Reducing Packing Factor of ZnIn₂S₄ to Promote Photocatalytic Activity

Due to the quite sluggish charge-carrier separation in semiconductor photocatalysts, the photocatalytic activity of these materials is still far inferior than anticipated. Herein, a novel approach to reducing the packing factor(PF) of ZnIn₂S₄ semiconductors to improve the charge-carrier separation is offered. The well-crystallized Zn₁-_xIn₂S_4-x(x=0, 0.05, 0.1) powders were productively prepared through solid-state reactions. Their structures were verified by the high-resolution transmission electron microscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy. The PF values of Zn₁-_xIn₂S_4-x(x=0, 0.05, 0.1) samples were calculated to be 0.683, 0.651, and 0.618, respectively. The reduction of the PF for Zn₁-_xImS_4-x with increasing x can promote the separation of photoexcited carriers, and this process was endorsed by their photoelectric response and photoluminescence emission spectra. The Zn_0.9In₂S_3.9 sample with a lower PF value presents roughly 21 times higher photocurrent density and four times higher photodegrading rate of methyl orange than those of pristine ZnIn₂S₄.