Xuehui Li

In situ sulfurized CoMoS/CoMoO4 shell–core nanorods supported on N-doped reduced graphene oxide (NRGO) as efficient electrocatalyst for hydrogen evolution reaction

Many strategies, such as doping metal, designing low-dimensional nanostructures, and enhancing the utilization of active sites based on a conductive support, have been intensively pursued to improve the intrinsic activity of transition metal chalcogenides for the hydrogen evolution reaction (HER). However, integrating all the above-mentioned merits into one electrocatalyst is still a significant challenge. Herein, we have successfully prepared uniform CoMoS/CoMoO4 (CMS) shell–core nanorods, with a diameter of 60 nm and a length of 800 nm, supported on N-doped reduced graphene oxide (NRGO). The obtained CMS/NRGO can combine many advantages, including transition metal doping, one-dimensional nanorods, and the superior conductivity of NRGO, resulting in very promising HER properties and excellent stability. The optimum sulfurization temperature for unsupported CMS nanorods has been explored using uniform CoMoO4 nanorods as a precursor. Although CMS-3 prepared with a sulfurization temperature of 300 °C has been found to possess the optimum activity for the HER, when adopting NRGO as a support, CMS-3/NRGO exhibits an impressive enhancement in HER performances with a low overpotential of 80 mV, a small Tafel slope of 58 mV dec−1, and a large exchange current density of 428 μA cm−2. In addition, the electrocatalytic activity of CMS-3/NRGO shows a negligible delay after 1000 cycles, indicating its robust electrochemical stability in acid electrolyte solution. Therefore, adopting low-temperature sulfurization of one-dimensional metal oxide precursors supported on NRGO may be a promising strategy for obtaining excellent electrocatalysts for the HER.

Novel Binary Promoter NiCoMo Layered Molybdate Catalyst: Synthesis, Characterization and Hydrodesulfurization Property

A novel binary promoter NiCoMo layered molybdate was synthesized as potential hydrodesulfurization (HDS) catalyst precursor by chemical precipitation from a solution containing nickel nitrate, cobalt nitrate and ammonium heptamolybdate. NiMo and CoMo layered molybdates were also prepared for comparison by the same method. The NiCoMo, NiMo and CoMo layered molybdates were characterized by means of N2 physisorption, XRD, FT-IR, TG–DSC–MS, SEM and HRTEM, and catalytic properties were evaluated in the continuous HDS of dibenzothiophene (DBT) and straight-run gas oil. The characterization results indicated the three precursors were endowed with the same structure of ammonium nickel molybdate, and catalytic results showed that the NiCoMo catalyst exhibited higher HDS activity towards DBT and straight-run gas oil, which might be more attractive for industrial applications.Graphical Abstract

A non-template approach to fabricate mesoporous alumina with predefined morphology by solid-state transformation of Al-based metal–organic frameworks

Mesoporous alumina with different morphologies was synthesized via thermal decomposition of the Al-based metal–organic frameworks (Al-MOFs) MIL-110 and MIL-100, in which Al-MOFs were used as the Al source and precursor. The hexagon rod-shaped and octahedron-shaped alumina products with morphology retained from their precursors were obtained and characterized. The results show that the construction of Al-MOFs, especially the aluminium building units plays a key role in the textural structure of the obtained alumina products. Besides, the differences in textural properties as well as the possible formation mechanism of the final alumina products are well explained by taking into account thermal behaviour and intrinsic structure features, especially the aluminium building units, of the Al-MOFs precursors. This work presents an easy new method to produce alumina with tailored morphology, tunable texture and microstructure, which is also an operational method fit for other metal oxide materials.

Waugh-Type NiMo Heteropolycompounds as More Effective Precursors of Hydrodesulfurization Catalyst

NiMo catalysts were prepared using Waugh-type NiMo heteropolycompounds as active phase precursors and evaluated in hydrodesulfurization (HDS) of dibenzothiophene (DBT). These catalysts were compared with corresponding reference catalysts prepared from the conventional precursors (ammonium heptamolybdate and nickel nitrate). Prepared catalysts were characterized by N2 physisorption, XRD, FT-IR, H2-TPR, DRIFT of CO adsorption and HRTEM techniques. It was found that NiMo catalysts prepared from Waugh-type NiMo HPCs showed higher performance in HDS of DBT than their counterparts. Possible reasons of this result were discussed.Graphical Abstract

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.