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Elucidating the synergistic catalytic mechanism between multiple active centers is of great significance for heterogeneous catalysis; however, finding the corresponding experimental evidence remains challenging owing to the complexity of catalyst structures and interface environment. Here we construct an asymmetric TeN2–CuN3 double-atomic site catalyst, which is analyzed via full-range synchrotron pair distribution function. In electrochemical CO2 reduction, the catalyst features a synergistic mechanism with the double-atomic site activating two key molecules: operando spectroscopy confirms that the Te center activates CO2, and the Cu center helps to dissociate H2O. The experimental and theoretical results reveal that the TeN2–CuN3 could cooperatively lower the energy barriers for the rate-determining step, promoting proton transfer kinetics. Therefore, the TeN2–CuN3 displays a broad potential range with high CO selectivity, improved kinetics and good stability. This work presents synthesis and characterization strategies for double-atomic site catalysts, and experimentally unveils the underpinning mechanism of synergistic catalysis. Elucidating the synergistic catalytic mechanism involving multiple active centers is of great significance for heterogeneous catalysis. Here the authors construct an asymmetric TeN2–CuN3 double atomic site catalyst featuring synergistic CO2 activation and H2O dissociation for CO2 electroreduction. [ABSTRACT FROM AUTHOR]

Hollow nanomaterials consisting of non‐noble metal oxides have wide applications in catalysis, and many preparation methods for this kind of structures are established. However, it is still challenging to fabricate non‐noble‐metal hollow structures featuring high crystallinity, regular polyhedral morphologies, and small sizes, owing to their relatively low chemical stability and the stringent hollowing conditions. Here in this work, an optimized self‐templating synthesis method with refined control over the heating program and solution environment, which can alleviate the common issues of morphology and crystallinity degradation from precursors during hollowing process, is reported. Through this method, highly crystalline Cu2O nanobox with sizes below 50 nm is successfully prepared. Benefiting from the unique hollow structures, the Cu2O nanobox/C catalyst gives outstanding performances in catalyzing the oxidative homocoupling of phenylacetylene, with the advantages of lower metal loading, mild reaction conditions, and no additives. This optimized method can be extended to the preparation of other non‐noble‐metal hollow materials with sophisticated architectures. [ABSTRACT FROM AUTHOR]

In this paper, uniform NaGdF4:Yb3+, Er3+ nanorods doped with Fe3+ were synthesized by a facile hydrothermal method. The prepared NaGdF4:Yb3+, Er3+ doped with Fe3+ displayed hexagonal phase structure from XRD pattern and uniform nanorods with narrow size distribution from TEM. The signal of Fe3+ is accompanied with the Yb3+ and Er3+ from EDX line-scanning, which was confirmed that Fe3+ was doped successfully. The NaGdF4:Yb3+, Er3+ nanorods doped with Fe3+ show absorption of near-infrared region from UV–Vis absorption spectra. The upconversion luminescence intensity enhances with increasing content of Fe3+ under 980 nm excitation. When stoichiometric ratio of Fe3+ is 20 mol%, the strongest upconversion emission intensity could be obtained. But the upconversion luminescence would become weak when the stoichiometric ratio of Fe3+ is above 20 mol%. Based on above analysis, it is inferred that there is energy conversion between Fe3+ and rare earth ions by the luminescence mechanism. In this work, it provides a facile method for preparation of NaGdF4:Yb3+, Er3+ nanorods, which displays improving upconversion luminescence by Fe3+ doping. [ABSTRACT FROM AUTHOR]

The well-defined NaGdF4:Yb,Er nanorods (NRs) with various aspect ratios were synthesized using a facile hydrothermal method. The morphology and crystal phase of NRs could be controlled by reaction conditions. NaGdF4:Yb,Er NRs with various aspect ratios could be synthesized and their upconversion (UC) luminescence was tuned. It is displayed that the NRs with aspect ratios about 5 exhibited the strongest UC luminescence among samples. The growth mechanism and morphology transition of NRs had been deduced by schematic diagram. And UC mechanism had been determined by energy level diagrams. Compared with previous reports, the work provided a facial method for UCNRs with various aspect ratios at lower temperature. NaGdF4:Yb,Er nanorods (NRs) with various aspect ratios were synthesized using a facile hydrothermal method at lower temperature. The upconversion luminescence of various aspect ratios was studied, and the NRs with aspect ratio of about 5 exhibited the strongest luminescence among the samples. Both the growth mechanism and upconversion mechanism of NRs had been deduced by schematic diagram. [ABSTRACT FROM AUTHOR]