Visible Light Photon Research Articles

Ultrasonic-Assisted Conversion of Micrometer-Sized BiI3 into BiOI Nanoflakes for Photocatalytic Applications

This work describes a novel method for converting bismuth triiodide (BiI3) microplates into bismuth oxyiodide (BiOI) nanoflakes under ultrasonic irradiation. To produce BiOI nanoflakes with a high yield and high purity, the conversion process was carefully adjusted. Rapid reaction kinetics and increased mass transfer are benefits of the ultrasonic-assisted approach that result in well-defined converted BiOI nanostructures with superior characteristics. The produced BiOI nanoflakes were examined utilizing a range of analytical methods, such as Transmission Electron Microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The progress in the ultrasonic conversion process with time was monitored through diffuse reflectance spectroscopy (DRS). The outcomes demonstrated the effective conversion of BiI3 microplates into crystalline, homogeneous, high-surface-area BiOI nanoflakes. Additionally, the degradation of organic dyes (methylene blue) under ultraviolet (UV) light irradiation was used to assess the photocatalytic efficacy of the produced BiOI nanoflakes. Because of their distinct morphology and electrical structure, the BiOI nanoflakes remarkably demonstrated remarkable photocatalytic activity, outperforming traditional photocatalysts. The ability of BiOI nanoflakes to effectively separate and utilize visible light photons makes them a viable option for environmental remediation applications. This work not only shows the promise of BiOI nanoflakes for sustainable photocatalytic applications but also demonstrates a simple and scalable approach to their manufacturing. The knowledge gathered from this work opens up new avenues for investigating ultrasonic-assisted techniques for creating sophisticated nanomaterials with customized characteristics for a range of technological uses.

Graphene-Templated Achiral Hybrid Perovskite for Circularly Polarized Light Sensing.

This study points out the importance of the templating effect in hybrid organic-inorganic perovskite semiconductors grown on graphene. By combining two achiral materials, we report the formation of a chiral composite heterostructure with electronic band splitting. The effect is observed through circularly polarized light emission and detection in a graphene/α-CH(NH2)2PbI3 perovskite composite, at ambient temperature and without a magnetic field. We exploit the spin-charge conversion by introducing an unbalanced spin population through polarized light that gives rise to a spin photoconductive effect rationalized by Rashba-type coupling. The prepared composite heterostructure exhibits a circularly polarized photoluminescence anisotropy gCPL of ∼0.35 at ∼2.54 × 103 W cm-2 confocal power density of 532 nm excitation. A carefully engineered interface between the graphene and the perovskite thin film enhances the Rashba field and generates the built-in electric field responsible for photocurrent, yielding a photoresponsivity of ∼105 A W-1 under ∼0.08 μW cm-2 fluence of visible light photons. The maximum photocurrent anisotropy factor gph is ∼0.51 under ∼0.16 μW cm-2 irradiance. The work sheds light on the photophysical properties of graphene/perovskite composite heterostructures, finding them to be a promising candidate for developing miniaturized spin-photonic devices.

Photocatalytic degradation of methylene blue under visible light using carbon-doped titanium dioxide as photocatalyst

A visible light-active photocatalyst, carbon-doped titanium dioxide (C-doped TiO2) with an anatase phase, was synthesized using a simple and cost-effective method, with glucose serving as the carbon source for doping. The surface morphology, crystal structure and elemental composition of the catalyst was analyzed by SEM, XRD and EDX respectively. Raman spectroscopic and XRD analysis showed the consistency of the anatase phase throughout the preparation process. FT-IR, TGA, and EDX depicted the purity of the prepared catalyst. SEM images revealed that the average particle size of the catalyst is approximately 178 nm, which is smaller than that of pure TiO2. Finally, as a proof-of-concept photocatalytic activity of the catalyst was investigated on a typical organic dye, methylene blue, under two different light sources (UV light and visible light) by varying the catalyst amount, the concentration of dye, and pH of the degrading medium. Results showed that the prepared C-doped TiO2 shows a promising result under the visible light irradiation which seems limited in case of pure TiO2. The optimum photocatalytic degradation conditions are pH 3, catalyst dosage 0.15 g, and dye concentration 3 × 10−5 M. At optimum conditions visible light shows 53 % degradation and UV light degrades almost all the dye molecules. The enhanced photocatalytic activity of C-doped TiO2 in visible light is due to carbon doping, which reduces the bandgap energy and enables the absorption of visible light photons. This convenient technique can be a great solution for the removal of dyeing wastes economically using low-cost visible light or sunlight and large scale production for industrial application.

