Stone-Wales Research Articles

Tuning the Nonradiative Electron-Hole Recombination with Defects in Monolayer Black Phosphorus.

We use nonadiabatic (NA) molecular dynamics to demonstrate that the nonradiative electron-hole recombination is delayed and accelerated by the Stone-Wales (SWs) and phosphorus divacancy (DV-(5|7)) defects in monolayer black phosphorus (BP). Both types of defects increase the bandgap by 0.1 eV without creating midgap states. Driven by P-P stretching vibrations, the recombination proceeds within 1 ns in the SW and within 100 ps in the DV-(5|7), respectively, which occurs within 332 ps in BP. The SW defect slows down recombination because the notably reduced NA coupling combined with a large bandgap competes to the long-lived coherence. In contrast, the DV defect accelerates recombination since long-lived coherence is superior to the slightly decreased NA coupling correlated with a tiny increased bandgap. The diverse time scales rationalize the broad range of charge carrier lifetimes reported experimentally. The study provides a strategy to engineer excited-state dynamics for improving the BP-based optoelectronics.

Molecular interaction with defected h-BN

Density functional theory simulations studied molecular (Phenol, pyridine, oxygen, and carbon monoxide) interactions with defected h-BN (boron nitride) monolayer structures. The simulation comprised of a supercell modelling the monolayers which contained mono-vacancies (boron or nitrogen) and Stone-Wales defect. Predictions from this analysis indicate that h-BN with vacancies are more reactive to CO and phenol when compared with the Stone-Wales defected configurations. Reacted products entail semiconductor characteristics with a band gap residing in the range 2.6 to 3.96 eV. Outcomes herein reveal a relatively strong interaction of phenol and pyridine, in comparison with smaller diatomic O2 and CO, with defect BN surfaces. A wide array of properties was computed to elucidate an insight into the observed interactive behaviour, including Bader charge’s; local atomic spin polarisation magnetic moments in the vacancy region, and energy band gap of the reaction outcome. These results should be useful in applications that target deployment of BN-based materials in optoelectronic devices, physical–chemical sensors.

Combined effect of Stone–Wales defects and titanium doping on electronic properties of a silicon carbide monolayer: DFT

Combined effect of Stone–Wales defects and titanium doping on electronic properties of a silicon carbide monolayer: DFT

Mechanical properties of pristine and nanocrystalline graphene up to ultra-high temperatures

Despite being the basic building block of most carbon materials used in high and ultra-high temperature applications, the mechanical properties of graphene at such temperatures remain totally unknown. Here we compute these properties using tensile molecular dynamics simulations at temperatures ranging from room temperature to 5000 K (i. e. about the melting temperature) for pristine and nanocrystalline graphene. Mechanical simulations at such temperatures are made possible via the use of the screened environment dependent reactive empirical bond order potential [Perriot et al. Phys. Rev. B 88, 064101 (2013)]. We show that even at the highest temperature, both graphene and nanocrystalline graphene retain high stiffness, strength and fracture strain. Analyses of tensile curves and trajectories (including an analysis of in-plane non-affine atomic displacements) show that both pristine and nanocrystalline graphene show brittle rupture, whatever the temperature, even though some early sign of ductility can be detected for the nanocrystalline graphene at 5000 K. This rules out the possibility of a ductile fracture in graphene at any temperature below the melting point. Finally, the simulations also highlight the importance of bond rotation (Stone-Wales) based defects in the fracture initiation mechanism for pristine graphene. Especially at intermediate temperature (3000 K) crack nucleation in pristine graphene is shown to take place exactly at the moment and place of the first Stone-Wales defect formation.

Interactions of amine functional group with Stone-Wales defects on single-walled carbon nanotubes: A theoretical study

Spin-polarized density functional theory has been used to investigate the functionalization of single-walled carbon nanotubes (SWNT) with and without a Stone-Wales (SW) defect by amine (NH2) functional group. The reactivity of SW defects is compared to that of the pristine sidewalls of (5,0), (8,0), and (13,0) SWNT. Our calculations demonstrate that the adsorption of NH2 on SW defect sites is more energetically favorable than that on pristine SWNT sidewalls. All SW defect sites, and particularly the site S1, were considered low-energy adsorption sites for the functionalization process. Furthermore, the binding between the amine group and SW-SWNT is improved for tubes with smaller diameters. The adsorption of NH2 groups on defect sites has a significant influence on the electronic properties of SWNT, changing the electronic states around the Fermi level and converting nonmagnetic semiconductor SWNT to magnetic nanotubes, which is beneficial for the electrical conductivity.

