Solar Photons Research Articles

Measurement of D/H and 13C/12C ratios in methane ice on Eris and Makemake: Evidence for internal activity

James Webb Space Telescope's NIRSpec infrared imaging spectrometer observed the outer solar system dwarf planets Eris and Makemake in reflected sunlight at wavelengths spanning 1 through 5 μm. Both objects have high albedo surfaces that are rich in methane ice, with a texture that permits long optical path lengths through the ice for solar photons. There is evidence for N2 ice absorption around 4.2 μm on Eris, though not on Makemake. No CO ice absorption is seen at 4.67 μm on either body. For the first time, absorption bands of two heavy isotopologues of methane are observed at 2.615 μm (13CH4), 4.33 μm (12CH3D), and 4.57 μm (12CH3D). These bands enable us to measure D/H ratios of (2.5 ± 0.5) × 10−4 and (2.9 ± 0.6) × 10−4, along with 13C/12C ratios of 0.012 ± 0.002 and 0.010 ± 0.003 in the surface methane ices of Eris and Makemake, respectively. The measured D/H ratios are much lower than that of presumably primordial methane in comet 67P/Churyumov-Gerasimenko, but they are similar to D/H ratios in water in many comets and larger outer solar system objects. This similarity suggests that the hydrogen atoms in methane on Eris and Makemake originated from water, indicative of geochemical processes in past or even ongoing hot environments in their deep interiors. The 13C/12C ratios are consistent with commonly observed solar system values, suggesting no substantial enrichment in 13C as could happen if the methane currently on their surfaces was the residue of a much larger inventory that had mostly been lost to space. Possible explanations include geologically recent outgassing from the interiors as well as processes that cycle the surface methane inventory to keep the uppermost surfaces refreshed.

Atmospheric dependence of the direct, diffuse, and global clear-sky conversion ratios between solar photosynthetic active irradiance and photon flux

The ratio of the global solar photosynthetic active radiation (PAR) photon flux (in μmol/m2s) to global solar PAR irradiance (in W/m2) is of interest to convert one into another. This ratio is usually considered as a constant value close to its extraterrestrial value, 4.55μmol/J. However, this ratio depends on the spectral composition of solar radiation at ground level and it is different for the diffuse and beam components of solar irradiance. Under clear-sky conditions, the three PAR ratios (global, beam and diffuse) are determined by the local atmospheric composition and the relative air mass. In this work, the SMARTS spectral irradiance model with MERRA-2 atmospheric inputs is used to evaluate the dependence of these ratios under clear-sky conditions with air mass, aerosol optical depth (AOD), precipitable water vapor and ozone column. The accuracy of the SMARTS beam spectral irradiance is previously assessed using local spectroradiometer measurements. The clear-sky ratios for the diffuse and direct components increase with increasing air mass, while the global ratio shows only a weak air mass dependence. The clear-sky ratios can be modeled with simple bi-variate linear models in air mass and AOD. These results can be used in similar climatic regions to convert PAR flux to PAR irradiance and vice versa with increased accuracy for the global, direct, and diffuse radiation under cloud-free conditions.

Optimized agrivoltaic tracking for nearly-full commodity crop and energy production

As the global population accelerates toward a full earth scenario, food, energy, and water demands will increase dramatically. The first order constraints that face resource generation technologies, such as static land availability, compound into second order challenges such as direct competition for the same land and solar photons. Within the contiguous United States, both agriculture and energy production such as solar have turned to densification schemes to increase yields and power per land area, respectively. These technologies coupled with water generation capabilities or management strategies, remain widely separated in their implementation or experience loss in combination. We propose an Agrivoltaic food and energy coproduction architecture to address these challenges, utilizing an Agrivoltaic Array, on-site micrometeorological condition analyses, on-site experimentally validated ray-tracing and irradiance modeling simulation software, as well as crop physiological stage, ear, and height data. Identification of critical time frames in which the relationship between irradiance and yield is highly significant (p less than 0.00005) enables implementation of ideal anti-tracking during those growth periods and solar tracking during all non-critical periods, collectively called critical-time anti-tracking. This reduces power generation to 13.68% during a six-week ideal anti-tracking time frame compared to solar tracking; still, this translates to 86.71% power generation over a year when compared to solar tracking. The reduction in power offsets yield loss, increasing land productivity. This research proposes a technology for near-neutral coproduction of food and energy leveraging already existing hardware for a viable pathway for widespread solar implementation throughout the contiguous United States.