Rational construction of surface doping of Cu in WO3 nano platelets with Fe rich layer oxyhydroxide on the porous BiVO4 catalyst: A solar driven heterostructure photoanode for efficient water oxidation

The (Cu:WO3/BiVO4/FeOOH) photoanode heterostructure is a significant semiconductor for solar water splitting owing to its wide absorption of visible light photons. The bulk particles are experiencing charge recombination, which limits the PEC performance of the WO3 and BiVO4. Wherein, the heterostructure Cu:WO3/BiVO4/FeOOH catalysts have a staggered connection of band edges and morphological variation that outperforms the photoelectrochemical properties. The FeOOH layer on the surface of the PEC catalyst efficiently boosts water oxidation and quickens water splitting under light illumination. As anticipated, the doping in the WO3 and BiVO4 loading on the WO3 plates attains an outstanding increase in the water splitting performance. The 2% copper doping in the WO3 exhibits 1.2 mA/cm2, which is increasing by 40 cycles of coated BiVO4 to 2.0 mA/cm2. The FeOOH-grown heterostructure photoanode results in a higher overall photocurrent density (2.8 mA/cm2) at water oxidation potential. Moreover, the photoanode exhibits good stability and low resistance (385.7 Ohm/cm2). The photon-to-electron conversion efficiency has been attained at 1.2% at the applied potential of 0.4 V vs. RHE. These results from the photoanode could be a good candidate for high-performance PEC applications.

Novel CuBi2O4-BiOCl/rGO heterostructure nanocomposite as high-performance visible light photocatalyst for the disintegration of persistent antimicrobials in aquatic environment

The article highlights the fabrication of a novel CuBi2O4-BiOCl/rGO heterojunction nanocomposite as a renewable visible light photocatalyst for the quick disintegration of a persistent fluoroquinolone-based antimicrobial drug, i.e., enrofloxacin (ENF) in aquatics. CuBi2O4-BiOCl (CBO-BOC) nanocomposites (NCs) of varying BOC stoichiometric ratios were synthesized, of which CBO-(30%) BOC NC (CB-30) revealed top photocatalytic traits, which was analogously dispersed onto reduced graphene oxide (rGO) nanosheets, to serve as the visible light photon responsive materials. The electron microscopic and spectroscopic techniques were deployed to understand the CB-30/rGO heterostructure's surface topography and structural morphology. The FE-SEM, HR-TEM and XPS analysis confirmed the dispersion of CBO nanospheres onto the BOC nanoflakes and further confirmed the successful imbuement of CB-30 NCs onto the rGO nanosheets. The CB-30/rGO photocatalyst revealed excellent porosity and surface area for the fast dissipation of pharmaceutical pollutants. The impact of various operating parameters, such as solution pH, drug concentration, CBO-BOC stoichiometry, CB-30/rGO dosage, photosensitizers/electron acceptors, light intensity and matrix tolerance limits, were augmented to enhance the photocatalytic efficiency of the proposed new-age photocatalyst. Under optimized conditions, complete drug mineralization was achieved in ≤0.33 h for complete mineralization of 30 ppm of ENF, using 0.075 g of photocatalyst. The time-dependent profiling of photoproducts/intermediates derived from the photocatalytic degradation of ENF was monitored by HR-MS analysis. The acute and chronic toxicity effects of ENF and its organic intermediate were predicted using the ECOSAR model for selected aquatic life forms. The photocatalyst exhibited reusability up to seven cycles, with excellent thermal/chemical stability, for pollutant decontamination from industrial effluents and environmental samples.

