Vacancy-Mediated Z-Scheme Heterostructure in SnO2-Decorated Spinel In3-xS4 with Boosted Photocatalytic Activity.

The widespread application of dyes and heavy metals causes increasing environmental pollution. One effective way to mitigate environmental pollution is to use semiconductor photocatalysts for redox purification of pollutants. Heterostructured photocatalysts can reduce the electron-hole recombination rate and improve light utilization. In this work, a novel SnO2/In3-xS4 composite with oxygen vacancy defect-mediated Z-scheme heterostructure is constructed for the first time by a one-pot method, in which SnO2 ultrasmall nanocrystals are decorated on nanopetals of flower-like In3-xS4. Material analyses show that the as-built three-dimensional hierarchical architecture is able to essentially increase the specific surface area and thus the active sites of the products. More importantly, the formation of Z-scheme heterojunction between the oxygen vacancy-induced SnO2 defect level and the In3-xS4 band structure not only promotes the separation of photogenerated charges but also makes them more reactive. Through the optimization of the composition ratio between the two phases, the visible-light-driven photocatalytic reaction rates of rhodamine B degradation and Cr(VI) reduction for the developed SnO2/In3-xS4 composite photocatalyst are 12.8 and 6.3 times of bare In3-xS4 and 32.0 and 76.0 times of bare SnO2, respectively. This work should provide a promising implication for designing new high-performance composite photocatalysts.

Sulfur-source-dependent phase-selective preparation of Cu3NiInSnS6 nanocrystals and their optical and magnetic properties.

Multifunctional multinary metal chalcogenides have long been a research hotspot in the field of materials chemistry due to their rich composition, flexible structure, excellent properties and wide range of applications. However, the exploration of complex quinary chalcogenides is still challenging. In this work, for the first time, we have developed the controlled synthesis of quinary Cu3NiInSnS6 nanocrystals, realizing the selective preparation of hexagonal wurtzite and cubic zinc blende metastable phases by simply tuning the sulfur source. The phase structure analysis reveals that both metastable phases possess a disordered structure with a random distribution of metal atoms in the unit cells. The fabricated wurtzite and zinc blende-structure Cu3NiInSnS6 nanocrystals have a direct band gap of 1.82 and 1.94 eV, respectively, and both exhibit superparamagnetic behavior at low temperatures. This work is of great significance for the development of novel multifunctional materials based on metastable multinary metal chalcogenide phases.