Degradation Efficiency Of Rhodamine B Research Articles

Ultrathin Graphitic Carbon Nitride Nanosheets as Efficient Catalysts for Degradation of Pollutants under Visible Light

AbstractIn this paper, ultrathin g‐C3N4 nanosheets (U‐CNs‐4) were prepared via short time sonication‐assisted exfoliation and solvothermal treatment method in ethylene glycol solvent. It was found that the obtained ultrathin g‐C3N4 nanosheets with a thickness of ranges from 4 to 5 nm, exhibited a higher specific surface area of 35.7 m2/g and larger electronic band structure (by 0.16 eV), enhanced photocurrent response and improved electron transport ability due to the quantum confinement effect. The photocatalytic activities have been proved by photocatalytic degradation Rhodamine B (RhB) and ciprofloxacin (CIP) under visible‐light irradiation. Results show that the U‐CNs‐4 exhibited obviously enhanced photocatalytic activity in comparison with other samples. The degradation efficiency of RhB was 4.4 times higher than that of the bulk g‐C3N4 (B‐CN). The enhanced photocatalytic activity was due to the more active sites, the enhanced oxidation ability and improved electron transport ability, which improving separation efficiency of photogenerated electron‐hole pairs. Finally, the possible for the enhancing photocatalytic mechanism was revealed based on the active species trapping and electron spin resonance (ESR) experiments.

Simple design and preliminary evaluation of continuous submerged solid small-scale laboratory photoreactor (CS4PR) using TiO2/NO3-@TC for dye degradation

In this paper, we report a development of small-scale laboratory photocatalytic reactor to degrade dyes, namely Continuous Submerged Solid Small-Scale Laboratory Photoreactor (CS4PR). To achieve this target, the material of TiO2/NO3− as a catalyst material in this photoreactor was selected. Then, it was coated onto traditional ceramic (TC) surface to form (TiO2/NO3−@TC) by using dip and spin-coating methods. Furthermore, the powder of TiO2/NO3− was characterized by Fourier transform infra red (FTIR), Scanning electronic microscopy-Energy disperse X-ray (SEM-EDX) and Ultra violet-visible (UV–vis) spectroscopy. In this research, rhodamine B (RhB) was chosen as a sample model to examine the photodegradation efficiency of photoreactor. The photodegradation of RhB was analyzed by LC–MS. Accordong to the analysis data, the best coating of TiO2/NO3− and sulfate concetration is at 8 times and 500 mg.L-1, respectively, with photodegradation rate constant and RhB degradation efficiency are 0.0149 per minute and 78.06%, respectively. From our research to realize 100% of RhB degradation, the ratio of catalyst plate, sulfate ion concentration and sample volume is 9 : 500 ppm : 500 mL/5 mg.L-1 of RhB. Based on LC–MS spectrum, it demonstrated that 29 intermediate compounds of RhB degraded before reaching their mineralization product.

Zeolitic imidazolate framework-supported Prussian blue analogues as an efficient Fenton-like catalyst for activation of peroxymonosulfate

Prussian blue analogues (PBAs) have gained extensive attention for peroxymonosulfate (PMS) activation. However, the poor recovery ability of PBAs has limited their practical applications. In this work, PBA was firstly immobilized using zeolitic imidazolate framework-8 (ZIF-8) via a facile in-situ growth method. The decoration of PBA onto the surface of ZIF-8 was well confirmed by TEM, XRD, FTIR and XPS. The catalytic efficiency of the PBA-ZIF8 composite was significantly higher than that of pure PBA and ZIF-8 on the activation process of peroxymonosulfate when rhodamine B (RhB) was employed as a target contaminant. RhB degradation efficiency was effectively promoted at relatively high PBA-ZIF8 dosage and PMS concentration, as well as in near-neutral pH medium. Sulphate radicals obviously played a predominant role in attacking RhB during the whole reaction. In addition, PBA-ZIF8 also possessed good stability and reusability with negligible cobalt leaching. Therefore, the PBA-ZIF8 composite was a conveniently prepared and promising catalyst that may be employed to remediate contaminated water due to its excellent catalytic activity and recyclability.

