A mild and green method for the nitro-reduction using PEG200(4)@C@MoSe2@MWCNT driven by UV light was developed. The photocatalytic performance of MoSe2 was improved by MWCNTs and polyethylene glycol, then characterized by SEM, XRD and TGA tests. 11 reduction applications had been accomplished, with the highest conversion of 99% for nitroarenes and the highest selectivity of 74% for aromatic amines. Although the current rate of selection for the target products was low, it provided a new approach for photocatalytic nitroarene reduction and also sheded new light on the photocatalytic applications of MoSe2.
The enhanced photocatalytic performance of doped graphene(GR)/semiconductor nanocomposites have recently been widely observed, but an understanding of the underlying mechanisms behind it is still out of reach. As a model system to study the effect of dopants, we investigate the electronic structures and optical properites of doped GR/Ag3PO4 nanocomposites using the first-principles calculations, demonstrating that the band gap, near-gap electronic structure and interface charge transfer of the doped GR/Ag3PO4(100) composite can be tuned by the dopants. Interestingly, the doping atom and C atoms bonded to dopant become active sites for photocatalysis because they are positively or negatively charged due to the charge redistribution caused by interaction. The dopants can enhance the visible light absorption and photoinduced electrons transfer. We propose that the N atom may be most appropriate doping for the GR/Ag3PO4 photocatalyst. This work can rationalize the available experimental results about N-doped GR-semiconductor composites, and enriches our understanding on the effect of dopants in the doped GR-based composites for developing high-performance photocatalysts.
The enhanced photocatalytic activity of SrTiO3(STO), a promising photocatalyst for decomposing organic compounds and overall water splitting for H2/O2 evolution, has been experimentally demonstrated by coupling the graphene (GR) sheet. Here, we reveal the mechanism of the enhanced photocatalytic activity of STO/GR composites using ab initio calculations. Due to C 2p states forming the bottom of the conduction band or the top of the valence band, the band gap is reduced to about 0.6 eV, resulting in a strong absorption in the visible region. The composites of STO coupled with reduced graphene oxide (RGO) and graphane (GRH) are also explored to investigate their potential photocatalytic activity. We demonstrate that the surface termination layer of the STO(100) surface plays an important role in determining the formation energy, interfacial distance, band gap, and optical absorption of these composites. Moreover, the GR sheet is a sensitizer for STO with a termination layer of TiO2; on the contrary, it is an electron shuttle carrying excited electrons from the STO with a termination layer of SrO. Interestingly, a type II, staggered band alignment is formed in the interface, thus improving photoexcited charge separation. The negatively charged O atoms in the RGO are considered to be active sites in photocatalytic reactions, leading to enhanced photocatalytic activity. The calculated results can rationalize the available experimental reports and provide design principles for optimizing the photocatalytic performance of the STO-based composites.
Two-dimensional structure of MoSe2 facilitates ionic pathways for sodium ions, while silicon oxide (SiOx) is lauded for its remarkable sodium-ion batteries(SIBs). This study skillfully integrates the complementary strengths of both materials to create C@SiOx/MoSe2@OMWCNT (oxidized multi-walled carbon nanotubes) for SIB. Experimental findings demonstrate that carbon coating enhances electrical conductivity while simultaneously mitigating the volumetric fluctuations of SiOx, thereby optimizing sodium storage capabilities. In sodium-ion batteries (SIB), C@SiOx/MoSe2@OMWCNT exhibits outstanding performance, achieving specific capacities of 820, 574, 451, and 408 mA h g−1 at 0.1, 1.0, 5.0, and 10.0 A g−1, respectively. Remarkably, at 5 A g−1, shows extensive cycling for 100, 1,000, 5,000, and 10,000 cycles, the discharge capacities remain commendably stable at 363, 307, 251, and 221 mA h g−1, respectively. Theoretical evaluations suggest that GR@SiOx/MoSe2@SWCNT (with GR referring to graphene and SWCNT to single-walled carbon nanotubes) possesses the ability to alleviate the expansion of active materials, thus enhancing the structural integrity of the anode within sodium-ion batteries. The synthesis method we have devised for C@SiOx/MoSe2@OMWCNT shows great promise for widespread application in various high-capacity anode materials.
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