Daylight Research Articles

Leaf-like MSX/TiN heterojunction photocathodes mimicking plant cell – An effective strategy to enhance photoelectrocatalytic carbon dioxide reduction and systematic mechanism investigation

Semiconductors, such as metal oxides and metal sulfides (MSX), are widely investigated as effectively catalytic materials to convert carbon dioxide (CO2) and water into chemicals under simulated solar light. These valuable investigations might address both the energy crisis and climate change in our modern society. Herein, a novel strategy to construct leaf-like heterojunctions of VS-ZnIn2S4/TiN-x is reported. The new semiconductor heterojunctions were then applied to photoelectrocatalytic CO2 reduction, achieving excellent performance (formate formation rate of 1173.2 μM h−1 cm−2) attributed to the plant cell-like morphology and enhanced electron mobility from the heterojunction interfaces to the active sites on the surface. Our findings suggest that titanium nitride (TiN) with good conductivity can improve the photoelectrocatalytic ability of MSX through heterojunction construction. The photocathode VS-ZnIn2S4/TiN-3 exhibits 81.0 % selectivity toward C2 products by optimizing the material structure and reaction conditions. According to the systematic investigation of operando Fourier transform infrared (FTIR) spectra, common intermediates such as *COO−, *COOH, *CO, *CHO, *COCHO, and *COCH3 reported in the literature were carefully verified. Among these, the carbene specie serve as the key intermediate responsible for generating other intermediates and resulting in all products.

Enhancing vitamin D levels in care homes: the role of healthy building design in preventing respiratory infections.

The recent article by Willcox etal. in the Journal of Public Health highlights the effectiveness of antiviral prophylaxis and high-dose vitamin D supplementation in reducing acute respiratory infections (ARIs) in care homes. This correspondence extends the discussion by emphasizing the critical role of healthy building design in enhancing vitamin D levels, which is vital for immune function and ARI prevention. Many care home residents suffer from vitamin D deficiency due to limited sunlight exposure. Incorporating architectural elements such as large windows, skylights, and outdoor spaces can significantly increase natural light exposure, thereby boosting vitamin D levels and potentially reducing ARI susceptibility. Despite the benefits of supplementation, addressing environmental factors through healthy building design offers a sustainable, long-term strategy that aligns with public health goals of preventive care and environmental sustainability. Prioritizing such design principles in care home planning and renovation can enhance residents' health and resilience against infections like influenza and COVID-19.

Changes in the liver of Djungarian hamsters under conditions of a three-month supply of water-soluble silicon of various concentrations

BACKGROUND: Silicon enters the human body through drinking water, air and food. Silicon nanoparticles used in the cosmetic, pharmaceutical and food industries are known to have biological activity. Taking into account the widespread prevalence of silicon compounds, the issue of the safety of its use is becoming more urgent. AIM: To study the effect of water-soluble silicon on the morphological structure of the liver of Djungarian hamsters for three months. MATERIALS AND METHODS: The experiment was carried out on Djungarian hamsters kept in normal vivarium conditions under natural light. The animals were divided into three groups: control, which received bottled drinking water; the first experimental group, which received the same water, but with the addition of sodium metasilicate nine-hydrate at a concentration of 10 mg/l in terms of silicon; the second experimental group, which also received the same water, but with the concentration of sodium metasilicate nine-hydrate doubled (up to 20 mg/l). After three months, the animals were removed from the experiment. Sections were processed by general histological (hematoxylin and eosin, Van Gieson method, toluidine blue), histochemical (monoamine oxidase-positive cells) methods. RESULTS: In the liver of hamsters from the experimental groups, changes in the micromorphological structure were revealed, such as an increase in the nuclear area, nuclear-cytoplasmic ratio of hepatocytes, and the diameter of sinusoidal capillaries. Moreover, more pronounced changes were observed in the liver of hamsters of the second experimental group, such as polymorphic cell infiltration of the portal tracts, an increase in the number of eosinophils, deformation of hepatocyte nuclei and the appearance of apoptotic bodies. A decrease in the area of mast cells and an increase in their number, as well as the number of monoamine oxidase-positive cells in the liver of hamsters of both experimental groups were recorded. CONCLUSIONS: An increase in the concentration of silicon supplied with drinking water in both cases is reflected in the micromorphological structure of the liver of hamsters. Moreover these changes are more pronounced in the liver of hamsters of the second experimental group.