Bio-templated synthesis of Fe3O4–TiO2 composites derived from Chlorella pyrenoidosa with enhanced visible-light photocatalytic performance

A series of Fe3O4–TiO2 composites were successfully synthesized using Chlorella pyrenoidosa as a bio-template. C. pyrenoidosa is not only a promising bio-template for obtaining Fe3O4 and TiO2 nanoparticles (NPs) but is also a natural dye sensitizer source that improves the photocatalytic activity of the TiO2 NPs under visible light. The bandgap energy of Fe3O4–TiO2 is narrower than that of TiO2 due to the coupling between the Fe3O4 and TiO2 NPs. The coupling and dye-sensitization lead to the rapid separation and suppressed recombination of electron-hole pairs in Fe3O4–TiO2, which enhances the photocatalytic activity of TiO2 under visible light. The photocatalytic activity of the as-prepared composites was evaluated by degrading a rhodamine B (RhB) aqueous solution under visible-light irradiation. Fe3O4–TiO2 exhibits a high degradation efficiency for RhB, and can be withdrawn from solution easily using an external magnetic field.

α-MnO2/Palygorskite composite as an effective catalyst for heterogeneous activation of peroxymonosulfate (PMS) for the degradation of Rhodamine B

The discharging of Rhodamine B (RhB) from wastewater has caused huge environment pollution. Peroxymonosulfate (PMS) oxidation is an effective way to remove it from wastewater. However, finding an environmentally friendly metal to activate PMS is a key step for the oxidation process. In this study, nanorod α-MnO2 loaded palygorskite (α-MnO2/Pal) was fabricated by a simple hydrothermal method. The analysis of field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) confirmed the loading of α-MnO2 on the surface of Pal and characterized the surface of the composite. The surface area of α-MnO2/Pal composite was 159.13 m2/g, which was much higher than that of Pal and α-MnO2. The Pal, α-MnO2, Mn2+, and α-MnO2/Pal were used to activate PMS for RhB degradation. Nearly 100% RhB degradation was obtained in α-MnO2/Pal + PMS system in 180 min and in α-MnO2 + PMS system in 300 min, while only 50% degradation was obtained in Pal + PMS system and 71.4% degradation in Mn2+ + PMS system in 300 min. The degradation fitted the pseudo-first-order reaction kinetics well with rate constant of 0.02041 min−1 for α-MnO2/Pal + PMS system, 0.01192 min−1 for α-MnO2 + PMS system, and 0.00435 min−1 for Mn2+ + PMS system, respectively. The factors affecting RhB degradation were further investigated. The RhB degradation efficiency increased with the increase of α-MnO2/Pal dosages, PMS dosages and temperatures. The degradation was inhibited at pH > 5.5, while was favorable at pH < 5.5. The major reactive radicals responsible for RhB degradation classified by radical quenching experiment were O2− and 1O2. The possible mechanism was further proposed based on the results. The α-MnO2/Pal composite showed nearly 50% mineralization ratio in the presence of PMS and an excellent reusability. The results from this study revealed that α-MnO2/Pal composite is an effective catalyst to activate PMS for RhB degradation.

Piezoelectric Material-Polymer Composite Porous Foam for Efficient Dye Degradation via the Piezo-Catalytic Effect.

Piezoelectric nanomaterials have been utilized to realize effective charge separation for degrading organic pollutants in water under the action of mechanical vibrations. However, in particulate form, the nanostructured piezoelectric catalysts can flow into the aqueous pollutant and limit its recyclability and reuse. Here, we report a new method of using a barium titanate (BaTiO3, BTO)-polydimethylsiloxane composite porous foam catalyst to address the challenge of secondary pollution and reusable limits. Piezo-catalytic dye degradation activity of the porous foam can degrade a Rhodamine B (RhB) dye solution by ∼94%, and the composite material exhibits excellent stability after repeated decomposition of 12 cycles. It is suggested that under ultrasonic vibrations, the piezoelectric BTO materials create separated electron-hole pairs that react with hydroxyl ions and oxygen molecules to generate superoxide (•O2-) and hydroxyl (•OH) radicals for organic dye degradation. The degradation efficiency of RhB is associated with the piezoelectric constant, the specific surface area, and the shape of the material.

