Special Effect of Urea as a Stabilizer in Thermal Immersion Method to Synthesis Porous Zinc Oxide Nanostructures

Abstract

ZnO nanostructure was prepared by catalytic immersion method (90°C) with zinc nitrate hexahydrate (Zn(NO3)26H2O) as a precursors and urea (CH4N2O) as a stabilizer. Different molarity concentration ratio of Zn(NO3)26H2O to CH4N2O, 2 : 1, 1 : 4, 1 : 6, and 1 : 8 is used in this work. The effect of urea concentration used during the synthesis process is discussed. The ZnO nanostructures were characterized by using field emission scanning electron microscope (FESEM), photoluminescene (PL), andI-Vprobe. Porous nanoflakes are successfully synthesized on p-type silicon substrate coated with gold layer with different size and dimension. High intensity photoluminescence (PL) at optimum concentration indicated that urea is good stabilizer to produce ZnO nanostructures with good crytallinity. Rectifying characteristics show dramaticaly change in turn-on voltage when the concentration of urea increases in aqueous solution. This is related to the theory about p-type doping of ZnO nanostructures by nitrogen from NH3.

Thermal Annealing Induced Controllable Porosity and Photoactive Performance of 2D ZnO Sheets

“…During the hydrothermal process, urea decomposed and produced NH 3 . NH 4 + ions will generate from NH 3 ions and markedly increase pH aqueous solution and support the hydrothermal ZnO crystal growth process ((1) and (2) reactions) [ 18 ]: CON 2 H 4 + 3H 2 O → CO 2 (g) + 2NH 3 H 2 O 2NH 3 · H 2 O + CO 2 → 2NH 4 + + CO 3 2− + OH − …”

The effect of urea:nitrate ratio on the structure and luminescence properties of YVO4:Dy3+ phosphors

“…It was observed that when increasing the concentration of urea the flake-like particles formed and exhibit some holes at the surface, which maybe due to the strong dispersant effect of gasses generated during the reaction. Husairi et al [17] reported that nano-flakes were observed when increasing the concentration of urea. BacalskiIn et al [18] prepared barium magnesium doped Dy 3 þ by combustion and observed the flakes-like particles when increasing ratio of urea.…”

Performance Evaluation of Crack-Like ZnO/PSi Nanostructure Chemical Solution Sensor via Electrochemical Impedance Technique

“…The crack-like structures effect may be caused by the lower concentration of carbonate ions (CO 3 2− ) and OH − that are available to combine with Zn + from zinc nitrate hexahydrate to form Zn(OH) 2 and crystalline ZnO nanostructures after drying. 5 The degree of supersaturation of Zn(OH) 2 in the interfacial zone is the factor that can influence the nucleation and growth of ZnO nanostructures. 17,18 When ZnO nanostructures are deposited on PSiNs, it will deposit along the outer wall of pores of PSiNs, partially by filling or by completely covering them.…”

“…This carrier redistribution is measured as changes in the conductivity or capacitance of the semiconductor. 4 Previously, the capability of ZnO nanostructures to detect N 2 gas 5 and potential of ZnO/PSi nanostructures to detect ethanol solution 6 was studied and reported. In the present study, the capability and performance of ZnO nanostructures on PSi nanostructure was compared with PSi nanostructure sensor to prove that detecting and identifying chemical solutions can be improved by grown ZnO nanostructures on PSi nanostructure.…”