垂直排列ReS2(1-x)Se2x合金纳米片的控制合成及带隙调控

二维过渡金属硫属化合物具有优异的电学和光学特性, 形貌控制及带隙调控对于其在光电子学、光子学、纳米电子学领域中的应用至关重要。研究采用CVD技术在SiO₂/Si衬底上生长了垂直排列ReS₂纳米片材料, 硒化处理后得到ReS_2(1-x)Se_2x合金纳米片, 并研究了硒化温度(700、850 和 920℃)及硒化时间(0.5、1和1.5 h)对ReS_2(1-x)Se_2x合金纳米片形貌及组分的影响。XPS元素定量分析及紫外-可见-近红外吸收光谱研究表明ReS_2(1-x)Se_2x样品中Se含量可以在x=0(纯ReS₂)到x=0.86之间调变, 相应材料的带隙可从1.55 eV (800 nm)调变到1.28 eV (969 nm)。SEM结果显示ReS_2(1-x)Se_2x纳米片的结构受到硒化温度和硒化时间的影响, 硒化温度升高和硒化时间延长会破坏纳米片的垂直结构。上述结果表明本研究成功合成了垂直排列ReS_2(1-x)Se_2x合金纳米片, 该材料在电化学催化、功能电子器件和光电子器件方面具有潜在应用价值。

Controllable Synthesis of Vertically Aligned ReS2(1-x)Se2x Nanosheets with Tunable Chemical Compositions and Bandgaps

2D transition metal dichalcogenides (TMDs) have been extensively studied in recent years because of their appealing electrical and optical properties. Both morphology control and bandgap modulation of TMD alloys are critical for their applications in optoelectronics, photonics and nanoelectronics. In this work, the synthesis of vertically aligned ReS_2(1-x)Se_2x alloy nanosheets with tunable compositions on SiO₂/Si substrate was achieved via CVD technology. The resulting ReS_2(1-x)Se_2x nanosheets were obtained by selenizing the vertically aligned ReS₂ nanosheets at various temperatures for different durations. The ReS_2(1-x)Se_2x samples were characterized by XRD, SEM, XPS, HRTEM, elemental mapping, Raman spectra, and UV-Vis-NIR absorption spectra. Experimental results showed that the Se contents in ReS_2(1-x)Se_2x nanosheets can be gradually tuned from x=0 (pure ReS₂) to x=0.86, and the bandgaps of the products were correspondingly modulated from 1.55 eV (800 nm) to 1.28 eV (969 nm). Moreover, the temperature and duration of selenization have huge effect on the morphology of the resulting ReS_2(1-x)Se_2x alloyed nanosheets, as evidenced by SEM observation. The vertical ReS_2(1-x)Se_2x alloy nanosheets may have significant application potential, e. g. , in the electrochemical catalysis, functional electeonic and optoelectronic devices.