可见光响应型Cu2O/Bi2WO6催化剂的构筑及光催化降解SCFA制取氢气和烷烃的机理

Photocatalytic degradation of pollutants in wastewater and simultaneous recovery of hydrogen gas and hydrocarbons as clean and renewable energy can be attained by use of water-splitting on photocatalysts under sunlight. In this study,we synthesize a novel Cu2O/Bi2WO6 photocatalyst with visible-light-response, unique structures, high activity and heterostructure. Electron struture (e.g. bangap) and photocatalytic activities can be regulated by operation factors. At the same time, key pollutants e.g. short chain fatty acids (SCFA,C2-C6) in wastewater from biological H2-production process are selected as sacrificial agents in photo-water-splitting system. Breakages of key chimical bonds and their breaking pathways during photocatalytic degradation of SCFA are researched using kinetic isotope effect (KIE) to reveal its mechanism of production hydrogen and hydrocarbons. Intermediates, products and their forming pathways during photocatalytic degradation of SCFA under vacuum are investigated using In Situ Fourier Transform Infared Spectroscopy (FTIR), Gas Chromatography-Mass Spectrometer (GC-MS) and Independent Component Analysis (ICA). The kinds, intensities and their origins of radicals during photocatalytic decomposition of SCFA are studied by on line Electron Spin Resonance (ESR). Based on above results, the mechanism on production of hydrogen gas and hydrocarbons during photocatalytic degradation of SCFA is cast light on. Further, the law regarding photocatalytic degradation of SCFA with different carbon chains will be uncovered as well.

基于太阳能光催化分解水技术，在降解水中有机物污染物的同时，还可以回收氢气、烷烃等可再生能源。本课题拟设计合成具有可见光响应、特殊形貌、异质结结构、高催化活性的Cu2O/Bi2WO6，通过合成条件来调控其禁带结构及光催化性能。以生物发酵制氢废水中短链脂肪酸（SCFA）为太阳能分解水制氢的牺牲剂，采用同位素动力学效应来研究短链脂肪酸光催化降解过程中关键化学键的断裂及路径，揭示氢气和烷烃的形成机理；采用原位红外吸收光谱、气质色谱及独立组分分析法(ICA)来研究真空条件下光催化降解短链脂肪酸的中间产物、产物及形成路径；通过在线电子自旋共振光谱（ESR）来识别短链脂肪酸分解过程中主要自由基的种类、强度及成因，解析SCFA在降解过程中重要自由基的形成路径；在此基础上，阐明太阳能光催化分解水溶液中短链脂肪酸制取烷烃和氢气的机理，揭示不同长度碳链脂肪酸光催化降解的规律性。

烷烃和氢气是可再生的清洁载体，在国民经济和社会生活应用广泛。本项目以短链脂肪酸为光催化体系的电子供体，利用各种形貌的Cu2O/Bi2WO6光催化剂来研究光催化降解短链脂肪酸来制取烷烃和氢气的性能，并开展了相关理论和技术研究。首先，围绕高可见光活性、p-n异质结结构、特殊形貌的Cu2O/Bi2WO6基复合光催化剂的制备和性能调控为主线，开展了不同形貌的氧化亚铜、不同形貌的钨酸铋及不同形貌的Cu2O/Bi2WO6复合光催化剂的制备及性能研究；开展了三元Cu2O/Bi2WO6基复合光催化剂的设计合成与光催化制取烷烃和氢气的性能优化；研究了光催化降解短链脂肪酸制取氢气和烷烃的中间产物、产物、自由基等分析鉴定和识别，验证光催化降解短链脂肪酸的机理和路径；比较研究了Cu2O/Bi2WO6基复合光催化剂的可见光光催化性能与紫外光光催化性能。