Photochemistry and Photoelectrochemistry of Quantized Matter: Properties of Semiconductor Nanoparticles in Solution and Thin‐Film Electrodes

Nanomaterials for Water Treatment

“…Quantum-size effects occur when the semiconductor particles become smaller than the Bohr radius of the first excitation state [74]. This has also been stated by other authors when the particle size of a colloidal particle becomes comparable to the DeBroglie wavelength of the charge carriers [72,76].…”

“…However, the size of a nanoparticle can be the same as or even smaller than the size of the first excited state. Thus, the electron and hole generated by illumination cannot fit into such a particle unless a state of higher kinetic energy is created [72].…”

“…In solid-state terminology this means that the bands split into discrete electronic states representing quantized levels in the valence and conduction bands [72] and the nanoparticle behaves like a giant atom [67]. Nanosized semiconductor particles that exhibit size-dependent optical and electronic properties are called quantized particles or quantum dots [75].…”

“…Quantization effects of TiO 2 nanoparticles have been observed at particles sizes at and below about 10 nm [45,72,[77][78][79][80][81].…”

Nanotechnological Advances in Catalytic Thin Films for Green Large‐Area Surfaces

“…For the case of bulk materials, the kinetic energies of photoexcited electrons can take various values as the density of states in the conduction band is rather high [85]. However, when the size of the particles gets as small as the size of the first excited state (or smaller), the generated electronhole pairs are enforced to move to an upper kinetic energy state [88]. Therefore, reduction of particle sizes to smaller than a threshold brings confined carriers in a potential well, similar to "particle in a box" case, which includes quantum mechanically interacting nanoparticles [89].…”