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As a multiple proton-coupled electron transfer process, photocatalytic conversion of CO2usually produces a wide variety of products. Improving the yield and selectivity of CO2to the single product is still a significant challenge. In this work, we describe that the rationally constructed W18O49/Cu2O{111} interfaces achieve highly selective CO2photocatalytic conversion to CH4. In situ Fourier transform infrared spectroscopy measurements reveal that the formation of W18O49/Cu2O{111} interfaces restrains the desorption of CO* intermediates in CO2photocatalytic conversion. UPS spectra, PL spectra, and photocurrent curves show that more photogenerated electrons are excited and transferred to W18O49/Cu2O{111} interfaces. All of these play critical roles in CH4production. As an outcome, the yield rate of CO2photocatalytic conversion to CH4was enhanced from 6.5 to 17.20 μmol g–1h–1with selectivity as high as 94.7%. The work demonstrates the feasibility and versatility of interface engineering in achieving highly selective CO2photocatalytic conversion.

Spinel Co3O4, consisting of two mixed valence states, Co2+and Co3+, has attracted enormous interest as a promising electrocatalyst for oxygen evolution reaction (OER). Proper control on the relative proportion of Co2+/Co3+in cobalt oxide can greatly tune the electronic structure and further optimize its catalytic performance. Herein, a hybrid coupling Co3O4with black phosphorus (Co3O4@BP) is designed as an efficient catalyst for OER. Electron migration from BP to Co3O4is achieved in Co3O4@BP, owing to the higher Fermi level of BP than that of Co3O4. Efficient electron transfer can not only create massive active sites with abundant Co2+but also remarkably suppress the deterioration of BP. Particularly, the Co3O4@BP catalyst outperforms the pristine Co3O4by over four times and is even 20 times higher than that of bare BP at a potential of 1.65 V versus reversible hydrogen electrode. Our finding provides insightful understanding for electronic engineering in Co3O4@BP by balancing advantages and utilizing drawbacks of Co3O4and BP.

Ni3S2nanosheets doped with tin (Sn) grown on nickel foam (Sn–Ni3S2/NF) through a facile hydrothermal process were found to be superior water-splitting electrocatalysts. As for overall water splitting (OWS), when the current density is 10 mA cm–2, the required voltage is only 1.46 V. Meanwhile, it exhibits a large current density property and long-time stability (>60 h current–time tests) for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). In order to reach the current densities of 100 and 1000 mA cm–2, Sn–Ni3S2/NF needs overpotentials of 0.17 and 0.57 V for HER, and 0.27 and 0.58 V for OER, respectively. The water-splitting property of Sn–Ni3S2/NF is much better than that of pure Ni3S2/NF or even 20 wt % Pt/C/NF and RuO2/NF. Furthermore, Sn–Ni3S2/NF showed a higher turnover frequency at different potentials, with ∼100% Faraday efficiency for both O2and H2. The improved activity of Sn–Ni3S2/NF activity for water-splitting is attributed to the doping of Sn, which enhanced the intrinsic activity of Sn–Ni3S2/NF for OWS. This article not only provides a new efficient and stable catalyst for OWS, but also proposes an interface design principle for NF-based high-performance water-splitting materials.

Mn4CaO5cluster in green plant is considered as the ideal structure for water oxidation catalysis. However, this structure is difficult to be constructed in heterogeneous catalyst because of its distorted spatial structure and unique electronic state. Herein, we report the synthesis of two-dimensional biomimetic Ca–Mn–O catalyst with Mn4CaO5clusterlike structure through ultrasonic-assisted reduction treatment toward Ca-birnessite. The synergistic effect between ultrasonic and reduction successfully reduced the Mn oxidation state in Ca-birnessite without breaking the structure of MnO2monolayers, forming a regular two-dimensional structure with Mn4CaO5cubanelike structure unit for the first time. The biomimetic catalyst shows a superior water oxidation activity (turnover frequency = 3.43 s–1), which is the best in manganese-based heterogeneous catalyst to date. This work provides a new strategy for the precise synthesis of specific structure and exhibits a great prospect of biomimic in heterogeneous catalyst.

Cation segregation of perovskite oxide is crucial to develop high-performance catalysts. Herein, we achieved the exsolution of α-Fe2O3from parent La0.85FeO3−δby a simple heat treatment. Compared to α-Fe2O3and La0.85FeO3−δ, α-Fe2O3-LaFeO3–xachieved a significant improvement of lithium-oxygen battery performance in terms of discharge specific capacity and cycling stability. The promotion can be attributed to the interaction between α-Fe2O3and LaFeO3–x. During the cycling test, α-Fe2O3-LaFeO3–xcan be stably cycled for 108 cycles at a limited discharge capacity of 500 mAh g–1at a current density of 100 mA g–1, which is remarkably longer than those of La0.85FeO3−δ(51 cycles), α-Fe2O3(21 cycles), and mechanical mixing of LaFeO3and α-Fe2O3(26 cycles). In general, these results suggest a promising method to develop efficient lithium-oxygen battery catalysts via segregation.

