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Enhancement of Photoelectrochemical Hydrogen Evolution of P-Type Silicon Nanowires Array by Loading MoS2
摘要： To improve photoelectrochemical properties of Si nanowires (SiNWs), MoS2/SiNWs is prepared via two-step method. SiNWs is synthesized by metal?catalyzed electroless etching (MCEE) method and MoS2 is subsequently deposited onto SiNWs through the direct thermal decomposition method. MoS2 is introduced as both light absorber and catalyst for hydrogen evolution reaction (HER). Moreover, it forms a heterojunction with SiNWs that contribute to the charge separation. Herein, MoS2/SiNWs attains excellent hydrogen evolution reaction (HER) catalysis with onset potential of 55 mV. A photocurrent density of 25 mA cm?2 at ?1.0 VRHE were achieved under simulated solar illumination, which is about 6 times higher than that of SiNWs, and the carrier concentration is increased by 100?fold. The enhanced photocatalytic activity of MoS2/SiNWs toward HER is attributed to the Schottky junction at the interface, which enhances the photo?generation of electron?hole pairs and suppresses the charge recombination, making them promising earth?abundant alternatives to noble metal?based photocathode for HER.
关键词： MoS2,P?type silicon wires array,Thermal decomposition,Hydrogen generation,Heterojunction
更新于2025-09-10 09:29:36
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Tunable Type I and II heterojunction of CoOx nanoparticles confined in g-C3N4 nanotubes for photocatalytic hydrogen production
摘要： This work reports tunable heterojunction architectures of cobalt oxides (CoOx) nanoparticles confined on well-arrayed graphitic carbon nitride nanotubes (C3N4 NTs) by using a facile one-pot method but under different annealing atmospheres. A Type II heterojunction of cobalt monoxide nanoparticles (CoO NPs)/C3N4 NTs was obtained after annealing under vacuum, and fine CoO NPs less than 8 nm in size were homogeneously anchored on the surface of C3N4 NTs. A Type I heterojunction of tricobalt tetraoxide (Co3O4)/C3N4 NTs were formed under air condition, and Co3O4 NPs in the size range of 20 to 80 nm were aggregated on the surface. The photocatalytic activities of these two heterojunctions were evaluated with hydrogen production from water splitting. The strategically developed CoO/C3N4 NTs with a 7 wt. % CoO shows the highest H2 yield under visible light irradiation and the best stability among the photocatalysts studied in this work. Comprehensive characterization results reveal that the superior performance of CoO/C3N4 NTs may be attributed to the uniformly distributed smaller nanoparticles on the well-arrayed nanotubes, the longer lifetime of excited electrons, the faster charge transfer and the stronger electronic interaction between the heterojunctions. Our Kelvin probe force microscopy results firmly verify that the CoO/C3N4 NT and Co3O4/C3N4 NT nanocomposites form a Type II and Type I heterojunction, respectively, and charge transfer pathways and reaction mechanisms are therefore established.
关键词： hydrogen production,carbon nitride nanotubes,tricobalt tetraoxide,Heterojunction architectures,cobalt monoxide
更新于2025-09-10 09:29:36
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Enhanced photocatalytic Cr(VI) reduction and diclofenac sodium degradation under simulated sunlight irradiation over MIL-100(Fe)/g-C3N4 heterojunctions
摘要： Metal-organic framework MIL-100(Fe) and g-C3N4 heterojunctions (MG-x, x = 5%, 10%, 20%, and 30%, x is the mass fraction of MIL-100(Fe) in the hybrids) were facilely fabricated through ball-milling and annealing, and characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, UV-visible diffuse-reflectance spectrometry, and photoluminescence emission spectrometry. The photocatalytic activities of the series of MG-x heterojunctions toward Cr(VI) reduction and diclofenac sodium degradation were tested upon irradiation with simulated sunlight. The influence of different organic compounds (ethanol, citric acid, oxalic acid, and diclofenac sodium) as hole scavengers and the pH values (2, 3, 4, 6, and 8) on the photocatalytic activities of the series of MG-x heterojunctions was investigated. MG-20% showed superior photocatalytic Cr(VI) reduction and diclofenac sodium degradation performance than did the individual MIL-100(Fe) and g-C3N4 because of the improved separation of photoinduced electron-hole charges, which was clarified via photoluminescence emission and electrochemical data. Moreover, the MG-x exhibited good reusability and stability after several runs.