SN 2022oqm–A Ca-rich Explosion of a Compact Progenitor Embedded in C/O Circumstellar Material

We present the discovery and analysis of SN 2022oqm, a Type Ic supernova (SN) detected <1 day after the explosion. The SN rises to a blue and short-lived (2 days) initial peak. Early-time spectral observations of SN 2022oqm show a hot (40,000 K) continuum with high ionization C and O absorption features at velocities of 4000 km s−1, while its photospheric radius expands at 20,000 km s−1, indicating a pre-existing distribution of expanding C/O material. After ∼2.5 days, both the spectrum and light curves evolve into those of a typical SN Ic, with line velocities of ∼10,000 km s−1, in agreement with the evolution of the photospheric radius. The optical light curves reach a second peak at t ≈ 15 days. By t = 60 days, the spectrum of SN 2022oqm becomes nearly nebular, displaying strong Ca ii and [Ca ii] emission with no detectable [O i], marking this event as Ca-rich. The early behavior can be explained by 10−3 M ⊙ of optically thin circumstellar material (CSM) surrounding either (1) a massive compact progenitor such as a Wolf–Rayet star, (2) a massive stripped progenitor with an extended envelope, or (3) a binary system with a white dwarf. We propose that the early-time light curve is powered by both the interaction of the ejecta with the optically thin CSM and shock cooling (in the massive star scenario). The observations can be explained by CSM that is optically thick to X-ray photons, is optically thick in the lines as seen in the spectra, and is optically thin to visible-light continuum photons that come either from downscattered X-rays or from the shock-heated ejecta. Calculations show that this scenario is self-consistent.

Hydrazine hydrate free one pot rapid hydrothermal synthesis of crystalline Zn1−xNdxSe nanostructures for wastewater treatment

Non-hydrazine based hydrothermal synthesis of ZnSe nanostructures is reported. Zinc dust and elemental selenium were the starting materials for the synthesis. 4 h were consumed for the synthesis wherein merceptoacetic acid and methylamine were used for the dissolution of elemental precursors. Influence of Nd doping on growth and properties of the nanostructures is studied. Structural properties (X-ray diffraction) revealed that the nanoparticles grow in cubic crystal phase. Morphology of the nanostructures showed formation of microspheres that are formed by the agglomeration of smaller spherical nanoparticles. Optical properties demonstrated that the nanoparticles show red shift in the transmittance band upon doping making ultraviolet active ZnSe suitable for visible light photocatalysis. The photocatalytic activity of the nanostructures was demonstrated in the presence of ultraviolet and visible light photons separately. The doped samples show prominent activity than ZnSe nanoparticles in the visible light and the reason for this is optimum band gap and the electron scavenging property of Nd3+ ions that reduces electron hole recombination rate. The doped nanoparticles degraded more than 80 % of rhodamine B (RhB) in just two hours of visible light irradiation. The nanoparticles retained their properties after photocatalytic experiments were done, revealing their high stability. Photocatalytic degradation of the dye molecules resulted because of formation of highly oxidative species (free radicals) upon light illumination that was determined by the scavenger experiments.

Investigation on structural, morphological, optical, magnetic properties of CdO-CoFe2O4 nanocomposites and their photocatalytic application

