Light-capturing Ability Research Articles

Constructing two-level nonlinear mixed-effects crown width models for Moso bamboo in China.

Bamboo crown width (CW) is a reliable index for evaluating growth, yield, health and vitality of bamboo, and light capture ability and carbon fixation efficiency of bamboo forests. Based on statistical results produced from fitting the eight basic growth functions using data from 1374 Phyllostachys pubescens in Yixing, Jiangsu Province, China, this study identified the most suitable function (logistic function) to construct a two-level mixed effects (NLME) CW model with the forest block and sample plot-level effects included as random effects in the model. Four methods for selecting sample bamboos per sample plot (largest bamboo, medium-sized bamboo, smallest bamboo, and randomly selected bamboos) and eight sample sizes (1-8 selected bamboos per sample plot) were evaluated to calibrate our NLME CW model. Using diameter at breast height (DBH), height to crown base (HCB), arithmetic mean diameter at breast height (MDBH), and height (H) as predictor variables, the model produced the best fit statistics (Max R2, min RMSE, and TRE). This model was further improved by introducing random effects at two levels. The results showed a positive correlation of CW with HCB and DBH and a negative correlation with H. The smallest two bamboo poles per sample plot used to estimate the random effects of the NLME model provided a satisfactory compromise regarding measurement cost, model efficiency, and prediction accuracy. The presented NLME CW model may guide effective management and carbon estimation of bamboo forests.

Synthesis and Characterization of Ternary Composite g-C3N4-MoO3/rGO for Photocatalytic Activity

<p>The present research prepared a ternary composite g-C3N4-MoO3/rGO using the ultrasonic-assisted wet impregnation method. The prepared photocatalyst was characterized by using Fourier transform infrared spectroscopy (FT-IR), Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and EDX(Energy dispersive X-ray) techniques. The structure and morphology of pure MoO<sub>3, </sub>g-C<sub>3</sub>N<sub>4</sub>, binary composite g-C<sub>3</sub>N<sub>4</sub>-MoO<sub>3,</sub> and ternary composite g-C<sub>3</sub>N<sub>4</sub>-MoO<sub>3</sub>/rGO have been studied in their photocatalytic performance in the degradation of Rhodamine B (Rh-B) was tested and compared. The ternary composite g-C<sub>3</sub>N<sub>4</sub>-MoO<sub>3</sub>/rGO exhibited better degradation efficiency of 80% than pure and binary composite. The synergistic effect of the three components resulted in enhanced light-capturing ability, high charge separation, and low recombination rate of electron-hole pair. </p>

Confined Space and Heterojunction Dual Modulation of ZnO/ZnS for Boosting Photocatalytic CO2 Reduction

The reduction of CO2 to chemical fuel driven by solar energy can not only meet the growing demand for renewable energy, but also balance the carbon cycle in nature. However, the current photocatalysts have low CO2 conversion due to their poor light capture ability, narrow light response range, and high recombination probability of photogenerated carriers. Herein, a heterogeneous photocatalyst of hollow structured ZnO/ZnS decorated with Pt nanoparticles is synthesized through the hydrothermal process and photodeposition method, showing excellent photocatalytic activity for CO2 reduction in long‐time stability and ≈100% CO selectivity, which can mainly contribute to natural enhanced light‐capture ability of the hollow confined space due to multiple reflection and scattering of light in the cavity, thus improving separation efficiency of photogenerated charge carriers due to the type II junction constructed between ZnO and ZnS and the additional reaction active sites after decorating Pt nanoparticles in the surface of the hollow structure.

