effects offer unique opportunities to modulate charge transport through single molecules. In recent years, several transmission selection rules have been developed to determine constructive and destructive QIs in an intuitive and simple manner, although some of these rules fail for cross-conjugated systems. In this work, we evaluate the performance of distinct transmission rules on a broad series of anthracene and fluorene derivatives with distinctive structural features including linear-, broken-, and cross-conjugation, heteroatoms, and five-membered rings as such species affords a predictive challenge for the qualitative selection rules for QI effects. The electron transport properties and local transmission plots are first evaluated by combining DFT and the nonequilibrium Green function method allowing for an equal-footing comparison of the conductance of the different polycyclic compounds. Our findings are in line with experimental observations on the influence of the type of conjugation and the connectivity to the metallic electrodes on the transport properties. Thus, cross-conjugated systems exhibit reduced conductance values as compared to the linear-conjugated ones, although the transmission is enhanced in the meta-connected junctions. Remarkably, our study reveals that aromatic cores exhibit generally larger zero-bias conductance for a given connectivity, in contrast to the negative aromaticity-conductance relationship found in literature.

First-Principles Insights into Highly Sensitive and Reusable MoS2 Monolayers for Heavy Metal Detection.

This study explores the potential of MoS2 monolayers as heavy metal sensors for As, Cd, Hg, and Pb using density functional theory (DFT) and Non-Equilibrium Green's Function (NEGF) simulations. Our findings reveal that As and Pb adsorption significantly alters the surface structure and electronic properties of MoS2, introducing impurity levels and reducing the band gap. Conversely, Cd and Hg exhibit weaker interactions with the MoS2 surface. The MoS2 monolayer sensors demonstrate exceptional sensitivity for all four target heavy metals, with values reaching 126,452.28% for As, 1862.67% for Cd, 427.71% for Hg, and 83,438.90% for Pb. Additionally, the sensors demonstrate selectivity for As and Pb through distinct response peaks at specific bias voltages. As and Pb adsorption also induces magnetism in the MoS2 system, potentially enabling magnetic sensing applications. The MoS2 monolayer's moderate adsorption energy facilitates rapid sensor recovery at room temperature for As, Hg, and Cd. Notably, Pb recovery time can be significantly reduced at elevated temperatures, highlighting the reusability of the sensor. These results underscore the potential of MoS2 monolayers as highly sensitive, selective, and regenerable sensors for real-time heavy metal detection.

Spin-filtering properties of topological structures based on stanene and bismuthene nanoribbons with one edge magnetism

The transport properties of spin filters based on two-dimensional magnetic topological insulators (TI) with magnetism at one edge are theoretically studied. The non-equilibrium-Green’s-function (NEGF) formalism based on density functional theory (DFT) derived Hamiltonian is used to study the one-way helical edge states in these structures. We investigated the electronic and magnetic properties of stanene and bismuthene nanoribbons with various metal edge modifications. Our DFT simulations predict the formation of one-way helical edge states in stanene nanoribbons with asymmetric edge passivation. Our results suggest that the spin filtering properties of such structures outperform a comparable spin filter based on spin-polarized quantum-anomalous-Hall effect, as it bypasses a need for a strict interplay of magnetism, topology, and a large electric field (around 2 V gate voltage difference).

Exploring the effects of molecular beam epitaxy growth characteristics on the temperature performance of state-of-the-art terahertz quantum cascade lasers

This study conducts a comparative analysis, using non-equilibrium Green’s functions (NEGF), of two state-of-the-art two-well (TW) Terahertz Quantum Cascade Lasers (THz QCLs) supporting clean 3-level systems. The devices have nearly identical parameters and the NEGF calculations with an abrupt-interface roughness height of 0.12 nm predict a maximum operating temperature (Tmax) of ~ 250 K for both devices. However, experimentally, one device reaches a Tmax of ~ 250 K and the other a Tmax of only ~ 134 K. Both devices were fabricated and measured under identical conditions in the same laboratory, with high quality processes as verified by reference devices. The main difference between the two devices is that they were grown in different MBE reactors. Our NEGF-based analysis considered all parameters related to MBE growth, including the maximum estimated variation in aluminum content, growth rate, doping density, background doping, and abrupt-interface roughness height. From our NEGF calculations it is evident that the sole parameter to which a drastic drop in Tmax could be attributed is the abrupt-interface roughness height. We can also learn from the simulations that both devices exhibit high-quality interfaces, with one having an abrupt-interface roughness height of approximately an atomic layer and the other approximately a monolayer. However, these small differences in interface sharpness are the cause of the large performance discrepancy. This underscores the sensitivity of device performance to interface roughness and emphasizes its strategic role in achieving higher operating temperatures for THz QCLs. We suggest Atom Probe Tomography (APT) as a path to analyze and measure the (graded)-interfaces roughness (IFR) parameters for THz QCLs, and subsequently as a design tool for higher performance THz QCLs, as was done for mid-IR QCLs. Our study not only addresses challenges faced by other groups in reproducing the record Tmax of ~ 250 K and ~ 261 K but also proposes a systematic pathway for further improving the temperature performance of THz QCLs beyond the state-of-the-art.

