Spectroscopy-led Development of Organic Photocatalysts for Sustainable Energy Production

可再生太阳能需要与储能相结合，以克服太阳能供应和能源需求之间每小时一次的不匹配。受植物自然光合作用的启发，太阳能可以储存在高密度化学键中。太阳能燃料--从阳光中产生的高能分子--可以由光催化剂产生，光催化剂可以驱动水分解(制造氢气)或光还原二氧化碳(制造液体燃料)。为了加快向低碳社会的过渡，必须开发出成本效益高、效率更高的太阳能燃料光催化剂。氮化碳(CNX)已成为一种领先的高性价比光催化剂。CNX可以通过对廉价分子进行简单的热处理来合成，并且具有必要的(光)化学稳定性。使用牺牲性氧化衬底已经证明了高的光催化效率(量子产率高达50%)。为了结束可持续的太阳能燃料循环，这些基材必须被水取代，水是能量释放时产生的产物。然而，水的氧化更具挑战性。由此产生的太阳能对燃料的效率&lt；1%远远没有达到10%的目标商业化障碍。我的研究计划将开发设计出卓越光催化剂所需的结构-活性关系。先进的瞬时吸收光谱(TAS)光谱技术将揭示CNX的光物理，并找出最严重的效率瓶颈。能量、结构和空间异质性对光效率的影响还知之甚少。为了全面了解决定光活性的关键过程，我的团队将研究在三个不同轴上修饰的CNX的载流子动力学：(纳米)形态、末端基团的化学性质和沉积的氧化还原共催化剂。为了揭示CNx中的空间异质性，我将发展微秒瞬时吸收显微镜()来描绘电荷捕获、电荷积累和界面电荷转移等过程。光谱学将产生指导光催化剂合成修饰所需的关键的光物理和结构洞察力。协同光谱和合成方法将优化CNX的形态和内部光物理，这是高效生产氢气和光还原CO2所必需的。我的长期愿景是利用优化的CNX光物理来开发太阳能驱动的碳捕获和利用，利用CNX和光在具有长寿命的材料中隔离二氧化碳。参与研究计划的HQP将获得合成、光谱、通信和管理技能的独特组合，使它们对不断增长的清洁技术部门具有吸引力。HQP将为清洁能源行业和重要的氢气行业做出贡献，到2025年底，该行业的产值将超过2000亿美元，发展加拿大经济，帮助实现较低的二氧化碳排放目标。

Renewable solar energy needs to be paired with energy storage to overcome the hourly mismatch between solar energy supply and energy demands. Inspired by the natural photosynthesis of plants, solar energy can be stored in high-density chemical bonds. Solar fuels - high energy molecules generated from sunlight - can be produced by photocatalysts that drive water splitting (to make H2) or photoreduction of CO2 (to make liquid fuels). To accelerate the transition to a low-carbon society, cost-effective photocatalysts that produce solar fuels with improved efficiencies must be developed. Carbon nitride (CNx) has emerged as a leading cost-effective photocatalyst. CNx can be synthesized by simple heat treatment of inexpensive molecules and has the requisite (photo)chemical stability. High photocatalytic efficiencies (quantum yields up to 50%) for H2 photogeneration have been demonstrated using sacrificial oxidation substrates. To close the sustainable solar fuel cycle, these substrates must be replaced with H2O, the product generated when energy is released. However, H2O oxidation is more challenging. The resulting solar-to-fuel efficiency < 1% is far from the targeted commercialization barrier of 10%. My research program will develop the structure-activity relationships needed to engineer superior photocatalysts. The advanced spectroscopic technique of transient absorption spectroscopy (TAS) will shed light on the photophysics of CNx and identify the most crippling efficiency bottlenecks. The impact of energetic, structural and spatial heterogeneities on photoefficiency is poorly understood. To gain a holistic view of the key processes that determine photoactivity, my group will investigate the charge carrier dynamics of CNx modified on three different axes: (nano)morphology, chemical nature of terminal groups, and deposited redox cocatalysts. To uncover spatial heterogeneities in CNx, I will develop microsecond - second transient absorption microscopy (TAM) to map out processes such as charge trapping, charge accumulation and interfacial charge transfer. Spectroscopy will yield crucial photophysical and structural insights needed to direct synthetic modifications of photocatalysts. The synergistic spectroscopic and synthetic approach will optimize CNx morphology and internal photophysics, required for both efficient H2 production and CO2 photoreduction. My long-term vision is to take advantage of the optimized CNx photophysics to develop solar-driven carbon capture and utilization, using CNx and light to sequester CO2 within materials with long lifespans. HQP involved in the research program will gain a unique combination of synthetic, spectroscopic, communication, and management skills that make them attractive to the growing clean technology sector. HQP will contribute to the clean energy sector and the important H2 industry that will surpass US$200 Bn by the end of 2025, developing Canada's economy and helping reach lower CO2 emissions targets.