Introduction
The World Energy Outlook 2013 [1] reported that the orientation of global energy sectors is currently shifting drastically, resulting in many major importers becoming exporters and former exporter countries becoming leading centres of growth in terms of global demand. Evidently, there is an urgent need for alternative global energy sources to allow us to decrease our dependence on fossil fuels, which will inevitably be depleted and whose use is implicated in environmental pollution and climatic change. Hydrogen gas (H2) is credited as one possible candidate with several socio-economic, technological and environmental benefits [2]. The gas offers great advantages over hydrocarbon fuels because its combustion yields 2.75 times more energy (122 kJ/g) than fossil fuels without the emission of CO2 and also because it can be directly used to power fuel cells [3] and [4]. In addition, this extremely clean and valuable energy carrier serves as an important