Current Research Activity
Zinc oxide (ZnO) is a versatile material with a wide range of applications. Of particular interest is its potential use in LEDs. When growing ZnO in aqueous solution, it has been observed that the aspect ratio can be controlled by the addition of citrate ions. Citrate is the completely deprotonated anion of the carboxylic acid citric acid. It is believed that this anion adsorbs onto the positive (0001) surface, stopping further growth in this direction, but allowing growth to continue in other directions. The development of this low temperature, aqueous environment growth of ZnO will provide a much cheaper means of producing ZnO than current methods involving high temperature vaporisation.
The purpose of my research is to understand the molecular interactions that occur between the citrate ions and ZnO surfaces. I am using ab initio modelling techniques such as Density Functional Theory (DFT) to simulate the system. Challenges include determining which model chemistry is best suited to this particular system as well as modelling the role played by water and the effects water has on the other species. Validation of the chosen model can occur by computing certain quantities and comparing to experimental values, such as the pKa or IR spectra. Once the interactions of citrate and ZnO are understood, it may be possible to suggest other anions that may offer improvements to the process.