NiAl2O4,CuAl2O4,and ZnAl2O4 aluminate spinel nanoparticles were synthesized by sol-gel auto combustion method using diethanolamine(DEA)as a fuel.The effects of calcination temperature on structure,crystallinity,morpho...NiAl2O4,CuAl2O4,and ZnAl2O4 aluminate spinel nanoparticles were synthesized by sol-gel auto combustion method using diethanolamine(DEA)as a fuel.The effects of calcination temperature on structure,crystallinity,morphology,and optical properties of MAl2O4(M=Ni,Cu,Zn)have been investigated by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),UV–visible diffuse reflectance spectroscopy(UV-DRS),and photoluminescence(PL)spectroscopy.The XRD and FT-IR results confirm the formation of single-phase spinel structure of NiAl2O4,CuAl2O4,and ZnAl2O4 at 1200,1000,and 600℃,respectively.The direct band gap of these aluminate spinels,calculated from UV-DRS spectra using the Kubelka–Munk function,is found to increase with calcination temperature.The PL spectra demonstrate that NiAl2O4 gives the highest blue emission intensity,while CuAl2O4 and ZnAl2O4 exhibit a very strong violet emission.During fluorescence process,the ZnAl2O4 emits visible light in only violet and blue regions,while Ni Al2O4 and CuAl2O4 emissions extend to the green region.It seems therefore that the transition metal type and intrinsic defects in these aluminate powders are responsible for these phenomena.展开更多
The density functional theory was employed to investigate the adsorption of Nin (n=1–4) on the perfect and O-defect CuAl2O4 surfaces. The computational results show that for single Ni atom on the perfect spinel (100)...The density functional theory was employed to investigate the adsorption of Nin (n=1–4) on the perfect and O-defect CuAl2O4 surfaces. The computational results show that for single Ni atom on the perfect spinel (100) surface, the adsorption energy is-5.30 eV, much larger than Ni on other CuAl2O4 surfaces. The adsorption of Nin (n=1–4) absorbed on the O-defect CuAl2O4 (100) surface is less stable than on the perfect CuAl2O4 (100) surface. However, the adsorption energy for Nin (n=1–4) on the O-defect CuAl2O4 (110) surface is close to on the perfect CuAl2O4 (110) surface. Bader charge and partial density of states (PDOS) analysis revel that the adsorption of Ni on the CuAl2O4 spinel surface is accompanied by charge transfer from the metal to the support. The growth and aggregations analysis show that the general growth and aggregation ability for Nin clusters follow the order:gas phase>γ-Al2O3 (110)>CuAl2O4 (110)>CuAl2O4 (100). This result can give reasonable explanations for the experimental phenomenon that Ni supported on the CuAl2O4 spinel performs much better stability than on the γ-Al2O3.展开更多
基金financially supported by Faculty of Science at Sriracha, Kasetsart University, Sriracha Campusthe Kasetsart University Research and Development Institute (KURDI), Bangkok, Thailand
文摘NiAl2O4,CuAl2O4,and ZnAl2O4 aluminate spinel nanoparticles were synthesized by sol-gel auto combustion method using diethanolamine(DEA)as a fuel.The effects of calcination temperature on structure,crystallinity,morphology,and optical properties of MAl2O4(M=Ni,Cu,Zn)have been investigated by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),UV–visible diffuse reflectance spectroscopy(UV-DRS),and photoluminescence(PL)spectroscopy.The XRD and FT-IR results confirm the formation of single-phase spinel structure of NiAl2O4,CuAl2O4,and ZnAl2O4 at 1200,1000,and 600℃,respectively.The direct band gap of these aluminate spinels,calculated from UV-DRS spectra using the Kubelka–Munk function,is found to increase with calcination temperature.The PL spectra demonstrate that NiAl2O4 gives the highest blue emission intensity,while CuAl2O4 and ZnAl2O4 exhibit a very strong violet emission.During fluorescence process,the ZnAl2O4 emits visible light in only violet and blue regions,while Ni Al2O4 and CuAl2O4 emissions extend to the green region.It seems therefore that the transition metal type and intrinsic defects in these aluminate powders are responsible for these phenomena.
基金the National Natural Science Foundation of China(Nos. 21763018, 21673270, 21503254 and 21875096)the Natural Science Foundation of jiangxi Province, China(Nos. 20181BAB203016, 20181BCD40004)
文摘The density functional theory was employed to investigate the adsorption of Nin (n=1–4) on the perfect and O-defect CuAl2O4 surfaces. The computational results show that for single Ni atom on the perfect spinel (100) surface, the adsorption energy is-5.30 eV, much larger than Ni on other CuAl2O4 surfaces. The adsorption of Nin (n=1–4) absorbed on the O-defect CuAl2O4 (100) surface is less stable than on the perfect CuAl2O4 (100) surface. However, the adsorption energy for Nin (n=1–4) on the O-defect CuAl2O4 (110) surface is close to on the perfect CuAl2O4 (110) surface. Bader charge and partial density of states (PDOS) analysis revel that the adsorption of Ni on the CuAl2O4 spinel surface is accompanied by charge transfer from the metal to the support. The growth and aggregations analysis show that the general growth and aggregation ability for Nin clusters follow the order:gas phase>γ-Al2O3 (110)>CuAl2O4 (110)>CuAl2O4 (100). This result can give reasonable explanations for the experimental phenomenon that Ni supported on the CuAl2O4 spinel performs much better stability than on the γ-Al2O3.