Thermal stability and melting mechanism of diamond nanothreads: Insight from molecular dynamics simulation

In recent years, diamond nanothreads (DNTs) have attracted a wide attention of many experimental and theoretical studies. DNTs are composed of carbon polygons such as 5-, 6-, 7-, and 8-membered carbon rings. In this study, via molecular dynamics simulation we have studied the thermal stability and melting process of 15 lowest-energy DNTs into three classes; achiral, stiff-chiral, and soft-chiral, respectively. The achiral, stiff-chiral, and soft-chiral classes consist of 6, 4, and 5 molecular models, respectively. The results showed that DNTs have different melting points due to the various morphologies and different arrangements of carbon rings. Also, results showed that DNTs composed of purely 6-membered carbon rings have high thermal stability and melting point, wheras DNTs with dissimilar and distorted carbon polygons have lower melting point. In addition, the results showed that DNTs with Stone-Wales defects (SW) have lower thermal stability and melting point. Moreover, the results showed that the achiral, stiff-chiral, and soft-chiral DNTs have the same melting mechanism. During melting process, the increasing sp3 C-C bonds length and their dissociation occurs as the themperature increases. The broken bonds resulting in the formation of larger sp2-carbon rings. The higher temperatures lead to the dissociation of formed large rings and the formation of polyethylene-like molecular chains. Finally, at the melting point or after the melting point, these chains dissociate and the DNTs break down. In this study, the melting point of nanoparticles supported on 15 DNT substrates was also investigated via molecular dynamics simulation. The results showed that all DNTs increase the thermal stability and melting point of the nanoparticles. The role of DNTs in increasing the melting point obey the following trend: soft-chiarl > achiral > stiff-chiral. Soft-chiarl-DNTs with their helical morphologies show lowest deformation in the nanoparticle structure during the melting process.

Graphene multilayers nanoribbons with chirality from molecular dynamics

In this study, we performed reverse nonequilibrium molecular dynamics simulations (RNEMD) to deeply explore the structural and thermal properties of nanometer sized N-layered graphene nanoribbons (GNRs) with N = 2, 3, 4 and 5. The effect of stacking-types, edge chirality, system’s width, number of layers, temperature, Stone–Wales defects and dislocations are all investigated. The correlation between the interlayer distances and the cohesive energies of N-layer GNRs shows the smallest cohesive energy values for the systems exhibiting the largest interlayer distance. The stacking-type of the layers, namely the AA- and the AB-stacking, influences the thermal conductivity (κ) in a pair-impair dependence of the number of layers which is in good accordance with the change in interlayer distance. Moreover, the κ of AA-stacked GNRs, which are more symmetrical in their lattice structure, is higher than AB-GNRs where the phonon coupling becomes weaker due to the significant phonon mismatch between layers. This anisotropic behavior of κ also depends on the armchair and zigzag edge shape of the multilayer GNRs. System size results reveal that thermal conductivities follow an increasing trend with length and a decreasing behavior with width as well as temperature. Overall, this work would offer a deep understanding of the stability as well as thermal conductivity of multilayer graphene nanoribbons and widen the scope of their potential applications in future GNRs-based nanoelectronic and thermoelectric devices.

Topological defects embedded large-sized single-walled carbon nanotubes for hydrogen storage: A molecular dynamics study

