Premium
Revisiting the Chemical Stability of Germanium Selenide (GeSe) and the Origin of its Photocatalytic Efficiency
Author(s) -
Boukhvalov Danil W.,
Nappini Silvia,
Vorokhta Mykhailo,
Menteş Tevfik Onur,
Piliai Lesia,
Panahi Mohammad,
Genuzio Francesca,
De Santis Jessica,
Kuo ChiaNung,
Lue Chin Shan,
Paolucci Valentina,
Locatelli Andrea,
Bondino Federica,
Politano Antonio
Publication year - 2021
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202106228
Subject(s) - materials science , germanium , band gap , selenide , germanium oxide , semiconductor , oxide , van der waals force , exfoliation joint , heterojunction , photovoltaics , nanotechnology , optoelectronics , graphene , chemistry , organic chemistry , molecule , ecology , selenium , silicon , metallurgy , photovoltaic system , biology
Recently, germanium selenide (GeSe) has emerged as a promising van der Waals semiconductor for photovoltaics, solar light harvesting, and water photoelectrolysis cells. Contrary to previous reports claiming perfect ambient stability based on experiments with techniques without surface sensitivity, here, by means of surface‐science investigations and density functional theory, it is demonstrated that actually both: i) the surface of bulk crystals; and ii) atomically thin flakes of GeSe are prone to oxidation, with the formation of self‐assembled germanium‐oxide skin with sub‐nanometric thickness. Surface oxidation leads to the decrease of the bandgap of stoichiometric GeSe and GeSe 1− x , while bandgap energy increases upon surface oxidation of Ge 1− x Se. Remarkably, the formation of a surface oxide skin on GeSe crystals plays a key role in the physicochemical mechanisms ruling photoelectrocatalysis: the underlying van der Waals semiconductor provides electron–hole pairs, while the germanium‐oxide skin formed upon oxidation affords the active sites for catalytic reactions. The self‐assembled germanium‐oxide/germanium‐selenide heterostructure with different bandgaps enables the activation of photocatalytic processes by absorption of light of different wavelengths, with inherently superior activity. Finally, it is discovered that, depending on the specific solvent‐GeSe interaction, the liquid phase exfoliation of bulk crystals can induce the formation of Se nanowires.