Full-spectrum Light Research Articles

Preparation of ZnO p-n homojunction nanorod via nitrogen ion injection coupled with Au induced SPR effect for enhanced photoelectrochemical water splitting

The photoelectrochemical (PEC) water splitting, which employs catalytic semiconductors to convert solar energy into hydrogen, is a promising approach for achieving securer and sustainable energy supply. Nanostructured ZnO have exhibited excellent PEC properties but the bottlenecks of limited visible-light response and poor electron-hole separation hindered their applications. In this work, nitrogen ions were injected into dense ZnO nanoarrays, which was hydrothermally grown on Au-NPs sputtered ITO substrate. The injected nitrogen preferably occupied oxygen vacancies in pristine ZnO, leading to the in-sit transition of p-ZnO and formation of p-n homojunctions. Benefiting from the surface plasmon resonance effect of Au and the internal electric field (IEF) of p-n homojunctions, full-spectrum light absorption and effective cross-interface carrier separation was achieved. The photocurrent density and hydrogen production rate of injected photoelectrode reaches 2.38 mA cm−2 and 4.56 mM cm−2 h−1, which is 21.64 and 7.35 times higher than that of pure-ZnO respectively. This PEC enhancement was attributed to the uniformly sputtered Au coupled with ZnO p-n homojunctions, which synergistically boosted light harvesting efficiency and suppress carrier recombination. This work contributes to the rational design of PEC photoelectrode via combining full-spectrum light absorption promoter with p-n homojunction induced IEF to harvest solar energy into chemical forms.

Synergistic photothermal-thermoelectric-photovoltaic energy generation via a transparent spectral modulating solar module

The efficiencies of photovoltaic (PV) and thermoelectric (TE) have been limited by the intrinsic materials properties. In solar applications, PV utilizes the shorter wavelength end of the solar spectrum while its longer portion (IR) can be photothermally (PT) converted to heat by special nano structures for TE electricity generation. We have developed spectral modulating nano systems made of Fe3O4@Cu2-XS nanoparticles and chlorophyllin capable of synergistic PT-TE-PV solar harvesting and energy generation. In this system, solar light is harvested through the transparent photothermal spectral modulator (TPSM) and segregated into different wavelengths: the IR is absorbed to photothermally heat up the TE hot end for the required thermoelectric temperature span; the UV/visible is directed to PV with reduced IR for significantly reduced heating, thus enhanced power conversion efficiency (PCE). Upon removal of IR, the PV surface temperature can be lowered from 86.9 ℃ to 65 ℃ after 120 min solar irradiation, resulting in PCE increase from 16.3 % (dropped from 25.1 % at 0 min) to 19. 4 %. A PT − TE − PV solar energy module (PTPSEM) is designed based on TPSM to synergistically generate energy by separately utilizing the full spectrum of solar light. Using the same solar light source, while generating electricity via PV, an additional 2.4 % is gained by a series of commercial thermoelectric generators (TEG), adding up to a total of 21. 8 % system efficiency which significantly exceeds the average efficiency of the commercial silicon PV panel used in this study. The spectral modulation mechanism through TPSM is identified based on the optical behaviors of chlorophyllin and Fe3O4@Cu2-XS. Also discussed is the design concept of PTPSEM.

Photoluminescence performance of BaAl2O4:Eu2+ cyan phosphor ceramics

Ba1−xAl2O4:xEu2+ (x = 0.005–0.1) cyan phosphor ceramics have been fabricated by high-temperature vacuum sintering technology. Under excitation of 365 nm near ultraviolet (NUV) light, a broad emission band with an emission peak at 497 nm can be obtained. White light-emitting diodes (w-LEDs) have been encapsulated by Ba0.9Al2O4:0.1Eu2+ phosphor ceramics, CaAlSiN3:Eu2+ phosphors in glass, and NUV-LED chips. When the w-LEDs have been driven by 300 mA electricity, the obtained white light shows a correlated color temperature of 5050 K and color rendering index of 75, which indicates that the cyan BaAl2O4:Eu2+ ceramic phosphors have potential application in the field of full-spectrum lighting.

