通过化学氧化块状石墨型氮化碳(g-C3N4), 获得在水中分散性好的片状g-C3N4。 XRD, FTIR和XPS表明, 所得片状g-C3N4含有氧官能团。 这不仅可以作为锚定点负载纳米银粒子(Ag NPs), 而且可以获得Ag NPs均匀分散的Ag NPS/g-C3N4纳米复合物。 制备的复合材料中银纳米颗粒的重量百分比也会随着硝酸银与片状g-C3N4的质量变化而发生变化。 基于g-C3N4对Co2+的明显的拉曼强度响应, Ag NPS/g-C3N4纳米复合物作为表面增强拉曼散射(SERS)传感器检测Co2+。 通过拉曼强度的对照, 发现随着Co2+浓度的增加, 拉曼信号增加; 而含有73%银纳米颗粒的Ag NPS/g-C3N4纳米复合物有高的灵敏性, 检测极限浓度达到10-9 mol·L-1; 复合材料同时显示出高的选择性, 对其他如Cd2+, Cu2+和Zn2+的金属离子没有明显的拉曼增强信号。 分析了复合材料对Co2+的增强机制。 由于Co2+与g-C3N4中的N/NH基团的耦合, 引发复合材料中Ag NPs聚集, 从而产生局部电磁场, 进而产生表面增强效应。 可以预知, Ag NPS/g-C3N4纳米复合物将作为一种用于制造SERS传感器的新的理想材料。

The graphite-like carbon nitride (g-C3N4) nanosheets with oxygen-containing functional groups, characterized by with XRD, FTIR and XPS, were obtained by applying chemical oxidation of bulk g-C3N4. The oxygen-containing functional groups not only can be used as anchoring sites for silver nanoparticles (Ag NPs), but also help the formation of high scatter for Ag NPs in Ag NPS/g-C3N4 nanosheets nanocompposites. The weight percentage of Ag NPS in the prepared nanocomposites can be controlled by adding silver nitrate. The Ag NPS/g-C3N4 nanosheets nanocompposites are developed as a superior sensor for the detection of Co2+ ions, which are based upon Raman intensity response of g-C3N4 nanosheets to Co2+ ions. With comparison, it was found that Raman signal increase as the increasing of the concentration in Co2+. Results from the weight percentage sensitivity investigations show that Ag NPS content of 73% in nanocomposites have very low limits of detection (10-9 mol·L-1 for Co2+) in contrast with other Ag NPS content. The sensors also exhibit greater selectivity for Co2+ ions than the other metal ions (Cd2+, Cu2+ and Zn2+). The mechanism is proposed. The localized electromagnetic field is produced around the aggregated Ag NPs with the complexation between Co2+ and N/NH groups in g-C3N4 occurs, so the increase of SERS signal in the intensity can be observed. It is anticipated that Ag NPS/g-C3N4 nanosheets nanocomposites can be a new class of promising material for fabricating SERS sensors.