One-dimensional nanotube of a metal-organic framework boosts charge separation and photocatalytic hydrogen evolution from water: synthesis and underlying understanding

One-dimensional (1D) nanostructured inorganic semiconductors have been extensively investigated for efficiently promoting their photocatalytic performances, but it still remains unclear for metal-organic framework (MOF)-based photocatalysis. Herein we present the synthesis 1D Mn-TBAPy MOF nanotubes (denoted as Mn-TBAPy-NT) and give the first demonstration of the marked ability of the 1D nanotube structure to promote charge separation of MOFs relative to that in the Mn-TBAPy single crystal (denoted as Mn-TBAPy-SC), a feature proposed to result from the effect of strain on the nanotubes. As specifically determined using transient absorption (TA) spectroscopy, Mn-TBAPy-NT exhibits a long-lived internal charge-separated (ICS) state (255.6 ns), longer than that for Mn-TBAPy-SC (4.6 ns) and a feature apparently responsible for its over 30-fold promoted hydrogen evolution with a rate of 203.5 mu mol h-1 (ca. 10.2 mmol h-1 gcat-1) under visible light and a benchmark apparent quantum efficiency (AQE), of 11.7% at 420 +/- 10 nm, among MOF-type photocatalysts. Our results open a new avenue for developing highly efficient MOF-based photocatalysts.