An enhancing effect of peroxymonosulfate (PMS) on photocatalytic activity has previously been demonstrated, but the research focus was concentrated primarily on the extent to which treatment efficiency was improved. To further comprehend the role of PMS, this study examined the TiO₂ photocatalytic systems in the presence of PMS for the oxidation of diverse organics and showed that the extent of performance enhancement via PMS addition was substrate-dependent. This resulted from the involvement of multiple oxidants owing to the dual role of PMS as an electron acceptor and a radical precursor, confirmed in the open circuit potential shifts and electron paramagnetic resonance spectra. Surface platinization, typically adopted to modulate charge carrier dynamics in photocatalysis, caused the nonphoton-driven degradative pathway, i.e., mediated electron transfer involving PMS as a two-electron acceptor, and promoted the one-electron reduction of PMS to sulfate radicals (SO₄^•–). The contribution of SO₄^•– was assessed based on efficiencies for decarboxylation and hydroxylation, isomer distribution in the hydroxylated intermediates, the quenching effect of alcohols, and net conversion of methanol to formaldehyde. Relying on the selective reactivity of Pt-activated PMS, Pt-TiO₂/PMS outperformed bare TiO₂/PMS in oxidatively treating the binary mixtures of organics and enabled effective organic degradation under periodic light irradiation.

中文翻译：

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重新审视过硫酸盐在 TiO2 介导的光催化氧化中的作用：动力学增强对目标基材和表面镀金的依赖性

先前已经证明过硫酸盐 (PMS) 对光催化活性的增强作用，但研究重点主要集中在提高处理效率的程度上。为了进一步理解 PMS 的作用，本研究检查了 TiO ₂PMS 存在下的光催化系统用于氧化多种有机物，并表明通过添加 PMS 提高性能的程度取决于底物。这是由于 PMS 作为电子受体和自由基前体的双重作用，涉及多种氧化剂，这在开路电位位移和电子顺磁共振光谱中得到证实。表面铂化通常用于调节光催化中的载流子动力学，导致非光子驱动的降解途径，即介导电子转移，涉及 PMS 作为双电子受体，并促进 PMS 的单电子还原为硫酸根 (SO ₄ ^•– )。SO ₄的贡献^•–基于脱羧和羟基化的效率、羟基化中间体中的异构体分布、醇的淬灭效果以及甲醇向甲醛的净转化率进行评估。依托铂活化PMS的选择性反应性，铂的TiO ₂ / PMS优于裸露的TiO ₂ / PMS在氧化处理有机物的二元混合物和定期在光照射下使能有效的有机降解。