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There is a research gap regarding the role of lone pair electrons of post‐transition metal cations in catalysis field, yet such studies hold significant implications for expanding their applications. Herein, the role of Bi3+ ion lone pair electrons in electrocatalytic oxygen reduction reaction (ORR) is elucidated using ternary mullite oxides as prototype catalysts. Among the three synthesized mullites ((Sm/Y/Bi)Mn2O5), BiMn2O5 exhibits notably superior ORR catalytic activity. Through advanced characterization techniques, including in situ Raman, in situ infrared, and X‐ray absorption spectroscopy, combined with theoretical calculations, it is determined that the superior electrocatalytic performance of BiMn2O5 originates from the lone pair electrons that activate catalytic sites through stereochemical effects. Specifically, the Bi3+ lone pair electrons in the 6s orbital near Fermi level interact with O 2p orbitals, causing a shift of the oxygen ligands, and significant variance in A─O bond lengths. This structural distortion of BiO8 coordination unit directly results in a large Mn─O bond angle at the active center of BiMn2O5 and strong covalent interactions, facilitating charge transfer and refining the adsorption behavior of oxygen intermediates to achieve the overpotential of 0.25 V vs. RHE. This study provides insights into developing next‐generation catalysts by harnessing the lone pair electrons of post‐transition metal cations. [ABSTRACT FROM AUTHOR] more...

Waste drilling fluids produced from oil extraction can cause serious harm to the ecological environment; thus, the treatment of waste drilling fluids is urgent and important to ensure the sustainability and development of the oil extraction. In this work, we used the Fenton-like reaction method to degrade waste drilling fluids with SiO2-supported MnO2@Fe2O3 composite material as a catalyst in the presence of H2O2. During the Fenton-like reaction process, the MnO2@Fe2O3 interface exhibits exceptional activity by facilitating the production of ·OH species with high activity and strong oxidizing properties, which degrade the organic substances in the waste drilling fluids into smaller inorganic molecules, thereby reducing its COD value. Compared to the reaction only with H2O2, after reacting with sufficient SiO2-supported MnO2@Fe2O3 catalyst for 4 h at 60 °C in the presence of H2O2, the COD value of the waste drilling fluids is reduced by 36,495 mg L−1, a decrease of more than 95%. This performance is significantly superior to that of the traditional Fenton reagent FeSO4, which reduced the COD by 32,285 mg L−1, a decrease of 84%. This work provides an important composite catalyst, which is practically useful for the treatment of waste drilling fluids. [ABSTRACT FROM AUTHOR] more...

Since the active sites in catalytic systems are either metal sites or lattice oxygen, simultaneously triggering metal and lattice oxygen redox pair with low energy barriers is expected to provide diversified and efficient sites to accelerate oxygen evolution reaction (OER) kinetics, but this is a great challenge. Herein, Ir species (Ir clusters and Ir single atoms) loaded on Ni‐doped Co3O4 is designed (Ir/Ni‐Co3O4), where metallic Ir clusters downsize to spread into high‐density Ir single atoms to load on reconstruction‐derived Ni‐doped CoOOH. In situ spectroscopy, isotope‐labeled, and chemical probe experiments demonstrate that metal site and lattice oxygen are simultaneously activated to participate in the OER. Further theoretical studies demonstrate that the Co site is the most favorable site to promote the OER through an adsorbate evolution mechanism with a low energy barrier of 1.69 eV. The Ni cooperating with Ir atoms synergistically upshifts energy positions of the O p band centers. Thus, the lattice O that bridges Ni and Ir atoms is activated to participate in the OER via coupling with adsorbed O on the Ir site to fulfill O─O bond formation. Benefiting from the conjoint participation of the metal and lattice oxygen redox pair, Ir/Ni‐Co3O4 affords extremely low OER overpotentials of 177 and 263 mV at corresponding 10 and 500 mA cm−2. [ABSTRACT FROM AUTHOR] more...