Breakthrough Sun Diving: The Rectilinear Option

A near-term possibility for utilization of Breakthrough Initiatives Project Starshot technology is application of the sun diving maneuver as a replacement for laser acceleration of highly miniaturized photon sails to interstellar velocities. This possibility was discussed during the June 2022 Breakthrough Discuss meeting in Santa Cruz California. Here, we consider application of statite-type photon sail probes to achieve rectilinear trajectories to explore outer solar system and near-interstellar destinations. Statite-Type solar photon sails are sufficiently thin and reflective that solar radiation pressure force on the sail exactly balances the solar gravitational force. In such a force-free environment, the spacecraft exits the solar system at its pre-sail-deployment solar-orbital velocity. Here we consider departures from a circular 1 AU solar orbit, the perihelion of a 0.7-1 AU elliptical solar orbit and the perihelion of a 0.3-1 AU solar orbit. Possible outer-solar system destinations of possible interest to Breakthrough Initiatives extraterrestrial-life/artifact -search researchers include Europa, Titan, Enceladus, Methone, and Arrokoth. More distant possible objectives are ‘Oumuamua and the Sun’s inner gravitational focus. To achieve a rectilinear trajectory, the sail must be oriented normal to the Sun and spacecraft areal mass thickness is 1.46 × 10-3 kg/m2. Current sail technology is reviewed to determine whether it can achieve the required areal mass thickness.

Multimode Luminescent Properties from Tb3+-Yb3+ Codoped CaMoO4 for Solar Cell Spectral Conversion

NIR and visible emitting CaMoO4:Tb3+/Tb3+-Yb3+ phosphors were synthesized to harness the energy losses attribute to wavelength mismatch between response spectrum of incident solar photons and solar cells. The X-ray diffraction (XRD), field emission scanning microscopy (FE-SEM), fourier transform infrared spectroscopy (FTIR), UV–vis diffuse reflectance spectroscopy, photoluminescence (PL), up-conversion and life time measurements were used to characterized the prepared phosphors. XRD study followed by Rietveld refinement confirms the tetragonal crystal structure with space group I41a(88). The phosphors exhibit strong green emission (5D4→7F4) in visible region after an excitation wavelengths 378 nm and 980 nm, respectively through down-shifting (DS) and up-conversion (UC) processes. The UV photons (378 nm) are also split it into two NIR photons (2F7/2→2F5/2) through down-conversion process. Fluorescence quenching was observed by increasing concentration of Tb3+ and Yb3+ ions. Lifetime measurements clearly illustrates the energy transfer from Tb3+ to Yb3+ ions and mechanism involved is co-operative energy transfer. The estimated values of energy transfer efficiency (ETE) and corresponding theoretical internal quantum efficiency are achieved as 69% and 169% respectively.

ZnO for Photoelectrochemical Hydrogen Generation

The rise in the Earth’s surface temperature on an annual basis has stimulated scientific and engineering interest in developing and implementing alternative energy sources. Besides cost, the main requirements for alternative energy sources are renewability and environmental friendliness. A prominent representative that allows the production of “green” energy is the conversion of solar photons into a practical energy source. Among the existing approaches in solar energy conversion, the process of photoelectrochemical (PEC) hydrogen extraction from water, which mimics natural photosynthesis, is promising. However, direct decomposition of water by sunlight is practically impossible since water is transparent to light waves longer than 190 nm. Therefore, applying a photoelectrochemical process using semiconductor materials and organic compounds is necessary. Semiconductor materials possessing appropriately positioned valence and conduction bands are vital constituents of photoelectrodes. Certain materials exhibit semiconductor characteristics that facilitate the reduction-oxidation (RedOx) reaction of water (H2O) under specific circumstances. ZnO holds a unique position in the field of photocatalysis due to its outstanding characteristics, including remarkable electron mobility, high thermal conductivity, transparency, and more. This article offers an overview of studies exploring ZnO’s role as a photocatalyst in the generation of hydrogen from water.