2D/3D g-C3N4/BiOI heterostructure catalyst for efficient and robust photocatalytic NO removal

Developing visible light responsive photocatalysts with strong light capture ability for catalytic NO removal is of great significance. In this work, we coupled the narrow-gap semiconductor BiOI with graphite-like carbon nitride (g-C3N4) to construct 2D/3D heterostructure and applied it for efficient photocatalytic elimination of NO under visible light irradiation. At relative humidity (RH) of 15 %, g-C3N4/BiOI achieves remarkable NO removal activity (80.5 %) under a gas hourly space velocity (GHSV) of 1,740,000 mL h−1 g−1. Outstanding durability was realized that the NO removal efficiency of g-C3N4/BiOI after 6 consecutive runs. Even at high RH of 50 % and 80 %, g-C3N4/BiOI still exhibited excellent NO removal performances of 80.3 % and 78.5 %, respectively. The heterostructure of g-C3N4/BiOI endowed the enhanced light harvesting, efficient charge separation and rapid charge transfer, which enables sufficient superoxide radicals (O2−) production to improve the efficiency and strengthen the durability of photocatalytic NO removal. This work provides insights into the rational design of heterostructure photocatalyst toward air purification.

The effects of potential and solar input on Z-scheme C3N4-TiO2 nanotubes @ Ti electrode in a broad potential window

Construction of Z-scheme graphitic carbon nitride-titanium dioxide nanotubes (C3N4-TNT) has been known useful to optimize the band structure for improving photon capture and for accelerating charge carrier separation and transfer rate in photoelectrochemical water splitting (PECWS) cells. However, the reported operating potential window in a PECWS cell, often in 0 – 1.23 VRHE (volt versus reversible hydrogen electrode) plus its overpotential, is too narrow to understand the C3N4-TNT electrode. Herein, a broad potential window of −0.5 − 2.5 VRHE is applied to C3N4-TNT@Ti and recorded via the polarization test under chopped sunlight to analyze the effect of both electrons from external electrical circuit and photons from simulated sunlight. In 0 – 2.5 VRHE, the potential enhances the photocurrent density. For example, at 1.6 VRHE, the C3N4-TNT sample exhibits 1.8-time higher photocurrent density than that of pure TNT. In −0.5 − 0 VRHE, i.e., both samples do not give photo-current response. In addition, for advanced water oxidation/reduction beyond WS to oxygen/hydrogen, a large potential window will be expected. Further, the light capture ability, the charge carrier recombination rate, and the electron flow path through the C3N4-TNT junction without and with reverse/forward potentials are discussed to elucidate the effect of the applied potential.

Ray-tracing analysis on the far-red induced light-capturing ability of kale

Far-red (FR, 700–800 nm) light has recently been used to regulate phytochrome-mediated morphological responses in vertical farms. Long-term morphological changes in different FR intensities are well known, but changes in photosynthetic capacity have not been sufficiently investigated. The objectives of this study were to quantitatively analyze the growth, photosynthetic responses, and light interception of kale (Brassica oleracea L. var. acephala) depending on the FR fraction. The plants were cultivated at a photosynthetic photon flux density (PPFD) of 240 μmol m−2 s−1 under red and white LEDs with FR LED (peak at 730 nm) for 16 h. The FR fractions determined as FR/R+FR were FR0.07 (control), FR0.28, FR0.60, and FR0.72. To evaluate the morphological and physiological responses in each FR fraction, the growth, chlorophyll content, chlorophyll fluorescence, P700 absorbance change, and photosynthetic rate were measured. Light interception was quantitatively calculated using 3D-scanned plant models with physiological changes and ray-tracing simulations. The dry weight of shoot and root, total petiole length, and leaf area increased with increasing FR fractions. As a result of ray-tracing analysis, the light interception and canopy photosynthetic rate increased with high FR fraction treatment. As the FR fraction increased, the effective quantum yield of photosystem II [Y(II)], the parameters of the JIP test that is related to quantum yield and efficiency for electron transport in photosystem II and photosystem performance indices decreased. Despite the decreased electron transport efficiency, the canopy photosynthetic rate increased in relation to the FR fraction. In conclusion, the increase in the FR fraction increased the yield of kale because of the synergistic improvement in morphological change and canopy photosynthesis.

