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Doping can greatly reduce the lattice thermal conductivity of thermoelectric materials, which is considered as one of the effective ways to improve the thermoelectric properties of thermoelectric materials. First of all, we use the simple and environmentally friendly solution thermal method combined with the tube furnace sintering technology to explore the optimal temperature of sintering Cu2S in the tube furnace. When the sintering temperature reaches 700 °C, we get the thermoelectric value of 0.21. Subsequently, Cu2S thermoelectric materials doped with xmol%Sn (x = 0.5, 1, 3, 5) were prepared and the optimal concentration of Sn was explored. The Sn atom replaces the Cu atom with a smaller radius, greatly reducing the thermal conductivity of the matrix material. In the sample doped with 1%Sn, the total thermal conductivity reaches 0.31 WK−1 m−1, which is 22.5% lower than that of the pure phase sample. In addition, above 623 K, the conductivity of samples doped with 1%Sn is better than that of intrinsic samples, indicating that Sn doping can optimize the conductivity of Cu2S to a certain extent. At 773 K, the ZT of Cu2S + 1 mol%Sn can reach 0.51. 132% higher than undoped Cu2S.This provides a new idea for the preparation and commercial application of Cu–S based thermoelectric materials. [ABSTRACT FROM AUTHOR]

In this article, density functional theory (DFT) was applied to research the structures of γ-Fe2O3 and MFe2O4 (M=Co, Cu, Zn) and to optimize the adsorption models of gases such as CO and NO onto the catalysts. Additionally, the study analyzed the CO oxidation reaction on MFe2O4 (M=Co, Cu, Zn) and the selective catalytic reduction (SCR) reaction of CO + NO in CuFe2O4 and ZnFe2O4. Results showed that CO can effectively adsorb on the reactive substrates, reacting with lattice oxygen to produce CO2 and oxygen vacancies during the CO oxidation process. γ-Fe2O3 (001) required an energy of 0.95 eV to complete the reaction, while CuFe2O4 (100) needed only 0.33 eV, offering better selectivity. In the reaction of CO + NO on CuFe2O4 and ZnFe2O4, NO adsorbed on the surface with double oxygen vacancy to form N2O2 intermediate, then reacted to produce N2 and fill the oxygen vacancy. CuFe2O4 and ZnFe2O4 required energy barriers of 0.68 eV and 0.73 eV, respectively, demonstrating the feasibility of the CO-SCR reaction on the catalyst surface. Further exploration of the reaction in an oxygen-enriched environment found that O2 can inhibit the CO-SCR reaction. The study reveals that MFe2O4 (M=Co, Cu, Zn) catalysts can improve the catalytic activity of the CO oxidation reaction and CO-SCR reaction, with CuFe2O4 exhibiting the best selectivity and catalytic activity. What's more, this study also provides insights for the simultaneous removal of CO and NO. [ABSTRACT FROM AUTHOR]

Based on density functional theory, this study investigates the impact of vacancies on the structural stability, electronic, and optical properties of the GaAs/InSe van der Waal heterostructure. The findings demonstrate that the introduction of vacancies can alter the band gap and density of states in the band structure. The energy band diagram follows a consistent trend with that of the density of states. The introduction of vacancies also affects the imaginary part of the dielectric function and optical absorption coefficient, resulting in a red shift. Overall, GaAs/InSe heterostructures exhibit good stability and desirable electrical and optical properties. However, vacancies can alter the electrical and optical characteristics of the heterostructure, making it a promising strategy for adjusting the optoelectronic properties of two-dimensional optoelectronic nanodevices. This approach has broad potential and practical applications. [ABSTRACT FROM AUTHOR]