Influence of environmental factors on the power produced by photovoltaic panels artificially weathered

Solar energy is an important renewable energy source and a great option to mitigate the greenhouse gases produced by fossil fuels in electricity production. The common way to use solar energy is through photovoltaic technology. This technology converts solar photons into electricity. However, power production by photovoltaic panels (PV) is strongly related to environmental, manufactured, and maintenance factors. The present work analyzed the exposure of PV panels to environmental conditions at different stages in their lifetime (new, five, ten, 15 years, and 20 years). For this purpose, the PV panel was subjected to a simulated weathering process. A Generalized Linear Model (GLM) approach was used to evaluate the influence of environmental conditions (meteorological and air pollution) on power production, which follows a Binomial Negative distribution due to the overdispersion. The proposed method was performed in the tropical Andean during the winter season and in the presence of the El Niño Southern Oscillation (ENSO). Generally, the specific humidity and temperature were the meteorological significant covariates, while the PM2.5 was the air pollution significant covariate. Higher power production efficiencies were obtained in the presence of precipitation and wind velocity as significant covariates. The model evaluation had adequate criteria values, NSE between 0.76 and 0.96, and correlation coefficient between 0.87 and 0.98 using a new and weathered 15-year PV panel, respectively.

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.

Heat-dissipation performance of photovoltaic panels with a phase-change-material fin structure

Photovoltaic (PV) power generation can directly convert solar radiation photons into electrical energy, but PV panels produce a large amount of waste heat during absorption of solar radiation, significantly increasing the working temperature and reducing the photoelectric conversion efficiency of the panels. In this study, a phase-change material (PCM) is used to cool the PV panels, and fins are added to enhance PCM heat transfer. Using numerical simulation, the effects of fin spacing, fin height, solar radiation intensity, and ambient temperature on the heat-dissipation performance of the PV/PCM system were then studied. The fin–PV/PCM structure showed a good cooling effect. With decreasing fin spacing, the increase in the panel temperature gradually decreased. Fin spacing of 6 mm exhibited the best cooling effect, with the battery plate temperature reduced by 31.9 °C compared with that of the natural convection condition without fins. The increase in the panel temperature gradually decreased with increasing fin height, and the cooling effect of the panel improved significantly when the fin height was increased from 30 to 70 mm. The heat-dissipation effect of the fin–PV/PCM system was better with higher solar radiation intensity and higher ambient temperature. The results of this study will have important reference value for performance improvement of PV panels.

γ-Ray and ultra-high energy neutrino background suppression due to solar radiation

The Sun emits copious amounts of photons and neutrinos in an approximately spatially isotropic distribution. Diffuse γ-rays and ultra-high energy (UHE) neutrinos from extragalactic sources may subsequently interact and annihilate with the emitted solar photons and neutrinos respectively. This will in turn induce an anisotropy in the cosmic ray (CR) background due to attenuation of the γ-ray and UHE neutrino flux by the solar radiation. Measuring this reduction, therefore, presents a simple and powerful astrophysical probe of electroweak interactions. In this letter we compute such anisotropies, which at the Earth (Sun) can be at least ≃5×10−3(1)% and ≃1×10−16(2×10−14)% for TeV scale γ-rays and PeV scale UHE neutrinos respectively. We briefly discuss observational prospects for experiments such as the Fermi Gamma-Ray Space Telescope Large Area Telescope (Fermi LAT), High-Altitude Water Cherenkov (HAWC) detector, The Large High Altitude Air Shower Observatory (LHAASO), Cherenkov Telescope Array (CTA) and IceCube. The potential for measuring γ-ray attenuation at orbital locations of other active satellites such as the Parker Solar Probe and James Webb Space Telescope (JWST) is also explored.

GaAs thin-film solar cells for perfect absorption in the visible and near-infrared bands

Improving the solar cell's ability to capture solar photons and enhancing its absorption of light have a significant impact on increasing the photoelectric conversion efficiency (PCE) of solar cells. In this study, we propose to embed a layer of light-trapping structure (LTS) utilizing Ti nanoparticles and their oxide TiO2 periodically arranged in the window layer of GaAs thin-film solar cells. This structure improves the light absorption efficiency by increasing the optical range and surface plasmon resonance of light inside the cell, which in turn improves the PCE of the solar cell. Simulation results show that the GaAs solar cell proposed in this paper achieves an average absorptivity of 94.99% in the visible and near-infrared wavelength bands, and the PCE reaches 31.77%, which is close to the Shockley-Queisser limit level of the single-junction solar cell. And it realizes the characteristic of perfect absorption in the wavelength range of 555–800 nm. The cell structure proposed in this study is characterized by high bandwidth perfect absorption and high PCE, which is insensitive to the angle of incidence, and provides a new idea for the design of new high-efficiency thin-film solar cells.

