重掺杂等离子体硫属半导体纳米晶的调控合成、性能研究及应用

发布时间：2018-09-17 17:44

【摘要】：局部表面等离子共振纳米晶独特的性能备受关注,已被成功应用于能源、催化及生物医学等领域。目前报道的等离子体纳米晶共振吸收峰主要位于紫外-可见光区,因此发展廉价、稳定、吸收宽的重掺杂近红外等离子体共振结纳米晶具有重要的理论与应用价值,将显著提高太阳能光催化、近红外光热成像与光热治疗效率。研究进展如下:1.发展了一种制备具有宽光谱近红外吸收的Cu_7S_4纳米晶的新方法,在理论模拟基础上,发现利用单颗粒纳米晶的自组装,从单颗粒、纳米棒到超晶格,其近红外(1500 nm)光热转换效率显著提高。以单一前躯体为原料,通过溶剂热技术,成功制备了具有高光热转换效率的Cu_7S_4纳米晶,其吸收光谱宽,近红外等离子体共振吸收峰位于1500 nm。理论计算发现,组装后的Cu_7S_4纳米晶的光热转换效率显著提高。在同样光照刺激下,单颗粒、组装棒状以及超晶格Cu_7S_4的近红外光热转换效率分别为48.62%、56.32%和65.7%。通过表面亲水性功能化修饰,纳米超晶格可成功用于肿瘤的光热治疗。2.发展了一种高效宽光谱、近红外等离子共振Cu_7S_4@Pd异质结纳米催化剂,可有效吸收太阳光的近红外光,提高太阳能光催化转化效率。在前期Cu_7S_4纳米晶制备基础上,发展了原位生长贵金属制备Cu_7S_4@Pd、Cu_7S_4@Pt、Cu_7S_4@Au、Cu_7S_4@Ag等异质结纳米晶的通用方法。借助Cu_7S_4纳米晶的宽光谱近红外局域表面等离子体共振吸收,将热空穴传给贵金属Pd,显著增强了光催化效果,成功用于铃木耦合、苯甲醇的选择性氧化和硝基苯的还原。在1500 nm激光(0.45 W/cm~2)照射下,Cu_7S_4@Pd异质结催化活性相比传统的加热反应提高了 3.3 -4.3倍。即使在光功率密度仅为40 mW/cm~2时的太阳光照射下,相关催化反应在2小时内的转化率也达到80%。该催化剂具有良好的稳定性,可多次循环使用。3.发展了单层MoS_2修饰的Cu_(1.75)S-Au光电复合纳米催化剂(Cu_(1.75)S-Au@S-MoS_2 ),成功用于等离子体共振光辅助电催化析氢(HER)。通过局域表面等离子体共振,在650nm光照下(1.0W/cm~2),其电催化析氢(HER)特性较无光照时提高了 29.5倍。在电流密度为200 mA/cm~2下的过电位仅为182.8 mV,其塔菲尔斜率为39 mV/dec,并具有很好的稳定性。结果表明,该异质纳米晶的优异催化性能主要源于来其良好的等离子体共振吸收,高效的电荷分离以及单层MoS_2所暴露的丰富活性位点。其宽的近红外等离子体共振吸收特别适合太阳能的高效转化利用。
[Abstract]:The unique properties of local surface plasmon resonance nanocrystals have been successfully applied in the fields of energy, catalysis and biomedicine. The reported resonance absorption peaks of plasma nanocrystals are mainly located in the UV-Vis region, so the development of low cost, stable and wide absorption heavily doped near infrared plasmon resonance nanocrystals has important theoretical and practical value. It will significantly improve the efficiency of solar photocatalysis, near infrared photothermal imaging and photothermal therapy. The research progress is as follows: 1. A new method for preparing Cu_7S_4 nanocrystals with wide spectrum near infrared absorption was developed. On the basis of theoretical simulation, it was found that self-assembly of single particle nanocrystals, from single particles, nanorods to superlattices, was used. The near infrared (1500 nm) photothermal conversion efficiency was improved significantly. Cu_7S_4 nanocrystalline with high photothermal conversion efficiency was successfully prepared from a single precursor by solvothermal technique. Its absorption spectrum was wide and the near infrared plasmon resonance absorption peak was located at 1500 nm.. Theoretical calculations show that the photothermal conversion efficiency of the assembled Cu_7S_4 nanocrystals is significantly improved. Under the same illumination, the near infrared photothermal conversion efficiency of single particle, assembled rod and superlattice Cu_7S_4 is 48.62% and 65.7%, respectively. By surface hydrophilic functionalization, nano-superlattices can be successfully used in photothermal therapy of tumor. A kind of high efficient wide spectrum near infrared plasmon resonance (Cu_7S_4@Pd) heterojunction nanocrystalline catalyst has been developed which can effectively absorb the near infrared light of solar light and improve the photocatalytic conversion efficiency of solar energy. Based on the preparation of Cu_7S_4 nanocrystals in situ, a general method for preparing heterojunction nanocrystals such as Cu_7S_4@Pd,Cu_7S_4@Pt,Cu_7S_4@Au,Cu_7S_4@Ag by in situ growth of noble metals was developed. Based on the wide spectrum near infrared local surface plasmon resonance absorption of Cu_7S_4 nanocrystalline, the hot hole transfer to noble metal Pd, enhances the photocatalytic effect. It has been successfully used in the coupling of Suzuki, selective oxidation of benzyl alcohol and reduction of nitrobenzene. Under 1500 nm laser irradiation (0.45 W/cm~2), the catalytic activity of Cu7Sd Heterojunction was 3.3-4.3 times higher than that of conventional heating reaction. Even when the optical power density is only 40 mW/cm~ 2, the conversion rate of the related catalytic reaction reaches 80% within 2 hours. The catalyst has good stability and can be reused for many times. A monolayer MoS_2 modified Cu_ (1.75) S-Au photo-electronic composite nanocatalyst (Cu_ (1.75) S-Au@S-MoS_2) was developed and successfully used in plasma resonance photo-assisted electrocatalytic hydrogen evolution (HER). By using local surface plasmon resonance (LSPR), the electrocatalytic hydrogen evolution (HER) properties of (HER) under 650nm illumination (1.0W/cm~2) were improved by 29.5 times compared with those without illumination. When the current density is 200 mA/cm~2, the overpotential is only 182.8 mV, and the Taffel slope is 39 mV/dec, and has good stability. The results show that the excellent catalytic performance of the nanocrystalline is mainly due to its excellent plasmon resonance absorption, high efficiency charge separation and abundant active sites exposed to monolayer MoS_2. Its wide near infrared plasmon resonance absorption is especially suitable for the efficient conversion and utilization of solar energy.
【学位授予单位】：北京化工大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O643.36;TB383.1

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