In reactions of aromatic oxygenates, one promising strategy for improving selectivity toward desirable products is to control the ensembles of available surface sites and thus the adsorbed conformations of reactive intermediates. For this study, alkanethiolate self-assembled monolayers with variable surface densities were employed to restrict the conformation of adsorbed benzyl alcohol on Pd for enhancing hydrodeoxygenation selectivity to toluene and reducing decarbonylation selectivity to benzene. Toluene selectivity was dramatically improved on a 1-octadecanethiol-coated catalyst at the cost of a large decrease in reaction rate. On the other hand, deposition of a sparser 1-adamantanethiol (AT) coating improved selectivity to a smaller extent, but resulted in a higher reaction rate than that of the uncoated catalyst. Auger electron spectroscopy and temperature-programmed desorption (TPD) were used to further characterize this chemistry on a Pd(111) surface in ultrahigh vacuum. The TPD results match the selectivity results for the thiol-coated supported catalysts, revealing that increasing the surface density of thiols selectively shuts down decarbonylation while still allowing hydrodeoxygenation. The improved activity and selectivity for the AT-coated surface is attributed to weakened interactions of the phenyl ring with the surface.

Metal catalysts coated with self-assembled monolayers have been found to exhibit improved performance in a number of reactions, but previous work has focused on deposition of uniform layers from a single precursor. In this study, we investigate how the use of variable-composition monolayers formed from mixtures of 1-adamantanethiol (AT) and 1-octadecanethiol (C18) can be used to control catalyst performance and provide insights into both monolayer ordering and surface reaction mechanisms. Benzyl alcohol hydrodeoxygenation to toluene was used as a probe reaction for these studies. The mixed monolayer composition was controlled by varying the proportion of AT to C18 in an ethanol solution used for deposition. For AT-modified catalysts, toluene selectivity was higher than for the uncoated catalyst. Increases in the C18 surface fraction (y C18) in the monolayers resulted in further increases in toluene selectivity, with selectivity approaching 98% near complete conversion at full C18 coverage. Infrared spectra collected after dosing CO or benzyl alcohol also indicated that increasing y C18 lowered the ratio of bridging and threefold adsorption on high coordination sites compared to linear adsorption on low coordination sites. These results suggested that the mechanism for selectivity enhancement was at least partly due to selective poisoning of terrace sites and reduction of contiguous active sites. Whereas selectivity was observed to follow a continuous

In this study, electrophoretic deposition (EPD) was employed to fabricate multi-wall carbon nanotube (MWCNT) counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). Firstly, raw MWCNTs were functionalized by means of an acid mixture solution and then subjected to EPD. The results obtained from Raman spectroscopy, Fourier transform infrared spectroscopy, field-emission scanning electron microscope, and cyclic voltammogram demonstrated that the defects and open ends on the MWCNTs can be obtained via chemical functionalization and thus facilitate the enhancement in the electrocatalytic activity for I 3 − reduction of MWCNT CEs. In addition to optimizing chemical functionalization of MWCNTs surface, the optimal thickness of MWCNT CEs prepared by EPD was also investigated. Additionally, consecutive cyclic voltammetric tests demonstrated that the MWCNT CE fabricated by EPD possessed excellent electrochemical stability. In comparison with MWCNT CEs fabricated by tape-casting approach, MWCNT CEs prepared by EPD presented a superior adhesion between MWCNT deposits and conducting glass substrates. Therefore, MWCNT CEs fabricated by EPD can be of great potential for use in lowcost plastic DSSCs.

Pd surface modification by thiolate SAMs resulted in preferential terminal-to-internal olefin isomerization instead of hydrogenation, particularly at high conversion.

The dayside equatorial ionospheric electrodynamics exhibit strong variability driven simultaneously by highly changeable external forcings that originate from the solar extreme ultraviolet (EUV), magnetosphere, and lower atmosphere. We investigate this variability by carrying out comprehensive data‐driven ensemble modeling using a coupled model of the thermosphere and ionosphere, with the focus on the vertical E × B drift variability during a solar minimum and minor storm period. The variability of vertical E × B drift in response to the changes and uncertainty of primary forcings (i.e., solar EUV, high‐latitude plasma convection and auroral particle precipitation, and lower‐atmospheric tide and wave forcing) is investigated by ensemble forcing sensitivity experiments that incorporate data‐driven stochastic perturbations of these forcings into the model. Second, the impact of assimilating FORMOsa SATellite‐3/Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT‐3/COSMIC) electron density profiles (EDPs) on the reduction of uncertainty of the modeled vertical E × B drift variability resulting from inadequately specified external forcing is revealed. The Communication and Navigation Outage Forecasting System (C/NOFS) ion drift velocity observations are used for validation. The validation results support the importance of the use of a data‐driven forcing perturbation methods in ensemble modeling and data assimilation. In conclusion, the solar EUV dominates the global‐scale day‐to‐day variability, while the lower atmosphere tide and wave forcing is critical to determining the regional variability. The modeled vertical E × B drift is also sensitive to the magnetospheric forcing. The ensemble data assimilation of FORMOSAT‐3/COSMIC EDPs helps to reduce the uncertainty and improves agreement of the modeled vertical E × B drifts with C/NOFS observations.

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