腐殖酸与典型碳纳米材料协同光致产生活性氧物种的研究

摘要

Effects of humic acid (HA) on photochemical production of singlet oxygen (1O2) and hydroxyl radical (·OH) induced by four typical carbon nanomaterials were investigated by using electron paramagnetic resonance (EPR).Based on the density functional theory, the frontier orbital energies of four typical carbon nanomaterials were calculated, and their ability of 1O2 generation by energy transfer and ·OH production by electron transform were compared, respectively.Results showed that C60, single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT) and graphene suspensions didn't induce the production of 1O2 and ·OH under UV irradiation.When HA was present, four typical carbon nanomaterials significantly enhanced 1O2 production.In addition, C60 and graphene in HA solutions also caused ·OH generation.The ability to produce 1O2 followed the order: SWNT > C60 > MWNT > graphene, and to produce ·OH followed the order: graphene > C60.The capacity of 1O2 production is attributed to the energy gap and particle aggregation degree of carbon nanomaterials, and the ability to induce ·OH mainly depended on the chemical hardness.In conclusion, our results indicated the synergistic photogeneration of 1O2 and ·OH by HA and carbon nanomaterials.%采用电子自旋共振光谱(EPR)技术,分析腐殖酸在光照下对4种典型碳纳米材料诱导产生单线态氧(1O2)和羟基自由基(·OH)的影响.基于密度泛函理论计算4种典型碳纳米材料的前线轨道能,比较了它们分别经能量转移诱导产生1O2的能力以及经电子传递诱导产生·OH的能力.结果显示,4种不同形状的碳纳米材料(富勒烯、单壁碳纳米管、多壁碳纳米管以及石墨烯)悬浮液在紫外光照下均无1O2和·OH产生.与腐殖酸共同存在下,4种碳纳米材料均显著诱导1O2的产生,且富勒烯和石墨烯还能光致生成·OH.协同产生1O2的能力大小为:单壁碳纳米管 > 富勒烯 > 多壁碳纳米管 > 石墨烯,协同产生·OH的能力大小为:石墨烯 > 富勒烯.1O2的产生能力与碳纳米材料的能隙大小和颗粒聚集程度有关,而诱导产生·OH的能力主要取决于化学硬度.总之,我们的研究表明腐殖酸与碳纳米颗粒可协同产生活性氧物种.