Co/MoS2 nanocomposite catalyzed H2 evolution upon dimethylamine-borane hydrolysis and in situ tandem reaction

Capturing Carbon Dioxide by Co-Decorated Molybdenum Disulfide: Boosting Efficiency Achievement of a Porous Two-Dimensional Nanomaterial via DFT Study

Stable and efficient conversion of carbon dioxide (CO₂) into useful products provides a desirable path toward achieving green fuel. Accurate sensing of CO₂ capacity is also desired and can be reached as a result of conversion or adsorption. In this study, the electronic and structural properties of cobalt (Co) transition metal doped over the two-dimensional (2D) porous molybdenum disulfide (P-MoS₂) surface toward CO₂ adsorption were studied using the D3-corrected density functional theory (DFT-D3) method. Results confirm that there are three most stable sites for Co decoration over P-MoS₂, having led to a maximum number of CO₂ molecules each adsorbed on a Co atom. The Co atom intends to bind to the P-MoS₂ surface as a single, double, and double-sided catalyst. The Co binding capacity and CO₂ adsorption ability on the Co/P-MoS₂ including the most stable CO₂ possible structure were investigated. This work demonstrates maximizing CO₂ capture by providing the possibility of CO₂ adsorption on a double-sided Co-decorated P-MoS₂. Therefore, thin-layer two-dimensional catalyst has great potential for CO₂ capture and storage. The charge transfer in the process of CO₂ adsorption complexation on Co/P-MoS₂ is high and encourages the development of high-quality 2D materials for well-organized gas sensing applications.

"On-Off" Control for On-Demand H2 Release upon Dimethylamineborane Hydrolysis over Ru0.8Ni0.2/MoS2 Nanohybrids

In spite of the fact that remarkable developments are achieved in the design and development of novel nanocatalysts for H₂ release upon dimethylamineborane hydrolysis, the development of an "on-off" switch for demand-based H₂ evolution upon dimethylamineborane hydrolysis is still a matter of supreme importance, however. Herein, we synthesized a string of MoS₂ nanosheet-supported RuNi bimetallic nanohybrids (Ru_xNi_1-x/MoS₂), by fixation of RuNi nanoparticles at the MoS₂ surface, for the H₂ evolution upon the hydrolysis of dimethylamineborane at 30 °C. For safely and effectively generating, transporting, and storing H₂ gas, the selective "on-off" switch for on-demand H₂ evolution upon dimethylamineborane hydrolysis over the Ru_0.8Ni_0.2/MoS₂ nanohybrid has been successfully realized by the Zn²⁺/EDTA-2Na system. In particular, the H₂ evolution is totally switched off by adding Zn(NO₃)₂. It seems that Zn²⁺ ions are attached and anchored at the Ru_0.8Ni_0.2/MoS₂ surface, inhibiting their surface-active sites, leading to the termination of H₂ evolution. Then, the H₂ generation is subsequently reactivated by adding the EDTA-2Na solution because of its excellent coordination ability with Zn²⁺ ions. This study not only offers a new and efficient RuNi nanocatalyst for dimethylamineborane hydrolysis but also proposes a new method for the demand-based H₂ production.

Polymer Hydrogel Supported Ni/Pd Alloys for Hydrogen Gas Production from Hydrolysis of Dimethylamine Borane with a Long Recyclable Lifetime

Hydrogen gas production can be produced from dimethylamine borane by the catalytic effect of metal nanoparticles. Past research efforts were heavily focused on dehydrogenation in organic solvents. In this study, hydrolysis of the borane in aqueous solutions was investigated, which bears two significant advantages: that two-thirds of the hydrogen generated originate from water and that the hydrogen storage materials are non-flammable. Polymer hydrogels serve as good carriers for metal particles as catalysts in aqueous solutions. Kinetic analysis of hydrogen production was performed for Ni/Pd bimetallic nanoclusters dispersed in a polymer hydrogel with a 3-D network structure. The reaction catalyzed by the bimetallic nanoclusters has an activation energy of only 34.95 kJ/mol, considerably lower than that by Ni or other metal catalysts reported. A significant synergistic effect was observed in the Ni/Pd bimetallic catalysts (Ni–Pd = 20/1) with a higher activity than Pd or Ni alone. This proves the alloy nature of the nanoparticles in the borane hydrolysis and the activation of water and borane by both metals to break the O–H and B–H bonds. The hydrogel with the Ni/Pd metal can be recycled with a much longer lifetime than all the previously prepared catalysts. The aqueous borane solutions with a polymer hydrogel can become a more sustainable hydrogen supplier for long-term use.

Mechanistic insights into H2 evolution via water splitting at the expense of B2(OH)4: a theoretical study

H₂ has been comprehensively deemed a promising potential candidate to replace traditional fossil fuel-based energy. Typically, the hydrolysis of most hydrogen-rich boron hydrides (e.g. NaBH₄, NH₃BH₃ and Me₂NHBH₃) catalyzed by nanomaterials generates H₂ with only one H atom supplied by water and the other one by a hydrogen-rich boron hydride. Interestingly, both H atoms of produced H₂ are provided by water upon hydrolysis of B₂(OH)₄. Herein, the catalytic mechanisms of H₂ evolution upon water splitting at the expense of B₂(OH)₄ in its hydrolysis reactions catalyzed by acid, base or metal nanoparticles have been investigated by density functional theory (DFT) calculations. By computational studies, the mechanisms of catalysis by base and metal nanoparticles are basically the same as those speculated from our previous experiments. The previously proposed acid catalytic mechanism has been overturned, however. This study not only provides important insights into the catalytic mechanism for water splitting at the expense of B₂(OH)₄, but also opens up an exciting opportunity to use water to store H₂.