Construction of 2D Zn-MOF/BiVO4 S-scheme heterojunction for efficient photocatalytic CO2 conversion under visible light irradiation

The construction of S-scheme heterojunction photocatalysts has been regarded as an effective avenue to facilitate the conversion of solar energy to fuel. However, there are still considerable challenges with regard to efficient charge transfer, the abundance of catalytic sites, and extended light absorption. Herein, an S-scheme heterojunction of 2D/2D zinc porphyrin-based metal-organic frameworks/BiVO4 nanosheets (Zn-MOF/BVON) was fabricated for efficient photocatalytic CO2 conversion. The optimal one shows a 22-fold photoactivity enhancement when compared to the previously reported BiVO4 nanoflake (ca. 15 nm), and even exhibits ~2-time improvement than the traditional g-C3N4/BiVO4 heterojunction. The excellent photoactivities are ascribed to the strengthened S-scheme charge transfer and separation, promoted CO2 activation by the well-dispersed metal nodes Zn2(COO)4 in the Zn-MOF, and extended visible light response range based on the results of the electrochemical reduction, electron paramagnetic resonance, and in-situ diffuse reflectance infrared Fourier transform spectroscopy. The dimension-matched Zn-MOF/BVON S-scheme heterojunction endowed with highly efficient charge separation and abundant catalytic active sites contributed to the superior CO2 conversion. This study offers a facile strategy for constructing S-scheme heterojunctions involving porphyrin-based MOFs for solar fuel production.