Ultrasensitive flexible ultraviolet detectors based on electrochemically deposited ZnO microspheres synthesized by the assembly of nanoplatelets

Zinc oxide microspheres synthesized by the assembly of nanoplatelets have been deposited on seeded polycarbonate substrates using the electrochemical deposition technique with the assistance of glycerol. An electrochemical cell with platinum mesh as anode and the seeded substrates as cathode was employed to deposit ZnO microspheres. A computer-controlled potentiostat was used to supply sufficient current for the growth of ZnO nanoplatelets. Zinc chloride was used as a Zn source, and glycerol was applied to assist in the formation of microspheres. The average diameter of formed microspheres was 4 µ m, and the average size of nanoplatelets that formed the microspheres was a few nanometers. The morphology of the nanostructures indicated the formation of ZnO nanoplatelets with various orientations, which can significantly increase the entrapment of incident photons. X-ray diffraction analysis showed a dominant peak related to (002) as a reflection corresponding to the hexagonal ZnO structure. The enhanced photoluminescence (PL) intensity revealed improvement in the light-capturing ability due to the multiple scattering of light in the nanostructures. The quantum confinement phenomenon in the ZnO crystallites was evident from the blue shift of the PL peak position. A flexible photodetector was fabricated using the metallization of ZnO nanostructures to investigate the capability of ZnO microspheres in light sensing. The optoelectrical properties of fabricated devices were tested under ultraviolet radiation. The devices based on ZnO microspheres exhibited high sensitivity to the incident photons and showed stable photoelectric behavior under various bending conditions. • Zinc oxide microspheres were synthesized by the assembly of nanoplatelets • The role of glycerol in the aggregation of ZnO nanoplatelets was investigated • The improved PL properties of microspheres revealed enhanced light-capturing ability • Flexible photodetectors were fabricated based on ZnO microspheres and nanoplatelets • The ZnO spheres showed stable photoelectric behavior under various bending conditions

Photoelectrochemical biosensor based on DNA aptamers and dual nano-semiconductor heterojunctions for accurate and selective sensing of chloramphenicol.

Nanosheets of anatase TiO2 and CdS quantum dots modified with thioglycolic acid (TGA-CdS QDs) were prepared and hierarchically modified on the indium tin oxides (ITO) electrodes. The heterojunction structure is formed to improve the light capture ability and carrier migration, significantly enhancing the sensitivity of photoelectrochemical (PEC) biosensors. Specific DNA sequences labeled with TGA-CdS QDs were placed on the electrodes to prepare a biosensor for the detection of chloramphenicol with ultrahigh selectivity. In addition, the heterojunction structure and the principle of photocurrent signal amplification on the electrode are described in detail. Under the optimal conditions, the photoelectrochemical biosensors showed good reproducibility and stability for chloramphenicol with a linear response in the range 10-10,000pM and a limit of detection (LOD) of 0.23pM. Due to the specific recognition of base pairs, the sensor has excellent anti-interference ability in practical applications. An effective method was developed for the accurate detection of antibiotics with far reaching prospects.

High-activity black phosphorus quantum dots/Au/TiO2 ternary heterojunction for efficient levofloxacin removal: Pathways, toxicity assessment, mechanism and DFT calculations

Black phosphorus quantum dots (BPQDs) have attracted extensive attention for different photocatalytic applications, but their fast charge recombination limits their application prospects. It is ideal to improve the photocatalytic activity to acquire effective carrier separation by using precious metals as carrier transport relays and surface plasmon resonance (SPR) motivators. In this study, a highly active ternary heterojunction BPQDs/Au/TiO2 was prepared to achieve efficient levofloxacin degradation. The results indicated that the decomposition efficiency of levofloxacin reached 93.7%, and the reaction rate constant (Kα) was as high as 0.03266 min−1. Based on the results obtained from both density functional theory (DFT) calculations and experiments, three possible decomposition pathways of levofloxacin were suggested. Moreover, photocatalysis can effectively decrease the toxicity of the intermediates. The outstanding activity of BPQDs/Au/TiO2 is due to the cooperative effect of all the components. First, Au, as an SPR motivator, can offer many high-energy electrons during the catalytic process. Second, the indirect interfacial electron transport mode from BPQDs to Au and then to TiO2 promotes the separation of photoinduced carriers, which prolongs the lifetime of e--h+ pairs and significantly improves the performance. Third, the good light-capture ability of BPQDs is an important feature. In summary, this study suggests a possible direction for the construction of heterojunction catalysts with excellent performance in advanced oxidation processes.

