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Open Access Research Article Issue
Enhanced thermoelectric properties of Cu3SbSe4-based materials by synergistic modulation of carrier concentration and phonon scattering
Journal of Materiomics 2024, 10 (2): 339-347
Published: 04 July 2023
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Cu3SbSe4, a copper-based sulfide free of rare earth elements, has received extensive attention in thermoelectric materials. However, its low carrier concentration restricts its widespread application. In this study, a microwave-assisted solution synthesis method was used to produce samples of Cu3SbSe4, which enabled the formation of CuSe in situ and increased the yield. Through the use of first-principles calculations, structural analysis, and performance evaluation, it was found that CuSe can enhance the carrier concentration and that induced nano-defects have a positive effect on reducing the lattice thermal conductivity. Moreover, doping with Sn decreases the band gap of the system and moves the Fermi level into the valence band, increasing the carrier concentration to 1.15 × 10−20 cm−3. Finally, the zT value of the Cu3Sb0.98Sn0.02Se4 sample was achieved at 1.05 at 623 K when the theoretical yield of a single synthesis was 10 mmol.

Research Article Issue
Mesoporous MnO2 nanosheets for efficient electrocatalytic nitrogen reduction via high spin polarization induced by oxygen vacancy
Nano Research 2023, 16 (4): 4664-4670
Published: 24 October 2022
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The electrochemical N2 reduction reaction (NRR) represents a green and sustainable route for NH3 synthesis under ambient conditions. However, the mechanism of N2 activation in the electrocatalytic NRR remains unclear. Herein, we found that the high spin state Mn3+-Mn3+ pairs induced by oxygen vacancy in MnO2 nanosheets greatly enhance the catalytic activities. The strong electron transfer between d orbital of Mn and orbital of N2 forces the N2 to be of radical nature, which activates the hydrogenation process and weakens the N≡N bond. Based on the density functional theory (DFT) calculation results, we precisely designed mesoporous MnO2 nanosheets with rich oxygen vacancies via using methyltriphenylphosphonium bromide (MPB) to induce more Mn3+-Mn3+ pairs (Mn3-3-MnO2), which can achieve a fairly high ammonia yield of up to 147.2 µg·h−1·mgcat−1. at −0.75 V vs. reversible hydrogen electrode (RHE) and a high Faradaic efficiency (FE) of 11%. Furthermore, these mesoporous MnO2 nanosheets exhibit the superior durability with negligible changes in both NH3 yield and FE after a consecutive 6-recycle test and the current density electrolyzed over a 24-hour period. Our findings offer an approach to designing highly active transition metal catalysts for electrocatalytic nitrogen reduction.

Research Article Issue
Highly stable Pt3Ni ultralong nanowires tailored with trace Mo for the ethanol oxidation
Nano Research 2022, 15 (4): 3230-3238
Published: 12 December 2021
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Pt3Ni alloy structure is an effective strategy to accelerate ethanol oxidation reaction (EOR), while the stability in acid electrolyte is the fatal weakness and the current density still needs to be enhanced. Herein, ultralong Pt3Ni nanowires tailored by trace Mo (Mo/Pt3Ni NWs) were successfully synthesized by surfactant free method. The specific activity of the optimized catalyst was 2.66 mA·cm–2, which is approximately 2.16 and 4.6-fold that of Pt3Ni NWs and commercial Pt/C catalyst, respectively. Most importantly, the Mo/Pt3Ni NWs catalyst showed negligible structure degradation after 3,000 cycles (42 h) of durability test in 0.1 M HClO4 and 0.5 M ethanol, as compared to severe structural collapse and Ni dissolution for the pure Pt3Ni NWs. The density functional theory (DFT) calculation also confirmed that both the surface and subsurface Mo atom could form Pt-Mo and Ni-Mo bonds with Pt and Ni, which were stronger than Pt-Ni bonds, to pin the Ni atoms in the unstable position and suppress the dissolution of surface Ni. The findings of this study indicate a promising pathway for the design and engineering of durable alloy nanocatalysts for direct ethanol fuel cell applications.

Research Article Issue
Atomically dispersed N-coordinated Fe-Fe dual-sites with enhanced enzyme-like activities
Nano Research 2022, 15 (2): 959-964
Published: 09 July 2021
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Replacement of enzymes with nanomaterials such as atomically dispersed metal catalysts is one of the most crucial steps in addressing the challenges in biocatalysis. Despite the breakthroughs of single-atom catalysts in enzyme-mimicking, a fundamental investigation on the development of an instructional strategy is still required for mimicking biatomic/multiatomic active sites in natural enzymes and constructing synergistically enhanced metal atom active sites. Herein, Fe2NC catalysts with atomically dispersed Fe-Fe dual-sites supported by the metal-organic frameworks-derived nitrogen-doped carbon are employed as biomimetic catalysts to perform proof-of-concept investigation. The effect of Fe atom number toward typical oxidase (cytochrome C oxidase, NADH oxidase, and ascorbic acid oxidase) and peroxidase (NADH peroxidase and ascorbic acid peroxidase) activities is systematically evaluated by experimental and theoretical investigations. A peroxo-like O2 adsorption in Fe2NC nanozymes could accelerate the O–O activation and thus achieve the enhanced enzyme-like activities. This work achieves the vivid simulation of the enzyme active sites and provides the theoretical basis for the design of high-performance nanozymes. As a concept application, a colorimetric biosensor for the detection of S2– in tap water is established based on the inhibition of enzyme-like activity of Fe2NC nanozymes.

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