Postcalcination has usually been used to remove organic residues from atomically thin two-dimensional (2D) semiconductor materials for CO₂ photoreduction, while the effect of calcination on their structure and photocatalytic activity has remained unclear yet. In this work, the structure transformation of atomically thin 2D TiO₂(B) nanosheets during calcination was analyzed, and the structure-function relationship was studied. The results show that after calcination at 350 °C in air for 10 h, hierarchical assembly of 2D TiO₂(B) nanosheets was collapsed into a uniform structure and the TiO₂(B) nanosheets were decomposed into interconnected high-crystallinity anatase nanoparticles. The morphology/phase transformation enhanced the chemical binding and activation of CO₂, and promoted the transfer/separation of photogenerated charges, resulting in the improved CO₂ photoreduction activity. This work aimed to show the importance of precise control over the postcalcination treatment for atomically thin 2D materials.

后煅烧通常用于去除原子薄的二维（2D）半导体材料中的有机残基以进行CO _2光还原，而煅烧对其结构和光催化活性的影响尚不清楚。在这项工作中，分析了煅烧过程中原子薄的2D TiO ₂（B）纳米薄片的结构转变，并研究了结构与功能的关系。结果表明，在350°C的空气中煅烧10 h后，二维TiO ₂（B）纳米片的分层组装塌陷为均匀结构，并且TiO ₂（B）将纳米片分解为相互连接的高结晶锐钛矿纳米粒子。形态/相变增强了CO ₂的化学结合和活化，并促进了光生电荷的转移/分离，从而提高了CO _2的光还原活性。这项工作旨在表明精确控制原子薄2D材料的后煅烧处理的重要性。