Interfacial engineering and chemical reconstruction of Mo/Mo2C@CoO@NC heterostructure for promoting oxygen evolution reaction.

Chemical reorganization and interfacial engineering in hybrid nanomaterials are promising strategies for enhancing electrocatalytic performance. Herein, MoO3@zeolitic imidazolate framework-67 (ZIF-67) heterogeneous nanoribbons are designed through coordination assembly. By following heat treatment, a Mo/Mo2C@CoO@NC heterostructure with nitrogen-doped carbon-encapsulated CoO hexagons (CoO@NC) anchored on the Mo/Mo2C jag matrix was fabricated. Notably, through controllable experimental optimization, the as-prepared Mo/Mo2C@CoO@NC heterostructure exhibits numerous active centers (e.g. Mo, Mo2C, CoO, and NC), fully exposed active sites (numerous pores and jagged structures), and abundant heterointerfaces (Mo/Mo2C, Mo2C/CoO@NC, Mo2C/amorphous, and CoO@NC/amorphous), and exhibits good conductivity (localized single-crystal behavior, graphitized carbon). As a result, the as-developed Mo/Mo2C@CoO@NC heterostructures inherit impressive oxygen evolution reaction (OER) performance with an overpotential of only 215 mV at 10 mA cm-2. Furthermore, Mo/Mo2C@CoO@NC heterostructures exhibit excellent stability with a current density retention of 98.4% after 20 h chronoamperometry. This work provides deep insights into chemical reconstructions and tuning heterointerfaces to efficiently enhance the OER activity of heterostructure-based electrocatalysts.

Calcium and sodium ions synergistically enhance the thermostability of a maltooligosaccharide-forming amylase from Bacillus stearothermophilus STB04.

Maltooligosaccharide-forming amylases (MFAses) are promising tools for a variety of food industry applications because of their ability to hydrolyze starch into maltooligosaccharides. However, high thermostability is a key requirement for enzymes used in these applications. In this work, we investigated the effect of Ca2+ and Na+ on the thermostability of an MFAse from Bacillus stearothermophilus (Bst-MFAse). The results showed that Ca2+ and Na+ synergistically prolong the half-life of Bst-MFAse. The most significant improvement, which preserved 71.1% of initial activity after incubation at 80 °C for 180 min, was achieved by adding 10 mM Ca2+ and 40 mM Na+ simultaneously. The increase in Bst-MFAse thermostability imparted by the addition of Ca2+ and Na+ may be associated with an important Ca2+-Na+-Ca2+ triad structure. This study provides an effective way to enhance the thermostability of Bst-MFAse and related enzymes.

Maltooligosaccharide-forming amylase: Characteristics, preparation, and application.

As member of glycosyl hydrolase family 13, maltooligosaccharide-forming amylases (MFAses) are specific and interesting because of their capacity to hydrolyze starch into functional maltooligosaccharides, which are usually composed of 2-10 α-d-glucopyranosyl units linked by α-1,4 glycosidic linkages. MFAses have been extensively studied during recent decades, and have shown promise in various industrial applications. This review begins by introducing the potential uses of maltooligosaccharides. Then it describes the progress in the identification, assay, action pattern, structure, and modification of MFAses. The review continues with tips concerning the preparation of MFAses, which aim to improve MFAse production to meet the needs of industry. Finally, the industrial uses of MFAses are described, focusing on the production of maltooligosaccharides and application in the bread industry. Recent progress has demonstrated that the MFAses are poised to become important industrial catalysts.