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Visible-Light Influenced Photocatalytic Activity of Polyaniline -Bismuth Selenide Composites for the Degradation of Methyl Orange, Rhodamine B and Malachite Green dyes
摘要： Polyaniline (PANI) when composited with bismuth selenide nanoflakes (Bi2Se3 NFs), a low bandgap semiconductor, reveals enhanced photocatalytic activity for degradation of organic dyes under irradiation of visible light. The composites synthesized using Bi2Se3NFs templates with different weight percentages of PANI by in-situ chemical oxidative polymerization have been used as efficient photocatalysts for degradation of anionic dye, Methyl Orange (MO), and cationic dyes, Rhodamine B (RhB) and Malachite Green (MG). Based on radical trapping experiments, the mechanism for the photocatalytic degradation of the dyes were proposed taking into account the synergistic effect of PANI with Bi2Se3NFs. The efficient visible-light active photocatalytic property of the polymer-inorganic composites is attributed to composites’ enhanced separation of photogenerated carriers compared to its individual constituents.
关键词： Photocatalysts,PANI,Bi2Se3,Visible light,Dyes,Composites
更新于2025-09-10 09:29:36
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Pd2+-conjugated reduced graphene oxide as a highly efficient visible-light-induced photocatalytic Suzuki-Miyaura coupling
摘要： In this work, we investigated Pd2+- and Pd0-loaded graphene oxide (GO) and reduced graphene oxide (r-GO) as water-soluble, visible-light-responsive photocatalysts for the Suzuki-Miyaura C-C coupling reaction. Nanosheets of r-GO (~ 200 nm) were found to be a more desirable substrate than GO nanosheets, since the corresponding catalyst showed higher activities than those of the GO catalysts in both the visible-light-induced and thermal-reactions. Furthermore, Pd2+-loaded GO and r-GO show higher catalytic activities than those of Pd0-loaded GO and r-GO because of the more efficient oxidative addition to Pd2+ compared with that to Pd0. Systematic studies under dark and light conditions demonstrated the synergic contributions of photoexcited electron transfer and the strong photothermal effect of r-GO. Pd2+- and Pd0-loaded r-GO show four-times higher photocatalytic activities compared to those of Pd0-MoS2 and Pd0-WS2 catalysts for the Suzuki-Miyaura C-C coupling reaction.
关键词： Suzuki-Miyaura coupling,reduced graphene oxide,Pd2+-conjugated reduced graphene oxide,graphene oxide,visible-light-induced photocatalytic
更新于2025-09-10 09:29:36
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Enhanced activity of β-Ga2O3 by substitution with transition metal for CO2 photoreduction under visible light irradiation
摘要： Gallium oxide semiconductors have been developed as effective photocatalysts for water splitting driven by UV light irradiation, but there is no relevant study for the CO2 photoreduction application. Herein, we report the first investigation of β-Ga2O3 applying to photocatalytic CO2 reduction under visible light irradiation by doping transition metal ions (M = V, Cr, Mn, Fe, Co, Ni and Cu) onto the framework. Using sol-gel method, a series of transition metal ions incorporated β-Ga2O3 have been successfully obtained, in which the transition metal substitution content is 2 mol %. The β-Ga2O3:M photocatalysts are characterized completely by diverse tests (e.g., XRD, XPS, UV-Vis DRS, SEM). The effective replacement of Ga3+ ion by M ions significantly expands the scope of spectral response from UV light to visible light, and Fe3+, Co2+, Ni2+ significantly enhance the photocatalytic activity under visible light irradiation. In these cases, CO and H2 are evolved as the reduction products from CO2 and H+ by the generated electrons, respectively. Among these effective catalysts we prepared, β-Ga2O3:Ni exhibits the most substantial CO formation rate of 14.3 μmol/h at 30 °C, and the selectivity for CO evolution exceeds 60.9 %. Furthermore, the CO formation rate increases to 24.6 μmol/h after loading of Ag as the co-catalyst. The stability of the Ag/β-Ga2O3:Ni are verified after five cycle of CO2 photoreduction under visible light.