Dynamic spectrum lighting impact on plant morphology and cannabinoid profile of medical and recreational cannabis – A novel leapfrog strategy towards shaping the future of horticulture lighting

It is well documented that the light is the main factor or one of the factors influencing plant growth and development. The role of light spectral quality in meeting the specific needs during a plant’s developmental stages (germination, vegetative and flowering) has not been well defined and investigated. The objective of this study was to investigate the impact of light spectral quality on the growth and yield of cannabis plants during different developmental stages. Cannabis plants were grown in a controlled environment with distinct light spectral quality treatments applied at different growth stages. The plants were monitored for morphological responses and cannabinoid content. This study evaluated the hypothesis that, just like the dietary needs of human beings change with age, plants' nutritional and lighting requirements change with their growth stage. Plants' metabolic responses can be triggered and maximized by giving them the right light spectrum and intensity as the plant undergoes the development phases of its cycle. The results showed that the dynamic spectrum lighting led to a 33 % increase in yield and significant improvement in cannabinoid content. These findings challenge the conventional belief that a fixed full-spectrum white light is optimal for plant growth and development. Furthermore, it is hypothesized that plant development stages can be divided into more than the existing three conventional stages. This optimization resulted in the highest yield and energy savings under the dynamic spectrum. These novel findings will have important implications in motivating plant scientists to go beyond the conventional norm and could pave the way for a paradigm shift towards dynamic spectrum lighting, thus taking a leapfrog jump in shaping the future of horticulture lighting.

Halloysite-based aerogels for efficient encapsulation of phase change materials with excellent solar energy storage and retrieval performance

Developing low-cost composite phase change materials with good shape stability, excellent mechanical strength, high thermal conductivity, large encapsulation ratio, strong light absorption and eminent solar-to-thermal conversion capacity is of great challenge to solve the scaling-up related issues of organic solid–liquid phase change materials during the utilization of solar energy. In this work, halloysite/poly(vinyl alcohol) and halloysite/poly(vinyl alcohol)/reduced graphene oxide aerogels with rich three-dimensional honeycomb structure were prepared by a freezing and freeze-drying method, which can significantly promote the encapsulation ratio of lauric acid in the pores of both aerogels and halloysite nanotube. Halloysite nanotube with high aspect ratio can improve the compressive strength of the aerogels and shape stability of the composite phase change materials, while reduced graphene oxide can reinforce the thermal conductivity and light absorption ability. After encapsulation of lauric acid, the halloysite/poly(vinyl alcohol) 9:1 and halloysite/poly(vinyl alcohol)/reduced graphene oxide 9:1 phase change composites demonstrate extraordinarily high latent heat of 195.4 J/g and 197.0 J/g, respectively, leading to high encapsulation ratios of 97.2 % and 98.1 % respectively, accompanied by good chemical and thermal stability over 300 thermal cycles. The thermal conductivity of lauric acid@halloysite/poly(vinyl alcohol)/reduced graphene oxide is remarkably elevated to 0.343 W/m∙K, exceeding 39.4 % that of pure lauric acid (0.246 W/m∙K). Besides, the lauric acid@halloysite/poly(vinyl alcohol)/reduced graphene oxide realizes a conspicuous solar-to-thermal conversion with solar absorption capacity of 95 % throughout the full spectrum of solar light. The marvelous improvement in the solar-to-thermal conversion efficiency can be attributed to thermally conductive interconnected network of halloysite nanotube and reduced graphene oxide. Thus, lauric acid@halloysite/poly(vinyl alcohol)/reduced graphene oxide and lauric acid@halloysite/poly(vinyl alcohol) are tentatively used in the catalytic hydrolysis of ammonia borane, and they can efficiently harvest, convert and store solar energy in the form of thermal energy and release it for the reaction, which obviously accelerates the extent of reaction with turnover frequency increasing from 29.50 (molH2/molcatalyst·min) at 25 °C to 59.18 and 41.74 (molH2/molcatalyst·min) under the heating of solar energy stored lauric acid@halloysite/poly(vinyl alcohol)/reduced graphene oxide and lauric acid@halloysite/poly(vinyl alcohol), respectively. This work paves a way for fabricating halloysite-based aerogel and composite phase change materials for thermal/solar energy saving application.

