| 摘要: | 近期新興活性觸媒之研究中，二硫化鉬在析氫效能及成本效益上，可望能取代貴金屬(如白金、銣)和過度金屬等。由於二硫化鉬的二維結構伴隨著暴露大量S原子的高活性邊界態，為產氫的關鍵。本研究以兩種不同的方式，增加暴露邊界態的活性位置：1. 以四硫鉬酸銨作前驅物與微流道成型(micromolding in capillaries, MIMIC)的方式，壓印出高密度的二硫化鉬奈米帶陣列，其二硫化鉬奈米帶的厚度為3.9 nm、線寬為157~465 nm、長為2 cm，具有極高的長寬比(~7.4×108)。另外，二硫化鉬奈米帶能被印製在各式各樣的基板上，比如SiO2/Si、藍寶石基板、鍍金薄膜、FTO導電玻璃或石墨烯薄膜上。在析氫反應中，密度越高的MoS2/MoSx奈米結構表現的效果越優(過電位約211 mV @10 mA/cm2，塔弗斜率為43 mV/dec)。2. 以冷凍乾燥技術創造出三維結構氧化型石墨烯，加上高溫退火(1000 oC)移除氧基團提升導電性，形成多孔、超輕量級、高比表面積及高導電性的載體，適合與二硫化鉬觸媒作複合電極。本研究選擇在四種不同的溫度退火，發現二硫化鉬的結晶性會影響到析氫效果的表現上(過電位約163 mV @10 mA/cm2塔弗斜率為41 mV/dec)。在這兩項工作中，對於水分解電催化性能的實驗裡，我們找到了二硫化鉬奈米帶的最佳線寬以及二硫化鉬三維複合材料的最佳合成條件(100 oC)。本研究探討二硫化鉬於結構與結晶性的產氫特性研究，於未來可望成為一種高活性與低成本的產氫候選材料。;Molybdenum disulfide (MoS2) has recently emerged as a promising catalyst for the hydrogen evolution reaction (HER) in water splitting that may replace the noble metals such as platinum and rubidium, a cost-effective and highly catalytic material. Two-dimensional MoS2 structures with exposed S-edge have been reported as active electrocatalytic catalyst for hydrogen production. We utilize these two different ways to generate exposed active sites: 1. Prepare dense arrays of MoS2 nanoribbons by combining procedures of micromolding in capillaries (MIMIC) and thermolysis of thiosalts ((NH4)2MoS4) as the printing ink. The obtained MoS2 nanoribbons had a thickness reaching as low as 3.9 nm, a width ranging from 157 to 465 nm, and a length up to 2 cm. MoS2 nanoribbons with an extremely high aspect ratio (length/width) of ∼7.4 × 108 were achieved. The MoS2 pattern can be printed on versatile substrates, such as SiO2/Si, sapphire, Au film, FTO/glass, and graphene coated glass. In the hydrogen evolution reaction (HER), the high-density MoS2/MoSx nanostructures has the best performance (overpotential of ∼211 mV @10 mA/cm2 and a Tafel slope of 43 mV/dec). 2. Freeze drying to produce three-dimensional structures of graphene oxide (rGO), and we then anneal them at 1000 oC to remove the oxide group, thereby enhancing the conductivity. The reduce graphene oxide has a high surface area, high porosity and low weight, so it could be used as a conductive substrate with attached MoS2 nanoparticles. At four different temperature, we discovered that the crystallinity of MoS2 will affect its performance in the HER (overpotential of 163 mV @10 mA/cm2 and a Tafel slope of 41 mV/dec). In those works, we found the best width of MoS2 nanoribbons and temperature to create large amounts of active sites in MoS2/FTO and MoSx/rGO, which facilitate the electrocatalytic performance for water splitting. In the future, it will be a potential material for fuel cell applications. |