关键词： MIL-100(Fe),Cr(VI) reduction,g-C3N4,Heterojunction,Diclofenac sodium
更新于2025-09-10 09:29:36
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Sensitizing effects of BiVO4 and visible light induced production of highly reductive electrons in the TiO2/BiVO4 heterojunction
摘要： BiVO4 is an e?cient and stable visible active photoanode material. However, due to its unfavorable conduction band position which falls below the H2 reduction potential, it fails to carry out the complete water splitting reaction. On the other hand, larger band gap TiO2 is able to photocatalytically split water, thanks to its negative conduction band energy. Aiming at verifying the possibility of sensitizing TiO2 with BiVO4 and employing the so obtained composite material in photocatalytic water splitting under visible light, we prepared and photoelectrochemically characterized TiO2/BiVO4 heterojunction electrodes. The photocatalytic reduction of methyl viologen, an electron acceptor probe with a reduction potential close to that of protons, was used to evaluate the reducing ability of the photoactive materials under visible light. An apparently counterintuitive electron transfer from photoexcited BiVO4 to the TiO2 conduction band occurs in the TiO2/BiVO4 heterojunction, resulting in TiO2 sensitization and production of highly reductive electrons, which appears to be favored by the band alignment occurring at the heterojunction.
关键词： Methyl viologen reduction,Photo(electro)catalysis,TiO2,BiVO4,Heterojunction,Visible light sensitization
更新于2025-09-10 09:29:36
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Three-dimensional Bi2MoO6/TiO2 array heterojunction photoanode modified with cobalt phosphate cocatalyst for high-efficient photoelectrochemical water oxidation
摘要： Three-dimensional Bi2MoO6/TiO2 array was fabricated by decorating TiO2 nanorods (NRs) with Bi2MoO6 nanosheets (NSs). Compared with pristine TiO2 NRs and Bi2MoO6 NSs, the obtained Bi2MoO6/TiO2 heterostructure showed an excellent photoelectrochemical (PEC) performance. The photocurrent density reached 0.54 mA/cm2 at 1.23 V vs.RHE, 61% higher than that of bare TiO2 NRs array and almost tenfold higher than that of Bi2MoO6 NSs array on FTO. The high performance of heterostructured Bi2MoO6/TiO2 composite was mainly attributed to the expansion of absorption band edge and the enhancement of charge separation efficiency as well as the simultaneously increased chemically active area after introducing Bi2MoO6 on TiO2 arrays. Cobalt phosphate (Co-Pi) was further decorated on the surface of the Bi2MoO6/TiO2 to accelerate the surface water oxidation reaction, and the photocurrent density increased to 0.72 mA/cm2 at 1.23 V vs.RHE.
关键词： Photoelectrochemical,Bi2MoO6,Photoanode,TiO2,Heterojunction
更新于2025-09-10 09:29:36
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Controllable synthesis of flower-root shaped Bi2O3/Bi2MoO6 heterostructures as an efficient photocatalyst under visible light irradiation
摘要： In this article, Bi2O3/Bi2MoO6 composites were synthesized hydrothermally under optimized conditions, by adjusting pH, the concentration of polyvinylpyrrolidone (PVP (K30)) and reaction time. During the synthesis process, flower-root shaped zero-gap Bi2O3/Bi2MoO6 heterojunctions were successfully synthesized. The adopted samples were characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), Diffuse reflectance spectra (DRS), Photoluminescence (PL), and Fourier transform infrared spectroscopy (FT-IR). The photocatalytic activity was measured under visible-light-irradiation (λ > 420 nm) by degrading tetracycline (TC), ciprofloxacin (CPFX) (antibiotics) and rhodamine B (RhB), methylene blue (MB) (dangerous dyes). The degradation results indicated that photocatalyst sample synthesized at pH 9.0, PVP (K30) 0.05 mol/L and 80 min reaction time (Sup-Bi2O3/Bi2MoO6) demonstrated highly efficient performance. The Sup-Bi2O3/Bi2MoO6 showed the highest apparent rate constant (Kapp) that’s 50% more than the samples prepared at ordinary conditions. Photocatalytic degradation order was i.e. RhB> TC> CPFX> MB, which depends on the polarity of the degrading medium.
