Role of inorganic layers on polysulfide decomposition at sodium-metal anode surfaces for room temperature Na/S batteries.

Sodium metal is a promising anode material for room-temperature sodium sulfur batteries. Due to its high reactivity, typical liquid electrolytes ( carbonate-based solvents and a Na salt) can undergo reduction to form a solid electrolyte interphase (SEI) layer, with inorganic components such as NaCO, NaO, and NaOH, covering the anode surface along with other SEI organic products. One of the challenges is to understand the effect of the SEI film on the decomposition of soluble sodium polysulfide molecules (, NaS) upon shuttling from the cathode to anode during battery cycling.

Polysulfide cluster formation, surface reaction, and role of fluorinated additive on solid electrolyte interphase formation at sodium-metal anode for sodium-sulfur batteries.

Room-temperature sodium-sulfur batteries are promising next-generation energy storage alternatives for electric vehicles and large-scale applications. However, they still suffer from critical issues such as polysulfide shuttling, which inhibit them from commercialization. In this work, using first-principles methods, we investigated the cluster formation of soluble NaS molecules, the reductive decomposition of ethylene carbonate (EC) and propylene carbonate (PC), and the role of fluoroethylene carbonate (FEC) additive in the solid electrolyte interphase formation on the Na anode.

Insight into the Roles of Metal Loading on CO Photocatalytic Reduction Behaviors of TiO.

The photocatalytic reduction of carbon dioxide (CO) into value-added chemicals is considered to be a green and sustainable technology, and has recently gained considerable research interest. In this work, titanium dioxide (TiO) supported Pt, Pd, Ni, and Cu catalysts were synthesized by photodeposition. The formation of various metal species on an anatase TiO surface, after ultraviolet (UV) light irradiation, was investigated insightfully by the X-ray absorption near edge structure (XANES) technique.

Electronic and thermodynamic properties of native point defects in VO: a first-principles study.

The formation of native point defects in semiconductors and their behaviors play a crucial role in material properties. Although the native defects of V2O5 include vacancies, self-interstitials, and antisites, only oxygen vacancies have been extensively explored. In this work, we carried out first-principles calculations to systematically study the properties of possible native defects in V2O5.

Electrochemical oxidation of resorcinol: mechanistic insights from experimental and computational studies.

This work investigates the mechanisms of resorcinol oxidation by density functional theory (DFT) calculation and cyclic voltammetry measurements. Complementary data from experimental and computational studies provide new insights into the reaction mechanisms. At both macro- and micro-electrodes, cyclic voltammetry of resorcinol is chemically and electrochemically irreversible over the whole pH range (1-14).

Transport properties of electron small polarons in a VO cathode of Li-ion batteries: a computational study.

Employing the first-principles plane-wave approach, we explored the behavior of electron transport in the VO cathode. Polaron migrations along different crystallographic directions in the presence and absence of Li ions were systematically examined using linear interpolation (LE) and nudged elastic band (NEB) methods. We find that the NEB calculations, based on structural optimizations of TS structures, generally exhibit lower hopping barriers than those obtained from the LE calculations.

On the Role of Sulfur for the Selective Electrochemical Reduction of CO to Formate on CuS Catalysts.

The efficient electroreduction of CO has received significant attention as it is one of the crucial means to develop a closed-loop anthropogenic carbon cycle. Here, we describe the mechanistic workings of an electrochemically deposited CuS catalyst that can reduce CO to formate with a Faradaic efficiency (FE) of 75% and geometric current density ( j) of -9.0 mA/cm at -0.

Origin of Nb O Lewis Acid Catalysis for Activation of Carboxylic Acids in the Presence of a Hard Base.

The Nb O surface catalyzes the amidation of carboxylic acids with amines through Nb Lewis acid activation of the C=O group. In this work, DFT calculations were applied to theoretically investigate the C=O bond activation of a model carboxylic acid (acetic acid) on θ-Al O (110), anatase TiO (101), and T-Nb O (100) surfaces. The adsorption sites, adsorption energies, reaction energy barriers, electronic properties, and vibrational frequency of acetic acid were examined in detail.

Trends in activity for the water electrolyser reactions on 3d M(Ni,Co,Fe,Mn) hydr(oxy)oxide catalysts.

Design and synthesis of materials for efficient electrochemical transformation of water to molecular hydrogen and of hydroxyl ions to oxygen in alkaline environments is of paramount importance in reducing energy losses in water-alkali electrolysers. Here, using 3d-M hydr(oxy)oxides, with distinct stoichiometries and morphologies in the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) regions, we establish the overall catalytic activities for these reaction as a function of a more fundamental property, a descriptor, OH-M(2+δ) bond strength (0 ≤ δ ≤ 1.5).

Shell-anchor-core structures for enhanced stability and catalytic oxygen reduction activity.

Density functional theory is used to evaluate activity and stability properties of shell-anchor-core structures. The structures consist of a Pt surface monolayer and a composite core having an anchor bilayer where C atoms in the interstitial sites lock 3d metals in their locations, thus avoiding their surface segregation and posterior dissolution. The modified subsurface geometry induces less strain on the top surface, thus exerting a favorable effect on the surface catalytic activity where the adsorption strength of the oxygenated species becomes more moderate: weaker than on pure Pt(111) but stronger than on a Pt monolayer having a 3d metal subsurface.

Vibrational spectra of anhydrous and monohydrated caffeine and theophylline molecules and crystals.

Density functional theory and classical molecular dynamics simulations are used to investigate the vibrational spectra of caffeine and theophylline anhydrous and monohydrate molecules and those of their crystalline anhydrous and monohydrated states, with emphasis in the terahertz region of the spectra. To better understand the influence of water in the monohydrate crystal spectra, we analyze the vibrational spectra of water monomer, dimer, tetramer, and pentamer, and also those of liquid water at two different temperatures. In small water clusters, we observe the progressive addition of translational and librational modes to the terahertz region of the spectra.