Lorna Jeffery Minggu

An overview on cellulose-based material in tailoring bio-hybrid nanostructured photocatalysts for water treatment and renewable energy applications

A combination between the nanostructured photocatalyst and cellulose-based materials promotes a new functionality of cellulose towards the development of new bio-hybrid materials for various applications especially in water treatment and renewable energy. The excellent compatibility and association between nanostructured photocatalyst and cellulose-based materials was induced by bio-combability and high hydrophilicity of the cellulose components. The electron rich hydroxyl group of celluloses helps to promote superior interaction with photocatalyst. The formation of bio-hybrid nanostructured are attaining huge interest nowadays due to the synergistic properties of individual cellulose-based material and photocatalyst nanoparticles. Therefore, in this review we introduce some cellulose-based material and discusses its compatibility with nanostructured photocatalyst in terms of physical and chemical properties. In addition, we gather information and evidence on the fabrication techniques of cellulose-based hybrid nanostructured photocatalyst and its recent application in the field of water treatment and renewable energy.

Photocatalytic degradation of bromothymol blue with Ruthenium(II) bipyridyl complex in aqueous basic solution

Ru(II) bipyridyl photocatalyst with the formula, [Ru(bpy)2(o-CH3-bzpypz)](PF6)2] (Ru01) and [Ru(bpy)2(o-Cl-bzpypz)](PF6)2] (Ru02), where bpy = 2,2’-bipyridyl, o-CH3-bzpypz = (3-(pyridin-2-yl)-1H-pyrazol-1-yl)(o-tolyl)methanone and o-Cl-bzpypz = (2-chlorophenyl)(3-(pyridin-2-yl)-1H-pyrazol-1-yl)methanone, has been successfully synthesized and characterized on the basis of C, H, N elemental analysis, IR, UV-Vis and NMR spectroscopy. Both Ru(II) complexes showed Infrared stretching frequencies at 1742-1736 cm−1 v(C=O), 1605 cm−1 v(C=N) and 842-837 cm−1 v(PF). Full geometry optimization of the complex structures were carried out using DFT method with B3LYP exchange-correlation functional and 6-31G (d,p) basis-set for H, C, N, O and Cl; and LAN2LDZ basis set as effective core potential for the ruthenium centre. The highest-occupied molecular orbital (HOMO) energy levels of Ru01 and Ru02 are −5.63 and −5.55 eV, respectively. The photocatalytic properties of the Ru(II) complexes were evaluated by studying the de...

Photoelectrochemical activity of WO 3 /Au in aqueous electrolyte with addition of methanol

Tungsten trioxide (WO3) thin films were prepared on fluorine-doped tin oxide (FTO) substrate by electrodeposition method using peroxotungstic acid with pH 1.3 as the electrolytes. The as-deposited sample was calcined at 350°C. The gold (Au) loading on WO3 films was carried out by using the sputtering method with a different sputtering time of 1s and 5s. The photoelectrochemical activities of bare WO3 and WO3/Au with different Au loading in 0.5 M Na2SO4 with and without addition 0.2 M methanol were studied. The linear scan Voltammetry in three electrode system was employed and the photocurrent generated was presented. The electrode prepared with Au loading shows higher photocurrent compared with WO3 alone. Meanwhile, photocurrent with the addition of methanol in the electrolyte is higher compared to the electrolyte without the addition of methanol. The structural properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and the absorption of light was measured using UV-Vis spectrophotometer. It has shown that the structure, thickness, crystallinity, and the band gap of WO3 does not change with Au loading.

Improvement of Photoelectrochemical water splitting with natural dye of pitaya peel

The clean and recyclable production of hydrogen gas by water splitting over a semiconductor photocatalyts using solar energy is a promising process. Photoelectrochemical (PEC) water splitting is one of most favourable hydrogen production technologies. The development of TiO2 semiconductor has been widely studied for its efficiency reasons. However, the large band gap of TiO2 can only absorb UV light thus reducing its performance in PEC. Besides, recombination of electron-hole pairs also influenced efficiency of photoelectrochemical reaction. Thus, a lot of efforts have been made to increase the performance of PEC and considerably attention is given to dye sensitizers especially natural dye due to their environmental friendliness and low cost. Hence, this research studied the natural dye of pitaya peel which contains betalains due to its availability in local area and low in conservation cost. Thus, the physical and chemical characterization of TiO2 thin film with dye has been investigated through SEM, XRD and UV-Vis analysis. The optical absorption for the dye is 546 nm show good absorption in visible light with band gap 2.3eV. For photoelectrochemical properties, photoelectrode TiO2/dye/PEDOT:PSS has the highest photocurrent which are 0.62 μAcm- and increased further to 1.4 μAcm-2 with the addition of pitaya dye in aqueous electrolyte.