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首页> 外文期刊>Langmuir: The ACS Journal of Surfaces and Colloids >Effect of particle size on the reactivity of quantum size ZnO nanoparticles and charge-transfer dynamics with adsorbed catechols
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Effect of particle size on the reactivity of quantum size ZnO nanoparticles and charge-transfer dynamics with adsorbed catechols

机译：粒径对量子尺寸ZnO纳米颗粒反应性和邻苯二酚吸附电荷转移动力学的影响

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The photophysics and reactivity of quantum size ZnO nanoparticles have been studied using static and time-resolved emission and absorption spectroscopy. Size quantization of ZnO nanoparticles is confirmed by steady-state optical absorption and emission spectroscopy. On band gap excitation, ZnO nanoparticles give both exciton and trap-state emission. The emission from ZnO nanoparticles is readily quenched by hole scavengers such as catechol (cat.) and naphthyl catechol (Ncat.). Quenching of ZnO emission has been attributed to the reactivity of ZnO nanoparticles with adsorbed catechols. Studies on particle size variation revealed that the reactivity of ZnO nanoparticles decreases as their size increases. The maximum reactivity of the excited ZnO nanoparticles with the catechols has been observed for the smallest size particles. Time-resolved emission studies of ZnO particles in the presence of the catechols confirmed that the catechols react in the same rate with both shallow and deeply trapped holes. We have also carried out time-resolved absorption studies of ZnO nanoparticles exciting at 355 nn laser light in the presence of the catechols. On laser excitation of ZnO nanoparticles, electrons and holes are generated. It has been observed that the holes react with the catechols and form oxidized species, which in turn convert to the phenoxyl radical of the catechols. The transient spectra of the phenoxyl radical of the catechols are confirmed by pulse radiolysis technique, which shows a strong absorbance peak in UV region and small shoulder at visible region for both the catechols. It has been observed that on the ZnO nanoparticle surface the spectrum of the phenoxyl radical of the catechols are little broader. [References: 59]
机译：已使用静态和时间分辨发射和吸收光谱研究了量子尺寸ZnO纳米粒子的光物理性质和反应性。 ZnO纳米粒子的尺寸量化已通过稳态光学吸收和发射光谱法确认。在带隙激发时，ZnO纳米粒子既给出激子发射，又给出陷阱态发射。 ZnO纳米颗粒的发射很容易被空穴清除剂（例如儿茶酚（类别）和萘基邻苯二酚（类别））淬灭。 ZnO发射的淬灭归因于ZnO纳米颗粒与吸附的邻苯二酚的反应性。对粒度变化的研究表明，ZnO纳米颗粒的反应性随其粒度的增加而降低。对于最小尺寸的颗粒，已观察到激发的ZnO纳米颗粒与邻苯二酚的最大反应性。在儿茶酚存在下对ZnO颗粒的时间分辨发射研究证实，儿茶酚与浅孔和深陷孔的反应速率相同。我们还对儿茶酚存在下在355 nn激光激发的ZnO纳米粒子进行了时间分辨的吸收研究。在ZnO纳米粒子的激光激发下，会产生电子和空穴。已经观察到，这些空穴与儿茶酚反应并形成氧化的物质，该氧化物又转化成儿茶酚的苯氧基自由基。脉冲辐射分解技术证实了邻苯二酚苯氧基自由基的瞬态光谱，该光谱在两个邻苯二酚的紫外线区域均具有很强的吸收峰，在可见光区域显示出较小的肩峰。已经观察到在ZnO纳米颗粒表面上，邻苯二酚的苯氧基自由基的光谱几乎不宽。 [参考：59]

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