W18O49/MnWO4 heterojunction for highly efficient photocatalytic reduction of CO2 under full spectrum light

Solar-energy-driven CO2 reduction for chemical reagents production, such as CH3OH, CH4 and CO, has tremendous potential for carbon neutrality in the energy industries. However, the low reduction efficiency limits its applicability. Herein, W18O49/MnWO4 (WMn) heterojunctions were prepared via one-step in-situ solvothermal process. Through this method, W18O49 tightly combined with the surface of MnWO4 nanofibers to form nanoflower heterojunction. It was found that under full spectrum light irradiation for 4 h, the yields of photoreduction of CO2 to CO, CH4 and CH3OH by 3–1 WMn heterojunction were 61.74, 71.30 and 18.98 μmol/g, respectively, which were 2.4, 1.8 and 1.1 times that of pristine W18O49, and ca.20 times that of pristine MnWO4 towards CO production. Furthermore, even in the air atmosphere, the WMn heterojunction still performed excellent photocatalytic performance. Systematic investigations demonstrated that the catalytic performance of WMn heterojunction was improved by superior light utilization and more efficient photo-generated carrier separation and migration as compared with W18O49 and MnWO4. Meanwhile, the intermediate products of the photocatalytic CO2 reduction process were also studied in detail by in-situ FTIR. Therefore, this study provides a new way for designing high efficiency of heterojunction for CO2 reduction.

Effects of light therapy on sleep/wakefulness, daily rhythms, and the central orexin system in a diurnal rodent model of seasonal affective disorder

BackgroundBright light therapy (BLT) is the first-line treatment for seasonal affective disorder. However, the neural mechanisms underlying BLT are unclear. To begin filling this gap, the present study examined the impact of BLT on sleep/wakefulness, daily rhythms, and the wakefulness-promoting orexin/hypocretin system in a diurnal rodent, Nile grass rats (Arvicanthis niloticus). MethodsMale and female grass rats were housed under a 12:12 h light/dark cycle with dim light (50 lx) during the day. The experimental group received daily 1-h early morning BLT (full-spectrum white light, 10,000 lx), while the control group received narrowband red light for 4 weeks. Sleep/wakefulness and in-cage locomotor activity were monitored, followed by examination of hypothalamic prepro-orexin and orexin receptors OX1R and OX2R expression in corticolimbic brain regions. ResultsThe BLT group had higher wakefulness during light treatment, better nighttime sleep quality, and improved daily rhythm entrainment compared to controls. The impact of BLT on the orexin system was sex- and brain region-specific, with males showing higher OX1R and OX2R in the CA1, while females showed higher prepro-orexin but lower OX1R and OX2R in the BLA, compared to same-sex controls. LimitationsThe present study focused on the orexin system in a limited number of brain regions at a single time point. Sex wasn't a statistical factor, as male and female cohorts were run independently. ConclusionsThe diurnal grass rats show similar behavioral responses to BLT as humans, thus could be a good model for further elucidating the neural mechanisms underlying the therapeutic effects of BLT.

In-situ constructed indirect Z-type heterojunction by plasma Bi and BiO2-X–Bi2O2CO3 co-modified with BiOCl@Bi–MOF for enhanced photocatalytic efficiency toward antibiotics

Currently, the chemical properties of metal–organic frameworks (MOFs) can be fully exploited by combining inorganic semiconductors with MOFs to improve their narrow light absorption range and high carrier separation efficiency. Therefore, in this paper, indirect Z-type multicomponent Bi/BiO2-X–Bi2O2CO3/BiOCl@Bi–MOF heterojunction with plasma Bi and BiO2-X–Bi2O2CO3 co-modified with BiOCl@Bi–MOF were successfully prepared through combining hydrothermal and photodeposition methods using BiOCl@Bi–MOF composites as active carriers. The ability to remove chlortetracycline (CTC) with Bi/BiO2-X–Bi2O2CO3/BiOCl@Bi–MOF was investigated by modulating the factors, such as photodeposition time, presence or absence of MOF structure, different water source, and different inorganic salts. In the CTC degradation experiments, the optimized Bi/BiO2-X–Bi2O2CO3/BiOCl@Bi–MOF-10-0.3 composite showed the best photocatalytic degradation efficiency (94.6%) within 90 min of full-spectrum light illumination. Its corresponding first-order kinetic rate constant (0.0315 min−1) was 2.5 and 1.6 times higher than those of MOF-free structural composites Bi/BiO2-X–Bi2O2CO3/BiOCl-10-0.3 and BiOCl@Bi–MOF, respectively. The increased photocatalytic activity is attributed to the synergistic effect between the MOF structure, metal Bi, BiO2-X–Bi2O2CO3, and BiOCl@Bi–MOF carrier. By combining the results of active species capture experiments, electron spin resonance techniques (EPR), and photoelectrochemical experiments, we have deduced a possible indirect Z-type heterojunction photocatalytic mechanism between Bi, BiO2-X–Bi2O2CO3 and BiOCl@Bi–MOF. The possible photocatalytic degradation pathways and products of CTC were deduced by combining liquid chromatography-mass spectrometry (LC-MS). This work supplies valuable guidance for preparing metal nanoparticles/semiconductor/MOFs with an indirect Z-type heterojunction photocatalyst for the repair of natural CTC wastewater.