Ag bridged step-scheme MoS2/Bi4O5Br2 heterojunction for enhanced visible light driven photocatalytic disinfection activity

Photocatalytic disinfection is one of the emerging green technologies for pathogenic microorganisms inactivation in water. Herein, a novel step-scheme Ag QDs/MoS2/Bi4O5Br2 heterojunction was successfully synthesized by a facile mechanical assembly route and applied in disinfection under visible light irradiation. Comparing to the pristine Bi4O5Br2, the Ag QDs/MoS2/Bi4O5Br2 heterojunction displays superior photocatalytic disinfection ability. In particular, the 1-Ag QDs/MoS2/Bi4O5Br2 heterojunction exhibits the most powerful disinfection capacity, which can completely inactivate the 7-log10 cfu/mL bacterial under 120 min irradiation. Additionally, the photocatalytic disinfection mechanism was intensively investigated with several techniques, such as biological macromolecules electrophoresis, fluorescent staining, and EPR. In this system, the h+, ·OH, and ·O2− are the major reactive species that led to the broken of the cell membrane, leakage of intracellular biomolecules and final death of bacteria. Additionally, the enhanced photocatalytic disinfection ability of 1-Ag QDs/MoS2/Bi4O5Br2 heterojunction is attributed to the improved light capture ability, efficient migration and transfer of photogenerated charge carriers and larger specific surface area. This work provides a novel approach to design step-scheme Bi4O5Br2-based heterojunction for pathogenic bacteria disinfection with abundant solar light.

Effects of canopy spectral composition on growth and photosynthetic fluorescence characteristics of Pinus koraiensis and Quercus mongolica seedlings

We investigated the responses of leaf and individual traits, growth, and fluorescence characteristics of seedlings of two dominant species of broad-leaved Korean pine forest in Changbai Mountain, i.e., Pinus koraiensis and Quercus mongolica, to five spectrum-attenuation treatments. Results showed that the architecture and growth of P. koraiensis and Q. mongolica seedlings were mainly regulated by ultraviolet B (UV-B) radiation and blue light. The attenuation of blue light significantly decreased leaf area ratio and relative growth rate of two species. The attenuation of UV-B radiation significantly increased leaf area ratio and relative growth rate of P. koraiensis seedlings by 41.8% and 47.7%, respectively, and significantly decreased plant height, total leaf area, and biomass accumulation of Q. mongolica seedlings. Furthermore, the attenuation of UV-B radiation significantly decreased the fluorescence regulation ability of two tree seedlings, with lower magnitude of P. koraiensis than Q. mongolica. The non-regulatory quantum yield (ΦNO) of P. koraiensis increased by 31.6%, and the ΦNPQ/ΦNO ratio, an indicator for photosynthetic fluorescence regulation ability, decreased by 37.5%. These results suggested that those two species might have evolved adaptation strategies to changes in canopy spectral compositions of their respective habitats. Q. mongolica seedlings tended to improve light capture ability through rapid morphological responses, while P. koraiensis seedlings preferred to increase carbon assimilation efficiency by adjusting fluorescence characteristics.

