Catalytic Methods for the Production of Sugar Esters

Nowadays, Sugar esters (SEs) have become the focus of researchers due to their biocompatibility and extensive industrial applications as surfactants. This trend provides new methods and opportunities for the development of green synthetic chemistry. Taking the above into consideration, a critical review presented in this work emphasized the efficiency of catalyzing the synthesis of SEs with minimal hazardous by-products. These catalytic media have been employed with various impacts involving chemical, biological, and other catalytic materials. Chemical methods have been reported to show limitations in terms of preparation and bio-compatibility. To solve these shortcomings, therefore, other technologies have been adopted; ionic liquids (eutectic solvents), chemo-enzymatic systems and chemo-enzymatic systems on a catalytic surface. The use of chemo-enzymatic systems on catalytic surfaces has proved to be suitable in solving biocompatibility and stability problems and correspondingly increasing the yield of esters formed. Therefore, finding an improved catalytic surface, and the sustainable optimal reaction conditions for enzymes will be vital to improving sugar ester conversion. This study highlights the different catalytic advances employed in the esterification of SEs.

Spatiotemporal imaging of anisotropic charge transfer in photocatalyst particles

Water-splitting reactions using photocatalyst particles are promising routes for solar fuel production1-4. Photoinduced charge transfer from a photocatalyst to catalytic surface sites is key in ensuring photocatalytic efficiency5; however, it is challenging to understand this process, which spans a wide spatiotemporal range from nanometers to micrometers and from femtoseconds to seconds6-8. Although the steady-state charge distribution on single photocatalyst particles has been mapped using microscopic techniques9-11 and the averaged charge transfer dynamics in photocatalyst aggregations have been revealed via time-resolved spectroscopy12,13, spatiotemporally evolving charge transfer processes in single photocatalyst particles cannot be tracked, and the mechanism of charge transfer is unknown. Here, we report spatiotemporally resolved surface photovoltage measurements on Cu2O photocatalyst particles to map complete charge transfer processes throughout the femtosecond to second time scale at the single-particle level. We found that photogenerated electrons are transferred to the catalytic surface ballistically on a sub-picosecond timescale and are retained at this location for the duration, whereas photogenerated holes are transferred to a spatially separated surface and stabilized via selective trapping on a microsecond timescale. We demonstrate that these ballistic electron transfer and anisotropic trapping regimes, which challenge the classical perception of the drift–diffusion model, contribute to efficient charge separation in photocatalysis and improve the photocatalytic performance. We anticipate our findings to demonstrate the universality of other photoelectronic devices and facilitate the rational design of photocatalysts.

Promoted Alkaline Hydrogen Evolution by N-doped Pt-Ru Single Atoms Alloy

Since water dissociation and H desorption kinetics essentially determine the performance of alkaline hydrogen evolution reaction (HER), rationally regulating surface adsorption behavior to achieve superior catalytic surface is always challenging...

A New Method of Bio-Catalytic Surface Modification For Microbial Desalination Cell

Microbial desalination cell (MDC) built on surface modification has been studied for seawater desalination. Herein, the bio-catalytic surface modification for maintenance the long-term MDC performance during desalination process has been developed. The goal of this study is to provide and develop a seawater desalination system without requiring energy support by applying a modification of anode as an electron acceptor, and the different potential charges that occur between anode and cathode can play as driving force for electrodialysis of seawater desalination. Yeast has been applied as biocatalyst, meanwhile neutral red has been chosen as redox mediator to facilitate the electron transport from bioactivity of cells. Several types of surface modification have been conducted, i.e. biocatalyst-mediator immobilization and electropolymerization of NR at the surface of the anode. The optimization of each device has been characterized by cyclic voltammetry, chronoamperometry, and observed in Microbial fuel cell (MFC) prior functioned in MDC. The concentrations of salt ion migration have been determined by Ion Exchange Chromatography. MFC results reported that the best configuration of surface modification was obtained from CF/PNR then applied in MDC. CF/PNR delivered the highly significant performance by having the maximum value of all tested parameters, i.e 42.2% of current efficiency; 27.11% of bio-devices efficiency; 92.5 mA m-2 of current density and also 61% of NaCl transport. The profiles of surface devices have been detected by Scanning electron microscope (SEM) and Energy Dispersive X-ray spectroscopy (EDX). A several spherical shapes around 4 nm within alginate layer have been detected from SEM images and it was confirmed as yeast, meanwhile 5.04% of N has been found from EDX spectrum and was indicated from PNR. The results show that surface modification could be a promising method for bioelectricity generation which simultaneously produces electricity and seawater desalination and provides a green chemistry technology.