Carbon-coated cubic-phase molybdenum carbide nanoparticle for enhanced photocatalytic H2-evolution performance of TiO2

Liu, Jinfeng; Wang, Ping; Fan, Jiajie; Yu, Huogen

doi:10.1016/j.jechem.2020.03.085

Cited by 49 publications

(28 citation statements)

References 62 publications

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“…The photocatalysts mostly used today are oxide semiconductor NPs, such as titanium dioxide (TiO 2 ), tin dioxide (SnO 2 ), copper oxide (CuO), iron oxide (III) (Fe 2 O 3 ), wolfram oxide (WO 3 ), ZnO, etc. [13][14][15][16][17][18]. ZnO is a material with excellent thermal stability and is a multifunctional material.…”

Section: Introductionmentioning

confidence: 99%

ZnO Semiconductor Nanoparticles and Their Application in Photocatalytic Degradation of Various Organic Dyes

et al. 2021

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The biosynthesis of oxide semiconductor nanoparticles (NPs) using materials found in nature opens a wide field of study focused on sustainability and environmental protection. Biosynthesized NPs have the capacity to eliminate organic dyes, which pollute water and cause severe damage to the environment. In the present work, the green synthesis of zinc oxide (ZnO) NPs was carried out using Capsicum annuum var. Anaheim extract. The photocatalytic elimination of methylene blue (MB), methyl orange (MO), and Rhodamine B (RhB) in UV radiation was evaluated. The materials were characterized by scanning and transmission electron microscopy (SEM and TEM) and SEM-coupled energy dispersive spectroscopy (EDS), attenuated total reflectance-infrared (ATR-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Photoluminescence (PL), and ultraviolet-visible spectroscopy (UV-Vis). The TEM analysis showed the NPs have an average size of 40 nm and quasi-spherical shape. ATR-IR showed the ZnO NPs contained functional groups from the extract. The analysis through XRD indicated that the NPs have a hexagonal zincite crystal structure with an average crystallite size of approximately 17 nm. The photoluminescence spectrum (PL) presented an emission band at 402 nm. From the UV-Vis spectra and TAUC model, the band-gap value was found to be 2.93 eV. Finally, the photocatalytic assessment proved the ZnO NPs achieved 100% elimination of MB at 60 min exposure, and 85 and 92% degradation of MO and RhB, respectively, at 180 min. This indicates that ZnO NPs, in addition to using a friendly method for their synthesis, manage to have excellent photocatalytic activity in the degradation of various organic pollutants.

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Section: Introductionmentioning

confidence: 99%

ZnO Semiconductor Nanoparticles and Their Application in Photocatalytic Degradation of Various Organic Dyes

et al. 2021

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“…3a and 4A) consists of uneven particles with a mean size of ca. 30 nm and mixed phases of two different crystal phases (anatase and rutile) 53,54 . When modified by the GO, the crystal structure and morphology of the obtained TiO2/GO (Figs.…”

Section: Microstructures Of Tio2/rgo-cooh Photocatalystsmentioning

confidence: 99%

Carboxyl-Functionalized Graphene for Highly Efficient H<sub>2</sub>-Evolution Activity of TiO<sub>2</sub> Photocatalyst

Wang¹,

Li²,

Cao³

et al. 2020

Acta Physico Chimica Sinica

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The use of semiconductor photocatalysts (CdS, TiO2, etc.) to generate hydrogen (H2) is a prospective strategy that can convert solar energy into hydrogen energy, thereby meeting future energy demands. Among the numerous photocatalysts, TiO2 has attracted significant attention because of its suitable reduction potential and excellent chemical stability. However, the photoexcited electrons and holes of TiO2 are easily quenched, leading to limited photocatalytic performance. Furthermore, graphene has been used as an effective electron cocatalyst in the accelerated transport of photoinduced electrons to enhance the H2-production performance of TiO2, owing to its excellent conductivity and high charge carrier mobility. For an efficient graphene-based photocatalyst, the rapid transfer of photogenerated electrons is extremely important along with an effectual interfacial H2-production reaction on the graphene surface. Therefore, it is necessary to further optimize the graphene microstructures (functionalized graphene) to improve the H2-production performance of graphene-based TiO2 photocatalysts. The introduction of H2-evolution active sites onto the graphene surface is an effective strategy for the functionalization of graphene. Compared with the noncovalent functionalization of graphene (such as loading Pt, MoSx, and CoSx on the graphene surface), its covalent functionalization can provide a strong interaction between graphene and organic molecules in the form of H2-evolution active sites that are produced by chemical reactions. In this study, carboxyl-functionalized graphene (rGO-COOH) was successfully modified via ring-opening and esterification reactions on the TiO2 surface by using an ultrasound-assisted self-assembly method to prepare a high-activity TiO2/rGO-COOH photocatalyst. The Fourier transform infrared (FTIR) spectra, X-ray photoelectron spectroscopy (XPS), and thermogravimetric (TG) curves revealed the successful covalent functionalization of GO to rGO-COOH by significantly enhanced -COOH groups in FTIR and increased peak area of carboxyl groups in XPS. A series of characterizations, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), XPS, and UV-Vis adsorption spectra, were performed to demonstrate the successful synthesis of TiO2/rGO-COOH photocatalysts. The experimental data for the hydrogen-evolution rate showed that the TiO2/rGO-COOH displayed an extremely high hydrogen-generation activity (254.2 μmol•h −1 •g −1 ), which was 2.06-and 4.48-fold higher than those of TiO2/GO and TiO2, respectively. The enhanced photocatalytic activity of TiO2/rGO-COOH is ascribed to the carboxyl groups of carboxyl-functionalized graphene, which act as effective hydrogen-generation active sites and enrich hydrogen ions owing to their excellent nucleophilicity that facilitates the interfacial hydrogen production reaction of TiO2. This study provides novel insights into the development of high-activity graphene-supported photocatalysts in the hydrogen-generation ...

