Excellent Light Absorption Ability Research Articles

Enhanced CO2 photoreduction by constructing BiOCl/NiS Schottky heterojunction with a giant internal electric field

Constructing Schottky junctions is a potent strategy for enhancing charge separation and charge dynamics, essential for optimizing the kinetics of efficient CO2 photoreduction reactions (CO2 RR). Yet, developing highly efficient Schottky heterojunction photocatalyst continues to be a formidable challenge. Here, we utilize two-step hydrothermal technology to prepare a BiOCl/NiS Schottky heterojunction with a powerful internal electric field (IEF) to accelerate the photo-conversion of CO2 to CO. Experimental results show that the charge separation efficiency and IEF strength of the BiOCl/NiS composite photocatalyst are 1.26 and 5.63 times those of BiOCl, respectively. In addition, the BiOCl/NiS composite sample has excellent light absorption ability. Under Uv–vis light irradiation, the BiOCl/NiS sample exhibits superior CO2 to CO photoreduction activity without any sacrificial agents, and a CO yield reaching 7.97 μmol⋅g−1⋅h−1, which is 2.97 times higher than that of BiOCl (2.68 μmol⋅g−1⋅h−1). This work provides a viable solution for designing efficient and stable Schottky junction composite materials.

Concurrent Mechanisms of Hot Electrons and Interfacial Water Molecule Ordering in Plasmon-Enhanced Nitrogen Fixation.

The participation of high-energy hot electrons generated from the non-radiative decay of localized surface plasmons is an important mechanism for promoting catalytic processes. Herein, another vital mechanism associated with the localized surface plasmon resonance (LSPR) effect, significantly contributing to the nitrogen reduction reaction (NRR), is found. That is to say, the LSPR-induced strong localized electric fields can weaken the intermolecular hydrogen bonds and regulate the arrangement of water molecules at the solid-liquid interface. The AuCu pentacle nanoparticles with excellent light absorption ability and the capability to generate strong localized electric fields are chosen to demonstrate this effect. The in situ Raman spectra and theoretical calculations are employed to verify the mechanism at the molecular scale in a nitrogen fixation process. Meanwhile, due to the promoted electron transfer at the interface by the well-ordered interfacial water, as well as the participation of high-energy hot electrons, the optimal catalyst exhibits excellent performance with an NH3 yield of 52.09 µg h-1 cm-2 and Faradaic efficiency (FE) of 45.82% at ─0.20V versus RHE. The results are significant for understanding the LSPR effect in catalysis and provide a new approach for regulating the reaction process.

Photocatalytic oxidative coupling of terminal alkynes with p-benzoquinone to diaryl ketones by the Cu(I)-PS-POM assembling system through synergistic effect

Photocatalytic C–C bonds formation is an effective approach to synthesize the significant drug intermediates diaryl ketones. Herein, a new polyoxometalate-based metal–organic framework (POMOF), CuW6–TPT, was synthesized by assembling an oxidation catalyst [W6O19]2− into photoactive MOF constructed by photosensitizer (PS) 4,6-tri(4-pyridyl)-1,3,5-triazine (TPT) and binuclear Cu(I) units. CuW6–TPT exhibits excellent light absorption ability and unique conductivity due to the coordination bond, strong π∙∙∙π interactions and H-bonding among Cu(I) ions, TPT moieties and [W6O19]2− in the defined spatial. The abundant exposed Cu(I) catalytic centres are conductive to activate phenylacetylene in situ formation Cu(I)-phenylacetylide, which then undergoes a reductive single electron transfer (SET) process to obtain the key intermediate Cu(II)-phenylactetylide for the Paterno-Buchi (2+2) cycloaddition with benzoquinone to form the labile Cu(II)-oxetane ring. It is a direct route to synthesize diaryl ketones with a hydroxyl group from simple starting materials such as terminal alkynes with p-benzoquinone.

