Redox regulation of Ni hydroxides with controllable phase composition towards biomass-derived polyol electro-refinery.

Electrocatalytic refinery from biomass-derived glycerol (GLY) to formic acid (FA), one of the most promising candidates for green H2 carriers, has driven widespread attention for its sustainability. Herein, we fabricated a series of monolithic Ni hydroxide-based electrocatalysts by a facile and in situ electrochemical method through the manipulation of local pH near the electrode. The as-synthesized Ni(OH)2@NF-1.0 affords a low working potential of 1.36 VRHE to achieve 100% GLY conversion, 98.5% FA yield, 96.1% faradaic efficiency and ∼0.13 A cm-2 of current density. Its high efficiency on a wide range of polyol substrates further underscores the promise of sustainable electro-refinery. Through a combinatory analysis via H2 temperature-programmed reduction, cyclic voltammetry and in situ Raman spectroscopy, the precise regulation of synthetic potential was discovered to be highly essential to controlling the content, phase composition and redox properties of Ni hydroxides, which significantly determine the catalytic performance. Additionally, the 'adsorption-activation' mode of ortho-di-hydroxyl groups during the C-C bond cleavage of polyols was proposed based on a series of probe reactions. This work illuminates an advanced path for designing non-noble-metal-based catalysts to facilitate electrochemical biomass valorization.

Highly efficient hydrodesulfurization driven by an in-situ reconstruction of ammonium/amine intercalated MoS2 catalysts.

Hydrodesulfurization (HDS) is a commonly used route for producing clean fuels in modern refinery. Herein, ammonium/amine-intercalated MoS2 catalysts with various content of 1T phase and S vacancies have been successfully synthesized. Along with the increment of 1T phase and S vacancies of MoS2, the initial reaction rate of the HDS of dibenzothiophene (DBT) can be improved from 0.09 to 0.55 µmol·gcat-1·s-1, accounting for a remarkable activity compared to the-state-of-the-art catalysts. In a combinatory study via the activity evaluation and catalysts characterization, we found that the intercalation species of MoS2 played a key role in generating more 1T phase and S vacancies through the 'intercalation-deintercalation' processes, and the hydrogenation and desulfurization of HDS can be significantly promoted by 1T phase and S vacancies on MoS2, respectively. This study provides a practically meaningful guidance for developing more advanced HDS catalysts by the intercalated MoS2-derived materials with an in-depth understanding of structure-function relationships.

Enhancing Low-Potential Electrosynthesis of 2,5-Furandicarboxylic Acid on Monolithic CuO by Constructing Oxygen Vacancies.

Electrosynthesis of 2,5-furandicarboxylic acid (FDCA) from the biomass-derived 5-hydroxymethylfurfural (HMF) is one of the most potential means to produce a bioplastic monomer. Copper oxide (CuO) catalyst shows promising prospects due to its high surface activity, conductivity, and stability, but relatively poor capability of oxygen evolution; however, the weak adsorption of substrates and the lack of facile synthetic strategies largely restrict its practical application. Here, a novel facile in situ method, alternate cycle voltammetry (denoted as c) and potentiostatic electrolysis (denoted as p), was proposed to prepare a monolithic cpc-CuO/Cu-foam electrocatalyst. Along with the increment of CuO and its surficial oxygen vacancies (OV), the FDCA yield, productivity, and Faradaic efficiency can reach up to ∼98.5%, ∼0.2 mmol/cm2, and ∼94.5% under low potential of 1.404 VRHE. Such an efficient electrosynthesis system can be easily scaled up to afford pure FDCA powders. In a combinatory analysis via electron paramagnetic resonance spectroscopy, H2 temperature-programmed reduction, open circuit potential, infrared spectroscopy, zeta potential, electrochemical measurement, and theoretical calculation, we found that the CuO was the active phase and OV generated on CuO surface can dramatically enhance the adsorption of *HMF and *OH (* denotes an active site), accounting for its superior FDCA production. This work offers an excellent paradigm for enhancing biomass valorization on CuO catalysts by constructing surficial defects.

Directional Electrosynthesis of Adipic Acid and Cyclohexanone by Controlling the Active Sites on NiOOH.

Dicarboxylic acids and cyclic ketones, such as adipic acid (AA) and cyclohexanone (CHN), are essential compounds for the chemical industry. Although their production by electrosynthesis using electricity is considered one of the most promising strategies, the application of such processes has been hampered by a lack of efficient catalysts as well as a lack of understanding of the mechanism. Herein, a series of monolithic msig/ea-NiOOH-Ni(OH)2/NF were prepared by means of self-dissolution of metal matrix components, interface growth, and electrochemical activation (denoted as msig/ea). The as-synthesized catalysts have three-dimensional cuboid-like structures formed by interconnecting nanosheets composed of NiOOH. By theoretically guided regulation of the amounts of Ni3+ and oxygen vacancies (OV), a 96.5% yield of CHN from cyclohexanol (CHA) dehydrogenation and a 93.6% yield of AA from CHN oxidation were achieved. A combined experimental and theoretical study demonstrates that CHA dehydrogenation and CHN oxidation were promoted by the formation of Ni3+ and the peroxide species (*OOH) on OV. This work provides a promising approach for directional electrosynthesis of high-purity chemicals with in-depth mechanistic insights.

Effect of Bletilla Striata Polysaccharide on the Pasting, Rheological and Adhesive Properties of Wheat Starch.

A combination of starch and hydrocolloids is a facile method for physically modifying native starch. Bletilla striata polysaccharide (BSP) is a glucomannan with various applications in the food and cosmetic industries as a thickening agent. This study focused on investigating the impact of BSP on the pasting, rheological and adhesive properties of wheat starch (WS). Results from a Rapid Visco-Analyzer (RVA) revealed that the addition of BSP (below 0.2%) resulted in increases in peak viscosity, breakdown and setback values. However, for the addition of BSP at a higher concentration (0.3%), the opposite trend was observed. Rheological measurements indicated that the presence of BSP increased the viscoelastic properties of WS-BSP gels. TGA results demonstrated that the presence of BSP promoted the thermal stability of starch. FTIR results indicated the short-range order structure decreased at low addition concentrations of BSP (0.05% and 0.1%) and increased with higher BSP addition concentrations (0.2% and 0.3%). SEM observation showed that the BSP improved the hydrophilic property of starch gels and decreased the size of pores in the starch gels. Further, the mechanical properties of paper samples unveiled that the present of BSP in starch gels obviously increased its bonding strength as an adhesive.

One-pot two-step process directly converting biomass-derived carbohydrate to lactide.

This study proposed a strategy for the production of lactide from biomass-derived carbohydrate with excellent yield, involving sugar to racemic lactic acid conversion over Sn-containing Beta zeolite and racemic lactic acid to lactide conversion over H-Beta zeolite. Structural characteristics of the resulting lactide and extensive applicability for various substrates are also presented.