Search

Solar-powered volatile organic compound oxidation attracts interest, but its efficiency suffers from poor utilization of photogenerated electrons. Oxygen can capture the electrons and convert them into superoxide radicals upon being activated. As a unique oxygen-deficiency oxide, WO2 chemisorbs and activates oxygen and functions as a potential cocatalyst for improving the utilization of charge carriers. Here, we report a WO2/SnS2 composite photocatalyst with SnS2 nanosheets vertically growing out of WO2 nanofibers. In situ X-ray photoelectron spectroscopy and density functional theory calculations suggest the electron transfer from WO2 to SnS2, creating an internal electric field (IEF) at the interfaces with a direction pointing from WO2 to SnS2. The IEF promotes spatial charge separation by driving photogenerated electrons in SnS2 to move to WO2, while photogenerated holes remain immobile. WO2 shows a strong affinity for oxygen-containing species and chemisorbs O2 and H2O molecules in a dissociative way, significantly reducing the kinetic barriers for the production of reactive oxygen species (•OH and •O2–). Under visible light irradiation, the WS30 nanofibers exhibit enhanced photocatalytic degradation of HCHO and CH3COCH3, 4.8 and 7.2 times greater than that of pristine SnS2, respectively. The enhanced performance is attributed to the one-dimensional fibrous nanostructures, robust chemisorption of reactants, and IEF-driven charge separation. This work may inspire efforts to develop higher oxygen-affinity photocatalysts for photodegradation. [ABSTRACT FROM AUTHOR]

In this study, we investigate Mn-doped CeO 2 nanoribbons as photocatalysts to address the issue of performance enhancement in volatile organic compounds (VOCs) removal. Our primary focus centers on elucidating the interplay between charge rearrangement and local electric field (LEF) effects to uncover how these key factors collectively contribute to the improved photocatalytic performance. The successful doping of Mn atoms into the CeO 2 lattice resulted in a strong dopant/matrix interaction effect. In situ XPS and density functional theory (DFT) calculations confirmed significant local charge rearrangement due to the dopant-induced local electric field, promoting charge carrier separation. The Mn dopant facilitated the generation of superoxide and hydroxide radicals. DFT simulations showed that Mn doping promoted VOCs adsorption on CeO 2 , favoring the subsequent oxidation process. The Mn-doped CeO 2 nanoribbons achieved enhanced photodegradation performance of HCHO and CH 3 COCH 3 compared to CeO 2. This work aims to provide guidance and insights for the development of advanced photocatalysts. [Display omitted] • Electron rearrangement occurs around Mn dopant owing to the strong dopant/matrix interaction. • A localized electric field (LEF) is present with direction pointing from Mn dopant to CeO 2 matrix. • Efficient charge separation and transfer are achieved owing to the LEF. • Mn doping leads to improved photodegradation of volatile organic compounds (VOCs). [ABSTRACT FROM AUTHOR]

[Display omitted] • Ti 3 C 2 /Pd was designed for efficient catalytic transfer hydrogenation of nitrobenzene. • Experimental and DFT theoretical studies unravel unique catalytic mechanism. • Electron transfer at Ti 3 C 2 /Pd interfaces changes Pd electron configure (4 d 10 → 4 d 10-x). • Electron-deficient Pd boosts formic acid dissociation for atomic H* production. • Ti 3 C 2 /Pd chemisorbs active H* and inhibits undesirable H 2 evolution. Catalytic transfer hydrogenation (CTH) with formic acid attracts much interest in catalysis, but the sluggish H* production and undesirable H 2 evolution reaction (HER) limit its practical applications. Herein we anchored Pd nanoparticles (NPs) on layered Ti 3 C 2 MXene for efficient and selective CTH of nitrobenzene in the presence of formic acid. Some electrons in Pd NPs transferred to Ti 3 C 2 MXene upon formation of Ti 3 C 2 /Pd nanohybrids, as confirmed by XPS and DFT simulations. The electron transfer changed Pd valance electron configuration from 4 d 10 to 4 d 10-x. Such electron-deficient Pd NPs tuned reaction pathway and promoted formic acid dissociation, both of which favored the production of active H* atoms, i.e., the exact reductant for CTH. Compared with Pd NPs, Ti 3 C 2 /Pd showed stronger adsorption of H* and therefore inhibited the occurrence of HER (2H*→H 2). Owing to favorable H* production and HER inhibition, Ti 3 C 2 /Pd (15 wt% Pd) showed enhanced nitrobenzene CTH performance with turnover frequency of 351.7 h−1 and 99% aniline selectivity, outperforming most of current catalysts. Our work might inspire designing more advanced CTH catalysts by tuning their valance electron configurations with 2D MXene materials. [ABSTRACT FROM AUTHOR]