关键词： Bi2O3/Bi2MoO6,Flower-root shaped,Heterojunction,Visible light irradiation,Photocatalyst
更新于2025-09-10 09:29:36
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Enhanced Sensing Performance to Toluene and Xylene by Constructing NiGa2O4-NiO Heterostructures
摘要： The selective detection of methyl benzene (e.g. toluene and xylene) using oxide semiconductor-based gas/vapor sensors is highly desirable but limited by the low chemical reactivity of the benzene compounds. Exploiting p-type semiconductor oxides (e.g., NiO) which provide distinctive catalytic activities for methyl benzene detection is an essential approach. However, the intrinsic responses of p-type semiconductor oxides are often low. In this paper, high-performance toluene and xylene detection has been realized by a sensor based on novel p-p heterojunction NiGa2O4-NiO nanospheres. Construction of optimized p-p heterojunctions, which resulting from the rationally controlling of the NiGa2O4 content in NiGa2O4-NiO, leads to significantly promoted sensing properties for toluene and xylene detection. It is found that the sensor based on 50% NiGa2O4-NiO exhibits the best sensing performances. Its highest response (Rg/Ra = 12.7 to toluene; Rg/Ra = 16.3 to xylene) is almost 10 times higher than that of the pure NiO (Rg/Ra < 2) to 100 ppm toluene and xylene at 230 oC. More importantly, the sensor exhibits superior selectively for detection of the methyl benzene even against more reactive interfering gases/vapors, such as formaldehyde and ethanol. The p-p oxide heterojunction suggests a promising sensing material for toluene and xylene detection with high response, excellent selectivity, good stability and rapid response/recover time.
关键词： Composite semiconductor,NiO,NiGa2O4,Heterojunction,Xylene,Toluene
更新于2025-09-10 09:29:36
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Fabrication of novel 1D/2D V2O5/g-C3N4 composites as Z-scheme photocatalysts for CR degradation and Cr (VI) reduction under sunlight irradiation
摘要： Photocatalytic materials for environmental remediation of organic pollutants and heavy metals require not only a strong visible light response and high photocatalytic performance, but also the regeneration and reuse of catalysts. In this work, 1D/2D V2O5 nanorods/g-C3N4 nanosheets (VONRs/CNNs) composites were prepared by a facile impregnation method and employed in the degradation of a Congo red (CR) and reduction of Cr (VI) under sunlight irradiation. The as-prepared samples were studied by several characterization techniques including XRD, SEM, TEM, EDS, XPS, FTIR, UV-vis DRS and PL. Results revealed that the interface interaction between VONRs and CNNs was recognized via V2O5 nanorods loading on the surface of g-C3N4 nanosheets, improving the separation and transfer of photogenerated electron-hole pairs and restraining the recombination rate of charge carriers. As a result, the photocatalytic activity of the composites was enhanced in comparison with pure CNNs and VONRs. The photocatalytic efficiency of optimal composite (4-VONRs/CNNs) for the removal of CR (Cr (VI)) was about 9.33 (4.22) and 73.52 (19.2) times higher than that of pure CNNs and VONRs, respectively. Meanwhile, the 4-VONRs/CNNs exhibited good photocatalytic stability in recycling experiments. Such enormous enhancement in photocatalytic performance was predominantly ascribed to the efficient separation and transfer of photogenerated electron-hole pairs at the VONRs/CNNs interface imparted through the direct Z-scheme charge carrier migration mechanism. Moreover, the energy band structure and the quenching effects of different scavengers demonstrated that the electrons of CNNs and holes of VONRs with higher oxidizability and reducibility are the real participants in photocatalytic reactions.
