Jinchong Zhao

Monodispersed nickel phosphide nanocrystals with different phases: synthesis, characterization and electrocatalytic properties for hydrogen evolution

Monodispersed nickel phosphide nanocrystals (NCs) with different phases (Ni12P5, Ni2P and Ni5P4) were synthesized via the thermal decomposition approach using nickel acetylacetonate as the nickel source, trioctylphosphine as the phosphorus source and oleylamine in 1-octadecene as the reductant. The phases of the as-synthesized nickel phosphide NCs could easily be controlled by changing the P : Ni precursor ratio. The structure and morphology of the as-synthesized nickel phosphide NCs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and N2 adsorption–desorption. A formation mechanism for the as-synthesized nickel phosphide NCs was proposed. We further studied the influence of the phase of the nickel phosphide NCs on the electrocatalytic properties for the hydrogen evolution reaction (HER). All phases showed good catalytic properties, and the Ni5P4 NCs with a solid structure exhibited higher catalytic activity than the Ni12P5 and Ni2P NCs. This superior catalytic activity is attributed to the higher positive charge of Ni and a stronger ensemble effect of P in Ni5P4 NCs. This study demonstrates that the crystalline phase is important for affecting the electrocatalytic properties.

Zinc-modified Pt/SAPO-11 for improving the isomerization selectivity to dibranched alkanes

Abstract Zinc-modified Pt/SAPO-11 catalysts were prepared by incipient wetness impregnation and assessed in the hydroisomerization of n -octane. Their physicochemical properties were investigated using powder X-ray diffraction, scanning electron microscopy, nitrogen adsorption-desorption, pyridine-adsorbed infrared spectroscopy, temperature-programmed desorption of NH 3 , temperature-programmed reduction of hydrogen, temperature-programmed desorption of hydrogen, transmission electron microscopy, and X-ray photoelectron spectroscopy. The addition of zinc resulted in high dispersion of platinum. Zinc acted as a competitive adsorbent, changed the location of platinum. The catalyst with a zinc loading of 0.5% gave the highest selectivity to dimethylhexanes, but the conversion was lower than those achieved with the other catalysts. Dimethylhexanes have large molecular diameters, and therefore their diffusion may be difficult. This weakens the catalytic activity of the zinc-modified catalysts and lowers the n -octane conversion.

A novel POMos-based hybrid with penta-coordinated Mo in trigonal bipyramid: structure and an efficient precursor for hydrodesulfurization catalyst

The first POMos-based hybrid with penta-coordinated Mo in trigonal bipyramid geometry for Mo–O clusters has been hydrothermally synthesized and characterized by IR, TG, XPS, and X-ray diffraction analysis. Structure analysis indicated penta-coordinated together with tetra-coordinated Mo existed in the POMos-based hybrid. The hybrid was successfully used as an efficient precursor for a hydrodesulfurization (HDS) catalyst for the first time.

Synthesis of Mesoporous γ-Al2O3 with Spongy Structure: In-Situ Conversion of Metal-Organic Frameworks and Improved Performance as Catalyst Support in Hydrodesulfurization

Over the past decades, extensive efforts have been devoted to modulating the textural properties, morphology and microstructure of γ-Al2O3, since the physiochemical properties of γ-Al2O3 have close correlations with the performance of hydrotreating catalysts. In this work, a spongy mesoporous γ-alumina (γ-Al2O3) was synthesized using Al-based metal-organic frameworks (Al-MOFs) as precursor by two-step pyrolysis, and this Al-MOF-derived γ-Al2O3 was used as hydrodesulfurization (HDS) catalyst support, to explore the effect of support on the HDS performance. Compared with industrial γ-Al2O3, the spongy alumina displayed well-developed porosity with relatively high surface area, large pore volume, and abundant weak Lewis acid sites. Based on catalyst characterization and performance evaluation, sulfurized molybdenum and cobalt molecules were able to incorporate and highly disperse into channels of the spongy mesoporous alumina, increasing the dispersion of active catalytic species. The spongy γ-Al2O3 was also able to enhance the diffusion efficiency and mass transfer of reactant molecules due to its improved texture properties. Therefore, the corresponding catalyst presented higher activities toward HDS of dibenzothiophene (DBT) than that from industrial alumina. The spongy mesoporous γ-alumina synthesized by Al-MOFs provides a new alternative to further develop novel γ-alumina materials with different texture and various nanoporous structures, considering the diversity of MOFs with different compositions, topological structures, and morphology.