Research on the Adaptability of Typical Denoising Algorithms Based on ICESat-2 Data

Photon-counting light detection and ranging (LiDAR) emits and receives weak photon signals, which are easily mixed with background noise caused by the sun, the atmosphere, etc., and is thus difficult to distinguish. Therefore, point-cloud denoising is a key step in point-cloud data processing of photon-counting LiDAR. To explore the adaptability of different denoising algorithms for photon-counting LiDAR data in different times and spaces, in this paper, NASA’s official differential, regressive and Gaussian adaptive nearest neighbor (DRAGANN) algorithm; Herzfeld’s radial basis function (RBF) denoising algorithm; and the density-based spatial clustering of applications with noise (DBSCAN) algorithm based on density clustering are used to denoise the ICESat-2 ATL03 photon point-cloud data. Airborne LiDAR data are used to verify the denoising accuracy, and then the adaptability of the three algorithms is discussed. The results show that the DRAGANN algorithm is suitable for data with moderate Fraction Vegetation Coverage (FVC) (45–75%) at night and is less affected by slope; therefore, it is not limited to terrain slope. The denoising accuracy of the RBF algorithm decreases with increasing FVC and decreases with increasing slope. It is suitable for data with low terrain slope (0~55°) and low FVC (0~220°), which is less affected by observation time; therefore, it is suitable for all-day data. The DBSCAN algorithm is suitable for data with moderate FVC (45~75%) at night, regardless of terrain slope. Unlike the DRAGANN algorithm, the DBSCAN algorithm is greatly affected by solar noise photons, but at night, its denoising accuracy is higher than that of the DRAGANN algorithm. The research results have certain reference significance for the subsequent processing and application of ICESat-2 data.

Solar Efficiency of Azo-Photoswitches for Energy Conversion: A Comprehensive Assessment.

Photoswitches can absorb solar photons and store them as chemical energy by photoisomerization, which is regarded as a promising strategy for photochemical solar energy storage. Although many efforts have been devoted to photoswitch discovery, the solar efficiency, a critical fundamental parameter assessing the solar energy conversion ability, has attracted little attention and remains to be studied comprehensively. Here we provide a systematic evaluation of the solar efficiency of typical azo-switches including azobenzenes and azopyrazoles, and gain a comprehensive understanding on its decisive factors. All the efficiencies are found below 1.0 %, far from the proposed limits for molecular solar thermal energy storage systems. Azopyrazoles exhibit remarkably higher solar efficiencies (0.59-0.94 %) than azobenzenes (0.11-0.43 %), benefiting from largely improved quantum yield and photoisomerization yield. Light filters can be used to improve the isomerization yield but inevitably narrow the usable range of solar spectrum, and these two contradictory effects ultimately reduce solar efficiencies. We envision this conflict could be resolved through developing azo-switches that afford high isomerization yields by absorbing wide-spectrum solar energy. We hope this work could promote more efforts to improve the solar efficiency of photoswitches, which is highly relevant to the prospect for future applications.

CO2 as the main parent source of atomic oxygen in comet C/2017 K2 (Pan-STARRS)

C/2017 K2 (Pan-STARRS) is an Oort cloud comet discovered in May 2017. Ground observations have revealed that this long-period comet was active at heliocentric distance of 35 au. At such a distance, activity cannot be driven by the sublimation or the exothermic crystallization of water ice. We assume that the activity of comet C/2017 K2 may be driven by the sublimation of super-volatile ices such as CO and CO2. The nature of parent molecules driving the unprecedented activity of comet C/2017 K2 can be investigated by analyzing its spectrum. In particular, the analysis of atomic oxygen emission lines and the calculation of the green (5577.339 Å) to red (6300.304 and 6363.776 Å) line intensity ratio (hereafter G/R) can reveal the nature of molecules driving cometary activity. We report on the detection of atomic oxygen lines in the spectra of comet C/2017 K2 (Pan-STARRS) from high-resolution spectra obtained at the Telescopio Nazionale Galileo (TNG) on 24 June and 2 July 2022 using the High Accuracy Radial velocity Planet Searcher North (HARPS-N) echelle spectrograph. We found G/R ratios equal to 0.29±0.02 (24 July 2022) and 0.27±0.01 (2 July 2022), which are consistent with a cometary activity driven by CO2, even if located at 2.8 au from the Sun. To better define the nature of the driving molecule, we measured the width of the three oxygen lines and found that the green line in the spectrum of 24 July 2022 is wider than either of the two red lines. This allows us to argue that CO2 is dissociated by highly energetic solar photons that produce O(1S) with a large excess velocity.