关键词： transition metal substituted,visible light irradiation,CO2 photoreduction,gallium oxide
更新于2025-09-10 09:29:36
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Highly Efficient Cu Induced Photocatalysis for Visible-light Hydrogen Evolution
摘要： Coinage metal (Au, Ag, Cu) induced photocatalysis has emerged as a promising strategy in developing visible-light responsive photocatalysts. Though much progress has been made, yet researchers in this field faced great challenges from both low efficiency and rigorously relying on noble metal Au. In this work, a series of Cu/SrTiO3 with gradually increased Cu particle size from 2.8 to 7.7 nm were successfully prepared with in situ multistep photodeposition method. A highly efficient visible-light photocatalytic H2 evolution is achieved over 0.5 wt% Cu/SiTiO3 with an average Cu particle size of 3.9 nm, which reaches 5 fold as compared with its counterpart Au. As far as we know, it is the first time that Cu induced visible-light photocatalytic water splitting show prominently superior activity than that of Au under the same conditions. Further study reveals that the increase of Cu particle size effectively mitigates Fano interference between interband transition and localized surface plasmon resonance (LSPR), which extends the photo-induced carriers lifetime. The discovery here is supposed to ignite great research interests in exploring efficient and nonprecious Cu induced visible-light photocatalysis.
关键词： Particle size effect,Cu nanoparticles,Visible-light photocatalysis,Fano interference
更新于2025-09-10 09:29:36
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Two–dimensional g–C3N4/α–AgAl0.4Ga0.6O2 p–n heterostructure with improved visible–light–driven photocatalytic property
摘要： Design and preparation of two–dimensional heterostructure is an effective strategy to obtain enhanced photo-electrochemical and photocatalytic performances. Herein, two–dimensional g–C3N4/α–AgAl0.4Ga0.6O2 p–n heterostructure is for the first time synthesized by phase transition method under hydrothermal treatment. It is found that the heterostructure shows the coexistence of two phases with high crystallinity. Platelet-like α–AgAl0.4Ga0.6O2 and g–C3N4 sheets couple each other face to face, resulting in the formation of close interfaces and efficient heterojunctions. UV–vis absorption of the heterostructure is modulated efficiently by controlling the phase component. When utilized as photocatalysts for MO degradation under visible light irradiation, the g–C3N4/α–AgAl0.4Ga0.6O2 with a molar ratio of 0.75 exhibits the most excellent photocatalytic performance with a rate constant of 0.0227 min?1. The further investigation of the photoelectrochemical property including small diameter of the arc radius and maximum photocurrent indicates that the separation efficiency of electron–hole pairs is greatly improved through heterojunctions with two–dimensional coupling interfaces. Besides, the reaction kinetics and the photocatalytic mechanism related to the energy band are proposed for degrading organic pollutants. The results prove that the g–C3N4/α–AgAl0.4Ga0.6O2 heterostructure has great potential application in photocatalysis for eliminating organic pollutants.
关键词： Charge carrier,Visible–light response,Heterostructure,Photocatalysis
更新于2025-09-10 09:29:36
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Convolution neural network-based time-domain equalizer for DFT-Spread OFDM VLC system
摘要： This paper presents a novel time-domain equalizer for visible light communication (VLC) system using machine learning (ML) method. In this work, we employ discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) as modem scheme and convolution neural network (CNN) as kernel processing unit of equalizer. After estimating channel state information (CSI) from training sequence, the proposed equalizer recovers transmitted symbols according to the estimated CSI. Numerical simulations indicate that the equalizer can significantly enhance bit error rate (BER) performance. For example, when signal-to-noise ratio (SNR) is 20dB and 16/32/64-quadrature amplitude modulation (QAM) is exploited, original BER is about 0.5 while the BER after recovery achieves 10?5, which is much lower than forward error correction (FEC) limit 3.8×10?3. This work promotes the application of ML in VLC domain. To the best of our knowledge, this is the first time a CNN-based equalizer has been explored.
关键词： Machine learning (ML),Discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM),Visible light communication (VLC),Convolution neural network (CNN)
更新于2025-09-10 09:29:36
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Janus Group-Ⅲ Chalcogenide Monolayers and Derivative Type-Ⅱ Heterojunctions as Water Splitting Photocatalysts with Strong Visible Light Absorbance
摘要： Search for two-dimensional (2D) water splitting photocatalysts is crucial to solve energy crises and environmental problems. In this research, we study the electronic and photocatalytic properties of single-layer Ga2X1X2 (Ga2SeTe, Ga2STe and Ga2SSe) and newly proposed α-Ga2S3/Ga2SSe-A, α-Ga2S3/Ga2SSe-B and α-Ga2S3/Ga2SSe-C van der Walls heterojunctions using first-principles calculations. Theoretical results indicate Ga2X1X2 monolayers present suitable band edges. 2D α-Ga2S3/Ga2SSe-B and α-Ga2S3/Ga2SSe-C belong to type-Ⅱ heterojunctions, and under biaxial strains embody suitable band edges. Comparisons of the valence band maximum (VBM) charge and electric dipole of α-Ga2S3/Ga2SSe-A and α-Ga2S3/Ga2SSe-B demonstrate it is possible to achieve suitable band edges for water splitting by switching electric dipoles. Especially, the three Ga2X1X2 monolayers, α-Ga2S3/Ga2SSe-B and α-Ga2S3/Ga2SSe-C heterojunctions absorb a large amount of visible light, promising they are photocatalysts for water splitting. More importantly, we find the optical absorption coefficients of 2D monolayers and heterojunctions in previous calculations are several times underestimated because the effective volume is not taken into consideration. To obtain reliable absorption coefficients, the real and imaginary parts of dielectric function must be renormalized.
