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Enzyme variants of the plant epoxide hydrolase StEH1 displaying improved stereoselectivities in the catalyzed hydrolysis of (2,3-epoxypropyl)benzene were generated by directed evolution. The evolution was driven by iterative saturation mutagenesis in combination with enzyme activity screenings where product chirality was the decisive selection criterion. Analysis of the underlying causes of the increased diol product ratios revealed two major contributing factors: increased enantioselectivity for the corresponding epoxide enantiomer(s) and, in some cases, a concomitant change in regioselectivity in the catalyzed epoxide ring-opening half-reaction. Thus, variant enzymes that catalyzed the hydrolysis of racemic (2,3-epoxypropyl)benzene into the R-diol product in an enantioconvergent manner were isolated.

Sn-decorated Cu (Cu-Sn) electrodes were proposed as an alternative to Ag-and Au-based electrocatalysts for the selective reduction of CO 2 to CO. Here we demonstrate that selectivity does not only depend on catalyst surface composition, but is strongly affected by the electrode morphology. At current densities above 10 mA•cm -2 , we find that morphology can control the CO 2 reduction pathways to CO and other products, including the competing H 2 evolution, on the Cu-Sn surface. An electrode design with dendritic morphological features yields the highest CO partial current density of 11.5 mA•cm -2 at -1.1 V vs. RHE, avoiding the significant loss of CO selectivity observed for an electrode with less sharp, rounder morphological features. Efficient CO 2 mass transport to the catalyst surface and a high local CO 2 concentration, promoted by the dendritic structure, stabilize the Cu-SnO overlayer, suppress the competing H 2 evolution reaction, and maintain CO selectivity above 85% over a wide potential range.

Novel corncob-derived solid acid catalysts were successfully synthesized for the first time by the hydrothermal method. The influences of different preparation conditions were investigated, and the structure-function relationships of the resulting catalysts were also discussed on the basis of the analysis of structure and composition. In comparison to conventional solid acid catalysts, the corncob-derived catalyst synthesized under optimized conditions exhibited higher catalytic activity in esterification reactions, yielding nearly 90% methyl oleate in only 2 h. The catalyst retained satisfactory catalytic activity for esterification, even after 8 reaction cycles. Solid-state magic angle spinning (MAS) (13)C nuclear magnetic resonance (NMR) investigations further indicated that the catalyst was composed of polycyclic aromatic carbon sheets bearing -SO3H, -COOH, and -OH groups in adequate amounts and with proper proportions, contributing to its excellent catalytic activity. This work provides a green method to synthesize solid acid catalysts from biomass wastes and may contribute to a holistic approach for biomass conversion.

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