Enhancement of the properties of ZnAl-LDHs for photocatalytic nitrogen reduction reaction by controlling anion intercalation

Abstract

Layered double hydroxides (LDHs) have been shown to be efficient photocatalysts for the nitrogen fixation reaction. However, the effect of interlayer anions on the catalytic performance has not yet been reported. Herein, the anion regulated channel of LDHs blocked by carbonate (Car) was opened by controlling the suberate (Sub) intercalation, thus obtaining a series of ZnAl-LDHs with different anions (carbonate, suberate, PMo_12−XV_X, X = 0, 1, 2, 3, 8). The photocatalytic performance test in pure water showed that Sub@ZnAl-LDH and PMo₉V₃@ZnAl-LDH improved the NH₃ yield from 11.37 μmol h⁻¹ g⁻¹_cat for Car@ZnAl-LDH to 48.91 μmol h⁻¹ g⁻¹_cat and 89.16 μmol h⁻¹ g⁻¹_cat, respectively. The improvement of the performance was attributed to the following: (1) nitrogen was allowed to enter between LDH layers due to the expansion of the interlayer spacing; (2) the hydrophobic suberic acid intercalation suppressed the hydrogen evolution reaction; (3) the POM intercalation broadened the light absorption range of LDH. In this paper, the photocatalytic properties of ZnAl-LDHs intercalated with different anions are explored and investigated for the first time, which provides a versatile strategy for enhancing the catalytic activity of LDHs in the photocatalytic nitrogen fixation reaction.