Atomically Dispersed Pt-Doped Co3 O4 Spinel Nanoparticles Embedded in Polyhedron Frames for Robust Propane Oxidation at Low Temperature

Dual effect of anchored sulphur and activated oxygen in the catalytic oxidation of organic sulfur over Pt single-atom catalysts

Foul-smelling organic sulfur gases removal of which is crucial for improving environmental quality and protecting human health. Herein, in this study, Pt single-atom (SA) loaded magnesium oxide (MgO) nanosheet catalysts were prepared, which exhibited the dual effects of anchored sulfur and activated oxygen that greatly enhanced the catalytic oxidation efficiency of methyl mercaptan (CH3SH), and 90 % complete oxidation of CH3SH could be achieved by Pt SA/MgO at 325 °C, with an oxidation efficiency that was 8 times higher than that of MgO nanosheets. A series of characterization results indicate that the valence state of Pt in the Pt SA/MgO catalyst ranges between 0 and +4, demonstrating its inherent electron-donating capability. Theoretical calculations show that the oxygen vacancy formation energy is reduced to 4.0 eV after the introduction of Pt SA, and the adsorption energy of atomic groups SH and CH3 is reduced to -1.5 and -2.0 eV. And the bond length of the MgO bond in Pt SA/MgO is shortened to 2.083 Å, forming an asymmetric structure with the PtO bond of 2.142 Å, effectively activating the lattice oxygen. Furthermore, A series of activity tests confirmed that the introduction of Pt SA reduced sulfate deposition, while the reaction pathway of CH3SH catalytic oxidation was optimised by changing the oxidation mechanism. The investigation offers a significant experimental foundation and novel viewpoints for the enhancement of high-performance catalytic oxidation catalysts targeting sulfur-containing volatile organic compounds (VOCs).

Structural Dynamic Evolution of Pt Nanoclusters in Ultra-Low-Temperature Methane Combustion with Nitrous Oxide

Tailoring and stabilizing the active sites of supported noble-metal catalysts to a semioxidized state with unsaturated coordination remain a long-standing challenge in heterogeneous catalysis. Herein, we develop a reaction-atmosphere-driven evolution approach for dynamic structural tuning of semioxidized metal sites in supported Pt catalysts. N2O as an alternative oxidant is used over Pt/TiO2 in CH4 combustion to dynamically prompt the transformation of Pt0 nanoclusters into Ptδ+ (0 < δ < 2) nanoclusters. Compared to CH4 combustion with O2 that inclines to overoxidize Pt0, the catalytic activity of CH4-N2O combustion is distinctly boosted, achieving complete CH4 combustion at only 200 °C, outperforming the state-of-the-art catalysts using O2 as the oxidant. Computational and experimental studies validate that N2O triggers less electron transfer from Pt than from O2, thereby facilitating the formation and preservation of Ptδ+ species during CH4 combustion. The newly emerged semioxidized Ptδ+ species with oxygen-deficient coordination structures simultaneously enhance lattice oxygen activation and the first C-H bond dissociation of CH4, contributing to ultralow temperature activity. Our work demonstrates that modulating the reaction atmosphere to achieve the structural dynamic evolution of semioxidized metal sites can provide new strategies for designing highly efficient catalysts for low-temperature CH4 combustion.

Inducing a Synergistic Effect on Ptδ+/Electron-Rich Sites via a Platinization Strategy: Generating Hyper-High Current Density in Hydrogen Evolution Reaction

Herein, we propose a platinization strategy for the preparation of Pt/X catalysts with low Pt content on substrates possessing electron-rich sites (Pt/X: X = Co3O4, NiO, CeO2, Covalent Organic Framework (COF), etc.). In examples with inorganic and organic substrates, respectively, Pt/Co3O4 possesses remarkable catalytic ability toward HER, achieving a current density at an overpotential of 500 mV that is 3.22 times higher than that of commercial Pt/C. It was also confirmed by using operando Raman spectroscopy that the enhancement of catalytic activity was achieved after platinization of the COF, with a reduction of overpotential from 231 to 23 mV at 10 mA cm-2. Density functional theory (DFT) reveals that the improved catalytic activity of Pt/Co3O4 and Pt/COF originated from the re-modulation of Ptδ+ on the electronic structure and the synergistic effect of the interfacial Ptδ+/electron-rich sites. This work provides a rapid synthesis strategy for the synthesis of low-content Pt catalysts for electrocatalytic hydrogen production.

Enhancing low-temperature CO removal in complex flue gases: A study on La and Cu doped Co3O4 catalysts under real-world combustion environment

Designing CO oxidation catalysts for complex flue gases conditions is particularly challenging in fire scenarios. Traditional flue gas simulations use a few representative gases but often fail to adequately evaluate catalyst performance in real-world combustion conditions. In this study, we developed doping strategies using La and Cu to enhance the water resistance of Co3O4 catalysts. Catalyst 0.1La-Co3O4-CuO/CeO2 exhibits exceptional low-temperature catalytic activity, achieving 100% conversion at 130 °C. This enhancement is largely due to the introduction of La, which increases the active Co3+/Co2+ ratio and suppresses hydroxyl group formation on the Co3O4 surface. Cu doping also changes the Co3O4 lattice structure, forming Cu+ as active sites and enhancing the activity at low temperatures. For the first time, steady-state tube furnace and fixed bed were employed to evaluate the catalytic performance of CO in actual combustion atmosphere. Catalyst 0.1La-Co3O4-CuO/CeO2 maintains excellent catalytic efficiency (T100 = 120 °C) under well-ventilated conditions. However, its activity significantly decreases in poorly ventilated environments, due to the competitive adsorption of small molecules at active sites, such as acetone, commonly found in smoke. This study provides valuable insights for designing water-resistant, low-temperature, non-noble metal catalysts and offers a methodology for evaluating CO catalytic activity in real-world environments.

A Low-Noble-Metal Ru@CoMn2O4 Spinel Catalyst for the Efficient Oxidation of Propane

Noble metals have become a research hotspot for the oxidation of light alkanes due to their low ignition temperature and easy activation of C-H; however, sintering and a high price limit their industrial applications. The preparation of effective and low-noble-metal catalysts still presents profound challenges. Herein, we describe how a Ru@CoMn2O4 spinel catalyst was synthesized via Ru in situ doping to promote the activity of propane oxidation. Ru@CoMn2O4 exhibited much higher catalytic activity than CoMn2O4, achieving 90% propane conversion at 217 °C. H2-TPR, O2-TPD, and XPS were used to evaluate the catalyst adsorption/lattice oxygen activity and the adsorption and catalytic oxidation capacity of propane. It could be concluded that Ru promoted synergistic interactions between cobalt and manganese, leading to electron transfer from the highly electronegative Ru to Co2+ and Mn3+. Compared with CoMn2O4, 0.1% Ru@CoMn2O4, with a higher quantity of lattice oxygen and oxygen mobility, possessed a stronger capability of reducibility, which was the main reason for the significant increase in the activity of Ru@CoMn2O4. In addition, intermediates of the reaction between adsorbed propane and lattice oxygen on the catalyst were monitored by in situ DRIFTS. This work highlights a new strategy for the design of a low-noble-metal catalyst for the efficient oxidation of propane.