Sol-Gel Synthesis

The aim of this article is to introduce the versatile sol–gel technique, particularly in the field of electrochemical energy conversion and storage. The multiplicity of parameters modulated in the different stages of the overall synthetic path includes (1) hydrolysis temperature, (2) reaction pH, (3) solvent removal (which by itself introduces many variables), and (4) introduction of unusual growing steps (hydrothermal, ultrasound, and microwave treatments) in addition to the (5) calcination procedure. The choice of the reaction conditions likely leads to nanomaterials with unique structural and morphological properties. The preparation of multicomponent oxide systems (e.g., SnO2–IrO2) is discussed in terms of the different procedures adopted to obtain the mixture (e.g., directly in the sol–gel reaction, impregnation, and mechanical mixing). The formation of oxide layers onto metallic supports is also investigated and the role played by the nature of the supporting material is specifically discussed