Direct conversion of methane to value‐added chemicals with high selectivity under mild conditions remains a great challenge in catalysis. Now, single chromium atoms supported on titanium dioxide nanoparticles are reported as an efficient heterogeneous catalyst for direct methane oxidation to C1 oxygenated products with H2O2 as oxidant under mild conditions. The highest yield for C1 oxygenated products can be reached as 57.9 mol molCr−1 with selectivity of around 93 % at 50 °C for 20 h, which is significantly higher than those of most reported catalysts. The superior catalytic performance can be attributed to the synergistic effect between single Cr atoms and TiO2 support. Combining catalytic kinetics, electron paramagnetic resonance, and control experiment results, the methane conversion mechanism was proposed as a methyl radical pathway to form CH3OH and CH3OOH first, and then the generated CH3OH is further oxidized to HOCH2OOH and HCOOH.
For single-atom catalysts (SACs), the catalyst supports are not only anchors for single atoms, but also modulators for geometric and electronic structures, which determine their catalytic performance. Selecting an appropriate support to prepare SACs with uniform coordination environments is critical for achieving optimal performance and clarifying the relationship between the structure and the property of SACs. Approaching such a goal is still a significant challenge. Taking advantage of the strong d-π interaction between Cu atoms and diacetylenic in Graphdiyne (GDY) support, we present an efficient and simple strategy for fabricating Cu single atoms anchored on GDY (Cu1/GDY) with uniform Cu1-C4 single sites under mild conditions. The Cu atomic structure was confirmed by combining synchrotron radiation X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and density functional theory (DFT) calculation. The as-prepared Cu1/GDY exhibits much higher activity than state-of-the-art SACs in direct benzene oxidation to phenol with H2O2 reaction, with turnover frequency values of 251 h−1 at room temperature and 1889 h−1 at 60°C, respectively. Furthermore, even with a high benzene conversion of 86%, high phenol selectivity (96%) is maintained, which can be ascribed to the hydrophobic and oleophyllic surface nature of Cu1/GDY for benzene adsorption and phenol desorption. Both experiments and DFT calculations indicate that Cu1-C4 single sites are more effective at activating H2O2 to form Cu = O bonds, which are important active intermediates for benzene oxidation to phenol.
We report a synergistic confinement strategy for high-entropy alloys nanoparticles (HEA-NPs) synthesis. The carbon nitride substrate and polydopamine coating layer synergistically confine the NPs growth and contribute to the homogeneous...
Ionic liquids (ILs) have the advantages of low cost, eco-friendliness, abundant heteroatoms, excellent solubility, and coordinated ability with metal ions. These features make ILs a suitable precursor for fabricating metal singleatom catalysts (SACs). Herein, we prepared various metal single atoms anchored on ultrathin N-doped nanosheets (denoted as Cu 1 /NC, Fe 1 /NC, Co 1 /NC, Ni 1 /NC, and Pd 1 /NC) by direct pyrolysis using ILs and g-C 3 N 4 nanosheets as templates. Taking benzene oxidation to phenol with H 2 O 2 as a model reaction to evaluate their catalytic performance and potential applications, Cu 1 /NC calcined at 1000°C (denoted as Cu 1 /NC-1000) exhibits the highest activity with a turnover frequency of about 200 h −1 in the first 1 h at 60°C , which is better than that of most metal SACs reported in the literature. High benzene conversion of 82% with high phenol selectivity of 96% and excellent recyclability were achieved using the Cu 1 /NC-1000 catalyst. This study provides an efficient general strategy for fabricating SACs using ILs for catalytic applications.
Direct conversion of methane to value‐added chemicals with high selectivity under mild conditions remains a great challenge in catalysis. Now, single chromium atoms supported on titanium dioxide nanoparticles are reported as an efficient heterogeneous catalyst for direct methane oxidation to C1 oxygenated products with H2O2 as oxidant under mild conditions. The highest yield for C1 oxygenated products can be reached as 57.9 mol molCr−1 with selectivity of around 93 % at 50 °C for 20 h, which is significantly higher than those of most reported catalysts. The superior catalytic performance can be attributed to the synergistic effect between single Cr atoms and TiO2 support. Combining catalytic kinetics, electron paramagnetic resonance, and control experiment results, the methane conversion mechanism was proposed as a methyl radical pathway to form CH3OH and CH3OOH first, and then the generated CH3OH is further oxidized to HOCH2OOH and HCOOH.
1T-phase molybdenum disulphide (MoS2) is considered as one of the most promising candidates to substitute noble metals in hydrogen evolution reaction (HER). Fabricating single layer 1T-phase MoS2 with abundance sulfur...
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