The nanoparticles of pure CdO and CoFe2O4 were synthesized by co- precipitation technique and the composites [(CdO)x- CoFe2O4)1−x] [(DF1 (x = 0.6), DF2 (x = 0.4), DF3(x = 0.2)] were synthesized via sono chemical route. X- ray diffraction (XRD) study validated the presence of two phases in the material. The crystallite size calculated using Debye Scherrer equation were in nano range having size from 8 nm to 59 nm. The morphological and compositional studies of the synthesized material are done by Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive Spectroscopy (EDS) respectively. EDS spectroscopy confirms the conversion of initial precursor salts into final material according to their stoichiometric ratios. The optical properties of the material were examined by ultra violet – visible (UV-Vis) Spectroscopy. Further, Tauc’s plot was employed to obtain the band gap of the material. The band gap (2.5 to 2.9 eV) falls within the range of visible light (typically 400 to 700 nm). This means that the material can effectively absorb visible light photons, which is a crucial requirement for many photocatalytic reactions. The cationic and anionic bonding at different interstitial sites was revealed by Fourier transform infrared spectroscopy (FTIR). The magnetic properties of the material were examined through Vibrating sample magnetometer (VSM). M-H curve gives information about saturated magnetization (Ms), coercivity (Hc) and retentivity (Mr) etc of the material. The maximum obtained values for Ms, Hc and Mr are 41.921 emu/g, 1651.6 Oe and 14.2 emu/g respectively, which confirm the ferrimagnetic nature of the material. The photocatalytic activity of the material under ultraviolet region is evaluated for Methylene Blue (MB) dye. The best photocatalytic results were shown by DF1 sample with discoloration efficiency of 84.5%. The active participation of hydroxyl ion (OH-) and singlet oxygen ion (O2-) is confirmed through scavenger test using Isopropyl alcohol (IPA) and Disodium ethylene diaminne tetraacetic acid (EDTA 2NA) respectively. The dye removal kinetics was tested by using various order rate models. Further to check the stability of the material, recycling efficiency of the material has been calculated for four consecutively cycle.

The photocatalytic ability of visible-light-responsive interfacial charge transfer complex between TiO2 and Tiron

The surface modification of commercial TiO2 powder with catecholate-type ligand Tiron (TIR) leads to the formation of the interfacial charge transfer complex (ICT) absorbing in the visible spectral range. The estimated band gap energy of the ICT complex (Eg = 2.2 eV) by density functional theory (DFT) calculations agrees with experimental measurements. The surface-modified TiO2 with TIR has enhanced sorption capacity towards Pb2+ ions compared to the pristine one due to the presence of free sulfonate groups. Our attempt to reduce Pb2+ ions to metallic form failed. The TiO2-based ICT complex with TIR can serve as an efficient sorbent to remove Pb2+ ions from the solution without the ability to recover them in metallic form in a photo-driven catalytic process. The photocatalytic ability of the ICT complex to induce oxidation reactions is significantly improved since the complete degradation of organic dye methyl orange occurs under exclusive excitations with visible light photons.

Effect of Gadolinium Oxide and Gadolinium Fluoride in Borophosphate Glasses Doped with Tb2O3 Content

The melt-quenching process synthesized gadolinium oxide and fluoride in borophosphate glasses doped with terbium ions (Tb3+). The effect of fluoride compounds and their impacts on physical, optical, and luminescent properties have been investigated. The glasses absorbed near-infrared, visible light, and ultraviolet photons. The bright green emission circa 542 nm via the 5D4 → 7F5 radiative state of Tb3+ originated. Depending on the excitation, there are several sorts of ultraviolet, visible light, and X-ray. The values of decay time are in the order of milliseconds (ms). The Gd3+-Tb3+ energy transfer is vital in green emission under 275 nm excitation. According to the results obtained in this work, the developed glasses can be suitable candidates for green emission medium.

Improved charge transport kinetics in PbBi2Nb2O9 photocatalysts: Comparative time-resolved recombination study with N-doped TiO2

(100) layered Aurivillius-phase perovskite single-phase PbBi2Nb2O9 (PBNO) photocatalyst was reported to be an efficient photocatalyst as compared to the conventionally known visible light photocatalyst of N doped TiO2 (NTO). We report here the specific photoluminescence studies of PBNO to understand its improved photocatalytic property. We have synthesized PBNO and NTO photocatalyst films. Further, their structural, optical and photocatalytic degradation properties have been studied. PBNO demonstrated superior methylene blue degradation as compared to NTO, under visible light photons. The steady-state and time-resolved photoluminescence (PL) studies were specially utilized at characterization tool to understand reason of the high photocatalytic activity of PBNO. We analyzed how high crystallinity of PBNO, and the longer recombination lifetime due to charge separation during photocatalytic reaction yields improved activity in PBNO as compared to NTO. Accordingly, mechanistic scheme for methylene blue photodegradation under solar light photons has been proposed. This study also indicates importance of photoluminescence study for photocatalysts.