Effect of slotting on the photothermal properties of silver nanopillars

Metal nanoparticles (MNPs) have attracted enormous research interest due to their excellent plasma properties. However, in the thermal utilization of solar energy, the narrowband absorption of MNPs limits their application. The investigation of MNP absorption through adjustment in the broadband spectrum holds significant scientific and practical implications. In this work, we study the effect of slotting on the light absorption and photothermal properties of silver nanopillars. The results show that the increase in the number of slots is beneficial to reduce scattering and improving the resonance absorption of silver nanopillar. Through the calculation of photothermal conversion efficiency, it is found that different slotting methods have different levels of improvement compared with silver nanopillars. The utilization of a combination of transverse and longitudinal slotting techniques leads to a 13 % enhancement in the photothermal conversion efficiency of silver nanopillars. The electric field distribution and temperature distribution at resonant wavelengths shows that the excellent light absorption ability of the slot nanopillars is caused by the “lightning rod” effect at the tip of the slit and the excitation of multiple plasmon resonances. The existence of slots is beneficial to compensate for the photothermal response of silver nanopillars in the near-infrared region. Our study proves that slotting helps enhance the application of silver nanopillars in solar thermal utilization.

HOF-101-based dual-mode biosensor for photoelectrochemical/electrochemiluminescence detection and imaging of oxytetracycline

A unique hydrogen-bonded organic frameworks (HOF-101)-based photoelectrochemical (PEC) and electrochemiluminescence (ECL) dual-mode biosensor using polydopamine nanoparticles (PDAs) as quencher was constructed for ultrasensitive detection and imaging of oxytetracycline (OXY). In particular, HOF-101 was a superior ECL material and can be observed with the naked eye. Furthermore, it also had outstanding PEC signal, so HOF-101 was a new dual-signal material with excellent performance, thus it was explored to realize dual-mode detection. As the main component of natural melanin, PDAs not only had good biocompatibility, but also contained rich functional groups on the surface. Additionally, PDAs had excellent light absorption ability and poor conductivity, which made it the excellent photoquencher. In this work, PDAs were introduced on the surface of HOF-101 to quench its ECL and PEC signals by using the dual-aptamer sandwich method, achieving ultrasensitive detection of antibiotic OXY. Particularly for ECL detection, HOF-101 was firstly used to visually detect OXY. The detection range can reach 0.1 pM-100 nM, and the limit of detection (LOD) can reach 0.04 pM. This work showed a great contribution to the development of new ECL-PEC materials and ECL visualization analysis, which had outstanding application potential in the fields of food safety and biochemical analysis.

Design and Fabrication of Carbon Dots/Semiconductor Photocatalysts with Superior Photocatalytic Activity: A Review

AbstractSemiconductor photocatalysts are being recognized as innovative materials for enhancing water quality and environmental optimization. Nevertheless, the limited activity and quick electron–hole pair recombination under visible light have hindered their widespread use in photocatalysis. Nanomaterials based on carbon dots (CDs) show promising applications due to their excellent light absorption ability. Notably, CDs/semiconductor photocatalysts have emerged as advanced photocatalytic materials. This review summarizes strategies to improve the performance of conventional semiconductor photocatalysts by incorporating CDs. These include TiO2, g‐C3N4, Bi‐based, Cu2O, and ZnO photocatalysts. Various effective synthesis routes for composites are discussed, including morphology optimization, heteroatom doping, heterojunction building, and creation of polymeric hybrids. Ultimately, the challenges and future prospects of CDs/semiconductor photocatalysts are discussed.

A porous polyacrylonitrile (PAN)/covalent organic framework (COF) fibrous membrane photocatalyst for highly efficient and ultra-stable hydrogen evolution

Photocatalytic water splitting has been regarded as one of the most promising technologies to generate hydrogen as an ideal energy carrier in the future. However, most of the experience for such process are derived from the researches based on the suspension powder photocatalysts under a stirring condition and a practical scaling application is urgently calling for the high-efficient panel reactors based on the membrane photocatalysts. Herein, we develop a new series of flexible and ultrastable membrane photocatalysts through a controllable growth of covalent organic framework (COF) photocatalysts on the polyacrylonitrile (PAN) electrospun fiber membrane. Multiple characterization techniques verify the successful anchoring of the COF-photocatalysts on the PAN fibers, forming a three-dimensional porous PAN/COF membrane photocatalyst with excellent light absorption ability, high specific surface area, and good hydrophily. As a result, the optimized PAN/COF membrane photocatalyst exhibits excellent hydrogen evolution rate up to 1.25 mmol g−1h−1 under visible-light irradiation without stirring, which is even higher than that of the corresponding suspension COF-powder photocatalyst with stirring. In particular, the PAN/COF membrane photocatalyst demonstrates a much more superior hydrogen evolution stability and also a much better recyclability. This study gives some experience for the practical scaling application of solar-driven water splitting.

