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Oxygen-tailoring in silicon suboxide (SiOX) can relieve its volume variation for highly structural integrity and form a stable solid electrolyte interface (SEI) layer. Herein, we propose the preparation of hierarchical SiOX/C with different oxygen contents and interfacially covalent Si–O–C bonds for advanced lithium ion batteries (LIBs). Oxygen-manipulating projects are performed to adjust the oxygen content in SiOX for low volume expansion (mechanical stress), in agreement with our experiment, stress distribution simulations and density functional theory analysis. The covalent Si–O–C bonds in metastable SiOX/C are constructed to enhance the adsorption of ethylene carbonate for a stable SEI layer and re-assemble the electrical field for fast interfacial charge responses. These synthetic advantages in hierarchical SiOX/C are beneficial for the structural integrity and the construction of a stable SEI layer. Prepared SiOX/C exhibits excellent electrochemical performance in terms of cyclic stability (1010.4 mA h g−1 after 300 cycles at 1 A g−1), highly stable coulombic efficiency and rate capability (413.6 mA h g−1 at 4 A g−1). The work based on oxygen-manipulating projects and interfacial covalent bonds provides deep insights into the preparation of durable SiOX-based anodes with a long lifespan and stable coulombic efficiency. [ABSTRACT FROM AUTHOR]

Cu2ZnSnS4 (CZTS) is a narrow band gap, non-toxic, environmentally friendly semiconductor photocatalytic material. Cu2ZnSnS4 nanoparticles were synthesized by a hydrothermal method at different temperatures. XRD and Raman results showed that CZTS with a high crystallinity kesterite structure was successfully prepared. Photoelectrochemical tests showed that CZTS is a p-type semiconductor with a band gap of 1.5 eV, and its photocurrent density could attain 0.3271 μA cm−2. It was found that CZTS had good photocatalytic activity for RhB via the photocatalysis of Rhodamine B (RhB) degradation with CZTS nanoparticles under visible light. The degradation efficiency of RhB by CZTS reached 98.20% within 90 min, and the degradation rate was about 0.02905 min−1. The photocatalytic degradation mechanism of CZTS was studied through free radical capture experiments, and results showed that photo-generated electrons could react with O2 and H2O in the solution to form ˙OH, which degraded RhB into H2O and CO2. [ABSTRACT FROM AUTHOR]

Nitrogen (N) doping is an efficient way to modulate the properties of graphene. The reported chemical vapor deposition (CVD) processes for synthesizing N-doped graphene mostly involve a metal catalyst and ammonia (NH3) dopant. However, the inevitable metal residual and toxicity of NH3 would significantly hinder its practical applications. In this paper, for the first time, metal-free synthesis of N-doped graphene films on glass was achieved through a plasma-assisted hot filament CVD method using eco-friendly N2 gas as the dopant. Both the hot filament and plasma source were proven to be essential for growing N-doped graphene of preferable quality. By adjusting the N2 flow, the N content, transmittance and electrical properties of graphene films could be facilely modulated. Furthermore, it was demonstrated that the electrical voltage induced by dropping ion droplets on graphene glass was significantly improved from 50 mV to 320 mV through N doping, exceeding those of reported graphene based electricity generators. This improvement was attributed to the higher surface potential of N-doped graphene glass compared to the pristine ones, as revealed by Kelvin probe force microscopy. The present work provides a promising strategy for direct synthesis and expands applications of N-doped graphene glass for high-efficiency energy harvesting. [ABSTRACT FROM AUTHOR]

Ge-doped CZTSSe thin films were obtained by covering a thin Ge layer on CZTS precursors, followed by a selenization process. The effect of the Ge layer thickness on the morphologies and structural properties of Ge-doped CZTSSe thin films were studied. It was found that Ge doping could promote grain growth to form a compact thin film. The lattice shrank in the top-half of the film due to the smaller atomic radius of Ge, leading to the formation of tensile stress. According to thermodynamic analysis, Sn was easier to be selenized than Ge. Thus, Ge preferred to remain on the surface and increased the surface roughness when the Ge layer was thin. CZTSe was easier to form than Ge-doped CZTSe, which caused difficulty in Ge doping. These results offered a theoretical and experimental guide for preparing Ge-doped CZTSSe thin films for the potential applications in low-cost solar cells. With a 10 nm Ge layer on the top of the precursor, the conversion efficiency of the solar cell improved to 5.38% with an open-circuit voltage of 403 mV, a short-circuit current density of 28.51 mA cm−2 and a fill factor of 46.83% after Ge doping. [ABSTRACT FROM AUTHOR]

Chemical doping with foreign atoms is an effective method to intrinsically modify the properties of the host materials. In this paper, we report a facile strategy to prepare nitrogen and boron doped monolayer graphene by using urea and boric acid as solid precursors. By adjusting the elemental precursors, the nitrogen content could be modulated from 0.9 to 4.8% for nitrogen doped graphene and the boron content from 0.7 to 4.3% for boron doped graphene respectively, as estimated by X-ray photoelectron spectroscopy. The mobilities of the nitrogen and boron doped graphene-based back-gate field-effect transistors are about 350–550 cm2 V−1 s−1 and 450–650 cm2 V −1 s−1 respectively. Our results are better than plasma treated nitrogen and boron doped graphene. Therefore the synthesis of nitrogen and boron doped graphene sheets by a solid doping elemental precursor method is considered to be an efficient approach to producing graphene with excellent optical and electrical performances at relatively low cost. [ABSTRACT FROM AUTHOR]