SiO2-Surface-Assisted Controllable Synthesis of TaON and Ta3N5 Nanoparticles for Alkene Epoxidation

Solar water oxidation using TaON–BiVO4 photoanodes functionalized with WO3

Enhancements in the water oxidation photocurrent densities at 1.23 V (vs. RHE) by 9.2-fold compared to unmodified TaON–BiVO₄ were achieved with the use of the WO₃/TaON–BiVO₄ photoanodes under visible-light irradiation in this work.

HfN Nanoparticles: An Unexplored Catalyst for the Electrocatalytic Oxygen Evolution Reaction

Water electrolysis is one of the most promising methods to produce H₂ and O₂ as high potential fuels. Comparing the two half-reactions, the oxygen evolution reaction (OER) is the more difficult to be optimized and still relies on expensive noble metal-based catalysts such as Ru or Ir. In this paper, we prepared nanoparticles of HfN and Hf₂ ON₂ and tested them for the OER for the first time. The HfN sample, in particular, showed the highest activity, requiring an overpotential of only 358 mV at 10 mA cm^-2 in Fe-free electrolyte and, above all, exhibiting long-term stability. This result places this system amongst one of the most promising catalysts for OER tested to date, in terms of sustainability, activity and stability. The prepared nanoparticles are small (less than 15 nm in diameter), well-defined in shape and crystalline, and were characterised before and after electrochemical testing also via electron microscopy (EM), powder X-ray diffraction (PXRD) and X-ray photoelectron spectroscopy (XPS).

A mononuclear tantalum catalyst with a peroxocarbonate ligand for olefin epoxidation in compressed CO2

A mononuclear tantalum complex bonded to a peroxocarbonate ligand has been proved to be particularly important in the epoxidation reactions.

Morphology-maintaining synthesis of NbN and its catalytic performance in epoxidation

A strategy for the synthesis of NbN with different morphologies was provided and the reactivity for epoxidation was investigated.

Structural Design and Electronic Modulation of Transition-Metal-Carbide Electrocatalysts toward Efficient Hydrogen Evolution

As the key of hydrogen economy, electrocatalytic hydrogen evolution reactions (HERs) depend on the availability of cost-efficient electrocatalysts. Over the past years, there is a rapid rise in noble-metal-free electrocatalysts. Among them, transition metal carbides (TMCs) are highlighted due to their structural and electronic merits, e.g., high conductivity, metallic band states, tunable surface/bulk architectures, etc. Herein, representative efforts and progress made on TMCs are comprehensively reviewed, focusing on the noble-metal-like electronic configuration and the relevant structural/electronic modulation. Briefly, specific nanostructures and carbon-based hybrids are introduced to increase active-site abundance and to promote mass transportation, and heteroatom doping and heterointerface engineering are encouraged to optimize the chemical configurations of active sites toward intrinsically boosted HER kinetics. Finally, a perspective on the future development of TMC electrocatalysts is offered. The overall aim is to shed some light on the exploration of emerging materials in energy chemistry.

From single-site tantalum complexes to nanoparticles of Ta x N y and TaO x N y supported on silica: elucidation of synthesis chemistry by dynamic nuclear polarization surface enhanced NMR spectroscopy and X-ray absorption spectroscopy

Air-stable catalysts consisting of tantalum nitride nanoparticles represented as a mixture of Ta x N y and TaO x N y with diameters in the range of 0.5 to 3 nm supported on highly dehydroxylated silica were synthesized from TaMe5 (Me = methyl) and dimeric Ta2(OMe)10 with guidance by the principles of surface organometallic chemistry (SOMC). Characterization of the supported precursors and the supported nanoparticles formed from them was carried out by IR, NMR, UV-Vis, extended X-ray absorption fine structure, and X-ray photoelectron spectroscopies complemented with XRD and high-resolution TEM, with dynamic nuclear polarization surface enhanced NMR spectroscopy being especially helpful by providing enhanced intensities of the signals of 1H, 13C, 29Si, and 15N at their natural abundances. The characterization data provide details of the synthesis chemistry, including evidence of (a) O2 insertion into Ta-CH3 species on the support and (b) a binuclear to mononuclear transformation of species formed from Ta2(OMe)10 on the support. A catalytic test reaction, cyclooctene epoxidation, was used to probe the supported nanoparticles, with 30% H2O2 serving as the oxidant. The catalysts gave selectivities up to 98% for the epoxide at conversions as high as 99% with a 3.4 wt% loading of Ta present as Ta x N y /TaO x N y .

