-    Develop chemical methods for fabrication of some materials with nanoparticle size Fe2O3, Al2O3, Nano-Zr–ZSM-5, ZrO2NPs, Au–ZrO2; NPs–SiO2, Cu(BTC)/GO...with desirable shape, size and chemical compositions;
-    Investigate the mechanism of the reduction reaction of phenol compounds on the synthesized nanocatalysts. Determination of the materials’ shape, size, surface chemistry and/or chemical compositions on the electrochemical activity of the reduction reaction of phenolic compounds. Evaluate the electrocatalysts’ selectivity;
-    Selecting suitable catalysts for the fabrication of electrochemical sensors for determination of interested phenol compounds in the environment and in foodstuffs;

-  Theoretical results: Fabricated some materials with nanoparticle size Fe2O3, Al2O3, Nano-Zr–ZSM-5, NPs-ZrO2, Au–ZrO2; NPs-SiO2, Cu(BTC)/GO...with desirable shape, size and chemical compositions. Characterized their phisyco-chemical properties using modern techniques. Details as below:

• The Zr-ZSM-5 material has a specific surface area of SBET 306.46 m2/g and an average micropore area Smicro of 201.55 m2/g. The capillary volume of the Zr-ZSM-5 nanomaterials 0.203 cm3/g and the pore diameter of DBJH 4.2 nm.
• The ZrO2 material has a specific surface area of SBET 100.68 m2/g and an average micropore area Smicro of 29.02 m2/g. The capillary volume of the ZrO2 nanomaterials 0.081 cm3/g and the pore diameter of DBJH 3.72 nm.
• The nanosilica material has a specific surface area of SBET 269,8m2/g and an average micropore area Smicro of 1.168 m2/g and the pore diameter of DBJH 15.85 nm.
• The Fe2O3 material has a specific surface area of SBET 34.66 m2/g and an average micropore area Smicro of 15.43 m2/g. The capillary volume of the Fe2O3 nanomaterials 0.44 cm3/g and the pore diameter of DBJH 61.64 nm.
• The Al2O3 material has a specific surface area of SBET 192.99 m2/g and an average micropore area Smicro of 56.95 m2/g. The capillary volume of the Al2O3 nanomaterials 0.081 cm3/g and the pore diameter of DBJH 11.88 nm.
• Cu(BTC)/GO has the surface area, pore volume and pore size of Cu-BTC/GO of 1591 m2/g, 1.485 cm3/g and 3.34 nm, respectively. Particle size of it Ca. 50-80 nm with uniform distribution.
• Above materials had been used for electrode modification in order to detect phenolic compounds in water environment. There are two kinds of electrodes modified: carbon paste electrode and glassy carbon electrode (GCE).
• For the first kind, carbon paste eletrode, synthesized materials were mixed with graphite powder with desired ratio (plus paraffine oil as well) for screening the electrocatalysis properties. As results, for 2,4-dimethyl phenol (2,4-DMP), Al2O3 showed being the best electrocatalyst. In the same way, Fe3O4 was used for electrode modification combined with the multivariable statistical method using partial least squares (PLS). Six phenolic compounds had been tested (2,4-dimethylphenol, 2,4,6-trichlorophenol, 2,4-dichlorophenol, 3-nitrophenol, 4-nitrophenol, and phenol). The results have shown that the proposed method is applicable to simultaneously detect six interested compounds with acceptable relative standard errors (less than 20% in most cases).
• For the second kind of modified electrode, GCE, some of above materials were used by dropcasting (with a certain amount) prepared materials on electrode surface and used for detection of 2,4-dichlorophenol (2,4-DCP) and bisphenol A (BPA). Data showed that LODs for 2,4-DCP were 0.083 µM and 0.053 using Cu(BTC)/rGO/GCE and AuNP/ZrO2/GCE respectively. For BPA case, LOD achieved of sensor AuND/CTAB/GCE was 2 nM.

