Zinc Oxide as a Multifunctional Material: From Biomedical Applications to Energy Conversion and Electrochemical Sensing

Zinc oxide (ZnO) is a very attractive material which has received growing attention in the academic and technological areas. This metal oxide shows several advantageous properties such as facile and inexpensive synthesis, low toxicity, high surface area, and rich surface chemistry. However, the most impressive property of ZnO is the possibility of obtaining ZnO nanoparticles with different morphologies and crystal size by merely changing the synthetic parameters, such as temperature, pH, or the solvent. Thus, the combination of the attractive chemical, optical, and electrical properties of ZnO to the possibility of easily producing ZnO nanoparticles with different sizes and morphologies makes this metal oxide an extremely versatile material. Because of this versatility, ZnO has found several applications, including the development of electronic and optoelectronic devices, energy conversion in solar cells and supercapacitors, sensing and electrochemical sensing, besides several biomedical applications in photodynamic therapy, disease diagnoses, and microbial killing. Therefore, the objective of this chapter is to highlight the main approaches used to achieve the efficient application of ZnO in biomedical, energy conversion, and electrochemical sensing fields.