Rh-doped ultrathin NiFeLDH nanosheets drive efficient photocatalytic water splitting

Abstract

NiFeLDH (Layered double hydroxide) semiconductors are promising for harnessing light energy. The development of transition metal-based photocatalysts consisting of rhodium building blocks is not only beneficial for the separation and transfer of photo-generated carriers in photocatalytic reactions but also an effective means of widening the optical window of light absorption. In this report, a facile hydrothermal approach is employed in modulating NiFeLDH nanosheets arrays with optimal molar ratio of Rhodium (Rh) in LDH to engineer a robust hierarchical NiFeLDH-Rh photocatalytic system towords efficient hydrogen evolution reaction (HER) under visible light. In a systematic investigation, the NiFeLDH is grown on nickel foam and controlled doping of Rhodium led to fine-tuning of their electronic structure and efficient visible light-driven proton reduction system due to its multiple accessible active sites boosting the photocatalytic performance. Furthermore, the 2D hierarchical nanosheet arrays can speed up electron diffusion and assure fast electron/mass transfer while maintaining high photocatalytic stability. The NiFeLDH-Rh composite demonstrated an enhanced hydrogen generation rate of 2.09 mmolg−1h−1 (AQY = 6.1%). The photocurrent density and transient photocurrent curve show rapid charge transfer as well as the unique electron transfer paths through the contact surface, resulting in efficient charge separation. Moreover DFT and photoelectrochemical studies reveal higher HER activity due to the augmented electric field between Rh and NiFeLDH complex. This research offers a novel strategy and new insights into the investigation of highly active photocatalysts for overall water splitting.