Density Functional Theory Provides Insights into β-SnSe Monolayers as a Highly Sensitive and Recoverable Ozone Sensing Material.

This study explores the potential of β-SnSe monolayers as a promising material for ozone (O3) sensing using density functional theory (DFT) combined with the non-equilibrium Green's function (NEGF) method. The adsorption characteristics of O3 molecules on the β-SnSe monolayer surface were thoroughly investigated, including adsorption energy, band structure, density of states (DOSs), differential charge density, and Bader charge analysis. Post-adsorption, hybridization energy levels were introduced into the system, leading to a reduced band gap and increased electrical conductivity. A robust charge exchange between O3 and the β-SnSe monolayer was observed, indicative of chemisorption. Recovery time calculations also revealed that the β-SnSe monolayer could be reused after O3 adsorption. The sensitivity of the β-SnSe monolayer to O3 was quantitatively evaluated through current-voltage characteristic simulations, revealing an extraordinary sensitivity of 1817.57% at a bias voltage of 1.2 V. This sensitivity surpasses that of other two-dimensional materials such as graphene oxide. This comprehensive investigation demonstrates the exceptional potential of β-SnSe monolayers as a highly sensitive, recoverable, and environmentally friendly O3 sensing material.

Design and characterization of colloidal quantum dot photoconductors for multi-color mid-infrared detection

This report paves the way for low cost, multi-color, room-temperature, and easily-feasible mid-IR photodetector with distinct output currents. The proposed device is designed and simulated to be fabricated by the solution-process technology thanks to its simplicity and fabrication ease, room-temperature operation capability, low production cost, and excellent photoelectric properties. In this approach, the proposed structure is composed of an array of n × n pixels, where each pixel is designed to enable multi-wavelength detection. The absorber layer consists of different sized quantum dots that absorb distinct wavelengths simultaneously through interband transitions in the mid-infrared region. Selective energy contacts based on quantum well structures are designed to be deposited on interdigitated contacts as a means of extracting the stimulated carriers from the absorber layers to the metal contacts. Through resonant tunneling, the excited carriers are transferred, which generates the output photocurrent and significantly reduces the dark current. In order to model the designed multi-color photoconductor, coupled rate equations and three-dimensional Schrodinger-Poisson equations have been developed and solved self-consistently. As a way of demonstrating the validity of the introduced model, a experimentally fabricated photoconductor and a theoretically modeled photodetector using the nonequilibrium Green’s function (NEGF) model have been simulated; the comparison between the simulation results is quite satisfactory. In order to simplify the theoretical model, two different sizes of InSb/ZnSe core/shell quantum dots have been considered in the theoretical model to detect two MIR wavelengths (3 µm and 4 µm) of the incident light. Simulation results indicate that the peak responsivities are about 3.3(A/W) and 6(A/W), and the high specific detectivities D* are about 9 × 1010(cm.Hz1/2W−1) and 15 × 1010(cm.Hz1/2W−1) for the wavelengths of 4 µm and 3 µm, respectively.

High tunneling magneto-resistance ratio in Co2FeAl Heusler alloy and WSe2 2D material tunnel barrier-based magnetic tunnel junctions

This paper presents a Magnetic Tunnel Junction (MTJ) based on Co2FeAl Heusler alloy and 2D material WSe2 with an enhanced tunnelling magneto-resistance (TMR). Our study is inspired by recent investigations of 2D materials and Heusler alloys. By employing static Density Functional Theory (DFT) simulations coupled with Non-Equilibrium Green’s Function (NEGF) transport models, we evaluate conductance properties in Co2FeAl/WSe2/Co2FeAl MTJ. The half metallicity of Co2FeAl and quantum confinement properties of WSe2 are compatible, which enhances the TMR of MTJ.