Observation of Helium in Mercury's Exosphere by PHEBUS on Bepi‐Colombo

AbstractOn 1 October 2021, Bepi‐Colombo performed its first flyby of Mercury. During the maneuver, the short wavelength channel (55–155 nm) of “Probing the Hermean Exosphere by UV Spectroscopy” (PHEBUS) was activated for a total duration of 1 hr. The helium resonance line at 58.4 nm was clearly observed during the whole sequence. At large distance from the planet, the emission was due to helium atoms in the interplanetary medium (interplanetary UV glow). Just after crossing the terminator of the planet and entering the dawn side of the exosphere, PHEBUS observed a clear additional emission due to scattering of solar photons by helium atoms in the exosphere of Mercury. The first detection of the 58.4 nm line in the exosphere of Mercury was reported by Broadfoot et al. (1976, https://doi.org/10.1029/gl003i010p00577) following the Mariner 10 flybys in 1974. The PHEBUS observation of exospheric helium emissions is the first for this element since the UVS measurements. In this paper, we present the results of our analysis of the PHEBUS data at 58.4 nm. Calibration of both instruments are compared with observations of the interplanetary glow, showing that the measurements of both instruments are accurate. However, we find that the exospheric density of helium atoms deduced from the PHEBUS data is 4.5–7.5 times lower than the previous estimate from UVS on Mariner 10. Possible explanations are considered. We show that some of the helium atoms present in the exosphere of Mercury could originate from the local interstellar cloud.

Study of the Electronic Interaction between NiO and Short Polythiophene Chains towards Solar Photon Harvesting.

The sustainable production of energy is a field of interest to which a new requirement is now imposed: the need to be respectful of the environment. New materials and techniques are being developed, but environmental concerns impose the necessity of keeping research active towards the development of green energy. For this reason, we present the study of short polythiophene (PTh) chains (three and five monomers) and their interaction with nickel oxide, looking for properties related to solar photon harvesting in order to produce electricity. The models of the molecules were developed, and the calculations were performed with an M11-L meta-GGA functional, specially developed for electronic structure calculations. The theoretical explorations demonstrated that the geometry of the PTh molecules suffer little distortion when interacting with the NiO molecule. The calculated value of Eg lies between 2.500 and 0.412 eV for a three-ring PTh chain and between 1.944 and 0.556 eV for a five-ring PTh chain. The chemical parameters indicated that, depending on the geometry of the system, the chemical potential varies from 81.27 to 102.38 kcal/mol and the highest amount of electronic charge varies from -2.94 to 21.56 a.u. for three-monomer systems. For five-monomer systems, the values lie within similar ranges as those of the three-monomer systems. The Partial Density of States (PDOS) showed that the valence and conduction electronic bands were composed of states in the NiO and PTh rings, except for a system where there was a non-bonding interaction.

Potential Application of Carbon Quantum Dots (CQD) Synthesis from Rice Husk Waste Composite as Advanced Solar Cells to Increase Photon Energy Absorption in Maximizing Solar Panels Power Output Production

The increase in national energy consumption has forced us to intensify renewable energy utilization. Solar panel is one optional answer for that purpose. Unfortunately, the product resistance and photon absorption from silicon-based solar cells are still not good enough. Carbon quantum dots (CQD) could be an alternative advanced material that can be utilized to maximize the performance of solar panels. Therefore, researchers are interested in finding out how to manufacture CQD from the synthesis of rice husk waste composite as an advanced solar cell and analyze its potential to maximize solar panel photon energy absorption. Researchers use mixed study that applies literature review methods (as part of the descriptive research aspect) and causal comparative research methods (as part of the quantitative aspect). Based on previous research, rice husk waste was pre-processed by washing using de-ionized water (DI water) to remove residue, then baked and blended into powder, and cleaned using HCl as impurities remover. The hydrothermal process was carried out at 190 oC for 12 hours to synthesize CQD which functioned by amino and carboxyl. For further purification, CQD was dialyzed against DI water in cellulose. Super-dense material due to quantum level compression, makes CQD have a higher resistance when compared to silicon as solar cells. In addition, the absorption of photon energy that can be done by CQD solar cells has a higher percentage when compared to conventional solar cells. However, in this paper, the researchers did not make CQD and only analyzed through modeling which became the research gap in this paper.

