ZnO超微粒子的EPR特性和光催化性能

利用XRD,TEM,XPS和EPR等研究了ZnO超微粒子的EPR特性和光催化性能.前驱物碱式碳酸锌在320,430,550和700℃经热处理制得的ZnO超微粒子粒径分别为13.5,19.3,26.1和38.5nm,属六方晶系纤锌矿结构;室温下ZnO超微粒子表现出稳定的单一谱线的EPR信号,其强度随粒径的增大而减小.而在液氮温度下,ZnO超微粒子的EPR谱具有6条强度不等的超精细谱线,在光催化氧化C₇H₁₆和SO₂过程中,其光催化活性随其EPR信号强度的减小而下降.说明O₂-空位在光催化反应中起重要作用.

Electronic Paramagnetic Resonance Characteristics of ZnO Ultrafine Particles and Their Photocatalytic Performance

EPRproperties of ZnOultrafine particles(UFP) and their photocatalytic activities were studied by using XRD, TEM, XPSand EPR. Results show that UFPobtained by calcining the precursor, zinc carbonate hydroxide at 320, 430, 550 and 700 ℃, have sizes of 13.5,19.3, 26.1 and 38.5 nm, respectively, with wurtzite structure attached to the hexagonal system. Results also show that at room temperature ZnO UFPhad a significant EPRsignal with single line resulting from the O₂-deficiencies on the surface of ZnO UFPwhich can capture and trap electrons so as to form a spin resources with S=1/2. Their EPRintensity decreased with the increase of their sizes. But at the liquid nitrogen temperature, the EPRhad six hyperfine structures resulting from the hyperfine interaction between the electrons traped by O₂-deficiencies and the17 Omagnetic nucleus with I=5/2 attached to the absorbed oxygen on the surface of ZnO UFP. The photocatalytic activities of ZnO UFPdecreased as their EPRintensity decreased during the process of photocatalytic oxidation SO₂ and C₇H₁₆, suggesting that oxygen-deficiencies on the surface of ZnO UFPplayed an important role in photocatalysis.