In this paper, we investigate the performance of large-sized single-walled carbon nanotubes (SWCNTs) incorporated with mono vacancy (MV), double vacancy (DV), and Stone-Wales (SW) topological defects as a medium for hydrogen adsorption using molecular dynamics (MD) simulations. A novel potential energy distribution (PED) method is employed with MD simulations to determine the adsorbed hydrogen molecules and associated binding energy. In addition, we extended our work to bundles of defected SWCNT (D-SWCNT) that provided the most prominent adsorption capacity subjected to temperature and pressure variations. In particular, four representative (8,8), (13,13), (19,19), and (33,0) SWCNTs are simulated under various thermodynamic conditions, and collected adsorption isotherms data reveals higher gravimetric density for large-sized SWCNT. At 77 K and 100 bar, the maximum hydrogen uptake in pristine SWCNTs is 6.88–7.73 wt%, depending on the size of the nanotubes. In contrast, the binding energy decreases as the nanotube size increases. At 77 K, (8,8) and (19,19) SWCNTs have average binding energies of 0.043 and 0.021 eV, respectively. Meanwhile, (19,19) SWCNT incorporated with 1% DV defects having 5–8 rings (DV1) and MV defects yields the maximum storage capacity of 9.07 wt% and 8.62 wt%, respectively, at 77 K. Furthermore, the increment of about 43.29% in wt.% is obtained for DV1 defected nanotube relative to pristine SWCNT at 300 K and 100 bar. Moreover, our results indicate the maximum hydrogen uptake of 8.65, 7.15, 2.57, and 1.33 wt% in the square array of DV1 defect embedded SWCNTs at 77, 100, 200, and 300 K, respectively, compared to 9.07, 6.65, 2.24, and 1.11 wt% in the isolated D-SWCNT at identical conditions. As a result, the D-SWCNT bundles are better suited for hydrogen storage at high temperatures than the isolated D-SWCNT. Our present study paves the way to progress toward the efficient usage of D-SWCNTs with few chemical alterations for scaled-up applications.

Tuning the carrier mobility and electronic structure of graphene nanoribbons using Stone–Wales defects

In the last decade, surface-assisted reactions involving well-defined molecular precursors have led to the controlled assembly of several clean-edged and defect-free graphene nanoribbons. The recent realization of a bisanthene-like quantum dot with pairs of pentagon–heptagon, or Stone–Wales (SW), defects has been successfully achieved. Based on the similarity between the pristine and SW-defective bisanthene blocks, we propose a set of systems based on the concatenation of SW-bisanthene motifs and study their electronic properties using density functional theory. We demonstrate that nanoribbons with SW-defects preserve the semiconducting character of their pristine counterparts. Furthermore, noteworthy behaviors involving the frontier levels emerge, which affect carrier mobilities of both electrons and holes. We also investigate the electronic transport properties of nanojunctions composed by graphene nanoribbons with a localized distribution of SW-defects compatible with the geometry of the corresponding bisanthene-like blocks. Our simulations shown that the transmission spectrum is sensitive to the position and concentration of SW-defects.

Effect of topological non-hexagonal rings and Stone Wale defects on the vibrational response of single and multi-layer ion irradiated graphene

Present study explores the observation of topological non-hexagonal rings (NHR) and Stone Wale (SW) defects by Raman experiments in both single (SLG) and multi-layer graphene (MLG) after they are irradiated with 100–300 eV Ar ions. Although predicted by theoretical studies, here it is experimentally shown that graphene SW/NHR defects have a signature in Raman. Broad bandwidth of the pertinent Raman features suggests the presence of more than one SW/NHR defect mode, in agreement with the DFT studies. Variations in the SW/NHR related Raman mode intensities demonstrate the annihilation of these topological defects at higher energies. Behavior of Raman allowed G and 2D excitations, as well as the disorder-activated D, D’ and G* lines, has also been investigated in SLG and MLG. These indicate an evolution of defects in graphene with ion irradiation, as well as presence of a transition state beyond which the Raman modes are dominated by a rise in sp3 content. Correlation of these aspects with the SW/NHR Raman provide significant insight into ion induced evolution of graphene. The direct observation of SW/NHR defects by Raman spectroscopy could be important in promoting exploration of rich topological aspects of Graphene in various fields.

Topological Stone-Wales Defects Enhance Bonding and Electronic Coupling at the Graphene/Metal Interface.

Defects play a critical role for the functionality and performance of materials, but the understanding of the related effects is often lacking, because the typically low concentrations of defects make them difficult to study. A prominent case is the topological defects in two-dimensional materials such as graphene. The performance of graphene-based (opto-)electronic devices depends critically on the properties of the graphene/metal interfaces at the contacting electrodes. The question of how these interface properties depend on the ubiquitous topological defects in graphene is of high practical relevance, but could not be answered so far. Here, we focus on the prototypical Stone-Wales (S-W) topological defect and combine theoretical analysis with experimental investigations of molecular model systems. We show that the embedded defects undergo enhanced bonding and electron transfer with a copper surface, compared to regular graphene. These findings are experimentally corroborated using molecular models, where azupyrene mimics the S-W defect, while its isomer pyrene represents the ideal graphene structure. Experimental interaction energies, electronic-structure analysis, and adsorption distance differences confirm the defect-controlled bonding quantitatively. Our study reveals the important role of defects for the electronic coupling at graphene/metal interfaces and suggests that topological defect engineering can be used for performance control.

