A titanium metal–organic framework/titanium dioxide (Ti-MOF/TiO₂) composed membrane was fabricated by light inductive growth of Ti-MOF ([Ti₂-(TpA)₂-NDI] _n ; TpA = terephthalic acid, NDI = 1,8,4,5-naphthalene-tetracarboxdiimide) on a titanium dioxide film composite optical waveguide (COWG) substrate. The Ti-MOF/TiO₂ membrane conforms to a mesoporous structure with a 24 nm pore size and a 108 nm thickness through continuous growth for 40 min under 340 nm ultraviolet light illumination. Under ambient conditions, in terms of COWG sensors, Ti-MOF/TiO₂ exhibited the greatest response to ethylenediamine (EDA), followed by nitrogen dioxide (NO₂), methylamine and trimethylamine, when exposed to 15 types of benzenes, amines and acidic gases. To improve response selectivity, the Ti-MOF/TiO₂ film was modified with 1,3,3-trimethylindolinonaphthospirooxazine (SP), forming an SP@Ti-MOF/TiO₂ COWG. This modified COWG showed improved selectivity response by showing robust response to EDA and a negligible response to others. When an EDA gas molecule was adsorbed on the surface of the membrane, charge transfer between them preferentially occurred, leading to a change in the optical parameter. The surface-modified SP@Ti-MOF/TiO₂ COWG showed a fast (3 s) and reversible response with a wide detection range (0.1–1000 parts per billion) to EDA gas without the interference of benzene, toluene, xylene, styrene and chlorobenzene; acidic gases; and other amines.

中文翻译：

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表面修饰Ti-MOF/TiO2膜及其气敏特性

通过光诱导生长Ti-MOF ([Ti 2 _{- (} TpA) ₂ -NDI] _n；TpA = 对苯二甲酸，NDI = 1,8,4,5-萘四甲酰亚胺）在二氧化钛薄膜复合光波导（COWG）基板上。Ti-MOF/TiO ₂膜在340 nm紫外光照射下连续生长40 min，形成孔径为24 nm、厚度为108 nm的介孔结构。在环境条件下，就COWG传感器而言，Ti-MOF/TiO ₂对乙二胺（EDA）表现出最大的响应，其次是二氧化氮（NO ₂ ）、甲胺和三甲胺，当暴露于15种苯、胺和酸性气体时。为了提高响应选择性，用1,3,3-三甲基吲哚啉萘螺恶嗪（SP）对Ti-MOF/TiO ₂薄膜进行改性，形成SP@Ti-MOF/TiO ₂ COWG。这种改进的 COWG 通过显示对 EDA 的强劲响应和对其他的可忽略不计的响应，显示出改进的选择性响应。当EDA气体分子吸附在膜表面时，它们之间优先发生电荷转移，导致光学参数发生变化。表面改性SP@Ti-MOF/TiO ₂COWG 对 EDA 气体表现出快速（3 s）、可逆的响应，检测范围广（0.1-1000 ppb），且不受苯、甲苯、二甲苯、苯乙烯和氯苯的干扰；酸性气体；和其他胺类。