Synthesis of the composites of carbon quantum dots and metal organic framework and their application in hydrogen evolution.

The Ti-MIL-125 metal-organic framework (MOF) functions as a nanoreactor, producing carbon quantum dots (CQDs) within its structure and forming CQD/MOF composites. Similarly, a Pt-CQD/MOF three-component composite is synthesized. Their properties, along with those of CQDs and MOF-free-CQDs (mf -CQDs) enclosed within the MOF, undergo assessment and comparison. Integrating CQDs and Pt minimally alters the MOF structure but reduces specific surface areas due to incorporation. The emitted wavelength of CQD/MOF (570 nm) differs from pristine CQDs (450 nm) and mf -CQDs (496 nm), indicating MOF influence on CQDs' growth and photoluminescence. HOMO and LUMO levels of CQDs/MOF, measured via ultraviolet photoelectron spectroscopy and low-energy inverse photoelectron spectroscopy, are more positive than those of the MOF, suggesting heterogeneous junction formation, aiding electron separation. CQD/MOF exhibits a modest photocatalytic hydrogen evolution rate of 20.4 μmol/g/h. Conversely, Pt-CQD/MOF significantly boosts the rate to 2213 μmol/g/h, underscoring Pt's pivotal catalytic role. [Display omitted] • Ti-MIL-125 MOF functioned as the nanoreactor in the synthesis of CQD. • The MOFs and the CQDs captured inside form the CQD/MOF composites. • The CQDs and those inside MOFs showed different emission wavelengths but similar QY. • Pt particles were incorporated into CQD/MOF for preparing Pt-CQD/MOF composites. • The rate of H 2 generation by Pt-CQD/MOF reached 2213 μ mol h⁻1g⁻1. [ABSTRACT FROM AUTHOR]