Study On The Electrochemical Sensor For Fast Detection Of Phosphate Ions In Nutrient Solution

With the acceleration of industrialization and implementation of Grain for Green Project, arable land resources in China are becoming less and less. Especially in the eastern coastal city, the contradictions between increased people and decreased land will become fiercer. Soilless cultivation techniques can be an effective selective and complementary way for high yield and quality of vegetable production. Facilities environment regulation and cultivation techniques are still relatively backward in China, resulting in an imbalance of nutrients supply and demand in the production system, thus seriously affecting the economic and ecological benefits of the system. As one of three most important nutrients in plants, phosphorus play significant role in the vegetable growth, thus, it is necessary to be monitored and managed. In recent years, the traditional analysis methods have disadvantages of time-consuming and labor-intensive. Therefore, it is important and meaningful to develop a rapid, accurate and reliable method for detecting phosphorus in nutrition solution.In this study, we reported an effective strategy to fabricate a novel phosphate sensor with high performance via the electrodeposition of cobalt into interspaces of nanoporous gold electrodes. The unique material architecture enabled wide linear responses, high sensitivity and good selectivity for fast detection of phosphates.In the first step, we compared the performance of matrix electrodes including cobalt rod, glassy carbon electrode (GCE), screen-printing electrode (SPE), gold electrode, and gold was chosen because of its faster electron transfer rate. Then, the performance and surface morphology of electrodeposition methods including potentiostatic deposition, cyclic-voltammetry deposition, galvanostatic deposition were compared. We selected galvanostatic deposition since the surface of electrode was more delicate and ordered. Finally, cobalt nanoparticles were electrodeposited into interspces of nanoporous gold electrode (NPG) that was prepared by a simple multicyclic alloying/dealloying method. By changing some parameters in the process of the electrodeposition (electrodeposition time and electrodeposition current), we can fabricate a best phosphate sensor.The results showed that the uniformly distributed nanopores on the electrode obtained after20-cycle alloying/dealloying process and larger effective surface area ofNPG electrodes owing to the nanoporous hierarchical structure. Meanwhile, under the electrodeposition time of600s and electrodeposition current of3mA, uniformly distributed Co particles (CoNPs) were generated to possess the best performance for phosphates sensing.The CoNPs/NPG electrode displayed linear response to phosphates over large concentration ranged from10-6to10-1M with a correlation coefficient of0.998. The slope of the fitted linear curve was-45.43mV/dec. The proposed CoNPs/NPG electrode also exhibited good long-time stability and reproducibility. The superior performance of the electrodes can be attributed to the enhanced synergistic electrocatalysis of gold skeleton and cobalt particles. As such, this work provided a feasible way to fabricate sensors with high performances for fast in-situ detection of phosphates and other chemicals.