A Strategy to Boost H₂ Generation Ability of Metal–Organic Frameworks: Inside‐Outside Decoration for the Separation of Electrons and Holes

Abstract

Inhibiting the recombination of electron and holes plays an essential role in photocatalytic process, particularly for metal-organic frameworks (MOFs), which had long been anticipated as high-efficient photocatalysts. Herein, we introduce a new strategy to make efficient separation of electrons and holes for the MOF-based photocatalyst, UiO-66-NH . At first, encapsulation of Pt nanoparticles (NPs) into UiO-66-NH (Pt@U6N) to shorten the electrons transport distance inside of MOF crystals, then using graphene oxide to wrap the external surface of Pt@U6N to facilitate the electrons transfer on the surface. The designed structure was found to possess superior H -generation ability compared to only inside or outside decorated samples, highlighting that the enhanced property strongly correlates with the inhibited recombination of electrons and holes by the inside/outside modification strategy. These findings suggest a synergistic effect of Pt NPs and graphene oxide on UiO-66-NH and reveal a new modification strategy to enhance the catalytic activity of the photocatalysts.

Thermally treated zeolitic imidazolate framework-8 (ZIF-8) for visible light photocatalytic degradation of gaseous formaldehyde

“…Although moisture competes with HCHO for adsorption by ZIF-8-T3, as revealed by the decreased HCHO adsorption amount at higher RH, the presence of moisture favors HCHO degradation signicantly. This is ascribed to the important role of moisture in the generation of H 2 O 2 , which is active for HCHO degradation, as shown in eqn (7) and (8). The produced H 2 O 2 by ZIF-8-T3 in a liquid-phase system was then detected by using p-hydroxyphenylacetic acid as the probe, with the total H 2 O 2 concentration of 11.1 mmol L À1 irradiated by simulated sunlight for 1 h (Fig.…”

“…A porous structure in photocatalysts can not only improve HCHO adsorption, but also elevate photocatalytic efficiency due to the more abundant active chemical sites and the shorter electrontransfer distance compared with non-porous photocatalysts. [8][9][10] A hierarchical porous structure is more attractive owing to the facilitation of mass diffusion and the improved light transmittance. [11][12][13] Therefore, a porous photocatalyst is desirable for HCHO elimination.…”

State of the Art and Prospects in Metal–Organic Framework (MOF)-Based and MOF-Derived Nanocatalysis

“…Liu et al elaborated a strategy to inhibit hole−electron pair recombination by introducing PtNPs into UiO-66-NH 2 followed by using graphene oxide wrapping around the external surface of the MOF in order to facilitate electron transfer on the MOF surface, and they therefore fabricated the catalyst GOWPt@ U 6 N-8 mL. 584 Because of efficient electron transfer, high molar absorptivity, and low aggregation tendency this catalyst provided a H 2 generation rate of 18.15 mmol h −1 g −1 , 21 times higher than the PtNP inside-only decorated sample and 32 times than the outside-only decorated one (GOWU6N). A decrease of the H 2 generation activity was observed after the first cycle, however.…”

“…There is continuous interest in Pt and other noble-metal catalysts given the initial impressive performances of Pt photocatalysts for H 2 evolution from water. − Liu and Su’s group synthesized a dye-sensitized photocatalyst Calix-3/Pt@UiO-66-NH 2 -1 . This catalyst achieved a high hydrogen production activity (1528 μmol h –1 g –1 ).…”

Metal–Organic Frameworks in Heterogeneous Catalysis: Recent Progress, New Trends, and Future Perspectives

“…In a similar way, Wang et al 547 encapsulated Pt nanoparticles in UiO-66-NH 2 and then used graphene oxide to wrap the external surface of the composite. The resultant material displayed a significantly enhanced electron−hole separation, as confirmed by PL spectroscopy.…”