Bifunctional TiO2/COF S-scheme photocatalyst with enhanced H2O2 production and furoic acid synthesis mechanism

Coupling photocatalytic H2O2 evolution with simultaneous furfuryl alcohol oxidation can avoid the slow water oxidation reaction and fully utilize photogenerated carriers to produce valuable chemicals. Herein, a COF (denoted as BTTA) was synthesized by the Schiff-base condensation and in-situ grown on the surface of TiO2 nanofibers. The resultant TiO2/BTTA composite has a large interface and a short carrier migration distance. Furthermore, the porous and ultrathin BTTA layers endow the composites abundant active sites and excellent light absorption ability. Remarkably, a H2O2-evolution rate of 740 μmol L−1 h−1 and a furoic alcohol conversion of 96 % are achieved. In-situ irradiated X-ray photoelectron spectroscopy and electron spin resonance confirm the S-scheme carrier transfer mechanism, which spatially separates photogenerated carriers with strong redox power. This work opens a new door to the rational design of S-scheme photocatalysts for economic and green photosynthesis of H2O2 and organic compounds.

Biosafety Photooxidation Strategy of Levofloxacin Driven by Manganese-Doped Indium Zinc Sulfide.

Overuse of antibiotics has led to ecological hazards such as the emergence of resistance genes and super bacteria, necessitating the development of water pollution control technology. Indium zinc sulfide (ZnIn2 S4 , ZIS) is a promising material for environmental applications due to its narrow band gap and excellent light absorption ability. This study investigates Mn-doped ZIS photocatalysts to enhance their photocatalytic oxidation efficiency. Structural morphology, electrochemical testing, and active species testing confirm that Mn-doping optimizes the energy band structure of ZIS and increases the concentration of active free radicals, improving the efficiency of charge separation. Mn-doping also causes lattice distortion, leading to trapping centers to enhance charge separation efficiency. The optimal ZIS-4% oxidation degradation rate of levofloxacin was 2.5 times higher than that of pristine ZIS, with degradation rates reaching almost 100% in 30 minutes. This study provides a novel approach to designing Mn-doped photocatalysts for antibiotic pollution control.

First-principles study on the optoelectronic properties of the quasi-one-dimensional flexible semiconductor K2PdPS4I

Inorganic semiconductors have superior electrical properties than organic semiconductors, but their application in some devices, such as wearable electronic devices, is subject to the limitations of their brittleness. Low-dimensional flexible inorganic semiconductors have superior electrical properties than organic semiconductors, but their application in some devices, such as wearable electronic devices, is subject to the limitations of their brittleness. Low-dimensional flexible inorganic semiconductors are promising candidates to overcome these disadvantages. Therefore, we pay our attention to a quasi-one-dimensional (Q-1D) chain-like material K2PdPS4I and explore its structural stability, electronic structure and optical properties by first-principles calculations. The phonon spectrum of K2PdPS4I is dynamically stable without any imaginary frequency. Furthermore, the orthorhombic crystal structure of K2PdPS4I meets the mechanical stability criterion according to the calculated elastic tensors. K2PdPS4I exhibits anisotropic mechanical properties and belongs to the ductile materials. K2PdPS4I is an indirect bandgap semiconductor with obviously anisotropic carrier effective masses and mobility, showing excellent light absorption ability in the visible and ultraviolet regions. The superior mechanical performance and excellent optoelectronic properties enable K2PdPS4I as a candidate material for promising applications as low-dimensional flexible optoelectronic semiconductors. The present study not only provides a meaningful supplement for the research of low-dimensional semiconductors, but also will attract extensive interest from a wide audience to explore the Q-1D materials.

