This study addresses the inherent photocatalytic activity of pure titanium dioxide (TiO₂), which limits its application as an industrial pigment. To mitigate this issue, a core–shell structure was employed, where TiO₂ cores were encapsulated within SiO₂ shells. Perhydropolysilazane (PHPS) was introduced as a superior SiO₂ precursor over tetraethylorthosilicate (TEOS), resulting in thinner and more uniform SiO₂ shells. Utilizing TiO₂'s photocatalytic properties, hydroxyl radicals facilitated the conversion of PHPS into SiO₂ via native Si–H bonds, eliminating the need for additional reducing agents. The formation of PHPS-derived TiO₂@SiO₂ core–shell nanoparticles demonstrated inherent self-limiting behaviour, ensuring uniform shell thickness regardless of PHPS concentration, simplifying the process for large-scale industrial applications compared to TEOS, which demands precise parameter control. Photocatalytic evaluations highlighted significant passivation of TiO₂ photocatalytic activity by PHPS-derived TiO₂@SiO₂ core–shell particles and TiO₂/SiO₂ thin films. Specifically, TiO₂@PHPS nanoparticles achieved 89–96% passivation compared to 30% with TiO₂@TEOS, while TiO₂/PHPS films degraded only 12% of Eosin B versus 80% with TiO₂ films. Moreover, both PHPS-derived nanoparticles and films maintained TiO₂'s inherent high whiteness and high-refractive-index optical properties, underscoring their suitability for applications in white paint production, cosmetics, and high-refractive-index coatings.

中文翻译：

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通过全氢聚硅氮烷衍生的 SiO2 超薄壳控制 TiO2 光催化行为


本研究解决了纯二氧化钛 （TiO₂） 固有的光催化活性，这限制了其作为工业颜料的应用。为了缓解这个问题，采用了核壳结构，其中 TiO₂ 核封装在 SiO₂ 壳层中。全氢聚硅氮烷 （PHPS） 作为优于正硅酸四乙酯 （TEOS） 的 SiO₂ 前驱体引入，从而产生更薄、更均匀的 SiO₂ 壳层。利用 TiO₂ 的光催化特性，羟基自由基促进了 PHPS 通过天然 Si-H 键转化为 SiO₂，无需额外的还原剂。PHPS 衍生的 TiO₂@SiO₂ 核壳纳米颗粒的形成表现出固有的自限性行为，无论 PHPS 浓度如何，都能确保壳层厚度一致，与需要精确参数控制的 TEOS 相比，简化了大规模工业应用的过程。光催化评估强调了 PHPS 衍生的 TiO₂@SiO₂ 核壳颗粒和 TiO₂/SiO₂ 薄膜对 TiO₂ 光催化活性的显着钝化。具体来说，TiO₂@PHPS 纳米颗粒实现了 89-96% 的钝化，而 TiO₂@TEOS 的钝化率为 30%，而 TiO₂/PHPS 薄膜仅降解了 12% 的曙红 B，而 TiO₂ 薄膜的降解率为 80%。 此外，PHPS 衍生的纳米颗粒和薄膜都保持了 TiO₂ 固有的高白度和高折射率光学特性，强调了它们适用于白色涂料生产、化妆品和高折射率涂料。