Synergistic redox enhancement: silver phosphate augmentation for optimizing magnesium copper phosphate in efficient energy storage devices and oxygen evolution reaction

The implementation of battery-like electrode materials with complicated hollow structures, large surface areas, and excellent redox properties is an attractive strategy to improve the performance of hybrid supercapacitors. The efficiency of a supercapattery is determined by its energy density, rate capabilities, and electrode reliability. In this study, a magnesium copper phosphate nanocomposite (MgCuPO4) was synthesized using a hydrothermal technique, and silver phosphate (Ag3PO4) was decorated on its surface using a sonochemical technique. Morphological analyses demonstrated that Ag3PO4 was closely bound to the surface of amorphous MgCuPO4. The MgCuPO4 nanocomposite electrode showed a 1138 C g-1 capacity at 2 A g-1 with considerably improved capacity retention of 59% at 3.2 A g-1. The increased capacity retention was due to the fast movement of electrons and the presence of an excess of active sites for the diffusion of ions from the porous Ag3PO4 surface. The MgCuPO4-Ag3PO4//AC supercapattery showed 49.4 W h kg-1 energy density at 550 W kg-1 power density and outstanding capacity retention (92% after 5000 cycles). The experimental findings for the oxygen evolution reaction reveal that the initial increase in potential required for MgCuPO4-Ag3PO4 is 142 mV, indicating a clear Tafel slope of 49 mV dec-1.

Phosphorus-Alloying as a Powerful Method for Designing Highly Active and Durable Metal Nanoparticle Catalysts for the Deoxygenation of Sulfoxides: Ligand and Ensemble Effects of Phosphorus

The modification of metal nanoparticles (NPs) by incorporating additional metals is a key technique for developing novel catalysts. However, the effects of incorporating nonmetals into metal NPs have not been widely explored, particularly in the field of organic synthesis. In this study, we demonstrate that phosphorus (P)-alloying significantly increases the activity of precious metal NPs for the deoxygenation of sulfoxides into sulfides. In particular, ruthenium phosphide NPs exhibit an excellent catalytic activity and high durability against sulfur-poisoning, outperforming conventional catalysts. Various sulfoxides, including drug intermediates, were deoxygenated to sulfides with excellent yields. Detailed investigations into the structure-activity relationship revealed that P-alloying plays a dual role: it establishes a ligand effect on the electron transfer from Ru to P, facilitating the production of active hydrogen species, and has an ensemble effect on the formation of the Ru-P bond, preventing strong coordination with sulfide products. These effects combine to increase the catalytic performance of ruthenium phosphide NPs. These results demonstrate that P-alloying is an efficient method to improve the metal NP catalysis for diverse organic synthesis.

Ni2P nanosheet array for high-efficiency electrohydrogenation of nitrite to ammonia at ambient conditions

Ammonia (NH₃) plays an important role in agriculture and industry. The industry-scale production mainly depends on the Haber-Bosch process suffering from issues of environment pollution and energy consumption. Electrochemical reduction can degrade nitrite (NO₂^-) pollutants in the environment and convert it into more valuable NH₃. Here, Ni₂P nanosheet array on nickel foam is proposed as a 3D electrocatalyst for high-efficiency electrohydrogenation of NO₂^- to NH₃ under ambient reaction conditions. When tested in 0.1 M phosphate buffer saline with 200 ppm NO₂^-, such Ni₂P/NF is able to obtain a large NH₃ yield rate of 2692.2 ± 92.1 μg h^-1 cm^-2 (3282.9 ± 112.3 μg h^-1 mg_cat.^-1), a high Faradic efficiency of 90.2 ± 3.0%, and selectivity of 87.0 ± 1.7% at -0.3 V versus a reversible hydrogen electrode. After 10 h of electrocatalytic reduction, the conversion rate of NO₂^- achieves near 100%. The catalytic mechanism is further investigated by density functional theory calculations.

Ethane dehydrogenation performance and high temperature stability of silica supported cobalt phosphide nanoparticles

Cobalt phosphide catalysts exhibit remarkable stability and selectivity for ethane dehydrogenation.

Niclosamide encapsulated in mesoporous silica and geopolymer: A potential oral formulation for COVID-19

COVID-19 is a rapidly evolving emergency, for which there have been no specific medication found yet. Therefore, it is necessary to find a solution for this ongoing pandemic with the aid of advanced pharmaceutics. What is proposed as a solution is the repurposing of FDA approved drug such as niclosamide (NIC) having multiple pathways to inactivate the SARS-CoV-2, the specific virion that induces COVID-19. However, NIC is hardly soluble in an aqueous solution, thereby poor bioavailability, resulting in low drug efficacy. To overcome such a disadvantage, we propose here an oral formulation based on Tween 60 coated drug delivery system comprised of three different mesoporous silica biomaterials like MCM-41, SBA-15, and geopolymer encapsulated with NIC molecules. According to the release studies under a gastro/intestinal solution, the cumulative NIC release out of NIC-silica nanohybrids was found to be greatly enhanced to ~97% compared to the solubility of intact NIC (~40%) under the same condition. We also confirmed the therapeutically relevant bioavailability for NIC by performing pharmacokinetic (PK) study in rats with NIC-silica oral formulations. In addition, we discussed in detail how the PK parameters could be altered not only by the engineered porous structure and property, but also by interfacial interactions between ion-NIC dipole, NIC-NIC dipoles and/or pore wall-NIC van der Waals in the intra-pores of silica nanoparticles.