Fabrication of g-C3N4 nanosheets immobilized Bi2S3/Ag2WO4 nanorods for photocatalytic disinfection of Staphylococcus aureus cells in wastewater: Dual S-scheme charge separation pathway

In this work, graphitic carbon nitride (g-C3N4) immobilized Bi2S3/Ag2WO4 (BS/AW/CN) heterojunction was successfully fabricated using a facile multi-step approach. The fabricated nanomaterials were characterized using different sophisticated technologies. The morphological investigations revealed the existence of g-C3N4 nanosheets loaded with Ag2WO4 and Bi2S3 in a nanorod-like structure. The BS/AW/CN nanocomposite exhibited improved surface area, which was attributed to the regular deposition of Bi2S3/Ag2WO4 on the surface of g-C3N4 nanosheets. The obtained BS/AW/CN heterojunction displayed excellent light absorption ability with promoted photoelectrochemical properties, which was attributed to the lower band gap energy of Bi2S3 species. The BS/AW/CN (0.25 g/L) showed superior photocatalytic antimicrobial activity against Staphylococcus aureus cells (∼1 × 107 CFU/mL) under 140 W of visible-light illumination, where complete inactivation activity was observed in 90 min. The disinfection kinetics verified the faster photoreaction process over BS/AW/CN compared with single and binary catalysts. The inactivated bacterial cells were further elucidated by fluorescence spectroscopy and electron microscopy techniques. The photocatalytic disinfection activity was also investigated under different operating conditions like pH, catalyst loading, and bacterial density. The stability studies verified the high photostability of the obtained heterojunction in five photoreaction runs, suggesting its potential applicability in wastewater disinfection systems. The electronic characteristics and radical trapping results were considered in justifying the dual-S-scheme heterojunction mechanism in the presence of BS/AW/CN. In conclusion, this work demonstrates the feasibility of an efficient visible-light responsive photocatalyst for Staphylococcus aureus cells disinfection in wastewater treatment systems.

Sea‐Urchin‐MnO2 for Broadband Optical Modulator

AbstractManganese dioxide (MnO2) is considered to be one of the nanomaterials with enormous value in research and application because of its high theoretical specific capacitance, large specific surface area and porosity, excellent electron transfer ability, and excellent light absorption ability. However, exploring superior nonlinear absorption of MnO2 in the broadband spectrum is still the key challenge to harvesting their greatest potential. In this paper, the optical modulator based on MnO2 is fabricated, and its nonlinear optical performance is measured. The results indicate that the modulation depth is 4.4% and the saturable intensity is 32.8 MW cm−2 at 1.5 µm region. What's more fascinating is that the modulator based on MnO2 is integrated into Er‐doped and Tm‐doped fiber resonators to successfully demonstrate its broadband mode‐locking operations. The coexistence of harmonic bound state pulse and conventional soliton pulse, as well as dual‐wavelength solitons, have been obtained in a communication window and conventional soliton in a 2 µm‐band can be also achieved. This demonstrates that MnO2 serves as a broadband optical modulator, which makes MnO2 more competitive in the future ultrafast photonics and helps to expand the frontier of photonic technology.

Photoelectrochemical sensors based on heterogeneous nanostructures for in vitro diagnostics

In vitro diagnostics with biochemical sensors are one of the most important technologies for medical diagnosis and the examination of human health. With the improvement of people's living standards, the demand for in vitro diagnostics is increasing, and the requirements for the performance of biochemical sensors are also getting higher. Compared to other biochemical sensors, photoelectrochemical sensors based on heterogeneous nanostructures have excellent light absorption ability and electron transfer performance, and are powerful alternatives for the detection of chemical substances and biochemical molecules for in vitro diagnostics. And this is the main reason why they are a hot topic among relevant analytical methods. However, comprehensive and detailed analyses based on these sensors are rarely reported, especially for in vitro diagnostics, so a complete review of this field is necessary. This review outlines the advantages and disadvantages of various current sensors and further demonstrates the superiority of photoelectrochemical sensors based on heterogeneous nanostructures by comparison. In addition, a detailed classification, introduction of principles and analysis of synthesis methods of heterogeneous nanostructured photoelectrochemical sensors are presented. Based on the above analysis, a detailed description of the use of this type of sensor for in vitro diagnosis of inorganic and organic (micromolecules and macromolecules) molecules in recent years is presented. Predicting and combating relevant diseases are realized by in vitro detection of molecules. Finally, it paves the way for subsequent researchers in the process of realizing practical applications of photoelectrochemical sensing based on heterogeneous nanostructures.