Since the active sites in catalytic systems are either metal sites or lattice oxygen, simultaneously triggering metal and lattice oxygen redox pair with low energy barriers is expected to provide diversified and efficient sites to accelerate oxygen evolution reaction (OER) kinetics, but this is a great challenge. Herein, Ir species (Ir clusters and Ir single atoms) loaded on Ni‐doped Co3O4 is designed (Ir/Ni‐Co3O4), where metallic Ir clusters downsize to spread into high‐density Ir single atoms to load on reconstruction‐derived Ni‐doped CoOOH. In situ spectroscopy, isotope‐labeled, and chemical probe experiments demonstrate that metal site and lattice oxygen are simultaneously activated to participate in the OER. Further theoretical studies demonstrate that the Co site is the most favorable site to promote the OER through an adsorbate evolution mechanism with a low energy barrier of 1.69 eV. The Ni cooperating with Ir atoms synergistically upshifts energy positions of the O p band centers. Thus, the lattice O that bridges Ni and Ir atoms is activated to participate in the OER via coupling with adsorbed O on the Ir site to fulfill O─O bond formation. Benefiting from the conjoint participation of the metal and lattice oxygen redox pair, Ir/Ni‐Co3O4 affords extremely low OER overpotentials of 177 and 263 mV at corresponding 10 and 500 mA cm−2. [ABSTRACT FROM AUTHOR] more...

Catalytic decomposition of aromatic polluters at room temperature represents a green route for air purification but is currently challenged by the difficulty of generating reactive oxygen species (ROS) on catalysts. Herein, we develop a mullite catalyst YMn 2 O 5 (YMO) with dual active sites of Mn 3+ and Mn 4+ and use ozone to produce a highly reactive O* upon YMO. Such a strong oxidant species on YMO shows complete removal of benzene from -20 to >50 °C with a high CO x selectivity (>90%) through the generated reactive species O* on the catalyst surface (60 000 mL g -1 h -1 ). Although the accumulation of water and intermediates gradually lowers the reaction rate after 8 h at 25 °C, a simple treatment by ozone purging or drying in the ambient environment regenerates the catalyst. Importantly, when the temperature increases to 50 °C, the catalytic performance remains 100% conversion without any degradation for 30 h. Experiments and theoretical calculations show that such a superior performance stems from the unique coordination environment, which ensures high generation of ROS and adsorption of aromatics. Mullite's catalytic ozonation degradation of total volatile organic compounds (TVOC) is applied in a home-developed air cleaner, resulting in high efficiency of benzene removal. This work provides insights into the design of catalysts to decompose highly stable organic polluters. more...

Large ambient temperature changes (-20->25 °C) bring great challenges to the purification of the indoor pollutant formaldehyde. Within such a large ambient temperature range, we herein report a manganese-based strategy, that is, a mullite catalyst (YMn 2 O 5 ) + ozone, to efficiently remove the formaldehyde pollution. At -20 °C, the formaldehyde removal efficiency reaches 62% under the condition of 60,000 mL g cat -1 h -1 . As the reaction temperature is increased to -5 °C, formaldehyde and ozone are completely converted into CO 2 , H 2 O, and O 2 , respectively. Such a remarkable performance was ascribed to the highly reactive oxygen species generated by ozone on the YMn 2 O 5 surface based on the low temperature-programed desorption measurements. The in situ infrared spectra showed the intermediate product carboxyl group (-COOH) to be the key species. Based on the superior performance, we built a consumable-free air purifier equipped with mullite-coated ceramics. In the simulated indoor condition (25 °C and 30% relative humidity), the equipment can effectively decompose formaldehyde (150 m 3 h -1 ) without producing secondary pollutants, rivaling a commercial removal efficiency. This work provides an air purification route based on the mullite catalyst + ozone to remove formaldehyde in an ambient temperature range (-20->25 °C). more...

Exploring the effect of interfacial structural properties on catalytic performance of hybrid materials is essential in rationally designing novel electrocatalysts with high stability and activity. Here, in situ growth of mullite SmMn 2 O 5 on nitrogen-doped reduced graphene oxide (SMO@NrGO) is achieved for highly efficient oxygen reduction reaction (ORR). Combining X-ray photoelectron spectroscopy and density functional theory calculations, interfacial chemical interactions between Mn and substrates are verified. Interestingly, as revealed by charge density difference, the interfacial Mn-N(C) bonds display a sponge effect to store and compensate electrons to boost the ORR process. In addition, bidentate adsorption of oxygen intermediates instead of monodentate ones is observed in hybrid materials, which facilitates the interactions between intermediates and active sites. Experimentally, the hybrid catalyst SMO@NrGO exhibits a half-wave potential as high as 0.84 V, being comparable to benchmark Pt/C and higher than that of the pure SMO (0.68 V). The Zn-air battery assembled with SMO@NrGO shows a high discharge peak power density of 244 mW cm -2 and superior cycling stability against noble metals. more...