2D/2D Cu-tetrahydroxyquinone MOF/N-doped graphene heterojunction as photocatalyst for overall water splitting. (19th April 2023)

• Record Type: Journal Article
• Authors: Szalad, Horatiu; Uscategui, Andres; Albero, Josep; García, Hermenegildo
• Is Part Of: International journal of hydrogen energy. Volume 48:Number 33(2023)
• Page Start: 12374
• Page End: 12384
• Publication Date: 2023-04-19
• Subjects: 2D MOF -- Graphene -- Photocatalysis -- Overall water splitting -- Charge separation -- Heterojunction; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2022.12.168
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: A novel 2D/2D heterojunction (CuTHQ/NG) has been prepared by in situ growth of the 2D CuTHQ MOF on defective N-doped graphene (NG), and its photocatalytic activity for overall water splitting studied in detail. CuTHQ/NG heterojunction has demonstrated better photocatalytic activity (480 μmol/g) than the individual components (257 and 65 μmol/g for CuTHQ and NG, respectively) for H2 evolution. Furthermore, unlike the individual components, the as-prepared 2D/2D CuTHQ/NG heterojunction promotes overall water splitting under simulated sunlight (164 μmol of H2 /g and 80 μmol of O2 /g). We have also studied the photo-induced charge separation and recombination reactions. Photocurrent measurements and emission quenching experiments have confirmed improved charge separation in the CuTHQ/NG heterojunction. Moreover, the charge recombination kinetics have been investigated with transient absorption spectroscopy. Electron/hole recombination in the heterojunction has been determined more than one order of magnitude slower (8.9 μs) than the mechanical mixture of CuTHQ and NG (0.35 μs). Finally, the photochemical stability of the 2D/2D heterojunction has been investigated performing a long-term (96 h) experiment, demonstrating near linear H2 evolution along the irradiation time. Highlights: A 2D Cu MOF with tetrahydroxyquinone linker (CuTHQ) has been synthesized. 2D/2D heterojunctions (CuTHQ/NG) of CuTHQ and N-doped graphene have been prepared. In contrast to its components, CuTHQ/NG promotes photocatalytic overall water splitting. Photo-induced charge separation confirms charge transfer within the heterojunction. CuTHQ/NG heterojunction stability was demonstrated in a 96 hç photocatalytic experiment.