Water-Splitting Activity of La-Doped NaTaO₃ Photocatalysts Sensitive to Spatial Distribution of Dopants

Abstract

Understanding the science behind highly active materials is essential for advancement in the field of photocatalytic water splitting for solar energy harvesting. Sodium tantalate (NaTaO 3 ) doped with La cations is one of the best engineered materials for efficient water splitting to evolve hydrogen. In this study, physical insights into the sensitivity of the watersplitting activity to the spatial La distribution are discussed. The spatial distribution of La cations placed at the Na site was found to dictate the energy gradient of the conduction band bottom (CBB), resulting in a tunable electron population and hence water-splitting activity. A less homogeneous sample with a sufficiently large CBB gradient exhibited higher water-splitting activity. The mechanism of gradient tuning of the CBB through controlling the spatial dopant distribution is expected to be applicable to a broad range of metal oxide perovskites for artificial photosynthesis.

Dependence of Photoexcited Electron Behavior on Octahedral Distortion in Barium-Doped NaTaO3 Photocatalysts

“…When using the solid-state method, the dopant cations are located predominantly at the surface region. − Since dopants were the ones that induced trap formation, we therefore supposed that trap sites for electrons were concentrated mostly at the surface region. In view of this supposition, the surface feature of the photocatalyst with the longest electron lifetime (Ba-NTO-1000) was examined by transmission electron microscopy (TEM).…”

50 Years of Materials Research for Photocatalytic Water Splitting

“…[15] By decorating it with NiO and doping with La, a record water splitting quantum efficiency of 56 % at 270 nm was achieved. [16] Until today, the origin of its exceptionally high activity is utilized in literature, [17,18] and a vast number of different dopants has been investigated into NaTaO 3 including e. g. Sr. [19,20] Another early metal oxide that has recently experienced a tremendous renaissance is SrTiO 3 . It was first reported for overall water splitting in 1980, when decorated with NiO.…”

“…By decorating it with NiO and doping with La, a record water splitting quantum efficiency of 56 % at 270 nm was achieved [16] . Until today, the origin of its exceptionally high activity is utilized in literature, [17,18] and a vast number of different dopants has been investigated into NaTaO 3 including e. g. Sr [19,20] …”

Computational Prediction of Speciation Diagrams and Nucleation Mechanisms: Molecular Vanadium, Niobium and Tantalum Oxide Nanoclusters in Solution

“…39 Despite that, controlling polyoxotantalate speciation is a promising asset for synthetizing solid materials. Indeed, tantalum oxides have excellent applications in photocatalysis 40 and technological materials such as transistors. 41 Solving the speciation of metal oxides in solution is intimately related to describing the chemical reaction network (CRN) that connects all possible stable species and the corresponding reaction intermediates.…”