In this research, we provide a simple but sound solution to address the low performance of lithium-ion batteries through preparation of wurtzite Cu9Sn2Se9nanoparticles with uniform size distribution and morphology via a hot injection colloidal approach as a promising anode material. The Cu9Sn2Se9nanoparticles anode exhibits superior rate performance and high reversible capacity of 979.8 mAh g–1in the 100th cycle at a current density of 100 mA g–1, which is approximate 2 times of reported Cu–Sn–S framework (563 mA g–1), 1.5 times of reported pristine Cu2SnS3(621 mA g–1) and comparable or higher than a number of reported Sn-based nanocomposites based anodes for lithium-ion batteries at the same cycle. The study demonstrate such outstanding properties are attributed to the high structural flexibility of the metal selenide and increased electronic connectivity by colloidal quantum dot ligand exchange procedure associated with mercaptopropionic acid (MPA). In addition, unlike most metal sulfides or selenides, it possesses a stepwise intercalation mechanism during the lithiation/delithiation cycles which is beneficial to buffer against volume variation of the alloy electrode materials. Such findings provide a new and feasible insight into guide the design and manufacturing of high performance lithium-ion batteries for a broad variety of engineering applications.

In this research, we reported the synthesis of quaternary Cu3InSnSe5nanoparticles with uniform size distribution and morphology for the first time through delicate controls over the chemical reaction kinetics. On the basis of the preparation strategy of Cu3InSnSe5nanoparticles, Pt–Cu3InSnSe5and Au–Cu3InSnSe5heteronanostructures were designed and yielded using a simple and efficient seed growth method. These two heteronanostructures remained monodispersed without presence of any Cu3InSnSe5nanocrystal impurities. To explore their application potentials for dye-sensitized solar cells, counter electrodes consisting of individual Cu3InSnSe5, Pt–Cu3InSnSe5, or Au–Cu3InSnSe5constituents were fabricated. Current density–voltage (J–V) characteristics evaluation reveals that Cu3InSnSe5nanoparticles, Pt–Cu3InSnSe5and Au–Cu3InSnSe5heterostructured nanoparticles display a comparative power conversion efficiency (PCE) of 5.8%, 7.6%, and 6.5% to that of a Pt-based counter electrode (7.9%), respectively. As such, we believe that the reported preparation strategy could provide new insights to the design and manufacture of counter electrode materials with controlled structure, morphology, and optimized power conversion efficiency for dye-sensitized solar cells.

Herein, sub-10 nm core–shell nanocrystals (NCs), which select Sr2LuF7:Yb/Er as core, Sr2GdF7as middle shell, and SrF2as an outermost shell, were synthesized by a seed-mediated growth process. The NCs possess good crystallinity, morphology, and up-conversion luminescent properties. After modification by polyethylenimine branched (PEI), in vitro cell up-conversion imaging with low autofluorescence was realized. Due to the presence of Gd3+ions, in vivo magnetic resonance (MR) imaging was also achieved with these designed NCs. More significantly, these special core–shell NCs exhibited high contrast in in vivo X-ray computed tomography (CT) imaging because of their good X-ray absorption ability. These results indicate that the core–shell up-conversion NCs can serve as promising contrast agents for up-conversion luminescence–MR–CT trimodal bioimaging.

Pure phase manganese oxides have been widely studied as water oxidation catalysts, but further improvement of their activities is much challenging. Herein, we report an effective method to improve the water oxidation activity by fabricating a nanocomposite of Mn3O4and δ-MnO2with an active interface. The nanocomposite was achieved by a partial reduction approach which induced an in situ growth of Mn3O4nanoparticles from the surface of δ-MnO2nanosheets. The optimum composition was determined to be 38% Mn3O4and 62% δ-MnO2as confirmed by X-ray photoelectron spectra (XPS) and X-ray absorption spectra (XAS). The δ-MnO2–Mn3O4nanocomposite is a highly active water oxidation catalyst with a turnover frequency (TOF) of 0.93 s–1, which is much higher than the individual components of δ-MnO2and Mn3O4. We consider that the enhanced water oxidation activity could be explained by the active interface between two components. At the phase interface, weak Mn–O bonds are introduced by lattice disorder in the transition of hausmannite phase to birnessite phase, which provides active sites for water oxidation catalysis. Our study illustrates a new view to improve water oxidation activity of manganese oxides.