Tunable titanium metal-organic frameworks with infinite 1D Ti-O rods for efficient visible-light-driven photocatalytic H 2 evolution.

Infinite 1D Ti-O rod-based metal-organic frameworks (MOFs) are promising photocatalysts for water splitting due to their high optical response and favourable photo-redox properties and stability, but have not been explored yet. In this study, three isoreticular porous 1D rod-based Ti-MOFs ZSTU-1 , ZSTU-2 and ZSTU-3 are successfully constructed from infinite [ Ti 6 ( μ 3 - O ) 6 ( μ 2 - OH ) 6 ] n secondary building units (SBUs) and tritopic carboxylate linkers 4,4',4″-nitrilotribenzoic acid (H ₃ TCA), 1,3,5-tris(4-carboxyphenyl) benzene (H ₃ BTB) and tris(4'-carboxybiphenyl)amine (H ₃ BTCA), respectively. Their porosities systematically increase with the larger and longer organic linkers. The two MOFs ZSTU-1 and ZSTU-3 built from the triphenylamino-based ligands can absorb visible light, exhibiting much better photocatalytic performance than ZSTU-2 as shown by the H ₂ production rate of ZSTU-1 and ZSTU-3 being 3-4 times higher than that of ZSTU-2 . The photocatalytic H ₂ production rates for ZSTU-1 , ZSTU-2 , and ZSTU-3 are 1060 μmol g ^-1 h ^-1 , 350 μmol g ^-1 h ^-1 and 1350 μmol g ^-1 h ^-1 , respectively. The extraordinary photocatalytic activity of ZSTU-3 is attributed to its visible light absorption, large surface area, and favorable charge separation.
Competing Interests: Conflicts of interest There are no conflicts to declare.