MIL-125(Ti)-derived titanium oxides, a functionalized cake-like 3D material, is becoming increasingly attractive to researchers. In this work, COOH functionalized anatase TiO₂ (TiO₂@C) was prepared by one-step calcination method. And the TiO₂@C, as a novel catalyst, was used to accelerate electron transfer from As(III) to Cr(VI) for simultaneous Cr(VI) reduction and As(III) oxidization in aqueous solution. The results showed that the addition of TiO₂@C greatly accelerates the coupled As(III)/Cr(VI) reaction. This reaction is further enhanced at acidic pH and higher concentrations of material. Furthermore, the mutual conversion is equally sensitive to ion initial concentration. Accordingly, a new microscopic redox reaction process of As(III) and Cr(VI) was proposed, which was first made clear of the mutual redox via XPS and FTIR analysis. To be specific, the carboxyl on anatase not only offers As(III) and Cr(VI) ions binding sites, but also initiates the electron transfer from As(III) to Cr(VI) on the solid surface. While the cake-like geometry with high surface area serves for the electron transfer pathways. This unparalleled reaction mechanism enlighten us on a new field of COOH functionalized catalyst used for the coupled removal of As(III)/Cr(VI).

MIL-125（Ti）衍生的二氧化钛是一种功能化的类似蛋糕的3D材料，对研究人员越来越有吸引力。在这项工作中，通过一步煅烧方法制备了COOH功能化的锐钛矿型TiO ₂（TiO ₂ @C）。TiO ₂ @C作为一种新型催化剂，被用来加速电子从As（III）到Cr（VI）的转移，以便同时还原Cr（VI）和水溶液中As（III）的氧化。结果表明，TiO _2的添加@C极大地促进了As（III）/ Cr（VI）偶联反应。在酸性pH和更高浓度的物质下，该反应会进一步增强。此外，相互转换对离子初始浓度同样敏感。因此，提出了一种新的As（III）和Cr（VI）的微观氧化还原反应过程，该过程首先通过XPS和FTIR分析消除了相互氧化还原。具体而言，锐钛矿上的羧基不仅提供As（III）和Cr（VI）离子结合位点，而且还引发了电子从固体表面上的As（III）传递到Cr（VI）。而具有高表面积的饼状几何形状则用于电子传递路径。这种无与伦比的反应机理使我们对用于偶合去除As（III）/ Cr（VI）的COOH官能化催化剂的新领域有所启发。