Ultrathin Visible-Light-Driven Mo Incorporating In₂O₃–ZnIn₂Se₄ Z-Scheme Nanosheet Photocatalysts

Inspired by natural photosynthesis, the design of new Z-scheme photocatalytic systems is very promising for boosting the photocatalytic performance of H₂ production and CO₂ reduction; however, until now, the direct synthesis of efficient Z-scheme photocatalysts remains a grand challenge. Herein, it is demonstrated that an interesting Z-scheme photocatalyst can be constructed by coupling In₂O₃ and ZnIn₂Se₄ semiconductors based on theoretical calculations. Experimentally, a class of ultrathin In₂O₃–ZnIn₂Se₄ (denoted as In₂O₃–ZISe) spontaneous Z-scheme nanosheet photocatalysts for greatly enhancing photocatalytic H₂ production is made. Furthermore, Mo atoms are incorporated in the Z-scheme In₂O₃–ZISe nanosheet photocatalyst by forming the MoSe bond, confirmed by X-ray photoelectron spectroscopy, in which the formed MoSe₂ works as cocatalyst of the Z-scheme photocatalyst. As a consequence, such a unique structure of In₂O₃–ZISe–Mo makes it exhibit 21.7 and 232.6 times higher photocatalytic H₂ evolution activity than those of In₂O₃–ZnIn₂Se₄ and In₂O₃ nanosheets, respectively. Moreover, In₂O₃–ZISe–Mo is also very stable for photocatalytic H₂ production by showing almost no activity decay for 16 h test. Ultraviolet–visible diffuse reflectance spectra, photoluminescence spectroscopy, transient photocurrent spectra, and electrochemical impedance spectroscopy reveal that the enhanced photocatalytic performance of In₂O₃–ZISe–Mo is mainly attributed to its widened photoresponse range and effective carrier separation because of its special structure.