Nonequilibrium Green's function approach to low-energy fission dynamics: Fluctuations in fission reactions

Nonequilibrium Green's function approach to low-energy fission dynamics: Fluctuations in fission reactions

Half-Metallic Transport and Spin-Polarized Tunneling through the van der Waals Ferromagnet Fe4GeTe2.

We examine the coherent spin-dependent transport properties of the van der Waals (vdW) ferromagnet Fe4GeTe2 using density functional theory combined with the nonequilibrium Green's function method. Our findings reveal that the conductance perpendicular to the layers is half-metallic, meaning that it is almost entirely spin-polarized. This property persists from the bulk to a single layer, even under significant bias voltages and with spin-orbit coupling. Additionally, using dynamical mean field theory for quantum transport, we demonstrate that electron correlations are important for magnetic properties but minimally impact the conductance, preserving almost perfect spin-polarization. Motivated by these results, we then study the tunnel magnetoresistance (TMR) in a magnetic tunnel junction consisting of two Fe4GeTe2 layers with the vdW gap acting as an insulating barrier. We predict a TMR ratio of ∼500%, which can be further enhanced by increasing the number of Fe4GeTe2 layers in the junction.

Enabling Ab Initio Molecular Dynamics under Bias: The CP2K+SMEAGOL Interface for Integrating Density Functional Theory and Non-Equilibrium Green Functions.

Density functional theory (DFT) combined with non-equilibrium Green's functions (NEGF) is a powerful approach to model quantum transport under external bias potentials at reasonable computational cost. In this work, we present a new interface between the popular mixed Gaussian/plane waves electronic structure package, CP2K, and the NEGF, code SMEAGOL, the most feature-rich implementation of DFT-NEGF available for CP2K to date. The CP2K+SMEAGOL interface includes the implementation of current induced forces. We verify this implementation for a variety of systems: an infinite 1D Au wire, a parallel-plate capacitor, and a Au-H2-Au junction. We find good agreement with SMEAGOL calculations performed with SIESTA for the same systems and with the example of a solvated Au wire demonstrating for the first time that DFT-NEGF can be used to perform molecular dynamics simulations under bias of large-scale condensed phase systems under realistic operating conditions.

Observing the Role of Electron Delocalization in Electronic Transport by Incorporating Actinides into Ligated Metal-Chalcogenide Superatoms.

Since delocalization of electronic states is a prerequisite for exerting unique electron transport properties, early actinides (An) with highly delocalized 5f/6d orbitals are natural candidates. However, given the experimental difficulties of such radioactive compounds and the complex relativistic effects in theoretical studies, understanding the electronic structure and bonding of actinides is underdeveloped on the periodic table. A further challenge is the very complicated electronic structures encountered in the confinement of actinides, as vividly illustrated by the weakly radioactive Th(Thorium)-encapsulated metal chalcogenide clusters, Th@Co6Te8L6 (L = PH3, PMe3, PEt3). Here we report the electronic structure and the electron transport properties of the Th@Co6Te8L6 clusters and compare them with those of the hollow Co6Te8L6 clusters using the nonequilibrium Green's function combined with relativistic density functional theory (NEGF-DFT). We found that the equilibrium conductance in Th@Co6Te8(PH3)6 (0.76 G0) has been greatly improved over that in Co6Te8(PH3)6 (0.03 G0), which has also been verified under an applied different bias voltage. The covalent bonding character between 6d (Th) and 3d (Co) atomic orbitals resulting from steric confinement is the source of the performance enhancement and a most important factor governing the accessibility of such 5f/6d orbitals. The results are of significance to the rapidly developing field of molecular nanoelectronics.

