Relative Photonic Efficiencies and Quantum Yields in Heterogeneous Photocatalysis
Relative Photonic Efficiencies and Quantum Yields in Heterogeneous Photocatalysis
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DOI：
10.1515/jaots-1997-0104
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发表时间：
1997-04
影响因子：
--
通讯作者：
N. Serpone
中科院分区：
文献类型：
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作者：
N. Serpone
摘要异质光催化（固/液或固/气系统）中使用的量子产率和量子效率（QY）经常被错误地用来表示给定事件的速率与撞击（外部）反应器壁的入射光子速率的比率，通常用于宽带辐射。对于如何表达流程效率，目前还没有达成一致。有时，QY 已被定义，但通常定义不明确，而且更常见的是，工人无法描述它是如何评估的。这导致了文献中的许多混乱，不仅因为它与均相光化学的含义不同，而且因为这种描述光子效率的方法由于光源、反应器几何形状和总体实验条件的变化而无法对不同实验室的结果进行比较。无论如何强调，报告的 QY 是表观量子产率，实际上是真实量子产率的下限。本立场文件讨论了这个问题，并认为除非确定了光收集器（光催化剂）吸收的光子的实际数量，否则任何提及异质介质中的量子产率或量子效率的做法都是不明智的。固体/液体异质介质中的光散射程度是显着的。最近提出了一种比较过程效率的实用且简单的替代方案（Serpone 等人，J Photochem. Photobiol. A.Chem., 94 (1996) 191-203），通过定义相对光子效率 (zr) 来实现。随后可以根据 Σr 确定量子产率，因为 θ = Σr θ 苯酚，其中苯酚是使用 Degussa P-25 TiO2 作为标准催化剂材料光催化氧化消失苯酚（标准二级光量计）的量子产率。
Abstract Quantum yield and quantum efficiency (QY) as used in heterogeneous photocatalysis (solid/liquid or solid/gas systems) have too often been used incorrectly to mean the ratio of the rate of a given event to the rate of incident photons impinging on the (external) reactor walls, typicallyfor broadband radiation. There is little accord on how to express process efficiency. At times QY is defined, often ill-defined, and more frequently workers fail to describe how it was assessed. This has led to much confusion in the literature, not only because of its different meaning from homogeneous photochemistry but also because this method of describing photon efficiency precludes a comparison of results from different laboratories owing to variations in light sources, reactor geometries, and overall experimental conditions. It cannot be overemphasized that the reported QY is an apparent quantum yield, indeed a lower limit of the true quantum yield. This position paper addresses this issue and argues that any reference to quantum yields or quantum efficiencies in a heterogeneous medium is ill-advised unless the actual number of photons absorbed by the light harvester (the photocatalyst) has been determined. The extent of light scattering in a solid/liquid heterogeneous medium is significant. A practical and simple alternative to compare process efficiencies was recently (Serpone et al., J Photochem. Photobiol. A.Chem., 94 (1996) 191-203) suggested by defining a relative photonic efficiency (ζr). A quantum yield can subsequently be determined from ζr since Θ =ζr Θphenol, where phenol is the quantum yield for the photocatalyzed oxidative disappearance of phenol (a standard secondary actinometer) using Degussa P-25 TiO2 as the standard catalyst material.