Effect of rGO Addition Toward Photocatalyst Properties of ZnO/rGO/TiO&lt;sub&gt;2&lt;/sub&gt; for Rhodamine B Degradation

The growth of the textile industry in Indonesia has resulted in increased textile dye waste production. Rhodamine B is one of the dyes that are often used in the textile industry. The use of these dyes will cause serious environmental and biological problems, even able to induce irritation of the skin and eyes. Thus, it is necessary to filter dyes from the textile industry waste in Indonesia. Some conventional methods for removing Rhodamine B are carried out by biochemical and physical-chemical methods, such as liquid membranes, ozonation and adsorption, but this method requires expensive and not very effective costs. One alternative method that can be applied in Indonesia is photocatalysts. Photocatalytics are processes where light and catalyst are simultaneously used to accelerate chemical reactions. In this study, the photocatalyst used was semiconductor material ZnO and TiO2 with the addition of rGO. rGO synthesis was carried out using the Hummer method, for the synthesis of ZnO using Zinc powder as a precursor, and the synthesis of TiO2 using precursor of TiCl3. This study was conducted to analyze the effect of adding 5%, 10%, and 15% rGO to the photocatalytic properties of ZnO / rGO / TiO2 composites for degradation of Rhodamine B. The characterization process carried out in this study included XRD, SEM &amp; EDX, FTIR, and photocatalytic testing. Photocatalyst materials ZnO / rGO / TiO2 with variations in the amount of rGO were synthesized as evidenced by XRD testing, where there was a peak for all three component, SEM, shows the morphology of Zn in the form of hexagonal nano rod, rGO in the form of transparent sheets and TiO2 in the form of agglomerated balls. From FTIR testing, rGO and TiO2 functional groups were seen. The highest efficiency for degradation of Rhodamine-B was obtained for the addition of 15% rGO with a 5-hour irradiation time, ie its efficiency reached 96.92% in degradation of Rhodamine B.

Fabrication of a magnetically separable and dual Z-scheme PANI/Ag3PO4/NiFe2O4 composite with enhanced visible-light photocatalytic activity for organic pollutant elimination

A novel polyaniline/silver phosphate/nickel ferrate (PANI/Ag3PO4/NiFe2O4) magnetic photocatalyst has been successfully fabricated by a precipitation-hydrothermal method. The composition, morphological structure and optical property of the as-prepared samples are characterized. All the PANI/Ag3PO4/NiFe2O4 composites with different PANI content show enhanced visible-light photocatalytic activity for rhodamine B (RhB) and methyl orange (MO) dyes degradation compared to pure Ag3PO4, Ag3PO4/NiFe2O4 and Ag3PO4/PANI composites. The highest degradation efficiency for RhB and MO via 3%-PANI/Ag3PO4/NiFe2O4 composite photocatalyst separately reach 100% and 94.97%, and their degradation rate (k) are close to 12.1 and 15.4 times faster than those of pure Ag3PO4, respectively. Meanwhile, the PANI/Ag3PO4/NiFe2O4 composite displays excellent photocatalytic performance on the degradation of colorless organic pollutants (tetracycline hydrochloride, nitrobenzene and bisphenol A) under the visible light irradiation. The PANI/Ag3PO4/NiFe2O4 catalyst exhibits a superior stability than pure Ag3PO4 after three consecutive reuses. The improved photocatalytic activity and stability of PANI/Ag3PO4/NiFe2O4 ternary composite can be attributed to the extended absorption capability in the visible light region as well as the high-efficiency separation of electron-hole pairs. Particularly, the construction of double Z-scheme heterojunctions in the ternary composite can facilitate the rapid transfer of electrons on the surface of Ag3PO4, thus inhibit its photocorrosion. This study provides an idea for enhancing the anti-photocorrosion and photocatalytic activity of photosensitive semiconductors.

Perovskite solar cells-TiO2 tandem assembly for photoelectrocatalytic degradation of organic pollutants

In this study, a self-powered photoelectrocatalytic (PEC) device was designed using multi-walled carbon nanotubes (CNTs) and methylamine (CH3NH2) modified perovskite solar cells (PSCs) as the power source and CNT/TiO2 as the photoanodes. In the PSCs, CNTs and CH3NH2 were used to modify the interface between the perovskite and carbon electrode to improve the photoelectronic performance. In particular, CH3NH2 induced surface-healing of the CH3NH3PbI3 perovskite thin films and the CNTs acted as a charge transport pathway among individual perovskite nanoparticles to facilitate the collection of photogenerated holes by the carbon electrode. A power conversion efficiency of 10.39% was achieved after modification with the CNTs and CH3NH2. In the photoanodes, the CNT-modified TiO2 electrode accelerated the electron–hole separation and transportation, thereby improving the degradation performance. After assembling the PSCs modified using CNT and CH3NH2 with CNT/TiO2, the solar-driven PEC system exhibited a high PEC degradation rate with rhodamine B (RhB). The optimal degradation efficiency for RhB with the tandem device was close to 100% after 80 min. This low-cost tandem assembly has promising applications in pollutant degradation research.

