Synthesis of Z-type heterojunction bifunctional composites with Mn-doped CdS nanoparticles supported on NH2-MIL-125(Ti) for hydrogen evolution and antibiotic degradation under visible light

Abstract

In this paper, a novel Mn-doped CdS@NH2-MIL-125(Ti) (MC@NT) photocatalytic composites was synthetized through hydrothermal method. Hydrogen desorption and tetracycline and oxytetracycline degradation were performed under visible light to test their photocatalytic activities. The composites were characterized by XRD, FTIR, SEM, TEM, XPS, UV–Vis diffuse reflectance spectroscopy (DRS), EPR, EIS, and transient photocurrent response. From the characterization consequence, it could be seen that Mn-doped CdS was tightly attached to the surface of tetragonal NT in the form of nanoparticles. The MC@NT composites exhibited more promising catalytic activity than pristine monomeric materials. The photocatalytic hydrogen evolution rate reached 3.61 mmol g−1 h−1. Within 110 min, the degradation efficiencies of TC and OTC were 90% and 88%, respectively. The free radical trapping experiments proved that ·O2− and h+ were decisive role for degrading pollutants in the degradation catalysis process. Radical trapping experiments and electron spin resonance (ESR) indicated that the Z-scheme heterojunction was formed between Mn-doped CdS and NT, leading to facilitate the migration and shift of photogenerated carriers and holes. Cycling experiments showed that the as-prepared composites have good stability and have good prospects for practical applications. We believe this work will offer new ideas on the future development of efficient heterojunction catalysts for light energy conversion and other applications.