Novel TiO2 nanomaterials as sonocatalytic agents for water-splitting

声化学是利用超声波产生的气泡来进行化学反应。声波会导致液体中气泡的形成，最终气泡的坍塌被称为声空化，这种坍塌会引起物理化学环境的局部变化，从而可以进一步用于催化反应。这种效应早已为人所知，并被用于药物输送；然而，在探索其在可持续催化中的潜在应用方面所做的工作有限。最近，多相催化剂(与反应物不在同一相的催化)的引入开辟了以前用传统超声化学无法实现的新反应。然而，空化的控制-声化学的主要驱动力-还没有实现。本研究旨在开发控制催化部位周围的空化的方法，了解潜在的物理和化学，并首次将这种声化学方法应用于部分水的分解。部分水分解是将水分解成其成分的反应。氢作为产品之一，是一种可以直接用于设备的无碳燃料，氧化化学反应可以同时发生，从廉价的原材料中生产出高市场价值的产品。换言之，本项目中研究的声化学为节省操作能量和生产两种有价值的化学品的成本提供了潜在的应用，并可能为了解空化和声化学做出巨大贡献。实验研究将包括合成异质结纳米粒子催化剂，并使用一种新型的定制声化学反应器，使空化监测能够在受控声场中进行。反应器的设置也将用于评估材料的超声催化性能。产品种类的化学分析(即表征)将使用光谱和色谱方法，如气相色谱、透射电子显微镜和X射线光电子能谱。最后，将进行计算，以探索进一步了解和控制声化学反应的化学机理。此外，空化噪声和化学物种分析的结果将促进我们对催化声化学的理解，并使未来使用本工作开发的方法设计声化学反应器、催化空化器和潜在化学可能成为可能。该项目属于EPSRC工程和能源研究领域。

Sonochemistry is the use of ultrasound generated bubbles to enable chemical reactions. Sound waves will cause the formation of bubbles in liquids and the eventual collapse of bubbles is termed as acoustic cavitation; the collapse induces local changes to the physicochemical environment which could be further used in catalytic reactions. This effect is long-known and used in drug deliveries; however, limited work has been done to explore its potential application in sustainable catalysis. Recently, the introduction of heterogeneous catalysts (catalysis that is not in the same phase as the reactants) has opened up new reactions not previously achievable using conventional sonochemistry. Yet, the control of cavitation - the primary driving force for sonochemistry - has yet to be achieved.This research aims to develop approaches for controlling cavitation around catalytic sites, understanding the underlying physics and chemistry, and, for the first time, applying this sonochemical approach towards partial water splitting. Partial water splitting is the reaction to split the water into its constituents. Hydrogen, as one of the products, is a carbon-free fuel that could be used directly in devices, and an oxidative chemical reaction could happen simultaneously to produce a high market value product from cheap raw material. In other words, the sonochemistry investigated in this project presents a potential application for saving operation energy and cost to produce two valuable chemicals, and could contribute greatly to understanding cavitation and sonochemistry.Experimental studies will include synthesising heterojunction nanoparticle catalysts and be conducted using a novel bespoke sonochemical reactor that will enable cavitation monitoring in controlled acoustic fields. The reactor setup will also be used to evaluate the sonocatalytic performance of the material. Chemical analysis (i.e. characterisation) of product species will be conducted using spectroscopic and chromatographic methods such as gas chromatography, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Finally, computations will be performed to explore the chemical mechanism for further understanding and control of the sonochemical reactions. Additionally, results from both the cavitation noise and chemical species analysis will advance our understanding of catalytic sonochemistry and enable future designs of sonochemical reactors, catalytic cavitation agents, and the potential chemistries possible using the approaches developed in this work.This project falls within the EPSRC Engineering and Energy research area.