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吸收热量的分子，即二氧化碳浓度的增加有关。碳捕获与利用（CCU）作为一种应对二氧化碳水平上升的策略，在科学研究中越来越受到关注。该项目应用光化学催化将二氧化碳激活并转化为密集的能量载体和化学前体，包括一氧化碳、醇和酸。为了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上，产生激发态，可以用来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，并通过修饰描述结构-性能关系。这项工作的目标是低温和低压工艺，使用金属/金属氧化物/硫化物材料作为吸收剂和催化剂。二氧化碳的光化学还原机制是复杂的，需要进一步研究控制速率、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CO2还原的机理，并在第二阶段提高光化学转化效率。在第一阶段，将用铜纳米颗粒修饰SrTiO3（钛酸锶）等吸收紫外线的催化剂。廉价且储量丰富的铜被认为是最佳的候选材料，因为它在热反应中作为甲醇（甲醇）合成催化剂的良好记录，以及它在从二氧化碳中产生C2+产物的电催化方面的记录。本文将比较制备纳米铜的不同方法，包括电合成、光氧化还原合成和化学合成。粒子催化剂的表面化学将通过原子层沉积和利用化学功能/反应性等技术进行探索。将研究和表征催化剂-颗粒界面，并在一系列不同条件下进行光化学催化活性测试。这一策略将使我们更深入地了解控制产物选择性和催化剂活性的因素，并将导致基于地球上丰富的二氧化碳再利用材料的高效光催化系统。这一具体的目标绩效将为解决本世纪的主要挑战之一做出巨大贡献，并支持社会和ESPRC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.