Recently, carbon dioxide capture and conversion, along with hydrogen from renewable resources, provide an alternative approach to synthesis of useful fuels and chemicals. People are increasingly interested in developing innovative carbon dioxide hydrogenation catalysts, and the pace of progress in this area is accelerating. Accordingly, this perspective presents current state of the art and outlook in synthesis of light olefins, dimethyl ether, liquid fuels, and alcohols through two leading hydrogenation mechanisms: methanol reaction and Fischer-Tropsch based carbon dioxide hydrogenation. The future research directions for developing new heterogeneous catalysts with transformational technologies, including 3D printing and artificial intelligence, are provided.

Molecular dynamics simulations and vibrational sum frequency generation (VSFG) experiments in the methyl-stretching spectral region have been used to study acetonitrile at the silica/liquid, silica/vapor, and liquid/vapor interfaces. Our simulations show that, at the silica/liquid interface, acetonitrile takes on a considerably different structure than in the bulk liquid. The interfacial structure is reminiscent of a lipid bilayer, and this type of ordering persists for tens of Ångstroms into the bulk liquid. This result has important implications for processes involving solid/acetonitrile interfaces, such as heterogeneous catalysis and chromatographic separations. Fitting of VSFG data that have an extremely low nonresonant background contribution provides strong evidence for interfacial populations pointing in opposite directions at these interfaces, in agreement with our simulations. The picture developed from our simulations and experiments reconciles conflicting interpretations of data from previous experimental studies of interfacial acetonitrile.

Glassy solidification is characterized by two essential phenomena: localization of the solidifying material’s constituent particles and a precipitous increase in its structural relaxation time τ. Determining how these two phenomena relate is key to understanding glass formation. Leporini and coworkers have recently argued that τ universally depends on a localization length-scale (the Debye-Waller factor) in a way that depends only upon the value of at the glass transition. Here we find that this ‘universal’ model does not accurately describe τ in several simulated and experimental glass-forming materials. We develop a new localization model of solidification, building upon the classical Hall-Wolynes and free volume models of glass formation, that accurately relates τ to in all systems considered. This new relationship is based on a consideration of the the anisotropic nature of particle localization. The model also indicates the presence of a particle delocalization transition at high temperatures associated with the onset of glass formation.

Optical Kerr effect (OKE) spectroscopy has become a prominent nonlinear optical technique for studying liquids, which allows for the direct, time-resolved probing of collective orientational diffusion as well as Raman-active intermolecular and intramolecular modes.The temperature-dependent orientational dynamics of 1, n-dicyano n-alkane liquids ranging from dicyanomethane to 1,8-dicyanooctane has been investigated by ultrafast OKE spectroscopy. The dependence of the reorientational times on temperature and viscosity is consistent with the molecules adopting a largely extended structure in the liquid state, with a preference for gauche conformations at the methylenes bonded to the cyanide groups. The data are also suggestive of temperature-dependent, collective structural rearrangements in these liquids.Ultrafast OKE spectroscopy has also been used to study the intermolecular dynamics of aromatic liquids. A model that links the differences in the OKE spectra to corresponding differences in the local ordering of the liquids has been proposed previously based on the temperature-dependent OKE study of five aromatic liquids.The spectra of some other aromatic liquids such as pyridine, pyridine-d5, 2,4,6-trifluoropyridine and 1,3,5-tris(trifluoromethyl) benzene has been obtained to test this model, and the relative importance of molecular shape and electrostatic forces in determining the form of the OKE reduced spectral density for such liquids has been realized. It has recently been shown that liquid tetrahydrofuran (THF) has an unusual structure that features voids of significant dimension. Such voids should affect other observable properties of this liquid. Temperature-dependent, optical Kerr effect spectra for THF and a number of related liquids (furan, cyclopentane, tetrahydropyran, cyclohexane, diethyl ether, hexamethylphosphoramide and n-pentane) has been obtained to test whether the shape of the spectra can be used to reveal the presence of sizeable voids in liquids. Liquid under tension is another interesting system to study:A method based on Berthelot tube technique has been developed to hold benzene and acetonitrile under tension successfully.A new scheme for measuring different tensor elements of the OKE response is developed. A dual-ring, polarization dependent Sagnac interferometer is used to create two co-propagating probe pulses that arrive at the sample at different times but that reach the detector simultaneously and collinearly. The tensor element of the response that is measured is determined by the polarization of the pump pulse. By controlling the relative timing of the probe pulses it is also possible to perform optical subtraction of two different tensor elements of the response at two different times, a strategy that can be used to enhance or suppress particular contributions to the OKE response. OPTICAL KERR EFFECT SPECTROSCOPY OF SIMPLE LIQUIDS

Of the various catalysts that have been developed to date for high performance and low cost, perovskite oxides have attracted attention due to their inherent catalytic activity as well as structural flexibility. In particular, high amounts of Pr substitution of the cation ordered perovskite oxide originating from the state-of-the-art BaSrCoFeO (BSCF) electrode could be a good electrode or catalyst because of its high oxygen kinetics, electrical conductivity, oxygen capacity, and structural stability. However, even though it has many favorable intrinsic properties, the conventional high-temperature treatment for perovskite synthesis, such as solid-state reaction and combustion process, leads to the particle size increase which gives rise to the decrease in surface area and the mass activity. Therefore, we prepared mesoporous nanofibers of various cation-ordered PrBaSrCoFeO (x = 0, 0.5, 1, 1.5, and 2) perovskites via electrospinning. The well-controlled B-site metal ratio and large surface area (∼20 m g) of mesoporous nanofiber result in high performance of the oxygen reduction reaction and oxygen evolution reaction and stability in zinc-air battery.