Construction of a direct Z-scheme CeO₂/UiO-66-NH₂ heterojunction for boosting photocatalytic organic pollutant degradation and H₂ evolution performance

In this study, hollow CeO2 nanospheres were grown on UIO-66-NH2 nanosheets to form a novel CeO2/UiO-66-NH2 (abbreviation, CUx) Z-scheme heterojunction photocatalyst by calcination and hydrothermal method for hydrogen production and photocatalytic degradation of organic pollutants. Under visible light, the H2 generation rate of the CU0.50 composite was 5662.1 μmol g-1 h-1, which was 22 and 7 fold than that of pure CeO2 and pure UiO-66-NH2, respectively. In addition, compared with CeO2 and UiO-66-NH2, the as-prepared CUx composites exhibited enhanced photo-degradation efficiencies for tetracycline (TC) and 2,4-dichlorophenol (DCP) under simulated solar light irradiation. Among them, the CU0.50 composite demonstrated the highest photocatalytic performance and reached 91.5% for TC, and 94.3% for DCP. In addition, a logical solid-state Z-type electron transfer mechanism is presented with the results of radical scavenging and ESR experiments to illustrate the intensive decomposed ability of the photocatalytic system. The enhanced photocatalytic performance of CUx heterostructures can be attributed to the formation of a band-position-matched hollow structure heterojunction between CeO2 and UIO-66-NH2, which can effectively inhibit the recombination of carriers and increase the specific surface area as well as the light absorption. Moreover, the oxidation and reduction ability of the charge carriers was also increased. This work resulted in a feasible idea for removing organic pollutants and hydrogen production by traditional inorganic semiconductor/MOF-based heterostructured photocatalysts.