Platform for molecular-material dual regulation: A direct Z-scheme MOF/COF heterojunction with enhanced visible-light photocatalytic activity

Series of novel metal-organic framework/covalent organic framework (MOF/COF) hybrid materials were constructed by encapsulating MOF with highly stable TTB-TTA (a COF synthesized from 4,4',4 ''-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde (TTB) and 4,4',4 ''-(1,3,5-triazine-2,4,6-triyl)trianiline (TTA)) layer, inheriting their merits of high crystallinity, large surface area, outstanding visible-light response and tunable band gaps. The introduction of NH2-MIL-125(Ti) into the hybrid materials could modulate their optical, electronic and redox properties, and promote the charge separation owing to the formation of heterojunction, thus resulting in an enhanced photocatalytic performance for organic pollutant decomposition. As such, NH2-MIL-125(Ti)TTB-TTA composite has a much higher photodegradation kinetic of methyl orange (MO) which is over 9 and 2 times the rates of pure NH2-MIL-125(Ti) and TTB-TTA, respectively. This versatile molecular-material platform can achieve dual adjusting modes consisting of a COF molecular engineering and a MOF type screening strategy, which will be applicable to a wide range of fields.