A Multiple Structure‐Design Strategy towards Ultrathin Niobate Perovskite Nanosheets with Thickness‐Dependent Photocatalytic Hydrogen‐Evolution Performance

Abstract

Hydrogen production by catalytic water splitting using sunlight holds great promise for clean and sustainable energy source. Despite the efforts made in the past decades, challenges still exist in pursuing solid catalysts with light-harvesting capacity, large surface areas and efficient utilities of the photogenerated carrier, at the same time. Here, a multiple structure design strategy leading to highly enhanced photocatalytic performance on hydrogen production from water splitting in Dion-Jacobson perovskites KCa Na Nb O is described. Specifically, chemical doping (N/Nb ) of the parent oxides via ammoniation improved the ability of sunlight harvesting efficiently; subsequent liquid exfoliation of the doped perovskites yielded ultrathin [Ca Na Nb O ] nanosheets with greatly increased surface areas. Significantly, the maximum hydrogen evolution appears in the n=4 nanosheets, which suggests the most favorable thickness for charge separation in such perovskite-type catalysts. The optimized black N/Nb -[Ca NaNb O ] nanosheets show greatly enhanced photocatalytic performance, as high as 973 μmol h with Pt loading, on hydrogen evolution from water splitting. As a proof-of-concept, this work highlights the feasibility of combining various chemical strategies towards better catalysts and precise thickness control of two-dimensional materials.

Dion–Jacobson Phase Perovskite Ca2Nan–3NbnO3n+1– (n = 4–6) Nanosheets as High-κ Photovoltaic Electrode Materials in a Solar Water-Splitting Cell

“…As mentioned above, the highest hydrogen evolution rate is 80.64 μmol h −1 in this research. As reported in previous studies, 8,34 the best catalytic performance of KCNNO was obtained from n = 4, which has a suitable thickness for photocatalytic water splitting.…”

“…As shown in Figure a–c, monolayer nanosheets are observed via contact-mode AFM with corresponding height profiles of 3.46, 4.02, and 4.42 nm for n = 4–6, respectively. According to the previous study, ,, the molecular thicknesses obtained are significantly different from each other. The height differences between the CNNO – nanosheets range from approximately 0.4 to 0.5 nm, which corresponds to the different numbers of NbO 6 octahedra.…”

Recent Advances in Niobium-Based Materials for Photocatalytic Solar Fuel Production

“…Later, the same group could also investigate the combination of elemental doping, liquid exfoliation, and composition control for a series of typical Dion-Jacobson phases KCa 2 Na n−3 Nb n O 3n+1 photocatalysts [40]. As seen in the scheme presented in Figure 5, KCa 2 Na n−3 Nb n O 3n+1 were prepared with various values of n in order to tune the thickness of the perovskite layer.…”

“…Schematic representation of (a) the general structure of KCa 2 Nb 3 O 10 (KCNNO), (b) KCa 2 Na n−3 Nb n O 3n+1 with thickness control of the perovskite layer by varying the n value, and (c) preparation of N/Nb 4+ codoped nanosheets (CNNO). Reproduced with permission from the authors of[40]. Copyright (2019), John Wiley & Sons, Inc., Hoboken, NJ, USA.…”

Physical–Chemical Exfoliation of n-Alkylamine Derivatives of Layered Perovskite-like Oxide H2K0.5Bi2.5Ti4O13 into Nanosheets

“…They can serve as multipurpose precursors for creating multilayer films, porous composites, and layered nanocomposites [33,[35][36][37][38]. The resulting nanolayers already show intriguing properties with potential uses in photoluminescence [39,40], catalysis [16,[41][42][43], and energy storage [44,45].…”