Smart materials that reversibly change color upon light illumination are widely explored for diverse appealing applications. However, light-responsive color switching materials are mainly limited to organic molecules. The synthesis of inorganic counterparts has remained a significant challenge because of their slow light response and poor reversibility. Here, we report a seeded growth strategy for the synthesis of TiO_2−x/WO₃·0.33H₂O hetero-nanoparticles (HNPs) with networked wire-like structure of ∼ 10 nm in diameters that enable the highly reversible light-responsive color switching properties. For the TiO_2−x/WO₃·0.33H₂O HNPs, Ti³⁺ species self-doped in TiO_2−x nanoparticles (NPs) act as efficient sacrificial electron donors (SEDs) and Ti-O-W linkages formed between TiO_2−x and WO₃·0.33H₂O NPs ensure the nanoscale interfacial contact, endowing the HNPs enhanced photoreductive activity and efficient interfacial charge transfer upon ultraviolet (UV) illumination to achieve highly efficient color switching. The TiO_2−x/WO₃·0.33H₂O HNPs exhibits rapid light response (< 15 s) and long reversible color switching cycles (> 180 times). We further demonstrate the applications of TiO_2−x/WO₃·0.33H₂O HNPs in ink-free, light-printable rewritable paper that can be written on freehand or printed on through a photomask using UV light. This work opens an avenue for designing inorganic light-responsive color switching nanomaterials and their smart applications.

人们广泛地探索了在光照射下可逆地改变颜色的智能材料，以用于各种吸引人的应用。然而，光响应性颜色切换材料主要限于有机分子。无机对应物的合成由于其缓慢的光响应和差的可逆性而仍然是一个重大挑战。在这里，我们报告了一种种子生长策略，该策略用于合成TiO _{2− x} / WO ₃ ·0.33H ₂ O异质纳米粒子（HNP），其网状线状结构的直径约为10 nm，从而实现了高度可逆的光响应颜色切换属性。对于TiO _{2− x} / WO ₃ ·0.33H ₂ O HNPs，Ti ³⁺自掺杂在TiO ₂ - _x纳米粒子（NPs）中的金属物种可作为有效的牺牲电子供体（SED），并且TiO _{2- x}与WO ₃ ·0.33H ₂ O NP之间形成的Ti-OW键确保了纳米级界面接触， HNP增强了光还原活性，并在紫外线（UV）照射下有效地转移了界面电荷，从而实现了高效的色彩切换。TiO _{2− x} / WO ₃ ·0.33H ₂ O HNP表现出快速的光响应（<15 s）和长的可逆颜色切换周期（> 180次）。我们进一步证明了TiO _2−x / WO ₃ ·0.33H的应用无墨水的可光印刷可擦写纸中的₂ O HNP，可以徒手书写或使用紫外光通过光罩印刷。这项工作为设计无机光响应性色彩切换纳米材料及其智能应用开辟了一条途径。