School of Material Science and Engineering, Ocean University of China, 238 Songling Road, Qingdao, Shandong 266100, China.
Anal Chem. 2022 Jul 19;94(28):10183-10191. doi: 10.1021/acs.analchem.2c01644. Epub 2022 Jul 1.
Trace analyte detection in a complex environment such as in seawater is usually challenging for classic redox-based electrochemical sensors since the matrix effect of high salinity and various interfering species with similar redox properties can generate false positive/negative signals, thus impacting the sensitivity and specificity of the sensors. In this work, unlike redox-based approaches, we propose a novel sensing mode that relies on dual-modulated interfacial energy barriers of heterojunctions. By constructing the hierarchical structure of Ni/TiO/porous-reduced graphene oxide/chitosan (CS), we introduce interfacial energy barriers of Schottky junctions into the electrochemical sensors for Cu. Most importantly, we found that two factors, light and the electrostatic interactions between the heterojunctions and Cu, can be coupled to regulate the height of the interfacial energy barrier and at last exponentially magnify the sensing signals in response to Cu. Since the electrostatic interaction is inert to redox, the proposed sensor is robust against most interfering species even in seawater. Illumination further enhances its sensitivity by 6.23 times and endows it a limit of detection of 0.22 nM. Such a dual-modulated sensing mode is also valid in other heterojunctions such as in the p-n junctions of Ni/NiO/MoS/CS, demonstrating its potential in more universal applications.
在复杂环境（如海水）中痕量分析物的检测通常对基于经典氧化还原的电化学传感器具有挑战性，因为高盐度和具有相似氧化还原性质的各种干扰物质的基质效应会产生假阳性/阴性信号，从而影响传感器的灵敏度和特异性。在这项工作中，与基于氧化还原的方法不同，我们提出了一种依赖于异质结双调制界面能垒的新型传感模式。通过构建 Ni/TiO/多孔还原氧化石墨烯/壳聚糖（CS）的分层结构，我们将肖特基结的界面能垒引入到用于 Cu 的电化学传感器中。最重要的是，我们发现两个因素，光和异质结与 Cu 之间的静电相互作用，可以被耦合来调节界面能垒的高度，并最终以指数方式放大对 Cu 的传感信号。由于静电相互作用对氧化还原作用是惰性的，因此所提出的传感器对大多数干扰物质具有很强的抗干扰能力，即使在海水中也是如此。光照进一步将其灵敏度提高了 6.23 倍，并赋予其 0.22 nM 的检测限。这种双调制传感模式在其他异质结（如 Ni/NiO/MoS/CS 的 p-n 结）中也是有效的，表明其在更通用的应用中具有潜力。