Anionic Regulation toward Bi3+ Selective Occupation for Full-Spectrum White Light Emission.

An activator's selective occupation of a host is of great significance for designing high-quality white light-emitting diode phosphors, while achieving a full-spectrum single-phase white light emission phosphor is challenging. In this study, a boron phosphate solid-solution Na2Y2(BO3)2-x(PO4)xO:0.005 Bi3+ (NYB2-xPxO:0.005 Bi3+) white phosphor was designed by selectively occupying Bi3+ activators in the mixed anionic groups. The substitutes of the anionic unit (BO3)3- by the (PO4)3- unit are supposed to force part of the Bi3+ ion to enter the Na lattice site, which produces an intense orange-red emission peaked at 590 nm. In parallel, spectral tuning from blue to white light and an internal quantum efficiency of 56.42% was obtained, and the thermal stabile luminescence intensity remains at 94.2% of the initial intensity after four heating-cooling cycles from 30 to 210 °C (luminescent intensity is 83.6% of room temperature (RT) at 150 °C, with excellent thermal stability and recovery performance). Finally, an excellent color rendering index (Ra = 90.8 and R9 = 85) was demonstrated for white light-emitting diode devices using only an NYB1.5P0.5O:0.005 Bi3+ phosphor and a near-ultraviolet (n-UV) 365 nm LED chip. This work delves into the different selective occupancy of Bi3+ ions and explores a new avenue for the design of phosphors for full-spectrum white light emission.

Growth of Populus × euramericana Plantlet under Different Light Durations

Using full-spectrum LED lights, six light treatments of 11 h, 12 h, 13 h, 14 h, 15 h, and CK (greenhouse natural light) were designed to examine the response of Populus euramericana plantlets to light duration in the greenhouse. Every 15 days during the 150-day experiment, plantlet height (H), ground diameter (GD), number of nodes (NN), number of leaves (NL), and the relative chlorophyll content(SPAD) were measured. The response of plantlets to different light durations was demonstrated by establishing and screening growth models, and rhythm and relative chlorophyll content were statistically analyzed. The light duration had a significant effect on the H and GD of Populus euramericana, and their growth was positively correlated with light duration. The short full-spectrum LED lighting duration will affect the rhythm and prematurely halt the growth of H, but the GD will continue to expand. The Gomperz model has the best fitting effect for the growth of Populus euramericana plantlets under LED lighting, with all R2s values greater than 0.89. Long light duration has a greater growth potential, and the rapid growth lasts longer. The delay in the cessation of the increase in the NN was a result of the increased illumination time. Compared with natural light, LED light lessens the NL. Poplar plantlets will have a lower SPAD value if the light duration exceeds 14 h. In the process of growing plantlets in the greenhouse, both light quality and light duration should be considered. In actual production, a combination of natural and artificial light can improve efficiency.

Antiproliferative Effect of Essential Oil Obtained from Oregano (Lippia palmeri S. Watson) Leaves Grown in Hydroponics and LED Light.

Nowadays, light-emitting diodes (LED) provide an alternative source to sunlight with specific intensity and wavelength that promotes plant growth. The features offered by LED could also stimulate the production of secondary metabolites of pharmaceutical interest. This work analyzed the cultivation of oregano (Lippia palmeri S. Watson) in a floating root hydroponic system supplemented by full-spectrum LED artificial light. Growth indicators like height, diameter, number of shoots, and leaf length and width were measured. The essential oil (EO) composition from the leaves of wild and hydroponic conditions found thymol (41.8 %) as the main product for the former and carvacrol (47 %) in hydroponics. The antiproliferative activity of EOs on human colorectal cancer HCT-15 shows that 6.4 μg/ml for hydroponic and 7.4 μg/ml for the wild plant reduce more than 50 % the cell viability. Overall, this study indicates that hydroponic conditions and full spectrum LED modifies the composition of the EO of L. palmeri on compared with the wild plant, which effectively induces cell growth inhibition in human colorectal cancer.

