New polymer photocatalyst architectures for solar fuel generation

清洁能源的生产和清洁水的获取是当代材料化学领域的两个非常重要的挑战。这两个挑战都可以通过半导体催化的光催化过程来解决，水分解产生氢，这是一种可储存的能量载体，或者将二氧化碳还原为太阳能燃料，光催化水消毒用于灭活水中的细菌。为了实现光催化水分解，需要一种半导体来吸收光并产生载流子，然后将载流子转移到水中，从而产生氢和氧。直到最近，该领域一直由无机半导体主导，如二氧化钛，通常与贵金属共催化剂结合。然而，2009年Antonietti的自然材料报告（Nat. Mater. 2009, 8,76）激起了人们对用于水分解的有机材料的兴趣，其中绝大多数与氮化碳及其变体有关。2015年，研究表明共轭聚合物可以与氮化碳竞争光催化析氢（J. Am.）。化学。光化学学报，2015,37(2):481 - 481。化学。[j] .中国生物医学工程学报，2016,32(1):591 - 591。同样，二氧化钛的光催化水消毒已经得到了很好的研究，但也需要紫外线来产生，因为它是一种宽带隙材料。未支化的共轭聚合物也被发现在光照下产生活性物质，如羟基和超氧自由基或过氧化氢，Schanze （Langmuir 2011, 27,4956）和几项后续研究证明了这一点，这可以用于细菌灭活。共轭微孔聚合物也被证明对这一应用具有活性(J. Mater。化学。B 2016, 4,5112)，但迄今为止还很少被探索。从根本上说，由于在有机材料中观察到的高激子结合能导致与无机光催化剂相比产生更少的电荷，这些过程的效率受到严重限制。Soc。中国农业科学，2020,49,3981)。该项目将开发具有能量补偿的新材料结构，这将显著增强光催化氧化和还原反应的活性。这些材料将用于从水中产生氢气、减少二氧化碳和灭活细菌。一个特别的重点将是材料的可加工性，允许在未来大规模制造设备。

The production of clean energy and access to clean water are two very important contemporary challenges in materials chemistry. Both challenges can be addressed through photocatalytic processes catalysed by semiconductors with water splitting yielding hydrogen which is a storable energy carrier or the reduction of carbon dioxide into solar fuels, and photocatalytic water disinfection being used to inactivate bacteria present in water. For photocatalytic water splitting to occur a semiconductor is required that absorbs light and creates charge carriers that are then transferred to water resulting in hydrogen and oxygen production. Until recently, the field was dominated by inorganic semiconductors, such as titanium dioxide, often coupled with a precious metal co-catalyst. However, the 2009 Nature Materials report by Antonietti (Nat. Mater. 2009, 8, 76) has provoked a surge of interest in organic materials for water-splitting, the vast majority relating to carbon nitride and its variants. In 2015 it was shown that conjugated polymers can compete with carbon nitrides for photocatalytic hydrogen evolution (J. Am. Chem. Soc. 2015, 137, 3265) and photocatalytic carbon dioxide reduction (J. Mater. Chem. A, 2021, 9, 4291).Similarly, photocatalytic water disinfection with titanium dioxide has been well studied, but also requires UV light to create as it is a wide band-gap material. Unbranched conjugated polymers have also been found to generate reactive species, such as hydroxyl and superoxide radicals or hydrogen peroxide, under illumination and it has been demonstrated for example by Schanze (Langmuir 2011, 27, 4956) and several follow up studies that this can be used for bacteria inactivation. Conjugated microporous polymers have also been shown to be active for this application (J. Mater. Chem. B 2016, 4, 5112), but are far less explored to date.Fundamentally, these processes are severely limited in their efficiency due to the high exciton binding energies observed in organic materials which result in fewer charges being generated compared to inorganic photocatalysts (Chem. Soc. Rev. 2020, 49, 3981). The project will develop new material architectures with energy offsets that will result in significantly enhanced activity for photocatalytic oxidation and reduction reactions. The materials will be used for the generation of hydrogen from water, carbon dioxide reduction and bacteria inactivation. A particular focus will be on processability of the materials allowing for the fabrication of devices at scale going forward.