SKYSURF-4: Panchromatic Hubble Space Telescope All-Sky Surface-brightness Measurement Methods and Results

The diffuse, unresolved sky provides most of the photons that the Hubble Space Telescope (HST) receives, yet remains poorly understood. The HST Archival Legacy program SKYSURF aims to measure the 0.2–1.6 μm sky surface brightness (sky-SB) from over 140,000 HST images. We describe a sky-SB measurement algorithm designed for SKYSURF that is able to recover the input sky-SB from simulated images to within 1% uncertainty. We present our sky-SB measurements estimated using this algorithm on the entire SKYSURF database. Comparing our sky-SB spectral energy distribution (SED) to measurements from the literature shows general agreements. Our SKYSURF SED also reveals a possible dependence on the Sun angle, indicating either nonisotropic scattering of solar photons off interplanetary dust or an additional component to zodiacal light. Finally, we update the diffuse light limits in the near-IR based on the methods from Carleton et al., with values of 0.009 MJy sr−1 (22 nW m−2 sr−1) at 1.25 μm, 0.015 MJy sr−1 (32 nW m−2 sr−1) at 1.4 μm, and 0.013 MJy sr−1 (25 nW m−2 sr−1) at 1.6 μm. These estimates provide the most stringent all-sky constraints to date in this wavelength range. SKYSURF sky-SB measurements are made public on the official SKYSURF website and will be used to constrain diffuse light in future papers.

NIR to intense UV-Blue photon transition by upconverting LuF3: Yb3+, Tm3+@BiOCl core@shell composite for pollutant degradation

Combining lanthanide ion (Ln3+)-doped upconversion luminescent materials with photocatalysts is an effective strategy to develop near-infrared (NIR)-responsive photocatalysts. Herein, a novel core-shell structured upconversion photocatalyst LuF3: Yb3+, Tm3+@BiOCl (LYT@BiOCl) was synthesized by hydrothermal/solvothermal method. The core is constituted of LuF3: Yb3+, Tm3+ (LYT) upconversion nanoparticles (UCNPs). A BiOCl shell with relatively narrow band-gap was coated on LYT core via a solvothermal process. Solar NIR photons were successfully converted to UV-Blue photons by LYT, which activated the BiOCl shell to produce electron-hole pairs. The excellent core-shell structure of LYT@BiOCl was confirmed by a series of test characterizations, which provides the necessary conditions for efficient energy transfer between LYT and BiOCl. The fluorescence lifetime decay of the 1G4 levels of Tm3+ in LYT@BiOCl further demonstrates the existence of an efficient Förster resonance energy transfer (FRET) channel between LYT and BiOCl. Moreover, photocurrent and EIS tests illustrated LYT(10)@BiOCl has greater photocurrent response and smaller interface transfer resistance. As a result, under the light irradiation of λ > 800 nm and λ > 400 nm (300 W Xenon lamp with a filter), the photocatalytic performance of LYT@BiOCl was always higher than pure BiOCl. Especially, a great enhancement of + 42% and + 64% on the MB degradation efficiency was achieved in LYT(10)@BiOCl compared with pure BiOCl, respectively. This work might provide a useful reference for the rational design of highly efficient NIR-responsive photocatalysts.

Quasi-Reversible Photoinduced Displacement of Aromatic Ligands from Semiconductor Nanocrystals.

Organic-inorganic nanohybrids using semiconductor nanocrystals (NCs) coordinated with aromatic organic molecules have been widely studied in the fields of optoelectronic materials, such as solar cells, photocatalysis, and photon upconversion. In these materials, coordination bonds of ligand molecules are usually assumed to be stable during optical processes. However, this assumption is not always valid. In this study, we demonstrate that the coordination bonds between ligand molecules and NCs by carboxyl groups are displaced quasi-reversibly by light irradiation using zinc sulfide (ZnS) NCs coordinated with perylenebisimide (PBI) as a model system. Time-resolved spectroscopy over a wide range of time from tens-of femtosecond to second timescales and density functional theory calculations show that the photoinduced ligand displacement is driven by ultrafast hole transfer from PBI to ZnS NCs and that the dissociated radical anion of PBI survives over the second timescale. Photoinduced ligand displacements are important to be considered in various organic-inorganic nanohybrids and offer a possibility of NCs covered by nonphotoresponsive organic ligands for advanced photofunctional materials.