Abstract: The piezoelectric effect in asymmetric semiconductors has been shown to be an effective strategy to reduce carrier recombination in photocatalysis. This means that mechanical energy-induced piezoelectricity can act as a flexible automatic valve to regulate the transfer and separation of light-induced carriers in the bulk phase and on photocatalyst surfaces. Two-dimensional graphitic carbon nitride (g-C3N4) has a non-centrally symmetrical pore structure and uniform pore distribution, so it has piezoelectric response characteristics, and has received extensive attention in the field of antibacterial applications. The molecular engineering of g-C3N4 can change the piezoelectric polarization of g-C3N4 to a certain extent, which will enhance the role of the piezoelectric effect in the antimicrobial process of g-C3N4. Therefore, in this work, two-dimensional g-C3N4 materials containing hydroxyl and carboxyl oxygen-containing functional groups were synthesized by KOH with high temperature alkali treatment and KSCN calcination acid leaching, respectively. The results show that g-C3N4 still exhibits a graphite structure after the modification of the agglomeration of oxygen. The piezoresponse force microscopy (PFM) confirms the non-uniform surface potential distribution of these composite materials, and significantly improves the piezoelectric performance after the carboxyl branching. Scanning electron microscopy (SEM) show that the composite material causes a certain physical damage to the bacteria. The active oxygen (ROS) test shows that the induction effect is introduced to promote the separation of the electron-acupuncture point, which enhances the ability of the materials to capture electrons in the piezoelectric field. As a result, the captured electrons are restarted around the adsorption oxygen, generating a large amount of superoxide anion, and inducing a change in the active oxygen level within the bacteria to change, causing bacterial death. In vitro, the oxidation-induced oxidation stimulation combined with physical cutting of the antibacterial activity to Escherichia coli (E. coli) is 5log (99.999%), and the antibacterial activity against Staphylococcus aureus (S. aureus) is 4log (99.99%), which is higher than the pure g-C3N4. These findings emphasize the antibacterial potential of the carboxylated g-C3N4 material, which may be a promising candidate as an antibacterial material in the light-restricted environment.

Key words: g-C3N4, antibacterial material, ROS, Escherichia coli, Staphylococcus aureus, piezoelectric response

摘要： 二维石墨相碳氮化物(g-C3N4)因具有规则分布的非中心对称孔，可以产生压电响应而在抗菌领域得到了广泛关注。本研究设计制备了两种含氧官能团包括羟基和羧基化的二维g-C3N4材料。研究表明，含氧官能团改性后g-C3N4的结构保持较好。压电响应力显微镜(PFM)测试证实了这些复合材料具有不均匀的表面电位分布且羟基化和羧基化材料压电性能均有显著提高。活性氧物种测试结果显示羧基化材料表现出了较强的超氧阴离子(?O2-)信号但是羟基化材料并未表现出自由基信号。这可能是由于羧基基团具有比羟基更强的吸电子能力，在压电场下促进了电子-空穴对的分离并增强了材料俘获电子的能力，俘获的电子再还原周围的吸附氧产生了大量?O2-。体外抗菌测试显示，?O2-诱导的氧化应激与物理切割相结合，对大肠杆菌的抗菌率达到了5log (99.999%)，对金黄色葡萄球菌的抗菌率达到了4log (99.99%)，超过了纯相g-C3N4和羟基化g-C3N4-H。这些发现突出了含氧官能团改性g-C3N4材料的抗菌潜力，可作为光限制环境中有希望的候选抗菌材料。

关键词: g-C3N4, 抗菌材料, 活性氧, 大肠杆菌, 金黄色葡萄球菌, 压电特性