Photocurrent quenching by competitive consumption of surface electron donor and light absorption for immunosensing

This work designs a competitive consumption strategy of surface electron donor and light absorption for quenching the photocurrent of ZnSnO3 nanocubes/BiOI nanoarrays/polydopamine (ZnSnO3 NCs/BiOI NAs/PDA) as a photoactive material. This material can be formed on electrode surface by successive coating and deposition to provide a substrate for immobilization of capture antibody, and producing strong photocurrent in the presence of ascorbate acid as a surface electron donor due to the well matching structure of band gaps between ZnSnO3 NCs and BiOI NAs, the excellent light absorption ability and high photo-electron conversion efficiency of BiOI NAs and PDA, and the accelerated electron transfer. Using ascorbate oxidase loaded dopamine-melanin nanosphere (DAM-AAO) as a label of the signal (secondary) antibody, the sandwich-type immunoreaction leads to dual photocurrent quenching of the label through the competitive consumption of ascorbate acid with enzymatic oxidation and the light absorption by DAM nanosphere. Thus, a sensitive “On-Off” photoelectrochemical (PEC) immunosensing method is constructed for the analysis of neuron specific enolase (NSE). The proposed method shows a detection range of 0.1 pg/mL −50 ng/mL and a detection limit of 0.03 pg/mL. The excellent performance and the recovery text demonstrated the practicability of the designed strategy and label in immunoassay of different protein biomarkers.

Investigating the Performance of Solar Steam Generation Using a Carbonized Cotton-Based Evaporator

Solar-driven steam generation as a potential green technology has attracted extensive attention to solve the freshwater scarcity crisis. Photothermal materials as the key section of solar steam generation have been widely reported. However, there is still a challenge in developing easily prepared, environmental-friendly, and low-cost materials. Herein, the simple, scalable, and porous carbonized cotton was prepared as an evaporator to enhance solar-based evaporation, which has excellent light absorption ability in the range of the full spectrum (300–2,500 nm). Benefiting from 95% solar absorption and the pores between the cellulose tubes, the carbonized cotton heated by plate carbonization reaches a steam generation rate of 0.8 kg m−2 h−1, which is about 5 times that of untreated cotton. Compared with tube furnace carbonization, flat plate heating carbonization of cotton requires lower equipment requirements and does not need nitrogen protection and cleaning tar, and the photothermal conversion efficiencies of both are similar. In addition, carbonized cotton as an evaporator was heated up rapidly under 1 sun irradiation and reached a stable temperature in 20 s, greatly improving the photothermal conversion rate. Therefore, plate heating carbonized cotton provides a good idea for preparing solar photothermal conversion materials and a novel strategy for simplifying the production of biomass thermal evaporators.

Ab Initio Calculations for the Electronic, Interfacial and Optical Properties of Two-Dimensional AlN/Zr2CO2 Heterostructure.

Recently, expanding the applications of two-dimensional (2D) materials by constructing van der Waals (vdW) heterostructures has become very popular. In this work, the structural, electronic and optical absorption performances of the heterostructure based on AlN and Zr2CO2 monolayers are studied by first-principles simulation. It is found that AlN/Zr2CO2 heterostructure is a semiconductor with a band gap of 1.790 eV. In the meanwhile, a type-I band structure is constructed in AlN/Zr2CO2 heterostructure, which can provide a potential application of light emitting devices. The electron transfer between AlN and Zr2CO2 monolayer is calculated as 0.1603 |e| in the heterostructure, and the potential of AlN/Zr2CO2 heterostructure decreased by 0.663 eV from AlN layer to Zr2CO2 layer. Beisdes, the AlN/Zr2CO2 vdW heterostructure possesses excellent light absorption ability of in visible light region. Our research provides a theoretical guidance for the designing of advanced functional heterostructures.