Facile one-pot synthesis of plasmonic gold nanoparticles decorated porphyrin-metal organic framework for photocatalytic hydrogen evolution

Plasmonic metals and single-atom nanocomposites have recently gained attention for their enhancement of photocatalyst ability to harvest energy from visible light photons and consequently increase their photoactivity. Over the last decade, the functionalization of Au nanoparticles has been extensively studied to support photocatalytic processes such as hydrogen generation. Furthermore, porphyrin metal-organic frameworks (MOF) materials have demonstrated promising properties such as high crystallinity, surface area, and electron transfer to favor this reaction. Thus, herein Au@PCN(M) nanocomposite was designed by anchoring surface-modified Au nanoparticles into a porphyrin MOF (PCN(M)) where M represents single-atom transition metals (Pt and Co), these nanocomposites were synthesized by both one-pot and post-synthesis methods. Post-synthesis method displayed a higher yield in comparison to the one-pot method, which could be related to the higher crystallinity and metalation of Co and Pt species on PCN-222. Nevertheless, the obtained results for the one-pot method demonstrated that the developed approach is comparable in terms of performance and is promising for the synthesis of efficient plasmonic photocatalysts and their possibility of scale-up in the future.

Photoredox catalysis harvesting multiple photon or electrochemical energies.

Photoredox catalysis (PRC) is a cutting-edge frontier for single electron-transfer (SET) reactions, enabling the generation of reactive intermediates for both oxidative and reductive processes via photon activation of a catalyst. Although this represents a significant step towards chemoselective and, more generally, sustainable chemistry, its efficacy is limited by the energy of visible light photons. Nowadays, excellent alternative conditions are available to overcome these limitations, harvesting two different but correlated concepts: the use of multi-photon processes such as consecutive photoinduced electron transfer (conPET) and the combination of photo- and electrochemistry in synthetic photoelectrochemistry (PEC). Herein, we review the most recent contributions to these fields in both oxidative and reductive activations of organic functional groups. New opportunities for organic chemists are captured, such as selective reactions employing super-oxidants and super-reductants to engage unactivated chemical feedstocks, and scalability up to gram scales in continuous flow. This review provides comparisons between the two techniques (multi-photon photoredox catalysis and PEC) to help the reader to fully understand their similarities, differences and potential applications and to therefore choose which method is the most appropriate for a given reaction, scale and purpose of a project.

Synthesis and VUV Spectral Properties of Red-Emitting K&lt;sub&gt;2&lt;/sub&gt;Gd&lt;sub&gt;0.97&lt;/sub&gt;Zr (PO&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&gt;3&lt;/sub&gt;:3mol%Eu&lt;sup&gt;3+&lt;/sup&gt; Phosphor via Down-Conversion

K2Gd0.97Zr (PO4)3:3mol% Eu3+ were prepared by the solid-state diffusion method and under a vacuum ultra-violet (VUV) region, photoluminescence properties of the phosphor were examined. The phenomenon of visible quantum harvesting via DC was observed in synthesized phosphor for the Gd3+–Eu3+ pair. In the process of quantum harvesting, the two visible light photons are emitted per absorbed VUV photon. This phenomenon occurred upon the 190 nm excitation of Gd3+ at the 6GJ level through a two-step energy transfer from Gd3+ to Eu3+ by cross-relaxation and sequential transfer of the remaining excitation energy. The consequences are that the quantum efficiency of the K2Gd0.97Zr (PO4)3:3mol% Eu3+ phosphor in the energy transfer process from Gd3+ to Eu3+ could reach 233%. The quantum efficiency goes to more than 200% (i.e., 233%) at just low concentration Eu3+ ions (i.e. 3% only). This novelty was found in the prepared phosphor. Therefore, the phosphor K2Gd0.97Zr (PO4)3:3mol% Eu3+ was a potential quantum harvester and potential candidate for mercury free fluorescent lamp and plasma display panel.

