[1] Univ Putra Malaysia, Fac Sci, Dept Chem, Upm Serdang 43400, Selangor, Malaysia
[2] Univ Putra Malaysia, Inst Adv Technol, Funct Device Lab, Upm Serdang 43400, Selangor, Malaysia
[3] Univ Malaya, Dept Phys, Fac Sci, Low Dimens Mat Res Ctr, Kuala Lumpur 50603, Malaysia
[4] Univ Nottingham, Fac Engn, Semenyih 43500, Selangor, Malaysia