Cyclohexane dehydrogenation over the platinum catalysts supported on carbon nanomaterials

Liberating C-H Bond Activation: Achieving 56% Quantum Efficiency in Photocatalytic Cyclohexane Dehydrogenation

The technology of liquid organic hydrogen carriers presents great promise for large-scale hydrogen storage. Nevertheless, the activation of inert C(sp3)-H bonds in hydrocarbon carriers poses formidable challenges, resulting in a sluggish dehydrogenation process and necessitating high operating temperatures. Here, we break the shackles of C-H bond activation under visible light irradiation by fabricating subnanometer Pt clusters on defective Ce-Zr solid solutions. We achieved an unprecedented hydrogen production rate of 2601 mmol gcat.-1 h-1 (turnover frequency >50,000 molH2 molPt-1 h-1) from cyclohexane, surpassing the most advanced thermo- and photocatalysts. By optimizing the temperature-dominated hydrogen transfer process, achievable by harnessing hitherto wasted infrared light in sunlight, an astonishing 56% apparent quantum efficiency and a 5.2% solar-to-hydrogen efficiency are attained at 353 K. Our research stands as one of the most effective photocatalytic processes to date, holding profound practical significance in the utilization of solar energy and the exploitation of alkanes.

The Attractiveness of the Ternary Rh-Pd-Pt Alloys for CO Oxidation Process

Ternary alloys of platinum group metals attract a growing interest due to their unique catalytic properties. The present research is aimed to synthesize a series of Rh-Pd-Pt alloys with varied ratios of metals using a single-source precursor approach. Rhodium and palladium are partly miscible metals, while each of these metals is unlimitedly miscible with platinum. Thermolysis of complex salts used as a precursor results in the formation of metastable systems. The 3D nanostructure alloys are being formed after the complete decomposition of the single-source precursor. High-resolution transmission electron microscopic studies have shown that the nanoalloys are composed of interconnected polycrystalline ligaments with a mean diameter of 50 nm. The single-phase composition is confirmed by an X-ray diffraction analysis. The ratio of metals plays an important role in determining the catalytic activity of alumina-supported alloys and their thermal stability. According to UV-vis spectroscopy data, the higher palladium portion corresponds to worse dispersion of initially prepared, fresh catalysts. Treatment of the catalysts under prompt thermal aging conditions (up to 800 °C) causes redispersion of palladium-rich alloyed nanoparticles, thus leading to improved catalytic activity and thermal stability.