A C-modified engineering strategy of porous In2O3 catalysts for point-concentrated solar-driven photothermal CO2 hydrogenation

The solar-driven photothermal CO2 conversion serves as an effective approach for addressing the substantial challenges of energy crises and global environmental issues. In this work, various forms of In2O3 catalysts, including In2O3-c, In2O3-r, In2O3-s, and porous spherical In2O3, along with a C-modified porous spherical In2O3 catalyst (C-In2O3), were successfully synthesized through a hydrothermal method. An in-depth analysis was conducted to evaluate the performance of these catalysts in the point-concentrated solar-driven photothermal CO2 hydrogenation. As a result, the porous C-In2O3 catalyst exhibited a superior CO2 conversion rate of approximately 13.2 % under simulated sunlight irradiation, with a light intensity of 44.6 mW/cm2. Notably, all catalysts demonstrated nearly 100 % selectivity towards CO (CO production rate of around 8.51 mmol gcat−1h−1) during the photothermal catalytic reaction, without any formation of CH4. The outstanding performance of the C-In2O3 catalyst was attributed to the modification of In2O3 band structure by the incorporation of C, which significantly enhanced the intensive solar light absorption of the catalyst. Furthermore, incorporating C into In2O3 substantially augments its basic strength and significantly elevates the quantity of basic sites, thereby endowing it with outstanding CO2 adsorption and conversion capabilities. This work provides a C-modified engineering strategy to design efficient photothermal catalysts for boosting point-concentrated photothermal CO2 hydrogenation.

Synthesis of high-value porous carbon from waste plastics and structure regulation promote solar interface water evaporation

Water scarcity and waste plastics elimination are long-term problems facing sustainable development, and solar interface evaporation to produce clean water is regarded as a promising water treatment technology. Herein, we report on low-cost waste plastic bottles synthetic carbon-based photothermal materials. By KOH activation and perforation, the surface crack structure of porous carbon is formed to facilitate multi-stage reflection of solar light, and significantly improve the solar light absorbance and photothermal conversion ability. Three-dimensional solar evaporators with low thermal conductivity and super hydrophilic wood sponge are fabricated, and the rectangular hole is designed to regulate water movement and prevent heat dissipation. When exposed to 1 sun illumination (1 kW/m2), an evaporation rate of 1.59 kg·m-2·h-1 is achieved, along with an energy conversion efficiency of 88.49 %. In addition, different micro-surface rough structures are constructed to boost the solar light absorption, thereby enhancing the photothermal conversion ability, among which the micro-cone structure increased the evaporation rate to 1.93 kg·m−2·h−1, demonstrating excellent stability over 15 cycles. In the simulated sewage purification process, the removal rate of pollutants is 99.9 %, and the evaporator without obvious salt accumulation in the seawater for 24 h, showing good salt resistance and self-cleaning ability. This research has important reference value for high-value preparation of carbon-based photothermal materials from waste plastics, extraction of clean water and environmental sustainable protection.

Maltese Coastline Never Sleeps: The Effects of Artificial Light at Night (ALAN) on the Local Infralittoral Assemblages—A Case Study

Aside from the most notorious threats, the Mediterranean Sea faces novel and poorly explored impacts from artificial light at night (ALAN), which influences natural light–dark cycles and affects marine ecosystems. This study investigates the impact of ALAN on coastal infralittoral assemblages in Malta, where such effects remain unexplored. Using Baited Remote Underwater Videos (BRUVs), we examined the influence of different light intensities on species assemblages and behaviour at two sites: a light-polluted harbour and a darker reef area. Our findings reveal significant differences in fish community composition between light treatments and habitats. Among the 23,955 individuals recorded across multiple taxa, Boops boops accounted for 80% of observations. From our results, light intensity had a more substantial impact on community structure than habitat type, with species-specific responses to light. Predatory species such as Trachurus trachurus displayed increased activity under high-intensity white light, while Apogon imberbis and Serranus scriba were more abundant under red light, irrespective of habitat. These results underscore the role of ALAN in altering marine community dynamics and emphasise the need for sustainable management strategies to mitigate its impact on the biodiversity of the Mediterranean. This study provides initial empirical evidence of ALAN’s effects in Maltese waters, contributing to broader efforts to understand and manage light pollution in marine ecosystems.

