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Research Article Issue
Bismuth clusters pinned on TiO2 porous nanowires boosting charge transfer for CO2 photoreduction to CH4
Nano Research 2024, 17 (3): 1190-1198
Published: 29 August 2023
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Artificial photosynthesis in carbon dioxide (CO2) conversion into value-added chemicals attracts considerable attention but suffers from the low activity induced by sluggish separation of photogenerated carriers and the kinetic bottleneck-induced unsatisfied selectivity. Herein, we prepare a new-style Bi/TiO2 catalyst formed by pinning bismuth clusters on TiO2 nanowires through being confined by pores, which exhibits high activity and selectivity towards photocatalytic production of CH4 from CO2. Boosted charge transfer from TiO2 through Bi to the reactants is revealed via in situ X-ray photon spectroscopy and time-resolved photoluminescence (PL). Further, in situ Fourier transform infrared results confirm that Bi/TiO2 not only overcomes the multi-electron kinetics challenge of CO2 to CH4 via boosting charge transfer, but also facilitates proton production and transfer as well as the intermediates *CHO and *CH3O generation, ultimately achieving the tandem catalysis towards methanation. Theoretical calculation also underlies that the more favorable reaction step from *CO to *CHO on Bi/TiO2 results in CH4 production with higher selectivity. Our work brings new insights into rational design of photocatalysts with high performance and the formation mechanism of CO2 to CH4 for solar energy storage in future.

Open Access Research Article Issue
Planar Zintl-phase high-temperature thermoelectric materials XCuSb (X = Ca, Sr, Ba) with low lattice thermal conductivity
Journal of Advanced Ceramics 2022, 11 (10): 1604-1612
Published: 15 September 2022
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A recent discovery of high-performance Mg3Sb2 has ignited tremendous research activities in searching for novel Zintl-phase compounds as promising thermoelectric materials. Herein, a series of planar Zintl-phase XCuSb (X = Ca, Sr, Ba) thermoelectric materials are developed by vacuum induction melting. All these compounds exhibit high carrier mobilities and intrinsic low lattice thermal conductivities (below 1 W·m−1·K−1 at 1010 K), resulting in peak p-type zT values of 0.14, 0.30, and 0.48 for CaCuSb, SrCuSb, and BaCuSb, respectively. By using BaCuSb as a prototypical example, the origins of low lattice thermal conductivity are attributed to the strong interlayer vibrational anharmonicity of Cu–Sb honeycomb sublattice. Moreover, the first-principles calculations reveal that n-type BaCuSb can achieve superior thermoelectric performance with the peak zT beyond 1.1 because of larger conducting band degeneracy. This work sheds light on the high-temperature thermoelectric potential of planar Zintl compounds, thereby stimulating intense interest in the investigation of this unexplored material family for higher zT values.

Open Access Research paper Issue
High thermoelectric performance of ZrTe2/SrTiO3 heterostructure
Journal of Materiomics 2022, 8 (3): 570-576
Published: 28 December 2021
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Achieving high thermoelectric performance in thin film heterostructures is essential for integrated and miniatured thermoelectric device applications. In this work, we demonstrate a mechanism and device performance of enhanced thermoelectric performance induced by interfacial effect in a transition metal dichalcogenides-SrTiO3 (STO) heterostructure. Owing to the formed conductive interface and elevated conductivity, the ZrTe2/STO heterostructure presents large thermoelectric power factor of 3.7 × 105 μWcm−1K−2 at 10 K. Formation of quasi-two-dimensional conductance at the interface is attributed for the large Seebeck coefficient and high electrical conductivity, leading to high thermoelectric performance which is demonstrated by a prototype device attaining 3 K cooling with 100 mA current input to this heterostructure. This superior thermoelectric property makes this heterostructure a promising candidate for future thermoelectric device.

Open Access Research Article Issue
Band structure manipulated by high pressure-assisted Te doping realizing improvement in thermoelectric performance of BiCuSeO system
Journal of Materiomics 2019, 5 (4): 649-656
Published: 15 June 2019
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Band structure engineering is an effective strategy for the improvement in thermoelectric performance, especially in electrical transport properties. In this work, high pressure is employed to assist Te doping to rapidly realize modulation of band structure in BiCuSe1-xTexO, and then achieving a superhigh carrier mobility of 129.6 cm2V–1s–1 due to significant reduction in the effective mass. The experimental observations have been verified by density functional theory (DFT) simulation. Meanwhile, the implementing of high pressure during synthesis process extends the optimization effect of Te doping on carrier-phonon transport of BiCuSeO system. The multiscale microstructures induced by synergistic effect of high pressure and Te content markedly modulate the scattering mechanisms of carriers and phonons, yielding an ultralow thermal conductivity of 0.3 W m–1K–1 at 873 K and a moderate effect on low-energy carriers. Ultimately, a maximum zT of 0.86 at 873 K is achieved for BiCuSe0.8Te0.2O, ~21% improvement in comparison with the previous reported value for state-of-the-art BiCuSe1-xTexO samples. This study provides a revelation for employing high pressure to manipulate band structure, promoting the effect of heteroatoms doping on the improvement in thermoelectric performance of the BiCuSeO or other systems.

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