Plant-Growth Promoting Microbes Change the Photosynthetic Response to Light Quality in Spinach.

In this study, the combined effect of plant growth under different light quality and the application of plant-growth-promoting microbes (PGPM) was considered on spinach (Spinacia oleracea L.) to assess the influence of these factors on the photosynthetic performance. To pursue this goal, spinach plants were grown in a growth chamber at two different light quality regimes, full-spectrum white light (W) and red-blue light (RB), with (I) or without (NI) PGPM-based inoculants. Photosynthesis-light response curves (LRC) and photosynthesis-CO2 response curves (CRC) were performed for the four growth conditions (W-NI, RB-NI, W-I, and RB-I). At each step of LRC and CRC, net photosynthesis (PN), stomatal conductance (gs), Ci/Ca ratio, water use efficiency (WUEi), and fluorescence indexes were calculated. Moreover, parameters derived from the fitting of LRC, such as light-saturated net photosynthesis (PNmax), apparent light efficiency (Qpp), and dark respiration (Rd), as well as the Rubisco large subunit amount, were also determined. In not-inoculated plants, the growth under RB- regime improved PN compared to W-light because it increased stomatal conductance and favored the Rubisco synthesis. Furthermore, the RB regime also stimulates the processes of light conversion into chemical energy through chloroplasts, as indicated by the higher values of Qpp and PNmax in RB compared to W plants. On the contrary, in inoculated plants, the PN enhancement was significantly higher in W (30%) than in RB plants (17%), which showed the highest Rubisco content among all treatments. Our results indicate that the plant-growth-promoting microbes alter the photosynthetic response to light quality. This issue must be considered when PGPMs are used to improve plant growth performance in a controlled environment using artificial lighting.

Design efficient energy transfer Ca2Al2SiO7: Bi3+, Eu3+ phosphors by cationic substitution for full-spectrum W-LED lighting

High lighting quality has become essential in indoor lighting with the continuous technological innovations in the illumination field. The existing mainstream white light implementation cannot completely cover the entire visible light area, whether it is a combination of a blue chip and YAG: Ce3+ (red gap and deep-blue gap) or a combination of an ultraviolet chip and three-color phosphor (cyan gap and deep-blue gap. This study uses Bi3+ as the luminescence center to obtain an efficient deep-blue emission phosphor through local lattice control (Internal Quantum Efficiency = 65%). Subsequently, a Bi3+-Eu3+ energy transfer system with a transfer efficiency of 97.15% was designed to obtain a double emission of deep-blue and red in Ca2Al2SiO7: 0.06Bi3+, 0.04Eu3+ (Internal Quantum Efficiency = 81%). The energy transfer between Bi3+-Eu3+ increases the emission integration intensity to 149% compared to single-doped Eu3+, and the CASO: 0.06Bi3+, 0.04Eu3+ thermal quenching resistance is excellent (3.8% integral strength loss at 425 K). Finally, 395 nm and 310 nm phosphor conversion (pc) W-LED devices with color rendering indexes of 84.2 and 91.6 were prepared by combining CASO: 0.06Bi3+, 0.04Eu3+ and commercially available phosphors, respectively. This result shows that these phosphors can be applied in full-spectrum white illumination.

Enhancement of Charge Separation and NIR Light Harvesting through Construction of 2D-2D Bi4 O5 I2 /BiOBr:Yb3+ , Er3+ Z-Scheme Heterojunctions for Improved Full-Spectrum Photocatalytic Performance.

Developing full-spectrum photocatalysts with simultaneous broadband light absorption, excellent charge separation, and high redox capabilities is becoming increasingly significant. Herein, inspired by the similarities in crystalline structures and compositions, a unique 2D-2D Bi4 O5 I2 /BiOBr:Yb3+ ,Er3+ (BI-BYE) Z-scheme heterojunction with upconversion (UC) functionality is successfully designed and fabricated. The co-doped Yb3+ and Er3+ harvest near-infrared (NIR) light and then convert it into visible light via the UC function, expanding the optical response range of the photocatalytic system. The intimate 2D-2D interface contact provides more charge migration channels and enhances the Förster resonant energy transfer of BI-BYE, leading to significantly improved NIR light utilization efficiency. Density functional theory (DFT) calculations and experimental results confirm that the Z-scheme heterojunction is formed and that this heterojunction endows the BI-BYE heterostructure with high charge separation and strong redox capability. Benefit from these synergies, the optimized 75BI-25BYE heterostructure exhibits the highest photocatalytic performance for Bisphenol A (BPA) degradation under full-spectrum and NIR light irradiation, outperforming BYE by 6.0 and 5.3 times, respectively. This work paves an effective approach for designing highly efficient full-spectrum responsive Z-scheme heterojunction photocatalysts with UC function.

