High-Entropy Lithium Niobate Nanocubes for Photocatalytic Water Splitting under Visible Light
Hao Ling, Muhua Sun, Hongbo Han, Lisha Lu, Lejuan Cai, Yingying Lan, Renjie Li, Pan Chen, Xuezeng Tian, Xuedong Bai, Wenlong Wang
Abstract
The vast compositional space available in high-entropy oxide semiconductors offers unique opportunities for electronic band structure engineering in an unprecedented large room. In this work, with wide band gap semiconductor lithium niobate (LiNbO 3 ) as a model system, we show that the substitutional addition of high-entropy metal cation mixtures within the Nb sublattice can lead to the formation of a single-phase solid solution featuring a substantially narrowed band gap and intense broadband visible light absorption. The resulting high-entropy LiNbO 3 [denoted as Li(HE)O 3 ] crystallizes as well-faceted nanocubes; atomic-resolution imaging and elemental mapping via transmission electron microscopy unveil a distinct local chemical complexity and lattice distortion, characteristics of high-entropy stabilized solid solution phases. Because of the presence of high-entropy stabilized Co 2+ dopants that serve as active catalytic sites, Li(HE)O 3 nanocubes can accomplish the visible light-driven photocatalytic water splitting in an aqueous solution containing methanol as a sacrificial electron donor without the need of any additional co-catalysts.