Recent Advances on Furan-Based Visible Light Photoinitiators of Polymerization

Photopolymerization is an active research field enabling to polymerize in greener conditions than that performed with traditional thermal polymerization. At present, a great deal of effort is devoted to developing visible light photoinitiating systems. Indeed, the traditional UV photoinitiating systems are currently the focus of numerous safety concerns so alternatives to UV light are being actively researched. However, visible light photons are less energetic than UV photons so the reactivity of the photoinitiating systems should be improved to address this issue. In this field, furane constitutes an interesting candidate for the design of photocatalysts of polymerization due to its low cost and its easy chemical modification. In this review, an overview concerning the design of furane-based photoinitiators is provided. Comparisons with reference systems are also established to demonstrate evidence of the interest of these photoinitiators in innovative structures.

Radiology blues: Comparing occupational blue-light exposure to recommended safety standards.

The blue-light hazard is a well-documented entity addressing the detrimental health effects of high-energy visible light photons in the range of 305 nm - 450 nm. Radiologists spend long hours in front of multiple light-emitting diode (LED)-based diagnostic monitors emitting blue light, predisposing them to potentially higher blue-light dosages than other health professionals. The authors aimed to quantify the blue light that radiology registrars are exposed to in daily viewing of diagnostic monitors and compared this with international occupational safety standards. A limited cross-sectional observational study was conducted. Four radiology registrars at two academic hospitals in Bloemfontein from 01 October 2021 to 30 November 2021 participated. Diagnostic monitor viewing times on a standard workday were determined. Different image modalities obtained from 01 June 2019 to 30 November 2019 were assessed, and blue-light radiance was determined using a spectroscope and image analysis software. Blue-light radiance values were compared with international safety standards. Radiology registrars spent on average 380 min in front of a diagnostic display unit daily. Blue-light radiance from diagnostic monitors was elevated in higher-intensity images such as chest radiographs and lower for darker images like MRI brain studies. The total blue-light radiance from diagnostic display units was more than 10 000 times below the recommended threshold value for blue-light exposure. Blue-light radiance from diagnostic displays measured well below the recommended values for occupational safety. Hence, blue-light exposure from diagnostic monitors does not significantly add to the occupational health burden of radiologists. Despite spending long hours in front of diagnostic monitors, radiologists' exposure to effective blue-light radiance from monitors was far below hazardous values. This suggests that blue-light exposure from diagnostic monitors does not increase the occupational health burden of radiologists.

Optimization of NH2-UiO-66/TiO2/Au composites for enhanced gas-phase CO2 photocatalytic reduction into CH4

Here we report on the optimization of NH2-UiO-66/TiO2/Au (ca. 1.5 wt%) composite photocatalysts applied to gas phase CO2 photocatalytic reduction in presence of water as reducing agent by varying NH2-UiO-66/TiO2 ratio and pH during synthesis. It is shown that 10 wt% NH2-UiO-66/TiO2/Au (at pH=7) composite leads to the best cumulated CH4 production rate of 136 μmol/gcatalyst with 70% electronic selectivity over 5 h of continuous test. This composite exhibits the best compromise between MOF surface area and thus CO2 adsorption sites, visible light photons absorption capacity and a large interface contact area, which ensured preferable metal(Zr)-to-metal(Ti) charge carrier. Au deposition by impregnation/chemical reduction in also required to perform CO2 photoreduction, and may presumably act as electron traps, co-catalyst or surface plasmon resonator.