First-principles study of CH4 adsorption on transition metal doped phosphorene with Stone-Wales defects

Based on density functional theory, the geometric, electrical, and magnetic properties of CH4 adsorption are determined on pristine, Stone-Wales (SW) defected, and transition metal (TM; Mn, Fe, Co, Ni) -doped phosphorene. The results show that doping with transition metals can enrich the magnetic behavior of P, and allow the SW-defected phosphorene (SWP) to exhibit a direct band gap. The adsorption mechanism of CH4 molecule on pristine and SWP is physisorption, which exhibits small adsorption energies and large interaction distances. After doping with TM, the CH4 adsorption mechanism transforms to chemisorption. Interestingly, the CH4 system adsorbed on the Ni-doped SWP exhibits half-metal properties. The recovery time of doping systems is very short due to the small adsorption energy. Compared with the SW-defected phosphorene, the band gap values of Mn, Fe, and Co doped systems decrease after adsorption, which can be used as a signal to detect CH4 gas. Furthermore, due to its highest adsorption energy and charge transfer, Co-doped SWP is more appropriate to be used as a multi-time reusable gas sensor material to detect CH4 gas.

Unraveling the Key Atomic Interactions in Determining the Varying Li/Na/K Storage Mechanism of Hard Carbon Anodes

AbstractHard carbons have been identified as competitive anodes for Li/Na/K‐ion batteries but their Li/Na/K‐ion storage mechanisms significantly vary in different batteries. It is fundamental to understand the basic science behind the difference. Herein, it is theoretically revealed that defects on the carbon layers generally have an influential impact on the atomic interactions including the metal–metal (M–M) and metal–carbon (M–C) interactions, thereby determining whether the stored alkali‐metal atoms are in ionic or quasi‐metallic states. Upon increasing the number of metal atoms on a carbon layer composed of only hexatomic rings, K tends to be stored in an ionic state similar to Li due to the dominant M–C interaction, while on a carbon layer with defects, K tends to be stored in a quasi‐metallic state similar to Na due to the dominant M–M interaction. For experimental verification, a glassy carbon, the extreme form of hard carbon with dominant sp2 hybridization and only Stone–Wales defects, is selected as a model anode, and its Li/Na/K‐ion storage mechanisms are exactly consistent with the theoretical prediction. More profoundly, for the first time, the quasi‐metallic K cluster information is captured by ex situ electron paramagnetic resonance.

Diameter-Change-Induced Transition in Buckling Modes of Defective Zigzag Carbon Nanotubes.

In general, the insertion of Stone-Wales (SW) defects into single-walled carbon nanotubes (SWNTs) reduces the buckling resistance of SWNTs under axial compression. The magnitude of reduction is more noticeable in zigzag-type SWNTs than armchair- or chiral-type SWNTs; however, the relation between the magnitude of reduction and aspect ratio of the zigzag SWNTs remains unclear. This study conducted molecular dynamics (MD) simulation to unveil the buckling performance of zigzag SWNTs exhibiting SW defects with various tube diameter. The dependencies of energetically favorable buckling modes and the SW-defect induced reduction in the critical buckling point on the tube diameter were investigated in a systematic manner. In particular, an approximate expression for the critical buckling force as a function of the tube diameter was formulated based on the MD simulation data.

Displacement field splitting of defective hexagonal lattices

In this paper, we propose a methodology that allows disentangling the interaction of two Stone-Wales defects in a two-dimensional model material, which has the crystalline structure of a honeycomb lattice. The nonaffinity of the material response is represented as a linear superposition of nonaffine displacements caused by every individual defect and a residual nonaffine displacement field. The latter is then identified as the interaction field linked to a weakening or---as also shown---strengthening effect. We perform various numerical deformation tests in the athermal quasistatic limit on selected configurations. In doing so, we introduce a field variable to validate the contribution of the defect interaction field that indicates the mode of material failure, which also explains why some configurations with two Stone-Wales defects have a higher tensile strength than other configurations with only one defect.

