Photoconductivity-Lifetime Product Correlates Well with the Photocatalytic Activity of Oxyhalides Bi4TaO8Cl and PbBiO2Cl: An Approach to Boost Their O2 Evolution Rates
Photoconductivity-Lifetime Product Correlates Well with the Photocatalytic Activity of Oxyhalides Bi4TaO8Cl and PbBiO2Cl: An Approach to Boost Their O2 Evolution Rates
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DOI：
10.1021/acsenergylett.9b00793
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发表时间：
2019-07-01
影响因子：
22
通讯作者：
Saeki, Akinori
中科院分区：
文献类型：
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作者：
Suzuki, Hajime;Higashi, Masanobu;Saeki, Akinori
由于 Bi/Pb 6s 和 O 2p 轨道杂化时产生的浅价带最大值，Bi4TaO8Cl 和 PbBiO2Cl 的层状卤氧化物是稳定且有前途的用于 Z 型水分解的 O-2 演化光催化剂。然而，关于它们的合成参数如何影响载流子动力学和整体光催化过程仍然存在一些问题。在这里，我们表明，通过时间分辨微波电导率 (TRMC) 测量评估，瞬态赝光电导最大值 (phi Sigma mu(max)) 和半衰期 (tau(1/2)) 的乘积与此类卤氧化物的 O-2 演化速率密切相关。 Bi4TaO8Cl 中的这种相关性是通过随着煅烧温度的升高而增加的微晶尺寸和降低的 Cl/Bi 原子比来合理化的。在此基础上，我们通过TRMC分析研究了很少研究的PbBiO2Cl的加工温度，并证明其O-2演化速率提高了3倍（表观量子效率为3%），这是固态反应制备的卤氧化物中性能最好的之一。这项研究表明 TRMC 评估提供了一种检查半导体光催化剂潜力的简便方法。
Owing to the shallow valence band maximum generated upon hybridization of Bi/Pb 6s and O 2p orbitals, layered oxyhalides of Bi4TaO8Cl and PbBiO2Cl are stable and promising O-2-evolving photocatalysts for Z-scheme water splitting. However, some questions remain regarding how their synthesis parameter influences the charge carrier dynamics and overall photocatalytic process. Here, we show that the product of the transient pseudophotoconductivity maximum (phi Sigma mu(max)) and half-lifetime (tau(1/2)), as evaluated by time-resolved microwave conductivity (TRMC) measurements, correlates well with the O-2 evolution rates of such oxyhalides. Such correlation in Bi4TaO8Cl is rationalized by the increased crystallite size and decreased Cl/Bi atomic ratio with the increasing calcination temperature. On the basis of this, we examined the processing temperature of the rarely studied PbBiO2Cl by TRMC analysis and demonstrate a 3-fold enhancement of its O-2 evolution rate (apparent quantum efficiency of 3%), which is among the best performances of oxyhalides prepared by a solid-state reaction. This study suggests that TRMC evaluation provides a facile means to examine the potential of semiconducting photocatalysts.