Novel B-site substituted KCuTa3-xNbxO9 solid solution photocatalysts with modulated band structure for visible-light-driven hydrogen evolution

Perovskite-like metal oxides (PLMOs), featuring unique structural and optical properties, exhibit great potential in photocatalytic water splitting field. However, the wide bandgap and strong carrier recombination severely suppress their photocatalytic hydrogen pro-duction activity. Thus, design and development of novel PLMO photocatalyst with extended photo-response range and enhanced photo-generated charge separation/trans-port efficiency remains an ongoing challenge. Herein, a series of novel B-site substituted KCuTa3-xNbxO9 solid solution photocatalysts were synthesized via a simple solid-state reaction method. With an increased content of Nb, a distinct red-shifted of the optical absorption edge of KCuTa3-xNbxO9 solid solution was observed, leading to a decreased bandgap (from 2.69 to 1.91 eV), and a positive shift of the conduction band bottom (from-0.54 to-0.49 eV vs RHE). All of the Nb-substituted KCuTa3O9 solid solutions exhibit enhanced separation efficiency of photoinduced charge carriers, which leads to increased hydrogen evolution activity, among which KCuTa0.75Nb2.25O9 exhibits the highest hydrogen evolution rate of 2.16 mmol h-1 under the visible light irradiation (l > 420 nm), which is approximately 7-fold higher than that of the pure KCuTa3O9. This study demonstrates the potential of modulating band structure through constructing solid solutions for efficient perovskite-like metal oxides photocatalysis.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, a series of novel B-site substituted KCuTa3-xNbxO9 solid solution photocatalysts were synthesized via a simple solid-state reaction method. By increasing the content of Nb, a red-shifted optical absorption edge, decreased bandgap, and positive shift of the conduction band bottom were observed, leading to enhanced separation efficiency of photoinduced charge carriers and increased hydrogen evolution activity. Among the photocatalysts, KCuTa0.75Nb2.25O9 exhibited the highest hydrogen evolution rate, approximately 7-fold higher than that of pure KCuTa3O9 under visible light irradiation.