Hybridization-Driven Introduction of Anion Vacancies to Boost the Photocatalytic Nitrogen Fixation Functionality of Low-Lattice-Energy Nanosheets.

Abstract

Defect engineering has attracted considerable research interest owing to its effectiveness in optimizing the catalytic performance of inorganic solids. Herein, we develop a hybridization-assisted defect control approach to fabricate efficient visible-light-active photocatalysts comprising low-lattice-energy nanosheets via a synergetic combination of hybridization and defect engineering. The hybridization between Cu-Cr-layered double hydroxide (Cu-Cr-LDH) and g-C₃N₄ nanosheets having relatively low lattice energies effectively increases the defect concentration and improves photocatalyst performance for the visible-light-driven N₂ reduction reaction (NRR). Using defect-introduced holey g-C₃N₄ nanosheets as building blocks further reinforces the interfacial interaction with the hybridized Cu-Cr-LDH nanosheets, producing additional crystal defects. The defective g-C₃N₄-Cu-Cr-LDH nanohybrid exhibits exceptional NRR activity showing an outstanding NH₄⁺ formation rate of 1.45 mmol h^-1 g_cat^-1 and one of the best NRR catalytic performances among the recently reported LDH-based photocatalysts. Combined in situ spectroscopic analysis and theoretical calculation reveal that the reinforced coupling with vacancy-introduced g-C₃N₄ nanosheets effectively improves the photocatalytic activity and stability of Cu-Cr-LDH via the facilitation of the associative reaction pathway. The high efficacy of hybridization-assisted defect control for efficient generation of photocatalysts is attributable to the mutual enhancement of defect concentration and interfacial interaction, which improves N₂ adsorption/activation, light absorption, and charge transport properties and prevents the recombination of electron-hole pairs.