Nickel Phosphide Catalysts as Efficient Systems for CO2 Upgrading via Dry Reforming of Methane

This work establishes the primordial role played by the support’s nature when aimed at the constitution of Ni2P active phases for supported catalysts. Thus, carbon dioxide reforming of methane was studied over three novel Ni2P catalysts supported on Al2O3, CeO2 and SiO2-Al2O3 oxides. The catalytic performance, shown by the catalysts’ series, decreased according to the sequence: Ni2P/Al2O3 > Ni2P/CeO2 > Ni2P/SiO2-Al2O3. The depleted CO2 conversion rates discerned for the Ni2P/SiO2-Al2O3 sample were associated to the high sintering rates, large amounts of coke deposits and lower fractions of Ni2P constituted in the catalyst surface. The strong deactivation issues found for the Ni2P/CeO2 catalyst, which also exhibited small amounts of Ni2P species, were majorly associated to Ni oxidation issues. Along with lower surface areas, oxidation reactions might also affect the catalytic behaviour exhibited by the Ni2P/CeO2 sample. With the highest conversion rate and optimal stabilities, the excellent performance depicted by the Ni2P/Al2O3 catalyst was mostly related to the noticeable larger fractions of Ni2P species established.

Naphthalene Hydrogenation Saturation over Ni2P/Al2O3 Catalysts Synthesized by Thermal Decomposition of Hypophosphite

A series of Ni₂P/Al₂O₃ catalysts with different Ni₂P loadings were synthesized via thermal decomposition of hypophosphite and employed for naphthalene hydrogenation saturation. Results showed that Ni₂P loading greatly affected Ni₂P particle size and the number of active sites of the as-synthesized catalysts, which was derived from the variable interaction between POx and Al₂O₃. When the hydrogenation saturation reaction was performed at 300 °C, 4 MPa, a H₂/oil volume ratio of 600, and a liquid hourly space velocity (LHSV) of 3 h^-1, 98% naphthalene conversion and 98% selectivity to decalin were achieved over Ni₂P/Al₂O₃ catalysts with 10 wt % Ni₂P. The superior naphthalene hydrogenation saturation performance was ascribed to the large specific surface area (169 m²·g^-1), small Ni₂P particle size (3.8 nm), and the high number of exposed active sites (CO sorption 30 μmol·g^-1), which were beneficial to the adsorption and diffusion of the reactant molecules on the catalyst.

Ni2P promotes the hydrogenation activity of naphthalene on wrinkled silica nanoparticles with tunable hierarchical pore sizes in a large range

Herein, a series of wrinkled silica nanoparticles with hierarchical pore (HPWSNs) supports were successfully prepared by dual-templating, and the special wrinkle pore structures in the monodisperse HPWSN samples were found to be beneficial for reducing the diffusion resistance of macromolecular aromatic compounds and achieving high dispersion of Ni₂P active phases. Moreover, the distance between wrinkles in silica nanoparticles could be easily tuned by changing the ratios of SDS/CTAB through charge-reversed interactions. It was found that the Ni₂P/HPWSNs-0.13 catalyst with smallest Ni₂P particles had highest surface area and biggest pore volume. Furthermore, the Ni₂P/HPWSNs-0.13 catalyst exhibited highest naphthalene hydrogenation conversion as well as 99.9% selectivity to decalin at 320 °C. To correlate the internal relationship between the macroscopic catalytic performance in the experiment and the atomic chemistry in the microscopic point of view, DFT calculations were performed, and the results showed that stronger adsorptions of naphthalene and tetralin occurred over the Ni(2) sites than those over the Ni(1) sites. Therefore, it can be concluded that the superior catalytic activity of the Ni₂P/HPWSNs-0.13 catalyst is due to the synergistic effect of the center-radical framework structure and the small sizes of Ni₂P particles, which are conducive to exposing more Ni(2) sites on the support surface, thus inducing more H for the naphthalene hydrogenation reaction.

One-Pot Synthesis of Active Carbon-Supported Size-Tunable Ni2P Nanoparticle Catalysts for the Pyrolysis Bio-Oil Upgrade

Catalytic hydrodeoxygenation (HDO) over Ni₂P-based catalysts is a promising technology for the pyrolysis bio-oil upgrading. However, substantial challenges still remain in the realization of the size effect for phosphide catalysts in catalyzing this reaction, and the precise size engineering of these catalysts is difficult. In this work, the Ni₂P/active carbon (AC) catalysts with varying nickel phosphide nanoparticle sizes were one-pot prepared via the modified organic liquid chemical reaction method. The Ni₂P-based catalysts were tested for HDO of the pyrolysis oil model compound (salicylaldehyde), and the conversion of salicylaldehyde first increases and then decreases with the increase of Ni₂P nanoparticle size, demonstrating that the activity for HDO of salicylaldehyde can be controlled by using nickel phosphides of varying nanoparticle sizes. The Ni₂P-2/AC catalyst with approximately 5.49 nm Ni₂P nanoparticle size exhibited the highest activity with conversion of salicylaldehyde reaching over 99% within 180 min under 220 °C, 2 MPa H₂ pressure, and the corresponding yield toward o-cresol was over 97%.