Yang Yong,Pu Hongbin,Li Lianbi,Di Junjie,Lin Tao,Hu Jichao,Zang Yuan,Zhang Shan
Chemical vapor deposition is one of the universally acknowledged methods to synthesize two-dimensional transition-metal dichalcogenides with high crystal quality and large size. However, variations in the process parameters directly influence the number of layers and the quality of molybdenum disulfide (MoS 2 ) films. Thus, achieving controllable growth of monolayer MoS 2 films is still a challenge. In this study, the immunity of the monolayer nature of MoS 2 domains to process parameters was systematically investigated by varying the vaporization/growth temperature, time of sulfur addition, ramp rate, and distance between the precursors and receiving substrate using a quasiclosed crucible in a modified atmospheric-pressure CVD system. The results indicated that incorporating a quasiclosed crucible could facilitate controllable growth of monolayer MoS 2 films where the monolayer nature is immune to process parameters. Further, we attempted to elucidate the growth mechanism of monolayer MoS 2 films, which will contribute toward precise control over the synthesis of MoS 2 and other transition-metal dichalcogenides within a broad processing window.
Xiu Yun Gu,Chao Yue Zhang,Jun Di Cheng,Shi Qiang Kang,Kun Wei,Geng Zhi Sun,Xiu Ping Gao,Xiao Jun Pan,Jin Yuan Zhou
To develop highly active catalysts as counter electrodes is another promising way for improving the photovoltaic conversion efficiency (PCE) of fibrous dye-sensitized solar cells (FDSSCs). Then considering their applications in wearable electronic system, the designed fibrous counter electrodes (FCEs) should possess a good mechanical flexibility except high catalysis performances. Here in this work, hexagonal nickel telluride (Ni 3 Te 2 ) microsheets with tunable diameters and thicknesses were in-situ prepared via an atmospheric pressure chemical vapor deposition method on nickel wires. Benefiting from their two-dimensional laminated structure and asymmetric crystalline structure, the Ni 3 Te 2 microsheets show a high catalytic activity for the reduction of I 3 - → I - during the photoelectrochemical processes in FDSSCs. And cell tests show that the maximum PCE of FDSSCs with Ni 3 Te 2 FCEs reaches 11.81% (with an average value of 10.47%), which is 2.10 times that of the ones with Pt FCEs (5.62%). Furthermore, series of optimization on the microscale morphologies of Ni 3 Te 2 microsheets indicates that the suitable diameter (30 ∼ 40 μm) and thickness (ca. 3.0 μm) are suitable for the diffusion and reduction of I 3 - ions. Besides, the FDDSCs with Ni 3 Te 2 PCEs show a high cycling stability and an excellent dynamic bending stability (attenuation rate of 0.12‰ per bending cycle). This research would provide some insights into the design of high-performance FCEs for FDSSCs towards wearable electronic devices.
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