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Formaldehyde, as a harmful gas produced by materials used for decorative purposes, has a serious impact on human health, and is also the focus and difficulty of indoor environmental polution prevention; hence, designing and developing gas sensors for the selective measurement of formaldehyde at room temperature is an urgent task. Herein, a series of SnS2/SnO2 composites with hollow spherical structures were prepared by a facile hydrothermal approach for the purpose of formaldehyde sensing at room temperature. These novel hierarchical structured SnS2/SnO2 composites−based gas sensors demonstrate remarkable selectivity towards formaldehyde within the concentration range of sub-ppm (0.1 ppm) to ppm (10 ppm) at room temperature. Notably, the SnS2/SnO2−2 sensor exhibits an exceptional formaldehyde-sensing performance, featuring an ultra-high response (1.93, 0.1 ppm and 17.51, 10 ppm), as well as good repeatability, long-term stability, and an outstanding theoretical detection limit. The superior sensing capabilities of the SnS2/SnO2 composites can be attributed to multiple factors, including enhanced formaldehyde adsorption, larger specific surface area and porosity of the hollow structure, as well as the synergistic interfacial incorporation of the SnS2/SnO2 heterojunction. Overall, the excellent gas sensing performance of SnS2/SnO2 hollow spheres has opened up a new way for their detection of trace formaldehyde at room temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] Photoreduction of CO 2 to value-added chemicals and fuels is an attractive solution to alleviate environmental problems and energy crisis at the same time. However, engineering efficient photocatalysts with high activity and product selectivity is still challenging. Herein, we achieved three-dimensional (3D) spatial configuration design at micro-scale and heterogeneous interface construction at nano-scale on a SnS 2 /SnO 2 composite, which featured hierarchical flower-like morphology consisted of nanosheets and type-II semiconductor structure. It behaved excellent selectivity and impressive photocatalytic CO 2 -to-CO performance with a yielding rate of 60.85 μmol g-1h−1, roughly 3 times higher than that of SnS 2 and was in the front rank of this kind catalysts under 300 W Xe lamp illumination without using any sensitizers or noble metals. The enhanced catalytic capability could be attributed to the elaborately built structure with suitable energetic position that afforded effective separation and migration of photo-generated electron/hole pairs as well as enhanced light caption and absorption. Meanwhile, main reactive intermediates (e.g., CO 2 – and *COOH) were captured by in-situ Fourier transform infrared spectroscopy (FTIR), suggesting a fluent catalytic pathway on the SnS 2 /SnO 2 platform. This work provides a new scheme to build advanced catalysts based on multiscale design and rational phase assembling. [ABSTRACT FROM AUTHOR]

Formaldehyde, as a harmful gas produced by materials used for decorative purposes, has a serious impact on human health, and is also the focus and difficulty of indoor environmental polution prevention; hence, designing and developing gas sensors for the selective measurement of formaldehyde at room temperature is an urgent task. Herein, a series of SnS2/SnO2 composites with hollow spherical structures were prepared by a facile hydrothermal approach for the purpose of formaldehyde sensing at room temperature. These novel hierarchical structured SnS2/SnO2 composites−based gas sensors demonstrate remarkable selectivity towards formaldehyde within the concentration range of sub-ppm (0.1 ppm) to ppm (10 ppm) at room temperature. Notably, the SnS2/SnO2−2 sensor exhibits an exceptional formaldehyde-sensing performance, featuring an ultra-high response (1.93, 0.1 ppm and 17.51, 10 ppm), as well as good repeatability, long-term stability, and an outstanding theoretical detection limit. The superior sensing capabilities of the SnS2/SnO2 composites can be attributed to multiple factors, including enhanced formaldehyde adsorption, larger specific surface area and porosity of the hollow structure, as well as the synergistic interfacial incorporation of the SnS2/SnO2 heterojunction. Overall, the excellent gas sensing performance of SnS2/SnO2 hollow spheres has opened up a new way for their detection of trace formaldehyde at room temperature.

In this work, the hydrothermally synthesized SnS 2 nanosheets were calcined to form SnO 2 nanoparticle decorated SnS 2 nanosheets. The formed "raisin cake" SnS 2 /SnO 2 complex increases the specific surface area and provides more contact area for gas molecule adsorption. The SnS 2 /SnO 2 nanocomposite has a high sensing response to 50 ppm NH 3 (392) and an excellent response/recovery time (6/8 s) to 50 ppm at room temperature. Therefore, SnS 2 /SnO 2 nanocomposite has excellent repeatability, excellent NH 3 gas selectivity, and humidity stability. And it is discussed that the reason for the enhanced NH 3 sensing mechanism is the synergistic effect of SnS 2 /SnO 2 structures. The existence of heterojunction was proved by XPS. These results demonstrate that the sensing material can effectively detect NH 3 gas. • 2D SnS 2 / SnO 2 material is prepared to solve the SnO 2 agglomeration problem. • SnS 2 /SnO 2 showed rapid response and recovery times and excellent selectivity. • SnS 2 /SnO 2 sensors have potential applications in the NH3 gas-sensing field. • The formation of the SnS 2 /SnO 2 heterojunction was demonstrated by XPS. [ABSTRACT FROM AUTHOR]

[Display omitted] • Design and synthesis of (100) facet exposed SnS 2 /SnO 2 heterostructures. • Efficient hydrogen production on the (100) facet. • Experimental and theoretical clarification of boosted hydrogen generation. Tin disulfide (SnS 2), one transition metal dichalcogenide (TMD) is a cost-effective and promising electrocatalyst for hydrogen evolution reactions (HER) in the alkaline electrolytes. Its electrocatalytic HER performance is unfortunately limited, originating from its un-conspicuous inherent catalytic activities and non-favorable adsorption sites for hydrogen. Herein, a tin disulfide/stannic oxide (SnS 2 /SnO 2) heterostructure is designed and grown on the nickel foam (denoted as SnS 2 /SnO 2 -NF). The SnS 2 /SnO 2 heterostructure introduces more active (100) facets or a high density of active sites, accelerates the diffusion kinetic of electrons and ions, lowers the water dissociation energies, and optimizes adsorption energies of hydrogen atoms. On this catalyst, superior HER performance is realized in an alkaline medium. An overpotential of 108 mV at a current density of −10 mA cm–2 with a Tafel slope of 50.1 mV dec–1 and long-term durability are achieved for HER in 1 M KOH. This work paves a new way to design high-performance HER electrocatalyst through facet engineering of the designed heterostructures. [ABSTRACT FROM AUTHOR]