Facet tailoring and Cu doping promoted photo-assisted peroxymonosulfate activation by oxygen-deficient α-MnO2 for efficient mineralization of bisphenol a

Revealing the synergistic mechanism between facets and metal doping during catalytic processes is an efficient approach to improve the catalytic performance. Herein, the synergetic effects between Cu doping and crystal facets over α-MnO2 on the peroxymonosulfate (PMS) activation towards bisphenol A (BPA) degradation under full-spectrum light irradiation were studied in details for the first time. The Cu-doped α-MnO2 with (100), (110), and (310) facets were synthesized by hydrothermal method. The Cu-doped (110)/PMS/Light system presented the highest BPA removal efficiency with high 1O2 generation and selectivity, being superior over the Cu-doped (100), Cu-doped (310) and pristine (110) counterparts. The corresponding mechanism showed that Cu doping for α-MnO2 enhanced the absorption of light, the formation of oxygen vacancies and electronic conductivity as well as PMS activation, especially for the (110) facet, as compared to the (100) and (310) facets. In addition, density functional theory (DFT) calculations and characterizations indicated that the synergetic effect between facet and oxygen vacancies played an important role in 1O2 generation. Moreover, oxygen vacancies accelerated the complexation of PMS with surface Mn(IV) and improved the generation of 1O2, different to that due to Mn(III). Toxicity assessment showed that BPA was partially decomposed into highly toxic intermediates during the degradation process. However, Cu doping and light synergistically improved the mineralization rate of pollutants, removing 95% of the total organic carbon (TOC) and reducing the toxicity of the intermediates. The ultrahigh TOC removal was attributed to the joint effect of 1O2, O2− and electron transfer. This work therefore provides an efficient and highly selective PMS catalyst for 1O2 generation, and reveals the synergistic mechanism between metal doping and crystal facets of the catalyst in advanced oxidation processes.

Facile synthesis of a novel recyclable dual Z-scheme WO3/NiFe2O4/BiOBr composite with broad-spectrum response and enhanced sonocatalytic performance for levofloxacin removal in aqueous solution

In recent decades, the overuse and misuse of antibiotics have caused serious harm to aquatic ecosystems. This work successfully designed a unique recyclable WO3/NiFe2O4/BiOBr (WNB) composite with dual Z-scheme heterojunction to degrade levofloxacin (LEV) in aqueous solution. The results indicated that the as-prepared WNB composite displayed the greatest sonocatalytic activity for LEV degradation. In particular, WNB showed the highest LEV (at 10 mg/L) removal efficiency (97.97 %) within 75 min under ultrasonic irradiation. The significantly enhanced catalytic activity of WNB was attributed to the unique dual Z-scheme structure, which makes it easier for the transfer and the spatial separation of photo-generated electron-hole (e−-h+) pairs, and dramatically increases the carrier lifespan. Furthermore, the ternary composite comprises three different semiconductors from narrow to broad bandgap, which are suitable for harvesting full-spectrum light. The recycle experiments demonstrated the catalyst's excellent sonocatalytic stability and easy recovery, which is attributed to its magnetic property. Furthermore, based on the intermediates identified during the degradation process, a potential mechanism and pathway for LEV degradation were presented. This work provides a unique perspective on designing efficient sonocatalysts for environmental remediation.

