Reasonable design of Cu₂MoS₄ heterophase junction for highly efficient photocatalysis

Phase junction can effectively improve spatial charge separation due to its good lattice matching at the interface. Developing phase junction materials with good visible light absorption and suitable electronic band structure is greatly important for photocatalytic environmental purification. In this work, we combined the P and I phases of Cu₂MoS₄ (CMS) by one-step solvothermal in situ phase transition route. The as-prepared samples are labeled as CMS-X, where X represents the reaction time (X = 2, 4, 6, 8, 10, 12, 24 h). XRD, SEM, HRTEM, and XPS confirmed the existence of the phase junction structure. Photocatalytic experiments revealed that the phase junction samples exhibit excellent photocatalytic performance and durability for methyl orange (MO) and tetracycline (TC) degradation. Among the samples, CMS-8h showed optimal phase composition and the best photocatalytic degradation performance. Approximately 50 ml of 20 ppm MO can be completely degraded within 8 min under visible light irradiation, which is approximately 12.5 and 10 times faster than that of pure phase P-CMS and I-CMS respectively, presenting the best photocatalytic efficiency of CMS. Photocatalytic mechanism studies combined with theoretical calculations demonstrated that CMS-8h (PI-CMS) possesses a typical type-II heterojunction structure, which significantly accelerates the separation of photogenerated carriers and reduces their radiation recombination. The synergistic effect of the advantages of each phase and optimized interfacial band alignment endow PI-CMS with highly efficient and long-lasting photocatalytic activity for organic pollutant degradation. Copyright © 2020 Elsevier B.V. All rights reserved.