“X-Scheme” Charge Separation Induced by Asymmetrical Localized Electronic Band Structures at the Ceria Oxide Facet Junction

Abstract

Photogenerated charge transfer can be tuned by crystal face controlling and heterostructure engineering. However, it is exceptionally challenging to understand the separation and transfer process of charge carriers, especially on the facet junction. Here, we show a separation pathway of the charge carriers in (111)/(100)CeO 2−x nanomaterials as the "X-Scheme junction" using selected region electron energy-loss spectroscopies. The driving force for the "X-Scheme junction" can be attributed to the localized electronic band structures' asymmetry of the ceria, which gathers the photogenerated electrons on the surface of the (111) plane and accumulates the photogenerated holes on the (100) face. Surface oxygen vacancies channel the photogenerated electrons and holes further to the Ce 3+ of the (111) plane and the Ce 4+ of the (100) plane, respectively, resulting in an enhanced photo-oxidative nitric oxide removal efficiency under visible-light irradiation. Furthermore, the system is found to integrate metal nanoparticles to form Pd− CeO 2−x , including Pd-(111)CeO 2−x and Pd-(100)CeO 2−x , which significantly restricts nitric dioxide production as a byproduct. This work provides a unique approach to understanding single-crystal photocatalysts based on the facet junction.

Facile Preparation of the ZnSe/Ag2Se Binary Heterojunction for Photocatalytic Antibacterial Efficiency

“…The enhancement of photocatalytic performance relies on the efficient segregation of photogenerated electron–hole pairs . The electron–hole separation efficiency of the catalyst was evaluated through a combination of electrochemical properties and photoluminescence characteristics .…”

“…The enhancement of photocatalytic performance relies on the efficient segregation of photogenerated electron−hole pairs. 55 The electron−hole separation efficiency of the catalyst was evaluated through a combination of electrochemical properties and photoluminescence characteristics. 56 As shown in Figure 9a, of all of the ZnSe/Ag 2 Se catalyst series, 15% ZA exhibits the highest transient photocurrent intensity.…”

Amorphous Gallium Oxide Nanosheets with Broad Absorption and Spin Polarization for Si‐Based UV‒Vis‒NIR Photodetectors

“…To promote photo‐induced charge carrier separation, semiconductor heterostructures are typically constructed to establish an inherent electric field that facilitates the separation of electron‐hole pairs. [ 12 ] However, this approach necessitates lattice and energy band matching of the heterogeneous interface. [ 13 ] Besides, electronic configurations with different spin states can significantly affect carrier behavior.…”

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

“…Among the most peculiar characteristics of CeO 2 is that it depicts oxygen vacancies/defects in the lattice structure that arise through the loss of oxygen, thereby giving rise to redox-active CeO 2 and CeO 2– x . Moreover, the redox-active nature of the Ce ion and the capability to switch the oxidation states from Ce 3+ to Ce 4+ while exposed to light indicate efficient photocatalytic activity due to the presence of oxygen vacancies in the CeO 2 . , Also, Ce 4+ with lower formation energy of the surface vacancies aids in oxidation, whereas the Ce 3+ and electron movements within the lattice oxygen provide the suitable parameters required for reduction. The Lewis acidic nature of Ce 4+ ions is comparatively higher than that of the oxygen molecule (O 2 ) that assists in faster electron trapping.…”