We report a real-time investigation on the photocatalytic decomposition of methanol over Cu2O-loaded TiO2 nanotube arrays (TNAs) in high vacuum. Cu2O-loaded TNAs were fabricated using all-electrochemical processes. TNAs were prepared by anodizing Ti foils, and Cu2O nanoparticles (CNPs) were pulse-electrodeposited onto anodized TNA surfaces. The photocatalytic decomposition of methanol was monitored using a quadrupole mass analyzer in high vacuum, where the partial pressures of intermediate and final reaction products were measured. Switching phenomena in the partial pressures of hydrogen (H2), formaldehyde (CH2O), water (H2O), and carbon monoxide (CO) were observed simultaneously according to the ON/OFF sequence of ultraviolet irradiations over TNA/CNP composites, thereby revealing that Cu2O can facilitate proton reduction like noble-metal-based cocatalysts such as platinum, even in a high vacuum environment. The intermediate reaction products suggest that the photocatalytic oxidation of gaseous methanol over TNA/CNP proceeds under the coexistence of direct and indirect hole transfer mechanisms.

中文翻译：

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高真空下负载Cu2O的TiO2纳米管阵列光催化甲醇分解的实时监测

我们报告了在高真空下通过负载 Cu2O 的 TiO2 纳米管阵列 (TNA) 光催化分解甲醇的实时研究。使用全电化学工艺制造负载 Cu2O 的 TNA。TNA 通过阳极氧化钛箔制备，Cu2O 纳米颗粒 (CNP) 脉冲电沉积到阳极氧化的 TNA 表面。在高真空下使用四极杆质量分析仪监测甲醇的光催化分解，测量中间和最终反应产物的分压。根据紫外线照射在 TNA/CNP 复合材料上的 ON/OFF 顺序，同时观察到氢气 (H2)、甲醛 (CH2O)、水 (H2O) 和一氧化碳 (CO) 分压的转换现象，从而表明即使在高真空环境中，Cu2O 也可以像铂等贵金属基助催化剂一样促进质子还原。中间反应产物表明气态甲醇在 TNA/CNP 上的光催化氧化在直接和间接空穴转移机制的共存下进行。