Recent progress in the nanoarchitectures of bismuth oxyhalides (BiOX) and binary bismuth oxyhalides (BiOX/BiOY, where X, Y = F, Cl, Br, and I; X ≠ Y) and their heterostructures

(X, Y = F, Cl, Br, I; X ≠ Y) solid solutions are discussed and distinguished from two-phase heterojunctions. Applications of well-defined BiOX nanoparticles, BiOX/BiOY heterojunctions, and their support-immobilised heterostructures in photo- and electrocatalysis, adsorption and separation, and biomedical use are also discussed.