Executive Summary : | Presently, as a primary energy source, fossil fuels are getting used enormously to fulfill the energy requirement per day globally. Now, it become a crucial time for all of us for a transition from nonrenewable to renewable energy sources because of high energy security and environmental issues. H2 can be considered as alternative fuel because of its high energy density and the ability to power fuel cells in zero-emission electric vehicles. It becomes more and more essential to unveil alternative electrocatalyst composed of non-precious metals or earth-abundant elements with high efficiency and stability to accomplish water electrolysis in large scale. Higher efficiency and longer stability can be attained, if we can focus for the development of single atom catalysts (SACs). It is very much challenging to produce a nonprecious single atom based electrocatalyst, which can replace the most efficient precious noble metal electrocatalyst and can be decorated on a suitable substrate and finally applied in water-splitting reactions. The generated hydrogen will be environmentally benign and cost-effective. A small nanocluster of metal nanoparticles or single atoms can increase the product selectivity and catalytic activity of water electrolysis reaction. However, high surface free energy for a single-atom facilitates easy aggregation, therefore, a single atom can easily be anchored on different substrates to get a stable configuration. SACs can produce highest atom economy with high efficiency and durability. Practically the reaction kinetics become sluggish due to the high kinetic barrier and the slow charge transportation of the electrocatalyst limits their applicability. SACs have attracted significant interest and are studied to replace the conventional Pt based catalysts, RuO2 and IrO2 for HER and OER. Poor conductivity and the inert sites of the catalyst also limit their applicability in electrocatalytic water splitting reaction. Therefore, our aim is to introduce SACs for overall water-splitting reaction to generate green hydrogen and oxygen. |