关键词： visible light absorbance,van der Waals heterojunctions,two-dimensional (2D) materials,Janus group-Ⅲ chalcogenide monolayers,water splitting photocatalysts,first-principles calculations
更新于2025-09-10 09:29:36
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Polydopamine-inspired Design and Synthesis of Visible-light-driven Ag NPs@C@elongated TiO2 NTs Core-shell Nanocomposites for Sustainable Hydrogen Generation
摘要： The primary challenge of photocatalytic hydrogen generation is to exploit a catalyst with good durability and low cost. Here, we designed a facile and efficient process of loading silver nanoparticles (Ag NPs) in situ on the core-shell nanocomposite of the elongated titanium dioxide nanotubes with carbon layer (C@TiO2 NTs) by polydopamine (PDA) without addition of any binder. The combination of C@TiO2 NTs with Ag NPs has excellent performance toward photocatalytic hydrogen production and degradation of rhodamine B (RhB) under visible light irradiation. The characterizations (SEM, TAM, XRD, XPS, etc.) showed that the carbon layer on nanotubes could conformably cover the whole of TiO2 NTs to form core-shell structure, which not only prevented Ag NPs from aggregating, but also acted as the electronic transport channel. Meanwhile, Ag NPs were uniformly distributed on the surface of C@TiO2 NTs. In conclusion, under the synergistic effect of Ag nanoparticles and outer-carbon layer, the utilization efficiency of visible light has been enhanced and the recombination of electrons/holes has been suppressed for Ag@C@TiO2 NTs nanocomposites. Therefore, the degradation efficiency of RhB and hydrogen generation rate is 2.5 times and 4.8 times as higher as pure TiO2 NTs, respectively. This work may provide fruitful experience for developing novel strategy into the design and fabrication of stable and highly active visible-light catalysts with noble metal modification toward sustainable hydrogen production in the energy filed.
关键词： elongated TiO2 nanotube,carbon shell,Ag nanoparticle,visible-light induced photo-catalyst,core-shell structure
更新于2025-09-10 09:29:36
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Outage of SEE-OFDM VLC-NOMA Networks
摘要： In this letter, an indoor spectrally and energy efficient orthogonal frequency division multiplexing (SEE-OFDM) based visible light communication (VLC) network with non-orthogonal multiple access (NOMA) is studied. An exact expression of the outage probability for K NOMA users is derived. We also provide an upper bound of the data rate of the SEE-OFDM VLC-NOMA network. Finally, the proposed system model shows its superiority compared to the orthogonal multiple access.
关键词： outage probability (OP),visible light communication (VLC),Non-orthogonal multiple access (NOMA)
更新于2025-09-10 09:29:36
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Metal-free Semiconductor Photocatalysis for sp2 C-H Functionalization with Molecular Oxygen
摘要： Designing metal-free catalysts for solar energy conversion is a long-standing challenge in semiconductor photoredox catalysis (SPC). With visible-light-responsive hexagonal boron carbon nitride (h-BCN) as a non-metal photocatalyst, this system affords C–H/N–H coupling products with broad substitution tolerance and high efficiency with molecular oxygen as the terminal oxidant. The catalyst exhibits remarkable performance for the selective C-H functionalization of electron-rich arenes to C-N products (yields up to 95%) and good stability (6 recycles). Both nitrogen heteroarenes and amine salts are competent coupling nucleophiles. Mechanically, the reactive oxygen species are superoxide anion radical (O2??) and H2O2, which are proved by electron spin resonance (ESR) data, KI-starch, and control experiments. In addition, kinetic isotope effect (KIE) experiments indicate that C–H bond cleavage is not involved in the rate limiting step. This semiconductor-based photoredox system allows for C–H amination free of any metals, ligands, strong oxidants, and additives. It provides a complementary avenue to C–H functionalizations and enables synthetic applications efficiently in a sustainable manner.
关键词： Radical,Semiconductor Photoredox Catalysis,Heterogeneous Catalysis,Visible Light,C-H Fuctionalizaition
更新于2025-09-10 09:29:36