Stable core–shell ZIF-8@ZIF-67 MOFs photocatalyst for highly efficient degradation of organic pollutant and hydrogen evolution

Compared to single metal–organic framework (MOF), core–shell MOF crystals are more promising due to their special structure and unique properties. Herein, since ZIF-8 and ZIF-67 have the same topology, crystal growth method is used to synthesize core–shell crystals ZIF-8@ZIF-67, which exhibit far superior light adsorption, charge separation capabilities, and excellent stability than ZIF-8 and ZIF-67. The photocatalytic H2 generation rate for ZIF-8@ZIF-67 (1:1) is about 17 times higher than that of pure ZIF-67 without cocatalyst loading under same reaction conditions. Through a series of characterizations, two connection modes between ZIF-8 and ZIF-67 frames in core–shell contact interface are proposed, and the corresponding photocatalytic mechanism is elucidated. Transient photovoltaic curve reveals the unique transfer paths of electrons through contact interface, which leads to efficient charge separation compared with other ZIF materials. This study provides a novel and simple strategy to synthesis high effective and stable core–shell ZIF photocatalyst for photodegradation and hydrogen evolution.