Thermoelectric voltage triggered self-biased photoelectrochemical water splitting utilizing visible light active Ag/NaNbO3 nanocomposite photoanode

Nanostructure semiconductor photoactive materials are often used as working photoelectrodes to absorb solar light in conventional photoelectrochemical (PEC) cells for water splitting to demonstrate enhanced PEC performance. However, an external bias is required to start PEC water splitting reactions for the generation of hydrogen. Here, we demonstrate a novel way of designing a self-biased hybrid system that combines a darkened thermoelectric device (TE) and a photoelectrochemical cell with a visible light-active n-type Ag/NaNbO3 photoanode to produce hydrogen via water splitting by utilizing the entire solar spectrum. This method can combine utilization of a visible light photon energy from the Ag/NaNbO3 photoanode with thermal energy from the darkened TE device to overcome the overpotential requirements. Upon light illumination, the photoactive behaviour of the Ag/NaNbO3 photoanode and the voltage generated from the darkened TE device in our hybrid system modifies the band positions of an Ag/NaNbO3 photoanode and spontaneously provide the external overpotential requirement for the PEC process and enhances the H2 production. Compared to the stand-alone PEC device, the TE-coupled PEC hybrid system exhibited ∼17 times enhancement in the photocurrent density and H2 production at zero bias. The electrochemical impedance spectroscopy analysis also shows that the charge transfer process gets significantly enhanced in the hybrid PEC system compared to the PEC cell alone. This finding indicates the synergistic coupling between TE and PEC cells, where a single light energy source can increase H2 production in the hybrid systems without needing an external bias.

Ionic liquid-induced construction of 0D/3D carbon quantum dots modified PbBiO2Cl/PbBiO2Br microspheres: Boosting molecular oxygen activation for efficient antibiotics degradation

Developing highly efficient heterostructured photocatalysts for contaminants removal has long been studied, which is mainly limited by ineffective capture of visible-light photon, undesirable recombination of photoinduced hole-electron pairs, and insufficient consumption of charge carriers during surface catalytic reactions. Herein, carbon quantum dots (CQDs) modified PbBiO2Cl/PbBiO2Br nanocomposite photocatalyst have been firstly developed through in-situ ionic liquids induced synthesis. The bridge function of ionic liquids guarantees the symmetrical disperse of CQDs around PbBiO2Cl/PbBiO2Br microspheres, for synchronically overcoming the above drawbacks and markedly promoting antibiotics degradation efficiency: (i) CQDs modification harness solar photons from visible to near-infrared region; (ii) tight coupling of PbBiO2Cl and PbBiO2Br endows the heterojunction with enhanced separation efficiency of charge carriers; (iii) particular delocalized conjugated construction of CQDs strength the enrichment and utilization of photogenerated electrons. Benefiting from these distinguished features, the optimized CQDs/PbBiO2Cl/PbBiO2Br nanocomposite displays obviously enhanced photocatalytic activity towards the elimination of ciprofloxacin and tetracycline under visible light irradiation. The spin-trapping ESR spectra and radicals trapping tests demonstrate that superoxide radicals, hydroxyl radicals and holes are the major active species participated in the purification of antibiotics and the conceivable photocatalytic mechanism has been promoted. This research provides new insights into the development of CQDs modified heterostructured photocatalyst for solar energy conversion applications.

Titanium carbide MXenes-initiated plasmonic metal-support interaction for effective photocatalysis on uncoated Ag nanoparticles

Localized surface plasmon resonances enable the effective harvesting of visible-light photons and yield energetic electrons and holes on short timescale in plasmonic nanoparticles (NPs). However, the balance between the higher stability (which requires stabilizing ligands) and the higher photocatalytic activity (which prefers a clean surface for adsorbing reactant molecules and diminishing the charge-recombination rate) is still a challenge, limiting the efficiency of light utilization. Herein, we show that by forming uncoated Ag-Ti3C2 nanohybrids via in situ reduction, the photocatalytic performance of plasmonic Ag NPs is promoted with the benefit of plasmonic metal-support interaction with Ti3C2 MXenes. The photodegradation efficiency of the organic pollutant methyl orange is elevated from 1.0% to 96.5% due to the excellent metal-like conductivity of Ti3C2 and Schottky barriers of interfacial Ag-TiO2-x. This work reveals the assistance of MXenes for stabilizing the illuminated Ag NPs and boosting efficient hot charge carrier separations in direct plasmonic photocatalysis.