Mechanistic study of two-dimensional CrS2/Sc2CF2 direct Z-scheme heterojunction as the solar-driven water-splitting photocatalyst

Direct Z-scheme based on biomimetic artificial photosynthesis is a promising strategy to enhance photocatalytic activity. The search for direct Z-scheme photocatalysts is imperative, and the photocatalytic efficiency is mainly influenced by the separation rate of photogenerated electron–hole (e--h+) pairs and the light capture ability. Herein, a two-dimensional (2D) van der Waals (vdW) heterostructure consisting of a monolayer of CrS2 and Sc2CF2 is predicted based on density functional theory (DFT) as a promising direct Z-scheme photocatalyst for water splitting. The CrS2/Sc2CF2 heterojunction possesses a large energy band interleaving arrangement and a small interlayer band gap, and the orientation of the built-in electric field promotes interlayer carrier complexes, with electrons and holes localized at the highest redox energy level, respectively. In addition, the CrS2/Sc2CF2 heterojunction possesses a high overpotential driving force and excellent light harvest ability. Our calculations indicate that the CrS2/Sc2CF2 heterojunction is a promising new photocatalyst.

Highly efficient photodegradation of ciprofloxacin by dual Z-scheme Bi2MoO6/GQDs/TiO2 heterojunction photocatalysts: mechanism analysis and pathway exploration

There is a high demand for photocatalysts that can efficiently degrade antibiotics; however, there are challenges in technological development related to charge transfer and light capture ability. In this study, ternary Bi2MoO6/GQDs/TiO2 (denoted as BGT; GQDs refer to graphene quantum dots) heterojunction photocatalysts with high ciprofloxacin (CIP) photodegradation efficiency were successfully prepared. BGT with a 0.20 mL GQD dispersion solution (BGT-2) exhibited the highest CIP photodegradation efficiency (90.21 %). The rate constant of BGT-2 was 15.49 × 10−3 min−1, which was 4.01, 4.16, and 9.22 times higher than those of Bi2MoO6/TiO2 (3.86 × 10−3 min−1), Bi2MoO6 (3.72 × 10−3 min−1), and TiO2 (1.68 ×10−3 min−1), respectively. The degradation efficiencies of amoxicillin and tetracycline hydrochloride were 78.98 % and 92.49 %, respectively. The effects of pH values, water sources, and inorganic anions on CIP degradation were systematically explored. In addition, three environmentally friendly degradation pathways were proposed based on liquid chromatography-mass spectrometry (LC-MS) results and the toxicity evaluation of the various intermediates. Testing the optical and electrochemical properties of the catalysts showed that the synthesized dual Z-scheme heterojunctions can significantly improve the light capture ability and reduce the photogenerated electron-hole recombination rate, effectively addressing the challenges encountered with the use of photocatalysts.

Few-layer porous carbon nitride anchoring Co and Ni with charge transfer mechanism for photocatalytic CO2 reduction

The low specific surface area and low charge transfer efficiency of conventional graphite carbon nitride (g-C3N4) are the main obstacles to its application in photocatalytic CO2 reduction. In this paper, graphite carbon nitride was protonated by phosphoric acid (H3PO4), and a new few-layer porous carbon nitride was prepared by intercalation polymerization with doping bimetal in the cavity of g-C3N4. Under visible light irradiation, the CO formation rate of Co/Ni co-doped g-C3N4 can reach 13.55 μmol g−1 h−1, which was 3.9 times higher than that of g-C3N4 (3.49 μmol g−1 h−1). The density functional theory (DFT) calculations showed that the addition of Co and Ni in the cavity of g-C3N4 can induce bimetallic synergistic regulation of the electronic structure, thus improving the separation efficiency of charges and visible light capture ability of g-C3N4. Our work has great reference value for designing and synthesizing novel bimetallic co-doped g-C3N4 photocatalytic materials.

Construction of oxygen defective ZnO/ZnFe2O4 yolk-shell composite with photothermal effect for tetracycline degradation: Performance and mechanism insight