Green synthesis of multifunctional copper sulfide for efficient adsorption and photocatalysis

Copper sulfide (CuS) was prepared by co-precipitation process at low temperature and atmospheric pressure without any additive while Cu(NO3)2 and thioacetamide were used as copper and sulfide sources, respectively. The effects of concentration, time, temperature, molar ratio of sulfur to copper and the pH of reaction system on the morphology of CuS were investigated. Rhodamine B (RhB) aqueous was employed to evaluate the photocatalysis and adsorption performances of the samples. The results showed that a pure hexagonal CuS has been successfully synthesized. Samples were demonstrated multifunctional of adsorption and photocatalysis under visible-light, which improved the degradation performance of high-dye wastewater. The degradation efficiency of RhB (20 mg L−1) was 99% in 120 min; when a small amount of H2O2 was used, 99% of RhB in high (50 mg L−1) wastewater can be removed within 60 min. This study provides a green preparation to choose for CuS with hollow spheres.

Realizing High Photocatalytic Performance of NaBiS2 Nanopowders via the Introduction of Rare‐Earth Elements

Rare earth (RE) elements (RE = Sm, Nd) added NaBiS2 nanoparticles are successfully synthesized by a facile one pot growth method. The photocatalytic performance of all samples are evaluated by the degradation of Rhodamine B (RhB) under the visible light irradiation. The results show that the existence of amorphous phase and RE ions lead to both act as electron traps to capture the electron and promote the separation of photoinduced charge carriers. In addition, the midgap energy levels induced by RE ions lead to further energy transfer in the up‐conversion process to enhance the absorption of photons and boost the lifetime of photocarriers to improve the photocatalytic performance. The NaBiS2 sample with 5%Nd and 5%Sm possess the best catalytic activity in which the degradation efficiency of RhB is beyond 90% under the visible light irradiation for 60 min. Furthermore, the photocatalytic mechanism of NaBiS2 is discussed in detail.

Facile Synthesis of Ag/ZnO Hollow Microspheres with Enhanced Photocatalytic Performance under Simulated Sunlight Irradiation

Water pollution caused by intensive use of organic dyes has become an increasingly serious problem recently. Green and efficient processes are desperately needed to remove persistent organic pollutants from waste waters. Herein, Ag nanoparticles loaded ZnO hollow microspheres were synthesized through a simple solvothermal method and used as a photocatalyst for dye degradation. The calculated band gap of Ag/ZnO — 5% (2.97[Formula: see text]eV) is much narrower than that of pure ZnO (3.37[Formula: see text]eV). The obtained Ag/ZnO samples show a remarkable photocatalytic activity in photodegradation of Rhodamine B (RhB) under simulated sunlight irradiation. The degradation efficiency of RhB for Ag/ZnO — 5% is 98.8% after 100[Formula: see text]min irradiation while only 52.8% degradation rate is obtained over pure ZnO. The enhancement is attributed to the exposed active ZnO (001) plane and the surface plasmon resonance (SPR) effect of Ag nanoparticles that promote the separation of photogeneated electrons and holes.

Establishing WO3/g-C3N4 Composite for “Memory” Photocatalytic Activity and Enhancement in Photocatalytic Degradation

Tungsten trioxide and graphitic carbon nitride composite materials (designed as WO3/g-C3N4) were constructed via a facile hydrothermal process. The excellent “catalytic memory” activity of WO3/g-C3N4 was discovered and applied in organic pollutants degradation for the first time. With 3 h pre-illumination, nearly 42.33% Rhodamine B (RhB) was removed in the dark by WO3/g-C3N4 via its nearly 8 h “memory” photocatalytic activity. In addition, the photocatalytic degradation efficiency of RhB was 97.46% with WO3/g-C3N4 under the visible light. Meanwhile, the “memory” photocatalytic activity enhanced photocatalysis and effectively promoted the WO3/g-C3N4 mediated organism degradation.

