3D/2D Heterojunction of CeO₂/Ultrathin MXene Nanosheets for Photocatalytic Hydrogen Production

Abstract

Two-dimensional (2D) nanomaterials benefit from the high specific surface area, unique surface properties, and quantum size effects, which have attracted widespread scientific attention. MXenes add many members to the 2D material family, mainly metal conductors, most of which are dielectrics, semiconductors, or semimetals. With excellent electron mobility, beneficial to electron–hole separation, and large functional groups that can be tightly coupled with other materials, MXenes have broad application prospects in photocatalysis. Meanwhile, the application of CeO 2 -based materials in organic catalysis, photocatalytic water splitting, and photodegradation of organic pollutants has been extensively explored, and studies have found that CeO 2 -based materials show good photocatalytic performance. In view of this, we synthesized regular octahedral CeO 2 with a homojunction in one step by a hydrothermal method and compounded it with ultrathin 2D material MXene, which exhibited fast carrier migration efficiency and a good interfacial effect, making the material show excellent photocatalytic activity. The results showed that the photocatalytic H 2 evolution performance of the MXene/CeO 2 heterojunction was significantly improved. In this study, a low-cost catalyst with high photocatalytic activity was prepared, presenting a new research idea for achieving a combined 3D/2D photocatalytic system.

Efficient Photocatalytic CO2 Reduction with High Selectivity for Ethanol by Synergistically Coupled MXene-Ceria and the Charge Carrier Dynamics

“…Notably, the Ce 3d spectra of CeO 2 in the heterostructure exhibit the characteristic multiplets ascribed to 3d 3/2 and 3d 5/2 that are further fitted into eight peaks. The peaks at 881.8, 888.5, 897.9, 900.4, 906.7, and 916.4 eV correspond to 3d 3/2 and 3d 5/2 peaks of Ce 4+ species, whereas the peaks centered at 883.7 and 902.5 eV are related to the 3d 3/2 and 3d 5/2 peaks of Ce 3+ , confirming the coexistence of both Ce 3+ /Ce 4+ states in the Ti 3 C 2 MXene/CeO 2 (Figure d). − …”

“…Nevertheless, the bidentate binding modes with two O atoms of CO 3 2– permit the attachment of H to the carbon to form the formate anion. Consequently, the process of the CO 2 photoreduction aid to modify the surface-level charges of the 5-TC/Ce photocatalyst by CO 2 adsorption on the surface of the photocatalyst thereby effectively facilitates the formation of CO 2 – species. − ,− …”

CeO2 Nanoparticles Modified on Graphite Sheet Electrodes for Photoelectrochemical Tobacco Wastewater Detection, Degradation, and Toxicity Measurement

“…Additionally, decreasing the CeO 2 particle size increases the surface-to-volume ratio, photon absorption, and free energy. 9,10 The electrode's pore structure, morphology, crystal structure, surface area, oxygen vacancy density, and bandgap energy improve wastewater treatment electrocatalysis. However, CeO 2 has a wide bandgap (3.27 eV), 11,12 which limits its visible region application.…”

“…We use a PEC sensor to monitor the electron transfer between the electroactive surface and the electrolyte in contaminated water to determine toxicity. , Cerium oxide (CeO 2 ) is used in batteries, catalysts, photoluminescent sensors, and anticorrosion applications due to its Ce 4+ MCe 3+ interconvertibility, high dielectric constant, wide bandgap, and good catalytic behavior. Additionally, decreasing the CeO 2 particle size increases the surface-to-volume ratio, photon absorption, and free energy. , The electrode’s pore structure, morphology, crystal structure, surface area, oxygen vacancy density, and bandgap energy improve wastewater treatment electrocatalysis. However, CeO 2 has a wide bandgap (3.27 eV), , which limits its visible region application.…”

Versatile Bifunctional Ag@g-C3N4/r-GO Catalyst for Efficient Photo- and Electrocatalytic H2 Production

“…The underwhelming performance of hydrogen evolution is mostly due to inefficient separation and transport of hydrogen by light-stimulated carriers and its fast recombination kinetics. − There are a variety of ways to address this issue. The special surface plasmon resonance (SPR) features of metal nanoparticles have attracted a lot of research interest in recent years, prompting their incorporation into photocatalyst matrices. , As a result of the collective oscillation of the conduction band electrons under irradiation, the powerful SPR light absorption produces a strong electric field adjacent to the metal surface.…”