Atomic layer deposition of metal phosphates

Because of their unique structural, chemical, optical, and biological properties, metal phosphate coatings are highly versatile for various applications. Thermodynamically facile and favorable functionalization of phosphate moieties (like orthophosphates, metaphosphates, pyrophosphates, and phosphorus-doped oxides) makes them highly sought-after functional materials as well. Being a sequential self-limiting technique, atomic layer deposition has been used for producing high-quality conformal coatings with sub-nanometer control. In this review, different atomic layer deposition-based strategies used for the deposition of phosphate materials are discussed. The mechanisms underlying those strategies are discussed, highlighting advantages and limitations of specific process chemistries. In a second part, the application of metal phosphates deposited through atomic layer deposition in energy storage and other emerging technologies such as electrocatalysis, biomedical, or luminescence applications are summarized. Next to this, perspectives on untangled knowledge gaps and opportunities for future research are also emphasized.