Spectroscopy-led Development of Organic Photocatalysts for Sustainable Energy Production

可再生太阳能需要与储能相结合，以克服太阳能供应与能源需求之间的小时不匹配。受植物自然光合作用的启发，太阳能可以储存在高密度的化学键中。太阳能燃料-从阳光中产生的高能分子-可以通过光催化剂来生产，这些光催化剂可以驱动水分解（产生H2）或CO2的光还原（产生液体燃料）。为了加速向低碳社会的过渡，必须开发具有成本效益的光催化剂，以提高效率生产太阳能燃料。氮化碳（CNx）已成为一种领先的具有成本效益的光催化剂。CNx可以通过简单的热处理廉价的分子合成，并具有必要的（光）化学稳定性。高的光催化效率（量子产率高达50%）的H2光生已被证明使用牺牲氧化基板。为了关闭可持续的太阳能燃料循环，这些基质必须用H2O（能量释放时产生的产物）取代。然而，H2O氧化更具挑战性。由此产生的太阳能-燃料效率< 1%，远未达到10%的商业化目标。我的研究计划将开发工程师上级光催化剂所需的结构-活性关系。瞬态吸收光谱（TAS）的先进光谱技术将揭示CNx的物理机制，并确定最严重的效率瓶颈。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，端基的化学性质和沉积的氧化还原助催化剂。为了揭示CNx的空间不均匀性，我将开发微秒-秒瞬态吸收显微镜（TAM）来绘制电荷捕获，电荷积累和界面电荷转移等过程。光谱学将产生至关重要的光物理和结构的见解需要直接合成改性的光催化剂。协同的光谱和合成方法将优化CNx形态和内部光物理学，这是高效的H2生产和CO2光还原所需的。我的长期愿景是利用优化的CNx物理学来开发太阳能驱动的碳捕获和利用，使用CNx和光将二氧化碳封存在寿命长的材料中。 参与研究计划的HQP将获得合成，光谱，沟通和管理技能的独特组合，使他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，该行业的价值将超过2000亿美元，发展加拿大经济，并帮助实现降低二氧化碳排放的目标。

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.