Enhanced dispersion of nickel nanoparticles on SAPO-5 for boosting hydroisomerization of n-hexane

Ni3S2/Co9S8 embedded poor crystallinity NiCo layered double hydroxides hierarchical nanostructures for efficient overall water splitting

Nickel-cobalt bimetallic layered double hydroxides (NiCo LDHs) are potential electrocatalysts with high performance and stability for overall water-splitting. However, its weak conductivity limits its practical applications. Herein, a simple hydrothermal in-situ conversion strategy is employed for constructing the novel heterogeneous electrocatalyst of Ni₃S₂/Co₉S₈ embedded poor crystallinity (Pc) NiCo LDH nanosheet arrays grown on the Ni foam (Pc-NiCo LDH/ Ni₃S₂/Co₉S₈), which can improve the conductivity via regulating the crystallinity. The crystallinity of NiCo LDH is well regulated by adjusting the amount of sulfur source, and the construction of Ni₃S₂/Co₉S₈ heterostructure exposes more active sites, improves the electrical conductivity, enhances the electronic interaction between NiCo LDH and Ni₃S₂/Co₉S₈, and significantly promotes the kinetics of water splitting. The optimized Pc-NiCo LDH/Ni₃S₂/Co₉S₈ hierarchical structure as both the anode and cathode exhibit the overall water splitting performance with the cell voltage of only 1.744 V to achieve the current density of 50 mA cm^-2 in the alkaline media and shows the competitive H₂ and O₂ production rate of 6.4 and 3.1 μL s^-1, respectively, suggesting its potential practical applications. This work provides a novel idea for the design of multiphase composite electrocatalysts applied in water splitting.

Hydrodeoxygenation–Isomerization of Methyl Palmitate over SAPO-11-Supported Ni-Phosphide Catalysts

Ni-phosphide catalysts on SAPO-11 were studied in the hydrodeoxygenation–isomerization of methyl palmitate (C15H31COOCH3—MP). The catalysts were synthesized using temperature-programmed reduction (TPR) of a phosphate precursor ((NH4)2HPO4 and Ni(CH3CH2COO)2), TPR of a phosphite precursor (H3PO3 and Ni(OH)2), and using phosphidation of Ni/SAPO-11 by PPh3 in the liquid phase. The samples were characterized by ICP-AES chemical analysis, N2 physisorption, NH3-TPD, XRD, and TEM. First, the screening of the catalysts prepared by the TPR method was carried out in a semi-batch autoclave to determine the influence of the preparation method and conditions on one-pot HDO–isomerization (290–380 °C, 2–3 MPa). The precursor’s nature and the amount of phosphorus strongly influenced the activity of the catalysts and their surface area and acidity. Isomerization occurred only at a low P content (Ni/P = 2/1) and blocking of the SAPO-11 channels by unreduced phosphates at higher P contents did not allow us to obtain iso-alkanes. Experiments with liquid phosphidation samples in a continuous-flow reactor also showed the strong dependence of activity on phosphidation duration as well as on Ni content. The highest yield of isomerized products (66% iso-C15–16 hydrocarbons, at complete conversion of O-containing compounds, 340 °C, 2 MPa, and LHSV = 5.3 h−1) was obtained over 7% Ni2P/SAPO-11 prepared by the liquid phosphidation method.