Asian Research Thesis Index

Abstract

Coordination polymers (CPs) have gained a great deal of attention because of their intriguing structures, beneficial uses in catalysis, drug-delivery, gas storage and separation etc. Four new CPs; CP-1 = [{CuII(4,4ʹ-dipy)2}{Ni(CN)4}]n·0.7(C2H6O2).1.6(H2O), CP-2 = [{NiII(4,4ʹdipy)4}{Ni(CN)4}]n·(4,4ʹ-dipy)·3H2O·C2H6O2, CP-3 = [Co3(pyz)(fa)3(dmso)2]n.2H2O and CP-4 = [{ZnII(4,4ʹ-dipy)2{Ni(CN)4}]n have been synthesized and fully characterized via range of analytical techniques. Two compounds, CP-1 and CP-2 were used as co-catalyst in combination with titania (TiO2) as efficient UV active photocatalysts for hydrogen generation from water-alcohol mixtures. Amongst different wt. % (2.5%, 5%, 7.5% and 10%) loading of CP-1 and CP-2 on TiO2, the 5 wt. % CP-1/TiO2 and CP-2 /TiO2 composites displayed the hydrogen production rate of 9.2 mmol h-1 g-1 and 11.2 mmol h-1 g-1, respectively in 5 vol. % glycerol/water mixture. Other two compounds, i.e. CP-3 and CP-4 were implied as electrocatalysts for water oxidation reaction (WOR). CP-3 executed excellent oxygen evolution reaction (OER) performance at neutral pH by producing a current density of 10 mA cm−2 at a relatively low over-potential value (η = 337 mV) with a Tafel slope value of 80.5 mV dec-1. These results are superior than previously reported cobalt based CPs. Whilst, CP-4 offered a turn over frequency (TOF) value of 0.25 s-1 at an over-potential of 324 mV (vs. RHE) which is far superior than those reported for similar cyanide bridged CPs. In addition, CP-1 was used as a single source precursor of Cu-Ni nanoparticles dispersed over TiO2 for photocatalytic hydrogen production. Amongst various synthesized photocatalysts, 1 wt. % Cu-Ni/TiO2-470 showed the maximum H2 production activity of 8.5 mmol h-1 g-1 in 20 vol. % glycerol-water mixtures. Development of some cost-effective catalysts is the key finding of this study.

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