This study is the first to employ combinatorial hydrothermal synthesis and facile spin-coating technology to fabricate TiO₂-reduced graphene oxide (rGO) nanorod composition spreads. The features of this study are (1) the development of a self-designed spin-coating wedge, (2) the systemic investigation of the structure–property relationship of the system, (3) the high-throughput screening of the optimal ratio from a wide range of compositions for photocatalytic and photoelectrochemical (PEC) applications, and (4) the effective coupling between the density gradient TiO₂ nanorod array and the thickness gradient rGO. The formation of rGO in the fabricated TiO₂–rGO sample was monitored through Fourier transform infrared spectrometry. Transmission electron microscopy images also suggested that the TiO₂ nanorod surfaces were covered with a thin layer of amorphous rGO. The rutile TiO₂ plane evolution along the composition variation was verified through X-ray diffraction. 7% TiO₂–93% rGO on the nanorod composition spread exhibited the most promising photocatalytic ability; the corresponding photodegradation kinetics, denoted by the photodegradation rate constant (k), was determined to be approximately 12.7 × 10^–3 min^–1. The excellent performance was attributed to the effective coupling between the TiO₂ and rGO, which improved the charge carrier transport, thus inhibiting electron–hole pair recombination. A cycling test implied that 7% TiO₂–93% rGO is a reliable photocatalyst. A photoluminescence spectroscopy study also supported the superior photocatalytic ability of the sample, which was attributed to its markedly poorer recombination behavior. In addition, without further treatment, the sample exhibited excellent PEC stability; the photocurrent density was more than three times higher than that exhibited by the density gradient TiO₂ nanorods.

中文翻译：

---

组合水热合成TiO ₂还原氧化石墨烯纳米棒的制备及其光催化和光电化学的应用

这项研究是首次采用组合水热合成和便捷的旋涂技术来制造TiO ₂还原的氧化石墨烯（rGO）纳米棒组合物。这项研究的特点是（1）自行设计的旋涂楔形物的开发；（2）对系统的结构-性能关系的系统研究；（3）通过高通量筛选最佳比例用于光催化和光电化学（PEC）应用的各种组合物，以及（4）密度梯度TiO ₂纳米棒阵列与厚度梯度rGO之间的有效耦合。人造TiO ₂中rGO的形成-rGO样品通过傅立叶变换红外光谱法进行监测。透射电子显微镜图像还表明，TiO ₂纳米棒表面覆盖有非晶态rGO薄层。通过X射线衍射验证了金红石TiO ₂平面沿组成变化的演变。纳米棒组成上7％的TiO ₂ –93％rGO表现出最有前途的光催化能力。相应的光降解动力学，以光降解速率常数（k）表示，约为12.7×10 ^–3 min ^–1。优异的性能归因于TiO ₂之间的有效偶联rGO改善了电荷载流子的传输，从而抑制了电子-空穴对的重组。循环测试表明7％TiO ₂ –93％rGO是可靠的光催化剂。光致发光光谱学研究还支持了样品的优异光催化能力，这归因于其明显较差的重组行为。另外，该样品未经进一步处理，显示出极好的PEC稳定性。光电流密度比密度梯度TiO ₂纳米棒高出三倍以上。