银/金刚石微粉复合材料对硝酸盐红外吸收特性的影响

Influence of Infrared Adsorption Properties of Sodium Nitrate with Silver/Diamond Powder (Ag/DP) Composites

中国海洋环境的污染日趋严重,其中大部分是由无机氮和磷酸盐导致。有效快速的监测海洋营养盐,尤其是硝酸盐,已成为一个显要的问题。传统的检测方法主要是利用化学分析法,更适合实验室测试之用。红外吸收光谱对海洋营养盐的实时监测具有重要意义,能够弥补传统方法的不足,并具有快速、同步监测多种营养盐等优点。但海水中的营养盐浓度极低,使得红外光谱检测极限难以满足要求。纳米材料能产生表面增强红外吸收(SEIRA)效应,利用此效应,使红外光谱检测海洋营养盐技术成为可能,优点得以发挥。纳米银(Ag)具有显著的表面等离子体共振效应,可以帮助实现SEIRA。金刚石具有过强的抗腐蚀性和其他特殊的性能,如高硬度和高光透射率,是理想的红外窗口材料。具体来说,利用热分解硝酸银的方法在硅基底(Si substrate)上制备了银/金刚石微粉(Ag/DP)复合材料,研究了银与金刚石微粉的不同比例对NaNO_3(一种主要海洋营养盐)的水溶液红外吸收的影响。结果表明,Ag/DP复合材料使NO_3^-的两种反对称伸缩振动νhigh和νlow的红外吸收有较大幅度提高;银与金刚石微粉比例为2∶1时,硝酸钠水溶液的红外吸收增强效果最佳。该实验结果将对海洋营养盐进行实时、长期、连续的检测提供重要信息,为海洋灾害预防、海洋环境污染治理等海洋领域提供有力的数据支持。

Marine environmental pollution in China has become increasingly serious with most pollution being caused by inorganic nitrogen and phosphate.An efficient monitoring and fast measurement of oceanic nutritive salts,especially nitrate salt,has gained greater significance.The traditional detection methods,mostly utilizing analytic chemistry,tend to be more suitable for laboratory testing.Infrared absorption spectrum is important for real-time monitoring of marine nutrients,since it not only makes up for the shortcomings of traditional methods,but also provides fast and simultaneous monitoring of various nutrients at the same time.However,marine nutrient concentrations in seawater are at particularly low level.As a result,normal IR detection is difficult to meet the requirements due to the limitation.This paper aims to utilize surface enhanced infrared absorption effect（SEIRA）of nanomaterials,making the detection of ocean nutrients with IR adsorption possible.Surface-enhanced infrared absorption（SEIRA）of nano-materials is expected to improve dramatically the sensitivity of traditional FTIR and positively achieve the goal of swift measurement of oceanic nutritive salts.Nano silver（Ag）has remarkable surface plasmon resonance effect that could help achieve high SEIRA.Diamond with extraordinarily strong anti-corrosion property is suitable for infrared window.In this paper,silver/diamond powder（Ag/DP）composites were prepared via pyrolysis of silver nitrate（AgNO_3）on silicon substrate.Proportion of Ag and DP（nAg∶nC）on the IR adsorption of NaNO_3 solution was investigated.Our results showed that Ag/DP composites significantly increased the IR adsorption of two individual antisymmetric stretching mods of NO_3^-.When nAg∶nC was 2∶1,Ag/DP composites indicated the strongest enhancement of IR adsorption of NaNO_3 solution.This paper will be an important contribution for real-time,long-term and continuous testing of marine nutrients.It will also provide important data support for marine disaster prevention,marine pollution control and other areas of the marine environment management.