MoOx–pyridine organic–inorganic hybrid wires as a reusable and highly selective catalyst for the oxidation of alcohols: a comparison study between reaction-controlled phase-transfer catalysis and heterogeneous catalysis

The different catalytic behaviors of Mo₃O₁₀(C₅H₆N)₂·H₂O wires (MoO_x–pyridine) in the selective oxidation of alcohols by means of molecular oxygen (O₂) and hydrogen peroxide (H₂O₂) as green oxidants were investigated.

C–N bond hydrogenolysis of aniline and cyclohexylamine over TaOx–Al2O3

Aniline denitrogenation over TaO_x–Al₂O₃ leads to chemically inert Ta-imido species.

Theoretical study on the surface stabilities, electronic structures and water adsorption behavior of the Ta3N5(110) surface

DFT calculations were performed to study the surface stabilities, electronic structures and water adsorption behavior of the Ta₃N₅(100) surface.

Activating Pd nanoparticles on sol–gel prepared porous g-C3N4/SiO2via enlarging the Schottky barrier for efficient dehydrogenation of formic acid

The g-C₃N₄/SiO₂ nanocomposite was prepared via a sol–gel method to activate Pd nanoparticles for hydrogen generation from formic acid.

Graphitic carbon nitride “reloaded”: emerging applications beyond (photo)catalysis

Despite being one of the oldest materials described in the chemical literature, graphitic carbon nitride (g-C₃N₄) has just recently experienced a renaissance as a highly active photo/electrocatalyst, and the metal-free polymer was also shown to be have diverse applications in various fields.

Defect-meditated efficient catalytic activity toward p-nitrophenol reduction: A case study of nitrogen doped calcium niobate system

This work reported on the synthesis of a series of nitrogen doped Ca2Nb2O7 with tunable nitrogen content that were found to be efficient and green noble-metal-free catalysts toward catalytic reduction of p-nitrophenol. XPS and ESR results indicated that the introduction of nitrogen in Ca2Nb2O7 gave rise to a large number of defective nitrogen and oxygen species. Defective nitrogen and oxygen species were found to play synergetic roles in the reduction of p-nitrophenol. The underlying mechanism is completely different from those reported for metallic nanoparticles. Moreover, the more negative conduction band edge potential enabled nitrogen doped Ca2Nb2O7 to show photo-synergistic effects that could accelerate the reduction rate toward p-nitrophenol under UV light irradiation. This work may provide a strategy for tuning the catalytic performance by modulating the chemical composition, electronic structure as well as surface defect chemistry.

Controlled nitridation of tantalum (oxy)nitride nanoparticles towards optimized metal-support interactions with gold nanocatalysts

Optimized metal-support interactions were achieved on ionothermally prepared tantalum (oxy)nitrides with controlled nitridation, and the as-formed Auδ⁻ species on TaON is efficient for nitrobenzene hydrogenation.

Metal non-oxide nanostructures developed from organic-inorganic hybrids and their catalytic application

The rational design of metal non-oxides is important for their catalytic application, which is however limited by the fact that the current synthetic strategies are short of effective control over formation reactions. Recently, the hybrids evenly integrating organic with inorganic molecules on a nanoscale significantly provided quasi-homogeneous reactions towards well-defined nanocatalysts of metal non-oxides, in which their structures and properties can be modulated in a wide range. Focusing on the nanostructures and the related catalytic behaviors, this feature article seeks to provide some control on the key structures and properties of metal non-oxides (e.g. carbides, nitrides, sulfides and selenides). It is thus anticipated to shed some light on the development of emerging materials for efficient catalysis, especially those used in energy utilization.