叶片拟态材料的构建及其人工光合作用研究

The leaf mimicry ultrathin carbon/α-Fe2O3 nano-film will be synthesized by the carbonization and confinement effect of plant blades. Especially, the reaction conditions will be idealized to translate iron ions to Fe3C through penetrating into the carbon nano-film. The purpose in this project will be addressed on the mechanisms for α-Fe2O3 stimulated to produce the electronic-hole after absorbing solar light energy. First, the effect of carbon nano-film band on the gap semiconductor, conduction band and valence band of α-Fe2O3, would be investigated. And then the relationship between the visible light absorption efficiency of material and structure should be revealed. The high-efficient solar energy leaf mimicry semiconductor photocatalytic materials will be designed and synthesized. In addition, the CO2 and H2O molecular adsorption ability of photocatalytic material structure would be studied. Moreover, the inner link between selective product and conversion efficiency of CO2 and material structure, concentration of reactants, catalyst dosage and light conditions would be analysized. Based on those studied issues, the artificial photosynthesis mechanism of leaf mimicry ultrathin carbon/α-Fe2O3 nano-film as photocatalyst will be formulated. Finally, the reaction efficiency of Fe3C content in composite materials should be analysized. The repeatability utilization ratio of material should be raised by Fe3C superparamagnetism catalyst recycling. In conclusion, it is expected that the use of magnetic leaf mimicry material as artificial photosynthesis photocatalyst for high-efficient conversion solar energy is promising in dealing with the greenhouse effect and promoting the harmonious development of economy and society.

利用植物叶片自身碳化和限域作用，合成叶片拟态碳/α-Fe2O3纳米复合薄层材料，控制反应条件将进入碳纳米薄层的铁离子转化为Fe3C。研究α-Fe2O3吸收太阳光能受激发产生光生电子-空穴的机制，阐明α-Fe2O3半导体导带、价带和能带间隙受碳纳米薄层的影响规律，揭示材料的可见光吸收效率与结构之间的关系，设计并构建高效利用太阳能的叶片拟态半导体光催化材料；研究光催化材料结构对CO2和H2O分子的吸附能力，分析CO2选择性产物及转化效率与材料结构、反应物浓度、催化剂用量和光照条件之间的内在联系，阐明以叶片拟态碳/α-Fe2O3纳米复合薄层为光催化剂的人工光合作用机理；分析复合材料中Fe3C含量对反应效率的影响规律，利用Fe3C的超顺磁性进行催化剂的回收，提高材料重复利用率，构建以可磁性回收的叶片拟态材料为太阳能转化材料的高效人工光合作用体系，缓解温室效应，推动经济与社会的和谐发展。

1本项目在基金资助下，采用多种植物叶片材料作为模板，制备了叶片拟态碳/α-Fe2O3纳米复合薄层材料，利用密度泛函理论对α-Fe2O3的禁带宽度进行计算，约为2.4eV，而实际最小宽度为1.9eV，这是因为形成了复合材料且其中部分Fe2O3被还原成了碳化铁；利用振动样品磁强计研究复合材料的磁学特性，复合材料磁性强于四氧化三铁和铁；利用该材料作为光催化剂，研究其二氧化碳光还原机理，水分子被光生电子还原得到活性氢原子，在液态水体系中与富集的二氧化碳反应生成甲醇，在气态水环境下产物则为甲醇，利用这一反应机理，建立以叶片拟态碳/α-Fe2O3纳米复合薄层材料作为人工光合作用高效还原催化剂的反应体系。以桂花叶作为模板的仿生结构碳/α-Fe2O3材料人工光合作用效率最高，气态状态模拟太阳光照下甲烷产量达到46.8μmol•g-1 cat.，液态状态模拟太阳光照下甲醇产量达到76μmol•g-1 cat.。碳化铁的磁性促进了材料的回收利用，在5次重复使用后，反应效率仍然能保持99%以上。在国内外重要学术刊物上发表论文20篇（其中SCI论文16篇，Journal of Power Sources、ACS Sustainable Chemistry and Engineering、Ultrasonics Sonochemistry、Journal of Alloys and Compounds等IF大于3的论文4篇，EI论文1篇，核心论文3篇）；申请国家发明专利6项，授权4项。