NiO-NiFe2O4-rGO Magnetic Nanomaterials for Activated Peroxymonosulfate Degradation of Rhodamine B

Magnetic spinel ferrites that act as heterogeneous catalysts and generate powerful radicals from peroxymono-sulfate (PMS) for the degradation of organic pollutants have received much attention in recent years due to the characteristic of environmental benefits. In this study, NiO-NiFe2O4-rGO magnetic nanomaterials were synthesized using a calcinated Ni-Fe-LDH-rGO precursor. The morphology, structure, and chemical constitution were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM). The catalytic performance of NiO-NiFe2O4-rGO nanoparticles was thoroughly evaluated for peroxymonosulfate (PMS) activation and its removal of rhodamine B (RhB) from water. The influence of different process parameters on the RhB degradation efficiency was examined. Further, the catalytic stability was evaluated. Under optimized conditions, the NiO-NiFe2O4-rGO/PMS system was very efficient; RhB fully degraded after 40 min at room temperature. Quenching experiments and electronic paramagnetic resonance (EPR) results suggested that SO4−· and OH· were the main active species in the degradation process. Moreover, NiO-NiFe2O4-rGO catalyst was stable without any apparent activity loss after three cycling runs.

Efficient Fe2O3/C-g-C3N4 Z-scheme heterojunction photocatalyst prepared by facile one-step carbonizing process

Photocatalytic water purification has emerged as new effective ways for an environment preserve and purification in few decades. As a part of studies on photocatalytic water purification, constructing heterojunction structured compounds with different photocatalysts for efficient organic pollutant degradation is regarded as key-strategy. Herein, facile one-step carbonizing process was introduced for synthesizing Fe2O3/C-g-C3N4 based Z-scheme heterojunction photocatalyst. The two times of photocatalytic organic pollutant degradation rate of Fe2O3/C-g-C3N4 based Z-scheme heterojunction photocatalyst was enhanced comparing with pristine Fe2O3/g-C3N4 heterojunction photocatalyst through rhodamine B (RhB) degradation under AM 1.5G (100 mWcm−2, 1 sun) illumination. The reasons for enhanced photocatalytic RhB degradation efficiency of Fe2O3/C-g-C3N4 based Z-scheme heterojunction photocatalyst were revealed to efficient charge transfer during light induced RhB degradation reaction by constructing junction structures among Fe2O3, amorphous carbon layer and g-C3N4, which proved by fluorescence spectroscopy, XPS, SEM, TEM and UV–Vis analysis.

Microwave Assisted Synthesis of Pure and Ag Doped SnO2 Quantum Dots as Novel Platform for High Photocatalytic Activity Performance

In this study, we report a simple and fast synthetic route to prepare pure and Ag doped SnO2 quantum dots via one step microwave irradiation method for the first time. Variety of analytical techniques including XRD, Raman, TEM, EDS, XPS, UV and PL were used to investigate the influence of Ag dopant concentration on structural, morphological, compositional and optical properties of SnO2 nanoparticles. The XRD pattern showed a dominant tetragonal rutile structure of both pure and Ag doped SnO2 and formed directly during the microwave irradiation process. TEM images revealed that quantum dots and the average particle size increases by Ag doping. The EDS and XPS results proved that the presence of silver as Ag3+ species. The optical properly of SnO2 was significantly improved and narrowing the band gap (3.54–3.09 eV) of pure SnO2 by Ag doping, which is confirmed through UV and PL results. The photocatalytic behavior of the catalyst powders were investigated using methylene blue and rhodamine B (RhB) as model organic pollutants. A maximum RhB degradation efficiency of 97.5% is achieved under visible light irradiation for Ag doped SnO2 catalyst. Furthermore, the Ag–SnO2 QDs catalyst demonstrates good reusability and stability after the seven cycles.

Visible-light photocatalytic capability and the mechanism investigation of a novel PANI/Sn3O4 p-n heterostructure.