Unveiling the Selectivity of CO2 Reduction on Cu2ZnSnS4: The Effect of Exposed Termination

With the advantage of excellent light absorption ability and earth-abundant elements, Cu2ZnSnS4 (CZTS) is widely applied in the photoelectrochemical (PEC) reduction of CO2. However, the microscopic mechanism of the CO2 conversion on CZTS is still unclear. Here, we have theoretically investigated the electronic properties of the CZTS to reveal the special bonding properties of CO2 under both exposed metal and sulfur terminations of the CZTS and the formation mechanisms of producing CO, HCOOH, and CH4 from a microscopic perspective. Our study shows that when the metal is exposed to the surface, CO2 will convert to HCOOH with a high selectivity with the limiting potential of 0.23 V (vs RHE). However, on the sulfur termination, the onset potentials of producing HCOOH, CO, and CH4 are all lower than 0.4 V, indicating the mix formations. These findings provide theoretical insight into the PEC experiments of CO2 reduction on CZTS.

Optical and oxide modification of CsFAMAPbIBr memristor achieving low power consumption

Due to its unique I-V property, memristor is considered to be the key device for artificial intelligence application. Among the alternative memristor materials, organometal trihalide perovskite (OTP) follow with interest in photoelectric coupling area with excellent light absorption ability. However, the power consumption of OTP memristor still remains to be reduced. Here, Cs0.05(FAxMA1−x)0.95PbIyBr3−y (CsFAMAPbIBr) with prominent photoresponse property is used as the functional layer of the memristor. Maximum high resistance state (HRS)/low resistance state (LRS) (~100) and maximum power of 9.8 × 10−9 W is reached under small voltage (−1 V~1 V) with W/OTP/Al structure. Since the oxide modification layer acts as a series resistance for the device, when 90 nm thickness of zinc oxide layer is added to the W/OTP interface, the power consumption of the device is reduced by an order of magnitude. Then, the maximum power of the device decreases by two orders of magnitude (to 2.5 × 10−11 W) under 2 mW/cm2 light condition, and the phenomenon called negative photoconductance (NPC) effect that defined as an increase in resistance upon exposure to illumination. Through the optical and oxide modification, OTP memristor with low power consumption is achieved.

A simple, flexible, and porous polypyrrole‐wax gourd evaporator with excellent light absorption for efficient solar steam generation

Solar interfacial water evaporation is considered as a potential green technology to solve the global shortage of freshwater resources. However, it is still an arduous task to develop a low-cost and efficient solar evaporator with a simple preparation method. Herein, a simple, flexible, and porous polypyrrole-wax gourd (PPy-wax gourd) biomass evaporator was reported for solar evaporation enhancement. Wax gourd had the advantages such as superhydrophilic wettability, massive microporous channels, and easy planting. PPy was a kind of black polymer with excellent light absorption ability, which greatly improved the light absorption of the PPy-wax gourd evaporator within a full spectrum of solar irradiance (300-2500 nm). The PPy-wax gourd evaporator prepared by the perfect combination of wax gourd and polypyrrole realized a superior vapor generation ability (1.57 kg m−2 hours−1) with a photothermal conversion efficiency of 77.3% under 1 solar intensity, which was better than some other biomass evaporators developed so far. In addition, the PPy-wax gourd evaporator also exhibited remarkable stability and durability under long-term recycling utilization and harsh environments. Importantly, the PPy-wax gourd evaporator demonstrated prominent wastewater purification capacity and desalination performance for dye wastewater and simulated seawater treatment. Based on these results, this work would offer a new strategy for developing novel biomass thermal evaporators the clean water production.

High-performance CuS/n-Si heterojunction photodetectors prepared by e-beam evaporation of Cu films as precursor layers

Transition metal dichalcogenides (TMDCs) are considered to be the most promising next-generation materials for electronics and optoelectronics due to their excellent properties. In this work, well-performing CuS films were prepared by e-beam evaporation of Cu films as precursor layers. Ag/n-Si/Al2O3/CuS/ITO heterojunction photodetector with high responsivity (0.41 A·W−1), detectivity (1.739 × 1011 Jones) and fast response speed (17 μs) at zero bias were prepared by optimising sulphuration temperature and using silicon wafers with inverted pyramid light-trapping structures as substrates. Besides, the photodetector exhibited excellent light absorption ability, with an EQE of 51.91% at 980 nm. All these results demonstrated that excellent photodetector materials can be obtained by using metal films as precursor layers, which provides novel ideas and methods for the synthesis of TMDCs materials.