Performance Exploration of Ni-Doped MoS2 in CO2 Hydrogenation to Methanol.

The preparation of methanol chemicals through CO2 and H2 gas is a positive measure to achieve carbon neutrality. However, developing catalysts with high selectivity remains a challenge due to the irreversible side reaction of reverse water gas shift (RWGS), and the low-temperature characteristics of CO2 hydrogenation to methanol. In-plane sulfur vacancies of MoS2 can be the catalytic active sites for CH3OH formation, but the edge vacancies are more inclined to the occurrence of methane. Therefore, MoS2 and a series of MoS2/Nix and MoS2/Cox catalysts doped with different amounts are prepared by a hydrothermal method. A variety of microscopic characterizations indicate that Ni and Co doping can form NiS2 and CoS2, the existence of these substances can prevent CO2 and H2 from contacting the edge S vacancies of MoS2, and the selectivity of the main product is improved. DFT calculation illustrates that the larger range of orbital hybridization between Ni and MoS2 leads to CO2 activation and the active hydrogen is more prone to surface migration. Under optimized preparation conditions, MoS2/Ni0.2 exhibits relatively good methanol selectivity. Therefore, this strategy of improving methanol selectivity through metal doping has reference significance for the subsequent research and development of such catalysts.

Mussel Inspired Trigger-Detachable Adhesive Hydrogel.

Adhesion to many kinds of surfaces, including biological tissues, is important in many fields but has been proved to be extremely challenging. Furthermore, peeling from strong adhesion is needed in many conditions, but is sometimes painful. Herein, a mussel inspired hydrogel is developed to achieve both strong adhesion and trigger-detachment. The former is actualized by electrostatic interactions, covalent bonds, and physical interpenetration, while the latter is triggered, on-demand, through combining a thixotropic supramolecular network and polymer double network. The results of the experiments show that the hydrogel can adhere to various material surfaces and tissues. Moreover, triggered by shear force, non-covalent interactions of the supramolecular network are destroyed. This adhesion can be peeled easily. The possible mechanism involved is discussed and proved. This work will bring new insight into electronic engineering and tissue repair like skin care for premature infants and burn victims.

Cellulose type chiral stationary phase based on reduced graphene oxide@silica gel for the enantiomer separation of chiral compounds.

The graphene oxide (GO) was covalently coupled to the surfaces of silica gel (SiO2 ) microspheres by amide bond to get the graphene oxide@silica gel (GO@SiO2 ). Then, the GO@SiO2 was reduced with hydrazine to the reduced graphene oxide@silica gel (rGO@SiO2 ), and the cellulose derivatives were physically coated on the surfaces of rGO@SiO2 to prepare a chiral stationary phase (CSP) for high performance liquid chromatography. Under the optimum experimental conditions, eight benzene-enriched enantiomers were separated completely, and the resolution of trans-stilbene oxide perfectly reached 4.83. Compared with the blank column of non-bonded rGO, the separation performance is better on the new CSP, which is due to the existence of rGO to produce special retention interaction with analytes, such as π-π stacking, hydrophobic effect, π-π electron-donor-acceptor interaction, and hydrogen bonding. Therefore, the obtained CSP shows special selectivity for benzene-enriched enantiomers, improves separation selectivity and efficiency, and rGO plays a synergistic effect with cellulose derivatives on enantioseparation.

Polysaccharide-Based Chiral Stationary Phases on Gold Nanoparticles Modified Silica Beads for Liquid-Phase Separation of Enantiomers.

Au nanoparticles (AuNPs) (10-15 nm in size) were prepared and deposited on the surfaces of silica particles functionalized using 3-aminopropyltriethoxysilane as the seeds under mild conditions. Then, Au seeds grew further and formed nanosheets by the method of gold chloride hydrate reduction. 3, 5-dimethylphenyl isocyanate derivative of cellulose as chiral selector was coated on the surfaces of SiO2/Au. The obtained spheres possessed a sandwich structure in which silica bead, the packed Au NPs monolayer and cellulose derivative were the core, the interlayer and the shell, respectively. The resultant packing material was evaluated by high-performance liquid chromatography (HPLC) as chiral stationary phase (CSP). The separations of nine pairs of enantiomers were achieved in the normal-phase liquid chromatography mode. The results showed that the new CSP has sufficient interaction with the analytes due to the existence of AuNPs on silica surfaces compared with coated cellulose-silica column.