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“…Besides, cocatalysts acting as alternative reaction sites can retard the photocorrosion of semiconductor resulted from the charge accumulation and thus improve the photostability. Therefore, loading cocatalysts on the semiconductor is common in the photocatalysis field 219,[271][272][273][274][275][276][277][278][279][280][281][282][283][284] .…”

Section: Cocatalystmentioning

confidence: 99%

“…Among the noble metal cocatalysts, Pt has the highest work function (5.65 eV) 219 , indicating the robust electron-extracting capacity, and thus Pt demonstrates outstanding performance in the reductive reactions. Besides, some novel reductive cocatalysts such as Mo-rich molybdenum carbide (Mo-Mo2C) 254 , Ni2P 272 , carbon-coated cubic molybdenum carbide (MoC@C) 282 , S 2− -adsorbed MoSx 283 and Pt-M (M = Co, Ni, Fe) alloy 284 et al have also been supposed, which provide alternatives for designing efficient and low-cost Z-scheme photocatalytic systems. The oxidation half reaction is the primary reaction of both water splitting and CO2 reduction reactions, which determines the overall performance of the two type reactions.…”

Section: Cocatalystmentioning

confidence: 99%

Review of Z-Scheme Heterojunctions for Photocatalytic Energy Conversion

Liu¹,

Chen²,

Li³

et al. 2020

Acta Physico Chimica Sinica

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Inspired by the photosynthesis of green plants, various artificial photosynthetic systems have been proposed to solve the energy shortage and environmental problems. Water photosplitting, carbon dioxide photoreduction, and nitrogen photofixation are the main systems that are used to produce solar fuels such as hydrogen, methane, or ammonia. Although conducting artificial photosynthesis using man-made semiconducting materials is an ideal and potential approach to obtain solar energy, constructing an efficient photosynthetic system capable of producing solar fuels at a scale and cost that can compete with fossil fuels remains challenging. Therefore, exploiting the efficient and low-cost photocatalysts is crucial for boosting the three main photocatalytic processes (light-harvesting, surface/interface catalytic reactions, and charge generation and separation) of artificial photosynthetic systems. Among the various photocatalysts developed, the Z-scheme heterojunction composite system can increase the light-harvesting ability and remarkably suppress charge carrier recombination; it can also promote surface/interface catalytic reactions by preserving the strong reductive/oxidative capacity of the photoexcited electrons/holes, and therefore, it has attracted considerable attention. The continuing progress of Z-scheme nanostructured heterojunctions, which convert solar energy into chemical energy through photocatalytic processes, has witnessed the importance of these heterojunctions in further improving the overall efficiency of photocatalytic reaction systems for producing solar fuels. This review summarizes the progress of Z-scheme heterojunctions as photocatalysts and the advantages of using the direct Z-scheme heterojunctions over the traditional type II, all-solid-state Z-schemel, and liquid-phase Z-scheme ones. The basic principle and corresponding mechanism of the two-step excitation are illustrated. In particular, applications of various types of Z-scheme nanostructured materials (inorganic, organic, and inorganic-organic hybrid materials) in photocatalytic energy conversion and different controlling/engineering strategies (such as extending the spectral absorption region, promoting charge transfer/separation and surface chemical modification) for enhancing the photocatalytic efficiency in the last five years are highlighted. Additionally, characterization methods (such as sacrificial reagent experiment, metal loading, radical trapping testing, in situ X-ray photoelectron spectroscopy, photocatalytic reduction experiments, Kelvin probe force microscopy, surface photovoltage spectroscopy, transient absorption spectroscopy, and theoretical calculation) of the Z-scheme photocatalytic mechanism, and the assessment criteria and methods of the photocatalytic performance are discussed. Finally, the challenges associated with Z-scheme heterojunctions and the possible growing trend are presented. We believe that this review will provide a new understanding of the breakthrough direction of photocatalytic performance and p...

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Carbon-coated cubic-phase molybdenum carbide nanoparticle for enhanced photocatalytic H2-evolution performance of TiO2

Cited by 49 publications

References 62 publications

ZnO Semiconductor Nanoparticles and Their Application in Photocatalytic Degradation of Various Organic Dyes

ZnO Semiconductor Nanoparticles and Their Application in Photocatalytic Degradation of Various Organic Dyes

Carboxyl-Functionalized Graphene for Highly Efficient H<sub>2</sub>-Evolution Activity of TiO<sub>2</sub> Photocatalyst

Review of Z-Scheme Heterojunctions for Photocatalytic Energy Conversion

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