Thermoelectric Phenomena in a Magnetic Heterostructure with AAH Modulation: Charge and Spin Figure of Merits

ABSTRACT We put forward a prescription of getting a higher value of the spin-dependent figure of merit in comparison with its charge counterpart in the case of a 1D magnetic heterostructure (a ferromagnetic (FM) chain sandwiched between two non-magnetic 1D lattices) where all the site energies of the heterostructure follow cosine form of modulation defined in Aubry-Andre-Harper (AAH) model. It is shown that due to having a greater number of non-uniform peaks in its transmission spectra, the thermoelectric efficiency of this heterostructure becomes superior compared to that is obtained in a fully ferromagnetic 1D chain. It is also reported that the maximum value of the thermoelectric figure of merit (for both spin and charge-dependent cases) of the heterostructure in a specified energy range gets enhanced in a continuous manner as the disorder strength of the AAH modulation is increased. The Hamiltonian of the proposed quantum system is described within a tight-binding (TB) framework and after the evaluation of transmission probability by utilizing the non-equilibrium Green’s function (NEGF) technique, all the important thermoelectric quantities are determined on the basis of Landauer formalism. We believe that our study on this particular topic of spin caloritronics, a subject associated with temperature-dependent spin transmission through a quantum channel, may help to explore several fascinating ideas about spin-related thermoelectric efficiency in many other ferromagnetic quasicrystals.

Thermoelectric Properties Regulated by Quantum Size Effects in Quasi-One-Dimensional γ-Graphdiyne Nanoribbons.

Using density functional theory combined with the first principles calculation method of non-equilibrium Green's function (NEGF-DFT), we studied the thermoelectric (TE) characteristics of one-dimensional γ-graphdiyne nanoribbons (γ-GDYNRs). The study found that the thermal conductivity of γ-GDYNRs has obvious anisotropy. At the same temperature and geometrical size, the lattice thermal conductivity of zigzag-edged γ-graphdiyne nanoribbons (γ-ZGDYNRs) is much lower than that of armchair-edged γ-graphdiyne nanoribbons (γ-AGDYNRs). We disclose the underlying mechanism for this intrinsic orientation. That is, γ-AGDYNRs have more phonon dispersion over the entire frequency range. Furthermore, the orientation dependence increases when the width of the γ-GDYNRs decreases. These excellent TE properties allow armchair-edged γ-graphdiyne nanoribbons with a planar width of 1.639 nm (γ-Z(2)GDYNRs) to have a higher power factor and lower thermal conductivity, ultimately resulting in a significantly higher TE conversion rate than other γ-GDYNR structures.

Electroluminescence Rectification and High Harmonic Generation in Molecular Junctions.

The field of molecular electronics has emerged from efforts to understand electron propagation through single molecules and to use them in electronic circuits. Serving as a testbed for advanced theoretical methods, it reveals a significant discrepancy between the operational time scales of experiments (static to GHz frequencies) and theoretical models (femtoseconds). Utilizing a recently developed time-linear nonequilibrium Green function formalism, we model molecular junctions on experimentally accessible time scales. Our study focuses on the quantum pump effect in a benzenedithiol molecule connected to two copper electrodes and coupled with cavity photons. By calculating both electric and photonic current responses to an ac bias voltage, we observe pronounced electroluminescence and high harmonic generation in this setup. The mechanism of the latter effect is more analogous to that from solids than from isolated molecules, with even harmonics being suppressed or enhanced depending on the symmetry of the driving field.

FeN4-Embedded Graphene as a Highly Sensitive and Selective Single-Atom Sensor for Reaction Intermediates of Electrochemical CO2 Reduction.

Exploring effective ways to detect intermediates during the electrochemical CO2 reduction reaction (CO2RR) process is pivotal for understanding reaction pathways and underlying mechanisms. Recently, two-dimensional FeN4-embedded graphene has received increasing attention as a promising catalyst for CO2RR. Here, by means of density functional theory computations combined with the non-equilibrium Green's function (NEGF) method, we proposed a detection device to evaluate the performance of FeN4-embedded graphene in intermediates detection during the CO2RR process. Our results reveal that the four key intermediates, including *COOH, *OCHO, *CHO, and *COH, can be chemisorbed on FeN4-embedded graphene with high adsorption energies and appropriate charge transfer. The computed current-voltage (I-V) characteristics and transmission spectra suggest that the adsorption of these intermediates induces significant type-dependent changes in currents and transmission coefficients of FeN4-embedded graphene. Remarkably, the FeN4-embedded graphene is more sensitive to *COOH and *COH than to *OCHO and *CHO within the entire bias window. Consequently, our theoretical study indicates that the FeN4-embedded graphene can effectively detect the key intermediates during the CO2RR process, providing a practical scheme for identifying catalytic reaction pathways and elucidating underlying reaction mechanisms.