Introducing transition-metal oxides as co-catalysts into classical Fenton chemistry holds great promise for improving the recycling of iron species. However, the underlying chemistry that controls the generation and transformation of ferryl species (Fe^IV) during such heterogeneous Fenton reactions is not fully understood. Herein, we modulated oxygen-vacancy-enriched WO_3−x and identified surface Fe^IV species using in situ spectroscopy and density functional theory calculations. Direct spectroscopic evidence shows that WO_3−x caused the reaction of Fe^II with H₂O₂ to switch from the formation of Fe^III complexes towards direct generation of Fe^IV. Fe^IV intermediates oxidize H₂O₂ to ˙O₂⁻/¹O₂, accompanied by the production of Fe^III. Fe^III is reduced to Fe^II by the electrons localized in the t_2g orbitals of WO_3−x, stimulating the generation of ˙OH. This study opens a new chapter in the mechanistic understanding of Fe^IV formation and extends the development of co-catalysts via surface engineering in remediation techniques.

中文翻译：

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氧空位调节界面化学：在非均相Fenton反应中鉴定铁（IV）

将过渡金属氧化物作为助催化剂引入经典的Fenton化学中，对于改善铁物种的循环利用具有广阔的前景。但是，尚不完全了解控制这种异质Fenton反应过程中Ferryl物种（Fe ^IV）的生成和转化的基本化学过程。在这里，我们调制了富氧空位的WO ₃ - _x，并使用原位光谱和密度泛函理论计算确定了表面的铁^IV物种。直接光谱证据表明，WO _{3- x}引起Fe ^II与H ₂ O ₂的反应从Fe的形成转向^III络合物直接生成Fe ^IV。的Fe ^IV中间体氧化ħ ₂ ö ₂至O ₂ ^- / ¹ Ò ₂，伴随着生产的Fe ^III。通过位于WO _{3- x}的t _2g轨道中的电子将Fe ^III还原为Fe ^II，从而刺激˙OH的生成。这项研究开启了对Fe ^IV形成机理的机械理解的新篇章，并通过修复技术中的表面工程扩展了助催化剂的开发。