Efficient Photocatalytic H2O2 Production and Cr(VI) Reduction over a Hierarchical Ti3C2/In4SnS8 Schottky Junction
Tong Zhou, Xue Liu, Liang Zhao, Mingtao Qiao, Wanying Lei
Abstract
Artificial photosynthesis is an appealing approach for generating hydrogen peroxide (H 2 O 2 ) from H 2 O and O 2 with solar energy as the sole energy input. However, the current catalyst systems commonly face challenges such as the limited optical absorption , poor electron-hole pair separation efficiency, and restricted surface reactivity, which hinders the overall photoactivity. Here, we immobilize cubic-phase ultrathin In 4 SnS 8 nanosheets ( E g = 2.16 eV) with thickness of 5–10 nm on the surface of few-layer Ti 3 C 2 to develop a sandwich-like hierarchical structure of Ti 3 C 2 /In 4 SnS 8 nanohybrid via in situ hydrothermal strategy. The enlarged interfacial area and close contact between Ti 3 C 2 and In 4 SnS 8 benefit for carrier transportation among nanohybrids. Characterization through X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) corroborates the successful construction of Ti 3 C 2 /In 4 SnS 8 nanostructures . Band structures investigation including valence band maximum and Mott-Schottky plots reveals the formation of Schottky junction in this 2D/2D heterostructure , that favors for ultrafast charge carrier separation and transportation from In 4 SnS 8 to Ti 3 C 2 and preventing the electrons backflow from Ti 3 C 2 to In 4 SnS 8 . Photoluminescene analysis and photo/electrochemical measurements prove that the combination of Ti 3 C 2 and In 4 SnS 8 accelerates the transportation of photoexcited electron-hole pairs and efficiently suppresses charge carrier recombination. Unsurprisingly, 7 wt% Ti 3 C 2 /In 4 SnS 8 catalysts exhibit the highest visible-light-driven photoreactivity with H 2 O 2 production rates of 1.998 μmol∙L −1 ∙min ‒1 that is 2.2 times larger than that of single In 4 SnS 8 . Additionally, Ti 3 C 2 /In 4 SnS 8 demonstrates a multifunctional capability in Cr(VI) reduction with the greatest reaction rates of 19.8 × 10 −3 min ‒1 that is almost 4-fold larger than that of individual semiconductor. Moreover, the nanohybrids exhibit excellent photostability after 5 cycles testing in both reaction systems. The morphology, crystal structure and composition for Ti 3 C 2 /In 4 SnS 8 remain unaltered after photoreaction. A comprehensive analysis including trapping agents and atmosphere experiments as well as electron paramagnetic resonance demonstrates that the H 2 O 2 evolution pathway consists of two channels: a two-step successive 1e ‒ oxygen reduction reaction and a one-step 2e ‒ water oxidation reaction. This work may provide a viable protocol for designing efficient and multifunctional photocatalytic systems for solar-to-chemical energy conversion. Download: Download high-res image (68KB) Download: Download full-size image