Starch as a Sustainable Fuel for Solution Combustion Synthesis: Nanomaterials for Energy and Environmental Applications

Background: Currently, solution combustion synthesis (SCS) is considered a reproducible, flexible, and low-cost synthesis method for the preparation of nanomaterials. A new trend in the SCS method is the use of less polluting fuels, such as starch. The use of starch as fuel in SCS is very interesting for green chemistry, as it is renewable and has several advantages, including its abundance, low-cost, and non-toxicity. Objective: This paper provides a comprehensive review of the SCS method using starch as fuel. The main advantages of using starch as fuel will be illustrated with a wide variety of examples, highlighting its impact on the preparation of nanomaterials for energy and environmental applications. Conclusion: In a combustion reaction using starch as fuel, several positive effects are expected, such as non-violent propagation, combustion with the production of non-toxic gases (mainly CO 2 and H 2 O), and development of pores during the release of gases. For example, several macroporous metal oxide foams were prepared using the SCS method, through an appropriate combination of urea and starch fuels. With this approach, it is possible to control the structure, lattice defects, crystallite size, specific surface area, porosity, and other characteristics of the synthetized nanomaterial. For example, by combining starch with other fuels, it is possible to control the concentration of lattice defects in metal oxides and modify the optical properties of these materials. These properties are of fundamental importance for the performance of these materials and their subsequent application in electrodes, electrocatalysts, and photocatalysts in the areas of energy and environment.