One-Step Hydrothermal/Solvothermal Preparation of Pt/TiO2: An Efficient Catalyst for Biobutanol Oxidation at Room Temperature

The selective oxidation of biobutanol to prepare butyric acid is an important conversion process, but the preparation of low-temperature and efficient catalysts for butanol oxidation is currently a bottleneck problem. In this work, we prepared Pt-TiO2 catalysts with different Pt particle sizes using a simple one-step hydrothermal/solvothermal method. Transmission electron microscopy and X-ray diffraction results showed that the average size of the Pt particles ranged from 1.1 nm to 8.7 nm. Among them, Pt-TiO2 with an average particle size of 3.6 nm exhibited the best catalytic performance for biobutanol. It was capable of almost completely converting butanol, even at room temperature (30 °C), with a 98.9% biobutanol conversion, 98.4% butyric acid selectivity, and a turnover frequency (TOF) of 36 h-1. Increasing the reaction temperature to 80 and 90 °C, the corresponding TOFs increased rapidly to 355 and 619 h-1. The relationship between the electronic structure of Pt and its oxidative performance suggests that the synergistic effect of the dual sites, Pt0 and Pt2+, could be the primary factor contributing to its elevated reactivity.

Catalytic, Antifungal, and Antiproliferative Activity Studies of a New Family of Mononuclear [VIVO]/[VVO2] Complexes

Ligands derived from 2-(1-phenylhydrazinyl)pyridine and salicylaldehyde (HL1), 3-methoxysalicylaldehyde (HL2), 5-bromosalicylaldehyde (HL3), and 3,5-di-tert-butylsalicylaldehyde (HL4) react with [VIVO(acac)2] in MeOH followed by aerial oxidation to give [VVO2(L1)] (1), [VVO2(L2)] (2), [VVO2(L3)] (3), and [VVO2(L4)] (4). Complex [VIVO(acac)(L1)] (5) is also isolable from [VIVO(acac)2] and HL1 in dry MeOH. Structures of all complexes were confirmed by single-crystal X-ray and spectroscopic studies. They efficiently catalyze benzyl alcohol and its derivatives' oxidation in the presence of H2O2 to their corresponding aldehydes. Under optimized reaction conditions using 1 as a catalyst precursor, conversion of benzyl alcohol follows the order: 4 (93%) > 2 (90%) > 1 (86%) > 3 (84%) ≈ 5 (84%). These complexes were also evaluated for antifungal and antiproliferative activities. Complex 3 with MIC50 = 16 μg/mL, 4 with MIC50 = 12 μg/mL, and 5 with MIC50 = 16 μg/mL are efficient toward planktonic cells of Candida albicans and Candida tropicalis. On Michigan cancer foundation-7 (MCF-7) cells, they show comparable cytotoxic effects and exhibit IC50 in the 27.3-33.5 μg/mL range, and among these, 4 exhibits the highest cytotoxicity. A similar study on human embryonic kidney cells (HEK293) confirms their less toxicity at lower concentrations (4 to 16 μg/mL) compared to MCF-7.

Atomic-level insight into effect of substrate concentration and relative humidity on photocatalytic degradation mechanism of gaseous styrene

Substrate concentration and relative humidity (RH) impact the photocatalytic efficiency of industrial aromatic hydrocarbons, but how they influence intermediate formation and degradation pathway remains unclear. With the help of oxygen isotope tracing method, the effects of these two environmental parameters on degradation mechanism of styrene were revealed at atomic level. Increasing styrene concentration favored product formation, which was however inhibited by RH elevation. Gaseous products were not directly formed in gaseous phase, but originated from desorption of interfacial intermediates. The volatile aldehydes and furans further exchanged their ¹⁶O with ¹⁸O in H₂¹⁸O. Increase of RH showed higher enhancement on ¹⁸O distribution in all products and pathways than that of substrate concentration. Low RH preferred high generation of ¹⁶O₂^•- and ⁽¹⁶⁾¹O₂, dominating reaction to form 1-phenyl-1,2-ethandiol, 2-hydroxy-1-phenyl-ethanon and phenylglyoxal monohydrate in sequence. Successive production of benzyl alcohol, benzaldehyde and benzoic acid through the reaction of styrene with promoted ^•18OH by increasing RH became predominant. Hydration was firstly observed and confirmed as an important gaseous transformation step of aldehyde and furan products. Our findings provide a deep insight into photocatalytic degradation mechanism of aromatic hydrocarbons regulated by environmental parameters to further improve their industrial purification efficiency, and are helpful predicting environmental geochemistry fate of organics and preventing their negative impact on natural environment.