Computational Study of Thermodynamic Overpotentials of Quinone Reduction on Carbon Electrodes to Accelerate Organic Redox Flow Battery Research

Redox flow batteries (RFBs) offer advantages as compared to conventional batteries, such as the possibility of decoupling the energy density (volume and concentration of the electrolyte) and the power density (surface contact between electrode and electrolyte) of the battery. Organic redox flow batteries (ORFBs) have gained attention recently because they promise to be more eco-friendly and cheaper than their inorganic counterparts. Particularly, organic molecules are highly tunable in terms of both solubility and redox potential. Many families of organic molecules have been reported for this purpose, with quinones being particularly promising [Symons, 2021]. However, ORFBs are limited in terms of their cell potential and stability. To discover optimal molecules for ORFBs, many research groups have employed molecular modelling methods [Er et al., 2015]. These studies using density functional theory (DFT) in implicit solvents only compute the Nernst potential [Zhang et al., 2020] of the one-step coupled e- and H+ redox reaction (see Figure 1(a)), ignoring the overpotential of the reaction.Our study addresses two aspects going beyond this state of the art: 1) considering the intermediate, semiquinone, of the reaction (see Figure 1(b)) and thus the thermodynamic overpotential; and 2) incorporating the effects of the electrode/electrolyte interface, where the actual electrochemical processes take place (see Figure 1(c)). Since the exact atomic structure of the carbon felt is unknown, we use different model carbon morphologies to calculate the thermodynamic overpotential of the given reaction.Grand-canonical DFT in combination with the linearized Poisson–Boltzmann implicit solvent model [Abidi et al., 2020] was used to calculate the overpotential (versus SHE) of the two-step reduction reaction of non-substituted p-benzoquinone (BQ) on 6 different models for carbon surfaces - graphite basal plane (0001), and edges (1100), (1000), zigzag nanotube, armchair nanotube and Buckyball. The overpotential on these surfaces was found to be between 0.2-0.5 V. The solution-phase overpotential due to the intermediate was 0.3 V for non substituted quinone, and 0.5 V for both the substituted quinones that we studied (R=CN and R=OMe). At the graphite basal plane, while for the non-substituted quinone, the overpotential negligibly increased, for the substituted ones, the overpotential reduced by ~0.2 V each (see Figure 1(d)). This showed an interesting relationship between the substituents of the quinone and the electrode surface.Extending our study further, we explored the effect of defects in the graphite basal plane: substitutional B or N doping, and the Stone-Wales (SW) defect. We found that the overpotential of the BQ reduction reaction did not change for the SW defect, and it increased by 0.1 V if a C-atom was substituted by a B-atom and decreased by 0.1 V, for N-atom substitution. The N-doped surface had the least overpotential (0.25 V), which suggests that doping the electrode with nitrogen would make better electrodes. From these results, we concluded that the atomic-level morphology of the surface does not affect the overpotential of the reaction as much as the dopants in the surface do.In summary, our results demonstrate that grand-canonical DFT leads to detailed insights on the chemistry of ORFB at the electrode. From an electrochemical viewpoint, we show that estimating the overpotential of ORFB requires the consideration of the intermediate in the reduction reaction, and that substituting the quinones with CN or OMe decreases the overpotential on the electrode surface. Finally, the effect of the atomic-level morphology of the electrode does not significantly affect the overpotential, while substitutional N-doping lowers the overpotential.

Bilayer armchair graphene nanoribbon photodetector with Stone-Wales defect: A computational study

Bilayer armchair graphene nanoribbons (BAGNRs), due to their low sensitivity to low frequency noise and high controllability of their bandgap have drawn a lot of attention as building blocks of photodetectors in recent years. In this work, using tight binding (TB) method and non-equilibrium Green's function formalism (NEGF) a computational study has been done on the BAGNR photodetector with perfect and Stone-Wales (SW) defected channel and the effect of defects' number and position on the device performance has been investigated. In order to validate the TB parameters used in this work, the bandstructures of both perfect and SW defected BAGNRs are compared with the results of DFT method and a good matching is obtained. Simulation results show that perfect BAGNR photodetector has quantum efficiency (QE) of 19.77% at 0.12 eV photon energy. Among defected photodetectors, highest QE of 21.77% belongs to the structure with single SW defect near the right contact (higher bias voltage) at 0.14 eV. This structure also possesses the highest Iph/Idark of 64.45 which is 1.8 times larger than Iph/Idark of perfect BAGNR photodetector. Moreover, the structure with two SW defects located at left and right sides of the channel exhibits a drastically low Idark which results in a high Iph/Idark. In addition, this structure yields the high QE (19.72%) at blue-shifted photon energy of 0.2 eV which makes it a suitable choice for mid-wavelength infrared applications.

