Summary

开发用于在水有条件条件下进行太阳能驱动 H2生产的光敏剂-钴氧混合剂

Published: October 05, 2019
doi:

Summary

我们直接将一种基于硅酸盐的有机染料加入钴氧液芯中,以产生用于光催化H2生产的光酸催化剂-催化剂。我们还开发了一个简单的实验设置,用于通过光催化组件评估光驱动H2生产。

Abstract

开发光催化H2生产装置是构建全球基于H2的可再生能源基础设施的关键步骤之一。出现了许多光活性组件,其中光敏剂和基于钴氧化物的H2生产催化剂协同作用,将光能转化为H-H化学键。然而,这些组件的长期不稳定和对危险质子源的需求限制了其使用。在这里,在这项工作中,我们通过独特的轴向丙氨酸连杆将一种基于硅酸盐的有机染料集成到钴氧核的外围。这一策略使我们能够开发具有相同分子框架的光敏剂-催化剂混合结构。在本文中,除了全面的化学特性外,我们解释了这种混合分子合成的详细过程。结构和光学研究已显示出钴氧芯和有机光敏剂之间的强烈的电子相互作用。即使在水作为质子源的情况下,钴氧烷也活跃于H2生产中。在这里,我们开发了一个简单的密封系统,与在线H2探测器连接,用于研究该混合复合物的光催化活性。这种光敏化剂-催化剂在实验装置中一旦暴露在自然阳光下,就会连续产生H2。混合复合物的这种光催化H2生产在完全有氧条件下,在牺牲性电子供体存在的情况下,在水/有机混合物介质中观察到。因此,该光催化测量系统以及光敏化剂-催化剂dyad为下一代光催化H2生产装置的开发提供了宝贵的见解。

Introduction

在现代世界中,煤炭、石油和天然气等化石燃料在能源中占了大部分。然而,在能量收集过程中,它们会产生大量的二氧化碳,对全球气候产生负面影响。随着人口的持续增长和人类生活方式的不断改善,预计未来几年全球能源需求将急剧上升。因此,正在积极寻找适合全球能源需求的替代能源。太阳能、风能、潮汐能等可再生能源由于其环保的零碳能源转导过程成为最佳解决方案之一。然而,这些能源的间歇性性质迄今限制了其广泛应用。这个问题的可能解决方案可以在生物学中找到;在光合作用3号期间,太阳能被有效地转化为化学能。根据这一线索,研究人员已经开发出人工光合策略,在一些小分子激活反应4、5之后,将太阳能储存到化学键中。H2分子被认为是最有吸引力的化学载体之一,由于其高能量密度和简单的化学转化6,7。

光敏剂和H2生产催化剂的存在对于活性太阳能驱动的H2生产设置至关重要。在此,我们将重点介绍催化部分的钴基分子复合钴氧体。通常,六角协调的钴中心在方形平面N4几何中结合,该几何体源自钴氧体中的二甲基溴(dmg)配体。互补的Cl离子,溶剂分子(如水或乙酰乙酰胺)或丙氨酸衍生物在残余轴向位置8。钴氧化物长期以来以活性H2生产电催化而闻名,其反应性可以通过在轴向丙氨酸9、10、11、12上附加可变功能来调谐.相对简单的合成、催化条件下的耐氧性以及钴氧的中度催化反应促使研究人员探索其光催化H2产生反应。Hawecker集团是利用Ru(多皮里基)基光敏剂13来展示钴氧石的光驱动H2生产活性的先驱。艾森伯格和他的同事利用铂(Pt)基无机光敏剂与钴氧化物催化剂14、15联合诱导光催化H2的产生。后来,切组利用有机金光敏剂复制了类似的活动16。丰特卡夫和阿尔特罗通过应用基于钛(Ir)的分子17,扩大了光敏剂的范围。由于使用昂贵的金属基光敏剂,这些光催化系统的实际应用正朝着障碍方向发展。艾森伯格和太阳研究小组通过独立设计有机染料光驱动H2生产系统18、19来反驳。尽管所有这些系统成功地生产了光驱动H2,但观察到整体催化周转率相对较慢20。在所有这些情况下,在溶液中添加光敏剂和钴氧子分子作为单独的莫伊奇,它们之间缺乏直接通信可能会妨碍系统的整体效率。为了纠正这个问题,开发了一些光敏剂-钴氧酰胺,其中各种光敏剂通过轴向的丙氨酸配体21、22、23与钴氧核直接相连 242526.Sun和同事甚至成功地开发了一种不含贵金属的装置,引进了一种锌-波芬图案作为光敏剂24。最近,Ott和同事成功地将钴氧酶催化剂整合在金属有机框架(MOF)中,该框架在有机染料27的存在下展示了光催化H2的产生。然而,将高分子量光敏剂纳入钴氧硅框架降低了水溶性,同时影响在催化条件下的dyads的长期稳定性。催化期间在水条件下活性dyads的稳定性至关重要,因为无所不在的水是催化过程中质子的诱人来源。因此,迫切需要开发一种水溶性、空气稳定的光敏剂-钴氧化物二分剂系统,以建立高效、经济的光驱动H2生产装置。

