Two-dimensional GaOOH framework materials: Ultrathin GaOOH nanosheets coordinated with organic linkers

Abstract

Two-dimensional (2D) materials have attracted growing interest in applications as adsorbent due to their high surface-to-volume ratio and tunable properties. However, randomly stacked 2D structures often suffer from restricted reactant diffusion and limited access to active sites, resulting in suboptimal adsorption performance. In contrast, orderly stacked 2D frameworks can facilitate efficient charge transfer and provide well-defined reaction pathways. Inspired by the concept of graphene organic frameworks (GOFs), we report the synthesis of a 2D gallium oxyhydroxide (GaOOH) framework coordinated by organic ligands via a facile hydrothermal method. Three ligands, including benzene-1,3,5-tricarboxylic acid (BTC), benzene-1,4-dicarboxylic acid (BDC), and benzene-1,3,5-triphenyl triboronic acid (TBA), are explored for framework formation. Among them, the GaOOH-BTC material exhibits significantly enhanced surface area, porosity, and a notably shifted conduction band edge compared to randomly stacked GaOOH. As a proof-of-concept, the GaOOH-BTC framework demonstrates outstanding adsorption efficiency, achieving 92% removal of Trypan Blue dye under visible light within 120 min, with excellent repeatability. In contrast, the randomly stacked GaOOH shows only 56.5% removal under the same conditions. The enhanced performance is attributed to the precise stacking, increased BET surface area, favorable valence band edge, and the availability of carboxylate functional groups in the framework. This work introduces 2D GaOOH frameworks as promising, thermally stable alternatives to GOFs for efficient adsorptive pollutant removal applications.