Oxygen vacancy induced photothermal effect is of great significant but lack of adequate attentions for environmental remediation. In this paper, green recyclable ZnO/ZnFe2O4 with oxygen vacancy was prepared by a solvothermal-calcination method. The UV-vis light capture ability of ZnO/ZnFe2O4 microspheres is improved with the multiple light reflections due to the yolk-shell structure, and the oxygen vacancy expands the absorption range of photocatalyst and enhances photothermal conversion. The optimized photocatalyst can heat the solution from room temperature to 70 °C within 60 min of visible light illumination, and the light to heat conversion efficiency is achieved by 61.3%. Compared with the degradation efficiency at 20 °C, photothermal catalysis achieves a stable degradation in 80 min, and the degradation efficiency is increased by 41.5%. This can be attributed to the fact that light induced thermal energy accelerates the migration of electrons and holes, and promotes the diffusion of free radicals by heating active centers in situ. The active species contributing to the degradation, in order of importance, are the superoxide radical, hydroxyl radical, hole and electron. The light-to-thermal assisted photocatalysis with ZnO/ZnFe2O4 provides a new sight for the pollution control in the future practical applications.

Preparation of CdS-P25/ZIF-67 composite material and its photocatalytic CO2 reduction performance

Commercial TiO2 (P25) is a potentially promising catalyst for photocatalytic CO2 reduction. Nonetheless, the inefficient light capture ability and egregious charge recombination restrict its further utilization. In this work, CdS and P25 are incorporated to form the composite CdS-P25, which is further immobilized on the surface of a copper-based organic metal framework (MOF), ZIF-67, so as to establish a ternary hybrid CdS-P25/ZIF-67 via a facile hydrothermal method. On the basis of the enhancement in light absorption resulted from the formation of CdS-P25, the incorporation of ZIF-67 further prolongs the light absorption edge of CdS-P25/ZIF-67, up to 552 nm. In addition, the introduction of ZIF-67 with the dual Z-Scheme system constructed could significantly suppress the charge recombination, as revealed by the transient photocurrent value of CdS-P25/ZIF-67, which is 3.47 μA cm−2, about 20.4 times than that of CdS-P25. Accordingly, the photocatalytic assessment of CdS-P25/ZIF-67 also presents a significantly amelioration in CO2 reduction reaction (CO2RR) in comparison with either CdS-P25 or ZIF-67, giving 1.58 μmol h−1 CH4 and 1.49 μmol h−1 CO production. Our work sheds light on the investigation of efficacious construction of P25 based hybrids for light-driven photocatalysis.

Controllable synthesis of a sponge-like Z-scheme N,S-CQDs/Bi2MoO6@TiO2 film with enhanced photocatalytic and antimicrobial activity under visible/NIR light irradiation

Multifunctional photocatalytic surfaces for pollutant degradation and antimicrobial application are often in high demand, however they confront many challenges in charge transfer and light capture ability. In this work, a sponge-like N,S-CQDs/Bi2MoO6@TiO2 film was constructed via hydrothermal technique aiming to solve above problems. As a result, the ternary film showed enhanced photocatalytic efficiency under visible and near-infrared (NIR) light, in which 85.8% and 44.6% of ciprofloxacin (CIP) were degraded after 240 min irradiation with visible and NIR light, respectively. Moreover, the composite film effectively realized photocatalytic sterilization of gram-positive B. subtilis and gram-negative E. coli under visible light irradiation. The bacterial colony decreased significantly from 7.56-log to 1-log cfu/mL after adding the ternary film within 1.5 h. The enhanced photocatalytic efficiency was closely related to both introduction of surface-functional N,S-CQDs and the construction of N,S-CQDs/Bi2MoO6@TiO2 Z-scheme system, in which the transfer efficiency of photoinduced carriers and the light absorption property were significantly improved. We consider that the N,S-CQDs/Bi2MoO6@TiO2 film is promising for the degradation of refractory pollutants and antimicrobial application under visible/NIR light irradiation. The relatively convenient recycling property and excellent photocatalytic performance of the N,S-CQDs/Bi2MoO6@TiO2 film are beneficial for industrial applications.

Dual-Functional Photocatalysis for Cooperative Hydrogen Evolution and Benzylamine Oxidation Coupling over Sandwiched-Like Pd@TiO2 @ZnIn2 S4 Nanobox.

