Optimizing a high-quality leveler has become the core task in developing the microvia copper filling technology. In this work, two nitrogen-containing heterocyclic compounds, iodonitrotetrazolium chloride (INT) and thiazolyl blue tetrazolium bromide (MTT) with a similar tetrazolyl group are selected as the levelers to investigated the molecular structure impacts on their microvia copper filling performance. Both INT and MTT inhibit the electroreduction of copper ions. The inhibiting effect of INT is greatly enhanced by convection while MTT is independent of convection, indicating a bottom-up filling performance of INT and a conformal filling performance of MTT. The microvias are supper-filled and poor-filled in electrolytes containing INT and MTT, respectively, as predicted by electrochemical analysis. Molecular dynamic simulation demonstrates that INT adsorbs in a flat orientation with its iodine and nitro group's two oxygen atoms interacting on the Cu(111) plane surface. MTT adsorbs on Cu(111) surface via positively charged tetrazole ring and its adsorption ability is much stronger than that of INT. The weak adsorption ability of INT on copper surface and the slow mass transfer rate result in its convection-dependent adsorption behavior and the excellent microvia copper filling performance.

Polyelectrolytes have been widely applied in electrochemical devices. Understanding the polyelectrolyte/electrode interfaces is pivotal for polyelectrolyte-based applications. Here, we measured the electrochemical potential drop and the local activity of the mobile ion of H+ or OH- at the polyelectrolytes/Au interfaces by in situ electrochemical surface-enhanced Raman spectroscopy and voltammetry in three-electrode cells. We found that the potential dependences of the electrochemical potential drop in polyelectrolytes were smaller than that in conventional electrolyte solutions. The interfacial activity of H+ or OH- was much lower than that of bulk polyelectrolytes. The potential-dependent molecular dynamics simulations showed that the mobility of ionomers of polyelectrolytes in an electrostatic field was limited by a polymer matrix. These results suggested a characteristically thicker compact layer in the electrical double layer of a polyelectrolyte/electrode interface due to the accumulation of mobile H+ or OH- with a thicker hydration layer and immobile ionomers.

In nature and technologies, many chemical reactions occur at interfaces with dimensions approaching that of a single reacting species in nano- and angstrom-scale. Mechanisms governing reactions at this ultimately small spatial regime remain poorly explored because of challenges to controllably fabricate required devices and assess their performance in experiment. Here we report how efficiency of electrochemical reactions evolves for electrodes that range from just one atom in thickness to sizes comparable with and exceeding hydration diameters of reactant species. The electrodes are made by encapsulating graphene and its multilayers within insulating crystals so that only graphene edges remain exposed and partake in reactions. We find that limiting current densities characterizing electrochemical reactions exhibit a pronounced size effect if reactant's hydration diameter becomes commensurable with electrodes' thickness. An unexpected blockade effect is further revealed from electrodes smaller than reactants, where incoming reactants are blocked by those adsorbed temporarily at the atomically narrow interfaces. The demonstrated angstrom-scale electrochemistry offers a venue for studies of interfacial behaviors at the true molecular scale.

Unraveling the origin of Helmholtz capacitance is of paramount importance for understanding the interfacial structure and electrostatic potential distribution of electric double layers (EDL). In this work, we combined the methods of ab initio molecular dynamics and classical molecular dynamics and modeled electrified Cu(100)/electrolyte and graphene/electrolyte interfaces for comparison. It was proposed that the Helmholtz capacitance is composed of three parts connected in series: the usual solvent capacitance, water chemisorption induced capacitance, and Pauling repulsion caused gap capacitance. We found the Helmholtz capacitance of graphene is significantly lower than that of Cu(100), which was attributed to two intrinsic factors. One is that graphene has a wider gap layer at interface, and the other is that graphene is less active for water chemisorption. Finally, based on our findings, we provide suggestions for how to increase the EDL capacitance of graphene-based materials in future work, and we also suggest that the new understanding of the potential distribution across the Helmholtz layer may help explain some experimental phenomena of electrocatalysis.

Computational electrochemistry, an important branch of electrochemistry, has shown its advantages in studying electrode/electrolyte interfaces, such as the structures of electric double layers. However, modeling electrochemical systems is still a challenge, especially in interface electrochemistry, because not only solvation effects and ion distribution in electrolyte solutions should be considered, but also the treatment of the electrode potential and the response of electrolytes to applied potentials. Here, we review the latest development in the field of computational electrochemistry. We first introduce various energy models used in simulating electrolytes and electrodes at multiple scales. Then, to better explain and compare between different methods, we discuss the calculation methods of solution electrochemistry and interface electrochemistry in separate. At last, we introduce the methods to electrify the interfaces in various multiscale models. This review aims to help understand various levels of methods in simulations of different scenarios in electrochemistry, and summarizes a set of schemes covering multiple scales.

