Tseng I-Hsiang, Sung Yu-Min, Chang Po-Ya, Chen Chin-Yi
Department of Chemical Engineering, Feng Chia University, Taichung 40724, Taiwan.
Department of Materials Science and Engineering, Feng Chia University, Taichung 40724, Taiwan.
Polymers (Basel). 2019 Jan 16;11(1):146. doi: 10.3390/polym11010146.
Three types of graphitic carbon nitride (gCN) nanosheets were derived from direct thermal condensation of urea, melamine, and dicyandiamide, respectively. As the sample (uCN) synthesized from urea exhibited porous morphology and highest surface area among other gCN, anatase TiO₂ nanoparticles were then in-situ deposited on uCN via solvothermal process without further calcination. The resultant Ti/uCN_x samples remained with higher surface area and exhibited visible-light activity. The derived band structure of each sample also confirmed its ability to photoreduce CO₂. XPS results revealed surface compositions of each sample. Those functional groups governed adsorption of reactant, interfacial interaction, electron transfer rate, and consequently influenced the yield of products. Carbon monoxide and methanol were detected from LED-lamp illuminated samples under appropriate moisture content. Samples with higher ratio of terminal amine groups produced more CO. The presence of hydroxyl groups promoted the initial conversion of methanol. The obtained Ti/uCN_0.5 and Ti/uCN_1.5 samples exhibited better quantum efficiency toward CO₂ conversion and demonstrated stability to consistently produce CO under cycling photoreaction.
三种类型的石墨相氮化碳（gCN）纳米片分别由尿素、三聚氰胺和双氰胺直接热缩合得到。由于由尿素合成的样品（uCN）在其他gCN中呈现出多孔形态和最高的比表面积，随后通过溶剂热法将锐钛矿型TiO₂纳米颗粒原位沉积在uCN上，无需进一步煅烧。所得的Ti/uCN_x样品保持较高的比表面积并表现出可见光活性。每个样品的推导能带结构也证实了其光还原CO₂的能力。XPS结果揭示了每个样品的表面组成。这些官能团控制反应物的吸附、界面相互作用、电子转移速率，从而影响产物的产率。在适当的水分含量下，从LED灯照射的样品中检测到一氧化碳和甲醇。末端胺基比例较高的样品产生更多的CO。羟基的存在促进了甲醇的初始转化。所获得的Ti/uCN_0.5和Ti/uCN_1.5样品对CO₂转化表现出更好的量子效率，并在循环光反应中表现出稳定地持续产生CO的性能。
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