Photocatalytic hydrogen evolution (PHE) over semiconductor photocatalysts is usually constrained by the limited light-harvesting and separation of photogenerated electron-hole pairs. Most of the reported systems focusing on PHE are facilitated by consuming the photoinduced holes with organic sacrificial electron donors (SEDs). The introduction of the SEDs not only causes the environmental problem, but also increases the cost of the reaction. Herein, a dual-functional photocatalyst is developed with the morphology of sandwiched-like hollowed Pd@TiO2 @ZnIn2 S4 nanobox, which is synthesized by choosing microporous zeolites with sub-nanometer-sized Pd nanoparticles (Pd NPs) embedded as the sacrificial templates. The ternary Pd@TiO2 @ZnIn2 S4 photocatalyst exhibits a superior PHE rate (5.35mmol g-1 h-1 ) and benzylamine oxidation conversion rate (>99%) simultaneously without adding any other SEDs. The PHE performance is superior to the reported composites of TiO2 and ZnIn2 S4 , which is attributed to the elevated light capture ability induced by the hollow structure, and the enhanced charge separation efficiency facilitated by the ultrasmall sized Pd NPs. The unique design presented here holds great potential for other highly efficient cooperative dual-functional photocatalytic reactions.

Active site regulated Z-scheme MIL-101(Fe)/Bi2WO6/Fe(III) with the synergy of hydrogen peroxide and visible-light-driven photo-Fenton degradation of organic contaminants.

Water pollution control is one of the major challenges currently faced. With the development of photocatalytic technology, an increasing number of new and efficient catalysts have been developed, but most of the catalysts have limited light capture ability and catalytic degradation efficiency. Therefore, in this work, hydrogen peroxide was further introduced to establish a photo-Fenton system to improve the photocatalytic effect by constructing a Z-scheme, and the degradation ability of the catalyst was maximized. Moreover, we successfully adhered bismuth tungstate nanosheets onto the surface of a MIL-101(Fe) framework and changed the number of active sites with iron ions of different doping amounts. We found that the number of active sites in the photo-Fenton system does not increase linearly, but increases and decreases regularly, which is similar to the change in band structure after doping. In addition, the results of the radical scavenger experiment and electron paramagnetic resonance (EPR) revealed that both hydroxide radical (˙OH) and superoxide radical (˙O2-) participated in methylene blue (MB) degradation, of which ˙OH was the main active species for pollutant degradation. Based on high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis, the possible degradation pathways were proposed. We believed that this work will provide insights into the heterojunction photo-Fenton system.

Systematic investigating on the broadband solar absorption and photo-thermal conversion performance of TiN@rGO plasmonic nanofluids

Strong solar capture and high heat transfer are extremely vital for designing solar-to-heat absorber to improve photo-thermal conversion efficiency in direct absorption solar collectors (DASCs). In this paper, the plasmonic nanofluids containing reduced graphene oxides (rGO) decorated with titanium nitride (TiN) nanoparticles were prepared. Their superior solar-thermal conversion efficiency and heat transfer property was based on the synergy between the Localized Surface Plasmon Resonances (LSPR) effect of TiN and the high thermal conductivity of rGO. The optical properties of plasmonic nanofluids were investigated with the concentration and penetration depth, which indicated that the existence of TiN on graphene could improve the light-capture ability. The results indicated that the TiN@rGO plasmonic nanofluids could be used for DASCs applications, even under the low mass concentrations. Specifically, the maximum photo-thermal conversion efficiency of the plasmonic nanofluids was 66.74% at 40 ppm concentration, which was about 23% higher than that of pure water. And, the experimental results show that the photothermal conversion efficiency will be reduced if the nanofluid concentration is higher than the optimal concentration. This work exhibited the potential application of plasmonic-graphene nanofluids in DASCs. • Hybrid nanofluids containing TiN nanoparticle and rGO nanosheets were prepared. • The photo-thermal potency promoted by the synergistic effects between rGO and TiN nanoparticles. • The plasmonic nanofluid could realize both broad spectrum absorption and high thermal conductivity. • A collector solar-to-heat efficiency of 66.74% is achievable for 40 ppm TiN@rGO nanofluid.