Hierarchical Cu₂O/CuO mesocrystals have been fabricated by a one-step, controllable and low-power method. A novel “Etch-Oriented Self-Assembly” growth mechanism is proposed to describe the formation of hierarchical Cu₂O/CuO mesocrystals. In an alkaline environment, Cu₂O nanoparticles are generated first; they are then etched into small sized (14–18 nm) CuO nanocrystals which assemble in an oriented way to form Cu₂O/CuO mesocrystal nano-petals. As the reaction progresses, the obtained nano-petals stagger together to construct a hierarchical nanoflower structure. All factors that may influence the morphology of the final product have been investigated. The sensing results indicate that the product at 10 h exhibits the highest sensitivity to NO₂ (73 162 to 10 ppm) at room temperature. Even when the concentration of NO₂ drops down to 1 ppb, the sensing response of the Cu₂O/CuO-10 mesocrystals can reach 13.5. In addition, the sensor's response speed is ultra-fast and its response can increase to 2658 in 2 s when exposed to 10 ppm NO₂ and recover 96% within 200 s. To study the sensor's response mechanism, the influence of pre-absorption of H₂O has been studied by experiments as well as the first-principles calculations, and a rational mechanism has been put forward to explain its distinctive sensing performance.

中文翻译：

---

基于分层Cu ₂ O / CuO介晶纳米花的超灵敏NO ₂气体传感器

通过一步，可控和低功耗的方法制备了Cu ₂ O / CuO介观晶体。提出了一种新颖的“刻蚀自组装”生长机理，以描述层级Cu ₂ O / CuO介晶的形成。在碱性环境中，首先会生成Cu ₂ O纳米粒子；然后将它们蚀刻成小尺寸（14-18 nm）的CuO纳米晶体，以定向的方式组装以形成Cu ₂O / CuO介晶纳米花瓣。随着反应的进行，获得的纳米花瓣交错排列在一起，以构建分层的纳米花结构。已经研究了可能影响最终产品形态的所有因素。感测结果表明，在室温下，该产品在10 h时对NO _2的敏感性最高（73 162至10 ppm）。即使当NO ₂的浓度下降到1 ppb时，Cu ₂ O / CuO-10中间晶体的感测响应也可以达到13.5。此外，传感器的响应速度超快，当暴露于10 ppm NO ₂时，其响应可以在2 s内增加到2658，并在200 s内恢复96％。要研究传感器的响应机制，H的预吸收的影响通过实验和第一性原理的计算研究了₂ O，并提出了一种合理的机理来解释其独特的传感性能。