Yibo Yan

Microwave-assisted synthesis of PtRu/CNT and PtSn/CNT catalysts and their applications in the aerobic oxidation of benzyl alcohol in base-free aqueous solutions

Ru promoted the reaction by reacting with surface Pt-hydride species to liberate free Pt active sites while adding Sn enhances the electronic interactions. Moreover, acid functionalized CNT was identified as the superior support due to its hydrophilic surfaces, conical stacking structures, and tubular structure with mesoporous open-ended morphology.

Heterojunction-Assisted Co3S4@Co3O4 Core–Shell Octahedrons for Supercapacitors and Both Oxygen and Carbon Dioxide Reduction Reactions

Expedition of electron transfer efficiency and optimization of surface reactant adsorption products desorption processes are two main challenges for developing non-noble catalysts in the oxygen reduction reaction (ORR) and CO2 reduction reaction (CRR). A heterojunction prototype on Co3 S4 @Co3 O4 core-shell octahedron structure is established via hydrothermal lattice anion exchange protocol to implement the electroreduction of oxygen and carbon dioxide with high performance. The synergistic bifunctional catalyst consists of p-type Co3 O4 core and n-type Co3 S4 shell, which afford high surface electron density along with high capacitance without sacrificing mechanical robustness. A four electron ORR process, identical to the Pt catalyzed ORR, is validated using the core-shell octahedron catalyst. The synergistic interaction between cobalt sulfide and cobalt oxide bicatalyst reduces the activation energy to convert CO2 into adsorbed intermediates and hereby enables CRR to run at a low overpotential, with formate as the highly selective main product at a high faraday efficiency of 85.3%. The remarkable performance can be ascribed to the synergistic coupling effect of the structured co-catalysts; heterojunction structure expedites the electron transfer efficiency and optimizes surface reactant adsorption product desorption processes, which also provide theoretical and pragmatic guideline for catalyst development and mechanism explorations.

Hydrothermally driven three-dimensional evolution of mesoporous hierarchical europium oxide hydrangea microspheres for non-enzymatic sensors of hydrogen peroxide detection

Hydrothermal synthesis of mesoporous europium oxide hierarchical hydrangea microspheres for electrochemical detection of hydrogen peroxide (H2O2) has been successfully achieved. The as-prepared stable enzyme-free sensor is capable of performing H2O2 detection in a broad linear range, with high sensitivity, a remarkably low detection limit and rapid response.

Cr‐MIL‐101‐Encapsulated Keggin Phosphomolybdic Acid as a Catalyst for the One‐Pot Synthesis of 2,5‐Diformylfuran from Fructose

The conversion of fructose into 2,5‐diformylfuran (DFF) is a tandem reaction that consists of the dehydration of fructose to 5‐hydroxymethylfurfural (HMF) catalyzed by an acid catalyst and subsequent oxidation of HMF to DFF by a redox catalyst. Phosphomolybdic acid encapsulated in MIL‐101 (PMA–MIL‐101), with high Brønsted acidity and moderate redox potential, was evaluated as a promising catalyst for the one‐pot synthesis of DFF directly from fructose. The results demonstrated that PMA–MIL‐101 was an efficient and recyclable bifunctional catalyst for the production of DFF from fructose in DMSO; it showed high activity and selectivity towards the direct transformation of fructose into DFF, and it could be reused. A satisfactory DFF yield of 75.1 % was obtained over 2 PMA–MIL‐101 in a one‐pot, one‐step reaction under optimal reaction conditions.

Understanding the role of hydrogen bonding in Brønsted acidic ionic liquid-catalyzed transesterification: a combined theoretical and experimental investigation

Brønsted acidic ionic liquids (BAILs) can play a dual role, as a solvent and as a catalyst, in many reactions. However, molecular details of the catalytic mechanism are poorly understood. We present here a density functional theory (DFT) study for the catalytic mechanism of the transesterification of methyl ester (ME) with trimethylolpropane (TMP), in the presence of three representative BAILs, namely, N-methylimidazole-IL, pyridinium-IL, and triethylamine-IL. The deprotonation of the BAIL cation and the transesterification step are investigated. Key inter- and intra-molecular hydrogen bonds (HBs) that govern the catalytic performance of BAILs were identified and analyzed using natural bond orbital (NBO) and atoms in molecule (AIM) methods. For the deprotonation of BAILs, it was found that the intermolecular O-HO HB between the hydroxyl group of TMP and the oxygen of the sulfonic group of BAIL was indispensable for proton transfer. DFT computed free energy barriers for the transesterification step are in excellent agreement with the experimental results only after taking into account the BAIL cation-anion interaction in terms of HBs in which the O-HO between the hydroxyl group of the anion and the oxygen of the sulfonic group of the cation was the strongest HB, suggesting the role of the anion in governing the catalytic activity of BAILs. The existence of the HBs suggested by DFT calculations was further validated using in situ FTIR experiments/ATR-FTIR.