Implanting single Sb sites as electron traps on MOF nanosheets for boosting H2O2 photosynthesis

초록

Metal-organic frameworks (MOFs) have emerged as promising candidates for photocatalytic H2O2 production but suffer from poor charge separation and reliance on sacrificial agents. Herein, we introduce Sb single-atom catalysts (SACs) into MOFs for the first time to promote charge separation and enhance charge transfer efficiency. The developed Sb-implanted Al-TCPP (aluminum tetra-(4-carboxyphenyl) porphyrin framework) (Al-TCPP-Sb5 %) demonstrates a remarkable H2O2 production rate of 663.2 mu mol/g/h under visible light in pure water, which is 3.5 times higher than that of pristine Al-TCPP without sacrificial agents, surpassing most of the reported MOF photocatalysts under comparable conditions. Further experiments such as Kelvin probe force microscopy (KPFM) and transient absorption (TA) spectroscopy verify that Sb atoms are suitable electron traps, which greatly increase the mobility of charge carriers and promote separation of charge carriers. Theoretical simulations also show that the Sb site not only enhances the O2 adsorption, but also lowers the energy barrier of *OOH intermediate, which is an important step of the reduction process with 2-electrons. These findings are also proved by in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. This work presented the first example of a MOF containing Sb SACs and puts forward a novel atomic-level design strategy toward oriented electron transfer in MOF photocatalysts.

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