Synthesis And Photocatalytic Hydrogen Production Application Of Bithiazole-metal Complex

The development of reliable and environmentally friendly approaches for energy conversion is one of the key challenges that our society is facing. In addition to solving the global energy need and environmental pollution, hydrogen（H2） has attracted much attention for its potential to replace fossil fuels. Currently, however, production of H2 is mostly based on fossil fuels, accompanied with high energy consumption. Among a variety of approaches, one-step photochemical water splitting is of particular interest because of its simplicity, low-cost operation and the use of water.Recently, metal（M） complexes have emerged as promising candidates for the synthesis of nano-materials, because of their unique structure, atomic metal dispersion and textural properties. M-complexes also known as porous coordination polymers, makes it an ideal platform for photochemical water splitting thanks to the enhanced charge carrier mobility and large surface area. It is well known that many molecules possessing the bithiazole moiety are ideal chromophores because they absorb strongly in the visible region and have been shown to transfer energy and electrons to acceptor sites with high efficiencies. Especially, increasing attention has been focused on expanding the thiazole-based system, such as triphenylamine（TPA） and other electron-donating groups. Broadly speaking, TPA and its derivatives have been widely used as donors for the construction of hole-transport materials, but they have also demonstrated promising properties in photo-induced electron transfer and charge separation. Based on the excellent hole-transport properties, it is easy to adjust light absorption and improve the efficiency of intramolecular charge separation, thereby achieving desirable photocatalytic properties for specific applications in photocatalytic H2 production.However, to the best of our knowledge, there is no reported investigation focused on the photocatalytic activity of triphenylamine functionalized bithiazole（2TPABTz）-metal complex composites. In this context, a variety of 2TPABTz-based complexes of copper（Cu）, cobalt（Co）, ruthenium（Ru） and the corresponding nanocomposites were simultaneously synthesized. Meanwhile, the details are summarized as following:（1） A series of novel cost-effective nanocomposite photocatalysts, containing a triphenylamine functionalized bithiazole-metal complex ave been synthesized and systematically characterized.（2） The bithiazole-metal complexes with C₆₀ serve both as a photosensitizer and a photocatalyst for hydrogen evolution under visible-light irradiation and their photocatalytic activities are approximately 4-6 times higher than those of the corresponding complexes.（3） A facile method is developed to prepare Cu NPs/Cu-2TPABTz composites, and those nanocomposites were characterized systematically. Amazingly, the resultant nanocomposite 3 has shown enhanced photocatalytic activity(15.38 mmol*h^-1*g^-1) under visible light irradiation, and still maintained 80% of catalytic activity after a long-term stability tests（24 h）.（4） In addition to resolving the energy crisis, it is long-standing demand to exploit novel and efficient photocatalysts. Various Ag QDs contents decorated triphenylamine functionalized bithiazole-cobalt complex were synthesized via one-pot reduction using silver nitrate as a precursor. Surprisingly, the resulting composite 3 showed extraordinarily photocatalytic hydrogen evolution(20.65 mmol*h^-1*g^-1) under visible light illumination, and maintained outstanding long-term stability after eight-cycle tests（32 h） as well.（5） Yttrium and aluminum co-doped Zn O were successfully synthesized by the sol-gel method, showing high photocatalytic activity for hydrogen production(5.71 mmol*h^-1*g^-1) in the water-lactic acid system under visible-light irradiation for the first time, exhibiting excellent stability and recyclability.