在这项工作中,我们锚定了一种基于硅酸盐的有机染料28,作为光敏剂,通过轴向的丙氨酸连结器固定在钴氧体芯上(图1)。染料的轻分子量确保了水溶性。这种石质-钴氧混合分子通过光学和1HNMR光谱及其单晶结构阐明,详细特征。电化学数据揭示了钴氧体图案的活性电催化H2生产,即使与附加的有机染料。这种混合复合物在30:70水/DMF(N,N,N+-二甲基甲酰胺)溶液中暴露于阳光直射下时,表现出显著的光驱动H2生产,而不会降解混合结构,辅之以光学光谱学研究。在混合复合物的光催化过程中,使用了一种由H2探测器组成的简单光催化装置,证明H2气体在水有氧条件下连续生产,没有任何初步滞后期。因此,该混合复合体有可能成为开发下一代太阳能驱动 H2生产催化剂的基础,实现高效可再生能源利用。

Protocol

1. 光敏剂-催化剂混合的合成 催化剂前体合成Co(mg)2Cl2复合物注:此复杂是在报告过程29的修改版本之后合成的。 在27 mL丙酮中溶解232毫克(1毫摩尔)二甲基卵黄素(dmg)配体(此反应中的两个等效物)。 将 CoCl2±6H2O(此反应中的一个等效物)分别溶解在 3 mL 的去离子水中,从而产生粉红色溶液。 …

Representative Results

在这项工作中,通过将衍生的丙氨酸图案(L1)锚定为钴芯的轴向配体,成功合成了一种硅酸盐光敏-钴氧混合复合物(C1)。混合复合物的1个H NMR数据清楚地证明了同一复合物中钴氧化物和有机染料质子的存在。如图2所示,上场脂肪区分别以β(ppm)2.34和2.97的比例突出氧化甲基和硅二甲基质子信号的适当比例存在。在6.74-7.82 ω(ppm)区域发…

Discussion

有机光敏剂,通过轴向的苯二胺连杆成功并入钴氧体芯(图1)。这一策略使我们能够设计一种光敏剂-钴氧混合复合C1。从C1的单晶结构(图4)可以看出,在同一分子框架中,草氧和有机染料的存在是显而易见的。stilbene 图案的苯基和丙氨酸功能通过拉长的连体通过盟友组存在于同一平面上。这些有机染料的可变组之间的相互?…

Divulgations

The authors have nothing to disclose.

Acknowledgements

甘地纳加尔国际特和印度政府提供了财政支助。我们还要感谢科学和工程研究委员会(SERB)提供的校外资金(文件号)。EMR/2015/002462)。

Materials

1 mm diameter glassy carbon disc electrode ALS Co., Limited, Japan 2412 1
Acetone SD fine chemicals 25214L10 27 mL
Ag/AgCl reference electrode ALS Co., Limited, Japan 12171 1
Co(dmg)2Cl2 Lab synthesised NA 100 mg
CoCl2.6H2O Sigma Aldrich C2644 118 mg
d6 dmso Leonid Chemicals D034EAS 650 µL
Deionized water from water purification system NA NA 500 mL
Dimethyl formamide SRL Chemicals 93186 5 mL
Dimethyl glyoxime Sigma Aldrich 40390 232 mg
Gas-tight syringe SGE syringe Leur lock 21964 1
MES Buffer Sigma M8250 195 mg
Methanol Finar 67-56-1 15 mL
Platinum counter electrode ALS Co., Limited, Japan 2222 1
Stilbene Dye Lab synthesised NA 65 mg
TBAF(Tetra-n-butylammonium fluoride) TCI Chemicals T1338 20 mg
Triethanolamine Finar 102-71-6 1 mL
Triethylamine Sigma Aldrich T0886 38 µL
Trifluoroacetic acid Finar 76-05-1 10 µL
Whatman filter paper GE Healthcare 1001125 2

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Mir, A. Q., Dolui, D., Khandelwal, S., Bhatt, H., Kumari, B., Barman, S., Kanvah, S., Dutta, A. Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions. J. Vis. Exp. (152), e60231, doi:10.3791/60231 (2019).

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