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Radical-Driven Decomposition of Graphitic Carbon Nitride Nanosheets: Light Exposure Matters
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2021-09-01 , DOI: 10.1021/acs.est.1c03804 Mengqiao Li 1 , Dairong Liu 2 , Xing Chen 3 , Zhihong Yin 3 , Hongchen Shen 1 , Ashlee Aiello 4 , Kevin R McKenzie 5 , Nan Jiang 2 , Xue Li 3 , Michael J Wagner 5 , David P Durkin 4 , Hanning Chen 6 , Danmeng Shuai 1
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2021-09-01 , DOI: 10.1021/acs.est.1c03804 Mengqiao Li 1 , Dairong Liu 2 , Xing Chen 3 , Zhihong Yin 3 , Hongchen Shen 1 , Ashlee Aiello 4 , Kevin R McKenzie 5 , Nan Jiang 2 , Xue Li 3 , Michael J Wagner 5 , David P Durkin 4 , Hanning Chen 6 , Danmeng Shuai 1
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Understanding the transformation of graphitic carbon nitride (g-C3N4) is essential to assess nanomaterial robustness and environmental risks. Using an integrated experimental and simulation approach, our work has demonstrated that the photoinduced hole (h+) on g-C3N4 nanosheets significantly enhances nanomaterial decomposition under •OH attack. Two g-C3N4 nanosheet samples D and M2 were synthesized, among which M2 had more pores, defects, and edges, and they were subjected to treatments with •OH alone and both •OH and h+. Both D and M2 were oxidized and released nitrate and soluble organic fragments, and M2 was more susceptible to oxidation. Particularly, h+ increased the nitrate release rate by 3.37–6.33 times even though the steady-state concentration of •OH was similar. Molecular simulations highlighted that •OH only attacked a limited number of edge-site heptazines on g-C3N4 nanosheets and resulted in peripheral etching and slow degradation, whereas h+ decreased the activation energy barrier of C–N bond breaking between heptazines, shifted the degradation pathway to bulk fragmentation, and thus led to much faster degradation. This discovery not only sheds light on the unique environmental transformation of emerging photoreactive nanomaterials but also provides guidelines for designing robust nanomaterials for engineering applications.
中文翻译：
石墨氮化碳纳米片的自由基驱动分解：曝光很重要
了解石墨氮化碳 (gC 3 N 4 )的转化对于评估纳米材料的稳健性和环境风险至关重要。使用集成的实验和模拟方法，我们的工作已经证明gC 3 N 4纳米片上的光致空穴 (h + )显着增强了纳米材料在• OH 攻击下的分解。合成了两个gC 3 N 4纳米片样品D和M2，其中M2具有较多的孔隙、缺陷和边缘，它们分别经过• OH单独处理和• OH和h +处理. D 和 M2 都被氧化并释放出硝酸盐和可溶性有机碎片，而 M2 更容易被氧化。特别是，即使• OH的稳态浓度相似，h +也使硝酸盐释放速率增加了 3.37-6.33 倍。分子模拟强调：• OH 仅攻击 gC 3 N 4纳米片上有限数量的边缘位置七嗪并导致外围蚀刻和缓慢降解，而 h +降低了庚嗪之间 C-N 键断裂的活化能势垒，将降解途径转变为本体碎裂，从而导致更快的降解。这一发现不仅揭示了新兴光反应纳米材料的独特环境转变，而且还为设计用于工程应用的坚固纳米材料提供了指导。
更新日期：2021-09-21
中文翻译：
石墨氮化碳纳米片的自由基驱动分解：曝光很重要
了解石墨氮化碳 (gC 3 N 4 )的转化对于评估纳米材料的稳健性和环境风险至关重要。使用集成的实验和模拟方法，我们的工作已经证明gC 3 N 4纳米片上的光致空穴 (h + )显着增强了纳米材料在• OH 攻击下的分解。合成了两个gC 3 N 4纳米片样品D和M2，其中M2具有较多的孔隙、缺陷和边缘，它们分别经过• OH单独处理和• OH和h +处理. D 和 M2 都被氧化并释放出硝酸盐和可溶性有机碎片，而 M2 更容易被氧化。特别是，即使• OH的稳态浓度相似，h +也使硝酸盐释放速率增加了 3.37-6.33 倍。分子模拟强调：• OH 仅攻击 gC 3 N 4纳米片上有限数量的边缘位置七嗪并导致外围蚀刻和缓慢降解，而 h +降低了庚嗪之间 C-N 键断裂的活化能势垒，将降解途径转变为本体碎裂，从而导致更快的降解。这一发现不仅揭示了新兴光反应纳米材料的独特环境转变，而且还为设计用于工程应用的坚固纳米材料提供了指导。
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