Catalysts for photochemical carbon dioxide reduction to green fuels and chemicals

气候变化和温室效应主要与大气中一种捕获热量的分子，即二氧化碳或二氧化碳的浓度增加有关。碳捕获和利用(CCU)作为一种应对二氧化碳排放水平上升的战略，正受到科学研究的越来越多的关注。该项目应用光催化技术将二氧化碳活化并转化为致密的能量载体和化学前体，包括一氧化碳、醇和酸。要推动二氧化碳的光催化还原，必须开发合适的半导体光催化剂。当它们与太阳光照射相互作用时，太阳的能量被转移到半导体，产生激发态，可用于将二氧化碳还原为有价值的化学物质。本研究旨在了解半导体/催化剂的激发态和电子结构，并通过修饰来描绘结构与性能的关系。这项工作以低温和压力过程为目标，使用金属/金属氧化物/硫化物材料作为吸收剂和催化剂。二氧化碳还原的光化学机理是复杂的，需要更多的研究来了解控制速率、选择性和产物形成途径的因素。该项目将开发稳定的光催化剂，有助于阐明光催化二氧化碳还原的机理，并在第二阶段提高太阳能到化学的转化效率。在第一阶段，紫外光吸收催化剂，如钛酸锶，将用铜(铜)纳米颗粒进行修饰。廉价、富含地球的铜被认为是最好的候选者，因为它作为热反应合成甲醇的催化剂的良好记录，以及它在从二氧化碳生产C2+产品的电催化方面的记录。本论文将比较不同的纳米铜制备方法，包括电合成法、光氧化还原合成法和化学合成法。将使用原子层沉积和开发化学功能/反应性等技术来探索颗粒-催化剂表面化学。我们将对催化剂-颗粒界面进行研究和表征，并在一系列不同的条件下进行光化学活性测试。这一策略将使我们更深入地了解控制产品选择性和催化剂活性的因素，并将产生一个基于地球上丰富的材料的高效光催化系统，用于二氧化碳的再利用。这一具体的目标表现将对解决本世纪的主要挑战之一作出重大贡献，并支持社会和环境保护与可持续发展委员会在保护环境的同时向低碳未来过渡。因此，该项目属于EPSRC能源研究领域。

Climate change and the greenhouse effect are mainly related to the increasing concentration in the atmosphere of a molecule that traps heat, namely CO2 or carbon dioxide. As a strategy to address CO2 increasing levels, carbon capture and utilisation (CCU) is gaining more attention in scientific research. This project applies photochemical catalysis to activate and transform carbon dioxide into dense energy carriers and chemical precursors, including carbon monoxide, alcohols and acids.To drive the photocatalytic reduction of carbon dioxide suitable semiconducting photocatalysts have to be developed. When these interact with solar light irradiation, the sun's energy is transferred to the semiconductor creating excited states which can be used in the reduction of carbon dioxide to valuable chemicals. This research aims to understand the semi-conductor/catalyst excited states and electronic structures and delineate structure-performance relationships through modifications. The work targets low-temperature and pressure processes, using metal/metal oxide/sulfide materials as both absorbers and catalysts.The photochemical mechanisms for carbon dioxide reduction are complex and more research is needed to understand factors controlling rates, selectivity and product formation pathways. This project will develop stable photocatalysts that can help elucidate the mechanism of photocatalytic CO2 reduction and in the second stage, improve the solar-to-chemical conversion efficiencies. In the first phase, UV light-absorbing catalysts such as SrTiO3 (strontium titanate) will be modified with copper (Cu) nanoparticles. Inexpensive, earth-abundant Cu is considered the best candidate due to its strong track record as a catalyst for MeOH (methanol) synthesis in thermal reactions and its track record in electrocatalysis producing C2+ products from carbon dioxide. The thesis will compare different means to produce copper nanoparticles, including electrosynthesis, photoredox synthesis and chemical synthesis. The particle-catalyst surface chemistry will be explored using techniques such as atomic layer deposition and by exploiting chemical functionality/reactivity. Catalyst-particle interfaces will be studied and characterized and catalytic activity tested photochemically under a range of different conditions.This strategy will give us more insight into the factors that govern product selectivity and catalyst activity and will result in an efficient photocatalytic system based on earth-abundant materials for CO2 reuse. This specific target performance has the impact to give a large contribution to addressing one of the main challenges of this century and support society and the ESPRC to transition towards a low- carbon future while protecting the environment. As such, this project falls within the EPSRC Energy research area.