Construction and properties analysis of Z-A-Z graphene nanoribbons transistors

Based on the first-principles theory combining density-functional theory and non-equilibrium Green’s function, A zigzag-armchair-zigzag (Z-A-Z) graphene nanoribbon transistor model was constructed using the quantumATK tool, and Stone-Wales (SW) defects were introduced. The transmission spectrum, electrical conductivity, gate potential and current-voltage (I-V) characteristics of Z-A-Z graphene nanoribbons were analyzed. By constructing Z-A-Z graphene nanoribbons with SW defects, the effect of defects on their transport properties was explored. The research results can provide a reference for the research on the characteristics of Z-A-Z graphene nanoribbons.

Density functional theory study on Ti/h-BN interface in resistance random access memory device

By applying density functional theory calculations, we analyzed the intrinsic propensity of the Ti/h-BN interface in a resistive random access memory (RRAM) device upon the existence of a Stone–Wales (SW) defect and boron vacancy (VB). Following the construction of the Ti(001) surface and h-BN(SW) stack, Ti/h-BN interface models with different configurations and terminated sites were proposed, among which h-BN(SW)I/Ti(001)_TN was identified as the most stable interface system according to the binding energy. The charge transfer from Ti(001) toward the h-BN layers, resulting in heavy doping, formed an Ohmic contact in the interface. Moreover, through analysis of structure optimization, an intrinsic tendency of Ti ion migration to pass through the interface was revealed in the presence of SW defects and VB in the h-BN interface layer. The result of the migration barrier suggested that SW defects, especially B–B bond heptagons, provide preferential pathways for the vertical penetration of Ti ions through the interface, whereas VB in defects contribute most to the facilitation of Ti ion migration. Finally, I–V curves of RRAM device models with different interface configurations showed that SW defects and VB in the interface are critical to resistive switching behavior and can improve performance parameters, such as set voltage and current on/off ratios.

Ab Initio Investigation of Covalently Immobilized Cobalt-Centered Metal–Organic Catalysts for CO2 Reduction: The Effect of the Substrate on the Reaction Energetics

Recently, experimental studies of covalently immobilized CO2 reduction organometallic catalysts have reported remarkable activity; however, the reason for this and the underlying mechanisms are not currently understood. To advance our understanding of such systems, we perform ab initio calculations investigating how covalent immobilization of such molecular catalysts and the substrate geometry affect the reaction pathways. We address this as realistically as possible by doing a survey of possible structures including common surface defects and nanotubes, as well as linkers. In particular, we study covalently immobilized cobalt-centered phthalocyanine (CoPc) and tetraphenylporphyrin (CoTPP), as used in CO2 electroreduction reactions (CO2ERR), immobilized on pristine and defective graphene and single-walled carbon nanotubes (SWCNTs), with and without linkers. The bonding energies of the CoPc and CoTPP catalysts to the different substrates are found to be consistently stronger on the SWCNTs and on defect sites, suggesting that such structures will be the anchoring sites for these immobilized molecular catalysts. Covalently immobilized CoPc and CoTPP catalysts show improved CO2ERR pathway performance compared to their homogeneous analogues. Favorable reaction pathways are found for upright bonded CoPc and CoTPP on a Stone–Wales defect and an octagon–pentagon line defect, respectively, in graphene. CoPc immobilized via a pyridine linker is found to have the most favorable reaction pathway due to strong exothermic behavior of CO2 adsorption and COOH formation while having a weak endothermic final step for CO desorption, consistent with its excellent experimental performance. We attribute this to unoccupied dz2 states just above the Fermi level. On comparing the calculated free energy reaction pathways with corresponding available experimental results of catalyst performance, we find consistent agreement. The present study provides a new detailed understanding into the covalent immobilization and function of these organometallic catalysts and the role that the charge, defects, and structure have on the free energy reaction pathways for CO2ERR.