Faculty of Electronic, Photonics and Microsystems, Wrocław University of Science and Technology, Janiszewskiego 11/17, 50-372 Wrocław, Poland.
Institute of Experimental Physics, University of Wrocław, Max Born 9, 50-204 Wrocław, Poland.
Sensors (Basel). 2023 Apr 8;23(8):3822. doi: 10.3390/s23083822.
Hydrogen is an efficient source of clean and environmentally friendly energy. However, because it is explosive at concentrations higher than 4%, safety issues are a great concern. As its applications are extended, the need for the production of reliable monitoring systems is urgent. In this work, mixed copper-titanium oxide ((CuTi)Ox) thin films with various copper concentrations (0-100 at.%), deposited by magnetron sputtering and annealed at 473 K, were investigated as a prospective hydrogen gas sensing material. Scanning electron microscopy was applied to determine the morphology of the thin films. Their structure and chemical composition were investigated by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The prepared films were nanocrystalline mixtures of metallic copper, cuprous oxide, and titanium anatase in the bulk, whereas at the surface only cupric oxide was found. In comparison to the literature, the (CuTi)Ox thin films already showed a sensor response to hydrogen at a relatively low operating temperature of 473 K without using any extra catalyst. The best sensor response and sensitivity to hydrogen gas were found in the mixed copper-titanium oxides containing similar atomic concentrations of both metals, i.e., 41/59 and 56/44 of Cu/Ti. Most probably, this effect is related to their similar morphology and to the simultaneous presence of Cu and CuO crystals in these mixed oxide films. In particular, the studies of surface oxidation state revealed that it was the same for all annealed films and consisted only of CuO. However, in view of their crystalline structure, they consisted of Cu and CuO nanocrystals in the thin film volume.
氢气是一种高效、清洁、环保的能源。然而，由于其在浓度高于 4%时具有爆炸性，因此安全性问题备受关注。随着其应用范围的扩大，迫切需要生产可靠的监测系统。在这项工作中，通过磁控溅射沉积并在 473 K 下退火的具有不同铜浓度（0-100 原子%）的混合铜钛氧化物（(CuTi)Ox）薄膜被用作有前途的氢气气体传感器材料。扫描电子显微镜用于确定薄膜的形态。通过 X 射线衍射和 X 射线光电子能谱分别研究了它们的结构和化学组成。所制备的薄膜是金属铜、氧化亚铜和锐钛矿型二氧化钛的纳米晶混合物，而在表面仅发现了氧化铜。与文献相比，(CuTi)Ox 薄膜已经在相对较低的 473 K 工作温度下对氢气表现出了传感器响应，而无需使用任何额外的催化剂。在含有相似原子浓度的两种金属的混合铜钛氧化物中，即 41/59 和 56/44 的 Cu/Ti，发现了对氢气气体的最佳传感器响应和灵敏度。很可能，这种效应与它们相似的形态以及这些混合氧化物薄膜中同时存在 Cu 和 CuO 晶体有关。特别是，表面氧化态的研究表明，所有退火后的薄膜都是相同的，仅由 CuO 组成。然而，从它们的晶体结构来看，它们由薄膜体积中的 Cu 和 CuO 纳米晶体组成。