-    Applied results:
The above synthesized materials have been used for removals some pollutants in the aquatic environment. The results have been published previously by project members. In the framework of this project, electrochemical sensors have been developed using these materials to directly measure real environmental samples and samples from LaVie bottles, which popularly used in Vietnam for drinking water.

These findings provide an effective tool for in situ and low-cost cost analysis of phenolic contaminants in water environments.
Development of electrode modification materials and successful applications in the detection of some toxic compounds such as Cu(BTC)/GO and AuNP/ZrO2 composite materials, which used for determine 2,4-DCP in water with allowable detection limits as WHO requirements.

Scientific papers in referred journals (list):
6.    Vu Thi Hong Nhung, Nguyen Ba Manh, Vu Thi Thu, Pham Thi Hai Yen, Le Ha Giang, Pham Hong Phong, Vu Anh Tuan, Vu Thi Thu Ha, Screening of several oxides used as efficient electrocatalysists for detection of 2,4-dimethyl phenol in aqueous medium, Vietnam J. Chem., 2020, 58(4), 512-516;
7.    Vu Hai Dang, Vu Thi Thu, Le Truong Giang, Pham Thi Hai Yen, Pham Hong Phong, Vu Anh Tuan, Vu Thi Thu Ha, Multivariate calibration combined differential pulse voltammetry for simultaneous electroanalytical determination of phenolic compounds using a Fe3O4-modified carbon paste electrode, Journal of Solid State Electrochemistry, 2020, 24, 2241–2248;
8.    Nguyen Thi Lien, Le Quoc Hung, Nguyen Tien Hoang, Vu Thi Thu, Dau Thi Ngoc Nga, Pham Thi Hai Yen, Pham Hong Phong, and Vu Thi Thu Ha, An Electrochemical Sensor Based on Gold Nanodendrite/Surfactant Modified Electrode for Bisphenol A Detection, Journal of Analytical Methods in Chemistry, Volume 2020, Article ID 6693595, 10 pages, https://doi.org/10.1155/2020/6693595
9.    Manh B. Nguyen, Vu Thi Hong Nhung, Vu Thi Thu, Dau Thi Ngoc Nga, Thuan Nguyen Pham Truong, Hoang Truong Giang, Pham Thi Hai Yen, Pham Hong Phong, Tuan A. Vu and Vu Thi Thu Ha. An electrochemical sensor based on copper-based metal–organic framework-reduced grapheme oxide composites for determination of 2,4-dichlorophenol in water,  RSC Advances, 2020, 10, 42212;
10.    Vu Thi Thu Ha, Manh B. Nguyen, Tran Nhu Tam, Vu Thi Thu, Pham Thi Hai Yen, Pham Hong Phong, Dao Ngoc Nhiem, Le Quoc Hung and Tran Quang Hai, Highly Sensitive Electrochemical Sensor for 2,4- Dichlorophenol by Zirconium Oxide-Decorated Gold Nanoflakes Nanocomposite, Journal of Applied Electrochemistry, 2021, Accepted.
Technological products:
-    ~10g/each materials produced: Fe2O3, Al2O3,Nano-Zr–ZSM-5, NPs-ZrO2NPs, NPs–SiO2, Cu-BTC/GO… and now storing in laboratory at Institute of Chemistry, VAST;
-    02 procedures and property characterizations of AuNP/ZrO2 và Cu(BTC)/GO, which accepted by the jury members;
-    02 technical reports about reduction mechnism of 2,4-DCP and BPA on meterials tested
Other products:
-    Data set of  property characterizations of Fe2O3, Al2O3,Nano-Zr–ZSM-5, NPs-ZrO2, Au–ZrO2; NPs–SiO2, Cu-BTC/GO;
-    20 sensors used for testing during the project implementation.

It is proposed to accept the topic and develop research direction for other interested contaminants such as pesticides, heavy metals (Hg, As...) by electrochemical sensors.