Interfacially bonded Co-N boosts photocatalytic H2 evolution in a closely coupled CoFe2O4/g-C3N4 composite structure

To create hybrid composites for highly effective photocatalytic hydrogen evolution reactions, the photogenerated charge separation efficiency at the hybrid interface and the surface reaction kinetics at the reactive sites are key factors. In this work, CoFe hydroxide nanosheets prepared by dealloying were first mixed with graphitic carbon nitride (g-C3N4) to synthesize a CoFe2O4/g-C3N4 composite with strong Co-N bonds at the interface by a simple hydrothermal method. It was found that the presence of Co-N bonds between the components in the composites enhances the separation and transfer by photogenerated carriers at the composite interface. Furthermore, the presence of Co-N bonds enhanced the synergistic effect of the hybrid, which significantly boosts their photocatalytic performance in comparison to their counterparts. Under full-spectrum light, the composite photocatalyst has a greater efficiency of photocatalytic water H2 evolution (6.793 mmol/g−1·h−1) and exceptional stability when compared to pure g-C3N4 (0.236 mmol/g−1·h−1) and CoFe2O4 (0.088 mmol/g−1·h−1). Under visible irradiation, the photocatalytic activity of the composite (0.556 mmol/g−1·h−1) for H2 evolution increased by factors of 28.37 and 75.8 when compared to pure g-C3N4 and CoFe2O4, respectively.

Effect of light environment on prey consumption in two species of larval stomatopods, Gonodactylaceus falcatus (Forskål, 1775) and Gonodactylellus sp. (Stomatopoda: Gonodactylidae)

Abstract While adult stomatopod crustaceans are relatively well studied, understanding of larval stomatopod ecology is lacking, largely due to difficulties studying larvae in their natural habitat. This study investigated how light environment (i.e., spectral composition) and time of day affected prey consumption in two species of larval stomatopod, Gonodactylaceus falcatus (Forskål, 1775) and Gonodactylellus sp. Individual larvae were placed with 20 Artemia nauplii prey in feeding chambers treated to produce different light environments with respect to ultraviolet (UV) light: full spectrum light UV+, full spectrum UV–, and a dark control. Chambers were lowered to a depth of 3 m for 2 hours at three times of day (noon, twilight, and night) to test 1) if larval feeding rates changed at different times of day and 2) if UV vision was involved in prey capture. We found that light was important for successful feeding, with both species eating significantly more in lighted treatments than the dark controls during daytime experiments. Gonodactylellus sp. also had a significantly higher feeding rate at twilight in the UV+ treatment than in the dark control. Both species showed decreased consumption at night compared to daytime rates, and decreased consumption in all dark controls. This study is one of the first to examine how ecological conditions affect feeding behavior in larval stomatopods. Our results suggest that light is important for larval stomatopod feeding, with differences between species in daily feeding activity periods. There was also a difference in total consumption between the two species, with the slightly larger Gonodactylaceus falcatus consuming nearly double the prey items as Gonodactylellus sp. at peak feeding times. Follow up studies should incorporate a variety of prey types to test how feeding changes based on food source and density.

Photocatalytic reduction of CO2 by two-dimensional Zn-MOF-NH2/Cu heterojunctions

The two-dimensional (2D) Zn-MOF-NH2/Cu heterojunctions were prepared via in situ photodeposition of Cu NPs on the surface of 2D Zn-MOF-NH2. The 2D Zn-MOF-NH2/Cu (1 wt%) heterojunction exhibited the excellent photocatalytic activity with a CO production rate of 0.76 μmol/h under irradiation of full spectrum light only using H2O as a hole sacrificial agent, which is 16.2 and 2.7 times that of bulk Zn-MOF-NH2 and 2D Zn-MOF-NH2 nanosheets, respectively. This work provides an insight into design of a highly efficient 2D MOFs-based photocatalysts in catalytic CO2 reduction.

Near-infrared-featured broadband CO2 reduction with water to hydrocarbons by surface plasmon

Imitating the natural photosynthesis to synthesize hydrocarbon fuels represents a viable strategy for solar-to-chemical energy conversion, where utilizing low-energy photons, especially near-infrared photons, has been the ultimate yet challenging aim to further improving conversion efficiency. Plasmonic metals have proven their ability in absorbing low-energy photons, however, it remains an obstacle in effectively coupling this energy into reactant molecules. Here we report the broadband plasmon-induced CO2 reduction reaction with water, which achieves a CH4 production rate of 0.55 mmol g−1 h−1 with 100% selectivity to hydrocarbon products under 400 mW cm−2 full-spectrum light illumination and an apparent quantum efficiency of 0.38% at 800 nm illumination. We find that the enhanced local electric field plays an irreplaceable role in efficient multiphoton absorption and selective energy transfer for such an excellent light-driven catalytic performance. This work paves the way to the technique for low-energy photon utilization.