Hierarchical 2D/2D interface of nickel aluminum oxide and nickel aluminum layered double hydroxide nanoflowers: An efficient and robust electrocatalyt for overall water splitting

Fabrication and evaluation of a sensitive electrochemical sensor based on double hydroxide in nickel-aluminum nanolayers for the quantification of pyrocatechol

Pyrocatechol, also known as catechol, is a commonly used compound in various industries; however, it can be toxic when used in high concentrations. Therefore, developing a highly sensitive electrochemical sensor for detecting pyrocatechol is important. Our study utilized a co-precipitation technique to fabricate a nanostructured nickel aluminum layered double hydroxide (Ni-Al-LDH). This material was thoroughly analyzed using advanced techniques to confirm its functionality, crystallinity, and morphology. Subsequently, Ni-Al-LDH was employed as an electrocatalyst for the detection of pyrocatechol in actual samples. The modified electrode showed significant responsiveness to pyrocatechol under specific conditions, with a detection limit of 1 nM. This sensor demonstrated analytical potential for the sensitive determination of pyrocatechol across a range of real samples.

Metal-organic framework-derived Se-blended ZrO2 with a nitrogen-doped carbon heterostructure for electrocatalytic overall water splitting

Designing low cost, highly active and efficient non-noble metal bifunctional electrocatalysts with remarkable operational reliability for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is indispensable for large-scale water electrolysis and the development of clean energy conversion technologies. Herein, we decorated a two-dimensional (2D) selenium-blended zirconium dioxide (Se-ZrO2) on the surface of a nitrogen-doped carbon heterostructure (Se-ZrO2@NC), which was derived from Zr-metal-organic frameworks (Zr-MOFs), and loaded it on a stainless-steel mesh electrode. Accordingly, phenomenal electrocatalytic performance was observed for the Se-ZrO2@NC-loaded electrode with a minimum overpotential of 48 mV for the HER and 251 mV for the OER at 10 mA cm-2 current density in acidic and alkaline mediums, respectively. Moreover, a complete cell set up was constructed, where the OER and HER were studied at the anode and cathode, respectively, with a cell potential of 1.58 V to reach a current density of 10 mA cm-2 together with an exciting long-term stability of over 48 h. The developed Se-blended 2D transition metal dioxides on the 2D nitrogen-doped carbon heterostructure extended to a variety of catalytically active materials that would provide highly active and stable electrocatalysts for alkaline water splitting studies.

Highly Active NiO-Ni(OH)2 -Cr2 O3 /Ni Hydrogen Evolution Electrocatalyst through Synergistic Reaction Kinetics

High activity catalysts for hydrogen evolution reaction (HER) play a key role in converting renewable electricity to storable hydrogen fuel. Great effort has been devoted to the search for noble metal free catalysts to make electrolysis viable for practical applications. Here, a non-precious metal oxide/metal catalyst with high intrinsic activity comparable to Pt/C was reported. The electrocatalyst consisting of NiO, Ni(OH)2 , Cr2 O3 , and Ni metal exhibits a low overpotential of 27, 103, and 153 mV at current densities of 10, 100, and 200 mA cm-2 , respectively, in a 1.0 m NaOH electrolyte. The activity is much higher than that of NiOx /Ni or Cr2 O3 alone, showing the synergistic effect of NiOx /Ni and Cr2 O3 on catalyzing HER. Density functional theory calculations shows that NiO and Cr2 O3 on Ni surface lower the disassociation energy barrier for breaking H-OH bond, while Ni(OH)2 and Cr2 O3 create preferred sites on Ni surface with near-zero H* adsorption free energy to promote H* to gaseous H2 evolution. These synergistic effects of multiple-oxides/metal composition enhance the disassociation of H-OH and the evolution of H* to gaseous H2 , thus achieving high activity and demonstrating a promising composition design for noble metal free catalyst.