Synthesis of ZnIn2S4/Ti3C2 Nanocomposites

All reagents were of analytical grade and used without further purification. Ti₃AlC₂ powder (>98 wt.% purity) was purchased from Beijing Lianli New Technology Co., Ltd., Beijing, China. By etching the Al layer of Ti₃AlC₂ with HF solution, Ti₃C₂ was obtained. In brief, 1 g Ti₃AlC₂ powder was slowly combined with 30 mL HF solution (content ≥ 40 wt.%, Xilong Chemical Co., Ltd., Shantou, China), and the mixture was stirred at room temperature for 72 h. The suspension was filtered and washed with deionized water several times, until neutral pH was achieved. The obtained Ti₃C₂ was dried under vacuum at 60 °C for 2 h.
Next, a hydrothermal reaction was employed to prepare the ZnIn₂S₄/Ti₃C₂ nanocomposites. An appropriate amount of Ti₃C₂ was dispersed in 70 mL of water by ultrasonication. To the Ti₃C₂ dispersion, ZnCl₂ (0.136 g, 1 mmol, Tianjin Fengchuan Chemical Reagent Technology Co. Ltd., Tianjing, China) and excess L-cysteine were added, and the mixture was ultrasonicated. Subsequently, InCl₃·4H₂O (0.586 g, 2 mmol., Adamas Reagent Co. Ltd., Beijing, China) and thioacetamide (TAA, 0.300 g, 4 mmol., Sinopharm Chemical Reagent Co., Ltd., Shanghai, China) were added, and the solution was transferred to a 100 mL Teflon liner, sealed in a stainless steel autoclave, and heated at 150 °C for 5 h. The product was collected by centrifugation, washed several times with de-ionized water, and dried under vacuum at 60 °C for 12 h. The mass ratio of ZnIn₂S₄ to Ti₃C₂ was varied to determine the optimal composition, and mass ratios of 2 wt.%, 5 wt.%, 10 wt.%, 20 wt.%, and 50 wt.% corresponded to samples ZIST-2, ZIST-5, ZIST-10, ZIST-20, and ZIST-50, respectively.