Advanced heterostructures as bifunctional electrocatalysts for overall water splitting - a review

Many countries such as India, China, Britain, France, etc. have decided to end the usage of vehicles based on fossil fuels. An appropriate solution to the present energy crisis is to convert and store intermittent but abundant natural energies such as wind, solar, etc. into the chemical energy of hydrogen Production of hydrogen on a large-scale requires electrocatalysts that are active, stable and more importantly low-cost. The application of bifunctional electrocatalysts in water splitting is a recent and developing trend that minimizes the cost of hydrogen production by making electrolysis simple and saving resources. In this review, recent progress in bifunctional electrocatalysts for water splitting especially involving advanced heterostructures with abundant hetero interfacial active sites is discussed. Emphasis is given on preparation methods of heterostructures and their superiority over single component counterparts. These bifunctional electrocatalysts have been broadly classified into those that are compatible with alkaline, acidic and neutral pH media. Extensive discussion is also presented on fundamental and experimental aspects as well as future perspectives and challenges of the bifunctional electrocatalysts.