关键词： g-C3N4 nanosheets,Z-scheme mechanism,Composites,Photocatalytic activity,V2O5 nanorods,1D/2D heterojunction
更新于2025-09-10 09:29:36
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Boosting the Photocatalytic Oxidative Desulfurization of Dibenzothiophene by Decoration of MWO4 (M=Cu, Zn, Ni) on WO3
摘要： The surface of WO3 was partially decorated with transition metal tungstate MWO4 (M=Cu, Zn, Ni) using impregnation method followed by solid-state reaction. It is found that MWO4/WO3 photocatalysts showed a higher activity for photocatalytic oxidative desulfurization (PODS) of dibenzothiophene (DBT) than pure WO3 or MWO4 under visible light irradiation. Moreover, the activity for PODS of DBT on MWO4/WO3 depends on the content of MWO4 decoration on WO3 surfaces. 0.2% CuWO4/WO3, 1% ZnWO4/WO3, and 0.5% NiWO4/WO3 exhibited the highest activity among CuWO4/WO3, ZnWO4/WO3 and NiWO4/WO3 samples. However, as compared with 1% ZnWO4/WO3 and 0.5% NiWO4/WO3, the 0.2 % CuWO4/WO3 sample exhibited superior visible light photocatalytic activity for DBT conversion. Brunauer-Emmett-Teller method (BET), SEM, and ultraviolet-visible diffuse reflectance spectra (UV-vis DRS), high resolution transmission electron microscope (HRTEM), photoluminescence spectroscopy (PL), and a series of titration experiments were used to seek the reason for the positive impact of MWO4 on the photocatalytic activity of WO3. As compared with pure WO3, no notable changes of specific surface areas, morphologies, and light absorption are observed after MWO4 (M=Cu, Zn, Ni) decoration. The formation of heterojunction structure between MWO4 and WO3, which promotes charge separation efficiency, was the main reason for the high photocatalytic activity of MWO4/WO3 photocatalyst. Moreover, difference in PODS activity between MWO4/WO3 heterojunctions is proved to be affected by their charge separation and transfer efficiency and amount of active species.
关键词： MWO4/WO3 heterojunction,photocatalytic oxidative desulfurization,dibenzothiophene,WO3
更新于2025-09-10 09:29:36
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A Novel In Situ Synthesis of Cu/Cu2O/CuO/Sulfonated Polystyrene Heterojunction Photocatalyst with Enhanced Photodegradation Activity
摘要： The heavy metal copper ion from the industrial wastewater were recycled by sulfonated polystyrene, which were converted to Cu/Cu2O/CuO/SPS heterojunction photocatalyst through the hydrothermal synthesis process. The hydrothermal synthesis temperature was investigated on the surface morphology, crystal structure and photocatalytic performance of the as-prepared samples. The samples were characterized by scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and UV–Vis diffuse reflectance spectra (UV–Vis DRS). The photocatalytic activities of the samples were investigated by the degradation of rhodamine B (RhB) under visible light irradiation. The results showed that Cu, Cu2O and CuO nanoparticles are uniformly distributed on the surface of sulfonated polystyrene microsphere. Meanwhile, the enhanced visible light absorption is originated from the surface plasmon resonance effect of Cu nanoparticles (CuNPs). The surface morphology and crystal structure of the sample were changed as the hydrothermal synthesis temperature rising. The sample by hydrothermal synthesis at 80 °C exhibited the preferable photocatalytic activity attributed the high dispersion of Cu, Cu2O and CuO nanoparticles and the formation of heterojunction between Cu2O and CuO.
关键词： CuO nanoparticles,Sulfonated polystyrene,Heterojunction,Cu2O nanoparticles,Cu nanoparticles,Photocatalysis
更新于2025-09-10 09:29:36