Ce3+/Ce4+–TiO2 Nano‐Octahedra as Active Photocatalysts for Ciprofloxacin Photodegradation Under Solar Light

AbstractCerium‐containing titania nano‐octahedra (CeTNOh) are obtained by ultrasonication‐hydrothermal synthesis of Ce‐containing titanate nanowires (0.35, 0.46, and 0.70 Ce mol %) from commercial TiO2 (Degussa P25). CeTNOh are tested as photocatalysts to degrade a target pollutant (ciprofloxacin) under simulated solar light and at mild conditions. CeTNOh are anatase polymorphs with increasing crystallite size as Ce content increases. Hydrothermal treatments enhance the specific surface area (SSA) compared to P25, although Ce addition slightly reduces SSA while increasing crystallite size. Electron Microscopy confirms the morphology, although higher Ce levels hinder a full transformation. X‐ray photoemission spectroscopy (XPS) shows the presence of Ce3+/Ce4+ redox pair, promoting electron mobility and Ti‐Ce interactions. Optical and electronic spectroscopy reveals that Ce loading reduces the bandgap from 3.20 to 2.74 eV, extending light absorption into the visible range, thus enhancing the photocatalytic activity. The best sample, CeTNOh0.35, achieved 83% degradation of ciprofloxacin after 360 minutes under solar irradiation, with poor adsorption in the dark period. Higher Ce loadings negatively affect photoactivity by partially covering titania active sites. Reusability tests confirm the stability and efficiency of CeTNOh0.35 over three cycles, highlighting the importance of octahedral morphology in Ce‐containing systems to boost the final photoactivity for water remediation.

Cobalt-Doped ZnO Nanocomposits for Efficient Dye Degradation: Charge Transfer.

Doping enhances the optical properties of high-band gap zinc oxide nanoparticles (ZnO NPs), essential for their photocatalytic activity. We used the combustion approach to synthesize cobalt-doped ZnO heterostructure (CDZO). By creating a mid-edge level, it was possible to tune the indirect band gap of the ZnO NPs from 3.1 eV to 1.8 eV. The red shift and reduction in the intensity of the photoluminescence (PL) spectra resulted from hindrances in electron-hole recombination and sp-d exchange interactions. These improved optical properties expanded the absorption of solar light and enhanced charge transfer. The field emission scanning electron microscopy (FESEM) image and elemental mapping analysis confirmed the CDZO's porous nature and the dopant's uniform distribution. The porosity, nanoscale size (25-55 nm), and crystallinity of the CDZO were further verified by high-resolution transmission electron microscopy (HRTEM) and selected area electron image analysis. The photocatalytic activity of the CDZO exhibited much greater efficiency (k=0.131 min-1) than that of ZnO NPs (k=0.017 min-1). Therefore, doped heterostructures show great promise for industrial-scale environmental remediation applications.

Triplet-Sensitized Switching of High-Energy-Density Norbornadienes for Molecular Solar Thermal Energy Storage with Visible Light.

Norbornadiene-based photoswitches have emerged as promising candidates for harnessing and storing solar energy, holding great promise as a viable solution to meet the growing energy demands. Despite their potential, the effectiveness of their direct photochemical conversion into the resulting quadricyclanes has room for improvement owing to (i) moderate quantum yields, (ii) poor overlap with the solar spectrum and (iii) photochemical back reactions. Herein, we present an approach to enhance the performance of such molecular solar thermal energy storage (MOST) systems through the triplet-sensitized conversion of aryl-substituted norbornadienes. Our study combines deep spectroscopic analyses, irradiation experiments, and quantum mechanical calculations to elucidate the energy transfer mechanism and inherent advantages of the resulting MOST systems. We demonstrate remarkable quantum yields using readily available sensitizers under both LED and solar light irradiation, significantly surpassing those achieved through direct excitation with photons of higher energy. In contrast to the conventional approach, light-induced back reactions of the high-energy products do not play any role, allowing quantitative switching within minutes. These results not only underscore the potential of triplet-sensitized MOST systems to leverage the high energy storage capabilities of multistate photoswitches but they might also stimulate the broader usage of sensitization strategies in photochemical energy conversion.

