Pd-Nanoparticles@Layered Double Hydroxide/ Reduced Graphene Oxide (Pd NPs@LDH/rGO) Nanocomposite Catalyst for Highly Efficient Green Reduction of Aromatic Nitro Compounds

A facile chemical method is developed to fabricate well-dispersed and an approx. 5 nm sized Pd-nanoparticles (Pd-NPs) deposited ZnAl-LDH/rGO nanocomposite (Pd NPs@LDH/rGO) as a highly efficient and stable catalyst for...

Cobalt nanoparticle supported on layered double hydroxide: Effect of nanoparticle size on catalytic hydrogen production by NaBH4 hydrolysis

Catalytic hydrolysis of sodium borohydride (NaBH₄) is a promising method to provide clean hydrogen (H₂) energy for portable devices. Therefore, designing a non-noble metal catalyst that performs well in this hydrolysis is essential. Cobalt-nanoparticles (Co-NPs) supported on magnesium-aluminium layered double hydroxide (LDH) with various mean diameter were synthesized by changing concentration of cobalt-citrate anion (Co-citrate) precursor used for ion exchange with the LDH host. Then the Co-citrate intercalated LDHs were reduced with NaBH₄ to form Co-NPs. Evidence of successful intercalation was shown by X-ray diffraction (XRD) and Fourier-Transform Infrared spectroscopy (FT-IR). Transmission Electron Microscope (TEM) and Scanning TEM (STEM) observations revealed that Co-NPs were in metallic state and their mean diameter increased with the concentration of Co-citrate solution. Nitrogen physisorption isotherms showed that the surface structure of LDHs transformed from non-porous to mesoporous after chemical reduction, which indicated that the Co-NPs were formed in the interlayer of LDHs. Catalytic hydrolysis of NaBH₄ at 25 °C clarified that the catalyst synthesized from 6 mM Co-citrate solution showed the highest H₂ generation rate of 4520 ± 251 mL min^-1·g_Co^-1, indicating the catalyst had the optimum size of Co-NP. This activity could be considered relatively higher compared to unsupported cobalt and many other supported cobalt-base catalysts previously reported. It was also clearly shown that size of Co-NPs supported on LDH could be a significant parameter as it allowed better accessibility of reactants to the active catalyst surface to obtain maximum activity. For this optimum catalyst, the activation energy was evaluated to be 56.9 kJ mol^-1. Although the catalyst was able to achieve almost the same conversion when the catalyst was repeatedly tested five times under the same condition, the catalytic activity decreased gradually. Overall, it could be revealed that Co-NPs supported on LDHs have a huge potential to be used for H₂ energy production.

Ag/LDH-itaconic acid-gellan gam nanocomposites: Facile and green synthesis, characterization, and excellent catalytic reduction of 4-nitrophenol

The catalytic reduction reaction is one of the most commonly used solutions to convert high-risk contaminants into safe or low-risk materials. Today, with the increasing water pollution, the urgent need for efficient and effective catalysts is felt more than ever. For this purpose, for the first time, a green catalyst composed of silver nanoparticles anchored on itaconic acid-modified Ca-Al layered double hydroxide/gellan gum nanocomposite (Ag/LDH-ITA-GG NC) was prepared from a green approach without the use of any toxic organic solvents. To gain an in-depth insight into the physicochemical properties of the catalyst, different techniques including nitrogen adsorption-desorption isotherms, FESEM/mapping, FTIR, TGA, and XRD were used. The catalytic performance of the Ag/LDH-ITA-GG NC toward 4-nitrophenol reduction by NaBH₄ was investigated. The calculated values of the apparent rate constant for this reaction are 0.2142 min^-1 (for 1.0 mg of the catalyst), 0.2375 min^-1 (for 3.0 mg of the catalyst), and 0.2550 min^-1 (for 5.0 mg of the catalyst), indicating that the catalytic conversion of 4-nitrophenol to 4-aminophenol on the Ag/LDH-ITA-GG NC catalyst follows the pseudo-first-order kinetics and is comparable to the previous findings in the literature. The results of this study indicated that Ag/LDH-ITA-GG NC can potentially be utilized as an auspicious high efficient green catalyst for the reduction of pollutants like 4-nitrophenol.

Synthesis of ultrasmall and monodisperse sulfur nanoparticle intercalated CoAl layered double hydroxide and its electro-catalytic water oxidation reaction at neutral pH

Ultrasmall and monodisperse sulfur nanoparticle (S-NP) intercalated CoAl-layered double hydroxide (CoAl-LDH) electrocatalyst exhibits an excellent electrocatalytic activity towards water oxidation with a low overpotential of 250 mV at a high current density of 7.9 mA cm-2 and a Tafel slope of 61 mV dec-1 at the neutral pH condition. The fabrication strategy to achieve a high-performance, robust and durable electrocatalyst is a scale-up in next generation renewable energy fields.

In situ growth of metallic Ag0 intercalated CoAl layered double hydroxides as efficient electrocatalysts for the oxygen reduction reaction in alkaline solutions

Metallic Ag⁰ intercalated CoAl LDHs synthesized via a facile redox process exhibited excellent ORR activity through a four-electron reduction process.

Magnetically separable palladium nanocluster supported iron based metal–organic framework (MIL-88B) catalyst in efficient hydrogenation reactions

A magnetically separable palladium nanocluster (Pd NCs) supported iron based metal–organic framework, Pd@MIL-88B catalyst for enhanced catalytic activity towards the reduction of 4-nitrophenol.