A novel polyaniline (PANI)/Sn3O4 heterojunction composed of PANI nanofibers and Sn3O4 nanosheets was fabricated by a facile physical milling technique. Modification of Sn3O4 with a PANI conductive polymer contributes to facilitating interfacial charge transfer efficiency, and thus, significantly enhances the visible-light Rhodamine B (RhB) photo-degradation. Results indicate that PANI/Sn3O4 heterostructures with 10 wt% PANI reached the maximum degradation efficiency (around 97%) for RhB within 5 h, which is 2.27 times higher than that of Sn3O4 alone. This improvement is due to the p–n heterostructure formation in PANI/Sn3O4. Moreover, the outcome of reactive species capturing experiments demonstrated that in PANI/Sn3O4, holes made the largest contribution to RhB degradation under visible light illumination, while hydroxyl radicals showed less significance under the same conditions. In addition, the photocatalytic mechanism was proposed based on evidence from the reactive species test and energy band structure analysis.

Engineering Charge Transfer Characteristics in Hierarchical Cu₂S QDs @ ZnO Nanoneedles with p⁻n Heterojunctions: Towards Highly Efficient and Recyclable Photocatalysts.

Equipped with staggered gap p-n heterojunctions, a new paradigm of photocatalysts based on hierarchically structured nano-match-shaped heterojunctions (NMSHs) Cu2S quantum dots (QDs)@ZnO nanoneedles (NNs) are successfully developed via engineering the successive ionic layer adsorption and reaction (SILAR). Under UV and visible light illumination, the photocatalytic characteristics of Cu2S@ZnO heterojunctions with different loading amounts of Cu2S QDs are evaluated by the corresponding photocatalytic degradation of rhodamine B (RhB) aqueous solution. The results elaborate that the optimized samples (S3 serial specimens with six cycles of SILAR reaction) by means of tailored the band diagram exhibit appreciable improvement of photocatalytic activities among all synthesized samples, attributing to the sensitization of a proper amount of Cu2S QDs. Such developed architecture not only could form p–n junctions with ZnO nanoneedles to facilitate the separation of photo-generated carries but also interact with the surface defects of ZnO NNs to reduce the electron and hole recombination probability. Moreover, the existence of Cu2S QDs could also extend the light absorption to improve the utilization rate of sunlight. Importantly, under UV light S3 samples demonstrate the remarkably enhanced RhB degradation efficiency, which is clearly testified upon the charge transfer mechanism discussions and evaluations in the present work. Further supplementary investigations illustrate that the developed nanoscale Cu2S@ZnO heterostructures also possess an excellent photo-stability during our extensive recycling photocatalytic experiments, promising for a wide range of highly efficient and sustainably recyclable photocatalysts applications.

Acoustic cavitation assisted plasma for wastewater treatment: Degradation of Rhodamine B in aqueous solution

A novel wastewater treatment process, acoustic cavitation assisted plasma (ACAP) is proposed in this study aiming at expanding the treatable range of water pollutants due to a synergetic effect of ultrasound irradiation and high voltage plasma discharge. In this process, the role of acoustic cavitation is not only to provide generation of chemically active OH radicals, as for example in conventional ultrasonic wastewater treatment techniques, but also to ensure conditions for stable plasma generation in wastewater and, thus, to extend the treatable range of water pollutants. Rhodamine B (RhB) was used as a model pollutant in experiments examining effects of ultrasound amplitude, RhB initial concentration, output voltage, solution pH and electrical conductivity on the RhB degradation efficiency. The results revealed that the ultrasound-assisted plasma generation requires lower output voltages and allows to increase the acceptable range of electrical conductivity of treatable solutions up to 1000 μS/cm, that is about 24 times higher than in the case of conventional plasma discharge treatment. The alkaline and acid medium were found to be favorable for higher degradation efficiency. Additional measurements and results of recent investigations concerning underwater plasma showed that microbubbles presented in cavitation zone could serve as “bridges” making the pulse discharge propagation between the electrodes easier than in the conventional case. Besides, acoustic cavitation assists a faster transition of plasma discharge from ineffective streamer type to more effective spark type that further contributes to the improvement of the treatment performance.

Polydopamine-Inspired Design and Synthesis of Visible-Light-Driven Ag NPs@C@elongated TiO2 NTs Core–Shell Nanocomposites for Sustainable Hydrogen Generation

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 a 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 the 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 the 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 are 2.5 times and 4.8 times higher than those of the pure TiO2 NTs, respectively. This work may provide fruitful experience for developing a 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.