We report a combined computational and exper-imental work aimed at estimating the equilibrium potential for theelectroreduction of CO2to CO2-(widely accepted to be a crucialand overpotential-determining step) and at providing an alternativeview on the reason behind the lower overpotential for CO2reduction in imidazolium-based ionic liquid/water mixtures. Tobegin with, we obtained an 80 ps ab-initio molecular dynamicstrajectory of the CO2-solvation structures in an 18% EMIM-BF4/water mixture, which delivered no evidence of interaction betweenEMIM+and CO2-. Next, using the Fc+/Fc couple as the non-aqueous reference, we calculated the equilibrium potential of theCO2/CO2-couple in the mixture and aligned it with the aqueousSHE scale, proving that the equilibrium potential of CO2/CO2-in the mixture is about 0.3 V less negative than in the aqueousmedium. We then looked for the origin of this catalytic effect by comparing the computed vibrational spectra with experimentalFourier transform infrared spectra. This revealed the presence of two water populations in the mixture, namely, bulk-like water andwater in the vicinity of EMIM-BF4. Finally, we compared the hydrogen bonding interactions between the CO2-radical and H2Omolecules in water and in the mixture, which showed that stabilization of CO2-by water molecules in the EMIM-BF4/watermixture is stronger than in the aqueous medium. This suggests that water in EMIM-BF4/water mixtures could be responsible forthe low overpotential reported in these kinds of electrolytes

The choice for representation of the electrolyte phase can vary from continuum models, molecular mechanics to ab initio molecular dynamics (AIMD) method. Increase of computational power has encouraged applications of AIMD to electrochemical interfaces, for example calculating interfacial structures, potentials of zero charge of metal/water interfaces, surface acidities, and band alignment of semiconductor/water interfaces, thermochemistry of surface reactions, etc. This chapter begins by introducing related theoretical background of electrochemistry, including the concept of the electrode potential and reference electrode. It summarizes the computational methods for modeling electrochemical interfaces. The chapter reviews the two main methods for computing the electrode potentials of the solid/liquid interfaces, i.e. work function based and reference electrode based methods. Finally, some applications of these methods for simulations of interfaces and determination of electrode potentials are mentioned.

Potential of zero charge (PZC) is an important reference for understanding the interface charge and structure at a given potential, and its difference from the work function of metal surface (ΦM) is defined as the Volta potential difference (ΔΦ). In this work, we model 11 metal/water interfaces with ab initio molecular dynamics. Interestingly, we find ΔΦ is linearly correlated with the adsorption energy of water (Eads) on the metal surface. It is revealed that the size of Eads directly determines the coverage of chemisorbed water on the metal surface and accordingly affects the interface potential change caused by electron redistribution (ΔΦel). Moreover, ΔΦ is dominated by the electronic component ΔΦel with little orientational dipole contributing, which explains the linear correlation between ΔΦ and Eads. Finally, it is expected that this correlation can be helpful for effectively estimating the ΔΦel and PZC of other metal surfaces in the future work.

The electrocatalytic reduction of CO2 is considered an effective method to reduce CO2 emissions and achieve electrical/chemical energy conversion. It is crucial to determine the reaction mechanism so that the key reaction intermediates can be targeted and the overpotential lowered. The process involves the interaction with the electrode surface and with species, including the solvent, at the electrode-electrolyte interface, and it is therefore not easy to separate catalytic contributions of the electrode from those of the electrolyte. We have used density functional theory-based molecular dynamics to calculate the Gibbs free energy of the proton and electron transfer reactions corresponding to each step in the electroreduction of CO2 to HCOOH in aqueous media. The results show thermodynamic pathways consistent with the mechanism proposed by Hori. Since electrodes are not included in this work, differences between the calculated results and the experimental observations can help determine the catalytic contribution of the electrode surface.

Electrode potential is the key factor for controlling electrocatalytic reactions at electrochemical interfaces, and moreover, it is also known that the pH and solutes (e.g., cations) of the solution have prominent effects on electrocatalysis. Understanding these effects requires microscopic information on the electrochemical interfaces, in which theoretical simulations can play an important role. This Perspective summarizes the recent progress in method development for modeling electrochemical interfaces, including different methods for describing the electrolytes at the interfaces and different schemes for charging up the electrode surfaces. In the final section, we provide an outlook for future development in modeling methods and their applications to electrocatalysis.

Energetically efficient electrochemical reduction of CO2 would offer the possibility of storing electricity from renewables in the form of fuels and other valuable chemicals. It may also help mitigate the increase of atmospheric CO2 associated with global warming. However, the process suffers from a low energy efficiency because of the large overpotentials required. In aqueous electrolytes, the competing hydrogen evolution reaction also decreases the faradaic efficiency (which contributes to the low energy efficiency of the process). Recent claims of high faradaic efficiency and low overpotentials for the reduction of CO2 in room-temperature ionic liquids (RTILs) and RTIL–water mixtures have spurred considerable research. Here, we offer a critical review of those claims and of recent work aimed at understanding the details of this important reaction in these nonconventional electrolytes.

Tricyclic carbazole is an important scaffold in many naturally occurring metabolites, as well as valuable building blocks. Here we report the reconstitution of the ring A formation of the bacterial neocarazostatin A carbazole metabolite. We provide evidence of the involvement of two unusual aromatic polyketide proteins. This finding suggests how new enzymatic activities can be recruited to specific pathways to expand biosynthetic capacities. Finally, we leveraged our bioinformatics survey to identify the untapped capacity of carbazole biosynthesis.

We have developed a scheme to compute the standard potential of the Ag/AgCl reference electrode using density functional theory-based molecular dynamics, similar to the computational standard hydrogen electrode (SHE) developed by Cheng, Sulpizi, and Sprik [J. Chem. Phys.2009,131, 154504], with which our new computational reference electrode was compared. We have obtained a similar value of the potential of the Ag/AgCl electrode versus SHE to the experiment. The newly developed computational reference electrode will be extended to nonaqueous solvents in the future, where it will be used to predict standard equilibrium potentials to be compared with experimental data.