Construction of S/g-C3N4@β-Bi2O3 heterojunction and its photocatalytic degradation of toluene in the gas phase.

In this paper, a modification of g-C3N4 was carried out by combining non-metal doping with the construction of heterojunctions, and a type II heterojunction composite, S/g-C3N4@β-Bi2O3, was prepared. The phase structure, morphology, elemental composition, valence band structure, and light absorption performance of the photocatalyst were analyzed using characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The performance of the composite photocatalyst in the photocatalytic degradation of gaseous toluene, one of the typical volatile organic compounds (VOCs), under simulated solar light was studied. The effects of preparation conditions, toluene concentration, and recycling on the photocatalytic performance of the composite photocatalyst were investigated. The results show that under the optimal preparation conditions, S/g-C3N4@β-Bi2O3 achieved a degradation efficiency of 74.0% for 5ppm toluene after 5h of light irradiation. Although the degradation efficiency decreased to 61.2% after five cycles, it maintained 83% of its initial activity, indicating good stability of the composite photocatalyst. Free radical quenching experiments demonstrated that h+ was the main active species in the photocatalytic degradation of toluene, followed by ·O2-. Based on all experimental results, the migration law of photo-generated charges was analyzed, and a possible photocatalytic mechanism was proposed. In this study, a new material was obtained for the photocatalytic removal of VOCs by improving the photocatalytic properties of g-C3N4.

Triplet‐Sensitized Switching of High‐Energy‐Density Norbornadienes for Molecular Solar Thermal Energy Storage with Visible Light

Norbornadiene‐based photoswitches have emerged as promising candidates for harnessing and storing solar energy, holding great promise as a viable solution to meet the growing energy demands. Despite their potential, the effectiveness of their direct photochemical conversion into the resulting quadricyclanes has room for improvement owing to (i) moderate quantum yields, (ii) poor overlap with the solar spectrum and (iii) photochemical back reactions. Herein, we present an approach to enhance the performance of such molecular solar thermal energy storage (MOST) systems through the triplet‐sensitized conversion of aryl‐substituted norbornadienes. Our study combines deep spectroscopic analyses, irradiation experiments, and quantum mechanical calculations to elucidate the energy transfer mechanism and inherent advantages of the resulting MOST systems. We demonstrate remarkable quantum yields using readily available sensitizers under both LED and solar light irradiation, significantly surpassing those achieved through direct excitation with photons of higher energy. In contrast to the conventional approach, light‐induced back reactions of the high‐energy products do not play any role, allowing quantitative switching within minutes. These results not only underscore the potential of triplet‐sensitized MOST systems to leverage the high energy storage capabilities of multistate photoswitches but they might also stimulate the broader usage of sensitization strategies in photochemical energy conversion.

How many surfaces can you distinguish by color? Real environmental lighting increases discriminability of surface colors.

Color supports object identification. However, two objects that differ in color under one light can appear indiscriminable under a second light, a phenomenon known as illuminant metamerism. Past studies evaluated the frequency of illuminant metamerism only under single, uniform illuminants. Here we used computer-graphics techniques to simulate a pair of planar surfaces placed under newly measured hyperspectral illumination maps that quantify the directional variability of real-world lighting environments. We counted the instances of illuminant metamerism that can be solved simply by viewing surfaces tilted to a different direction. Results show that most instances of illuminant metamerism can in theory be resolved for both trichromatic and dichromatic observers, suggesting that the physical directional variability available in natural lighting environments substantially mitigates the biological limitations of trichromacy or dichromacy.

Stakeholders’ Perceptions on Influence of Energy Efficiency Practices Adopted on Economic Performance of Selected Small and Medium Sized Manufacturing Enterprises in Nakuru County, Kenya

The adoption of environmental policy among large manufacturing firms has been recognized for enhancing their economic performance. This is crucial for achieving Kenya's Vision 2030, the fourth medium term plan (2023-2027) and the Bottom-Up Economic Transformation Agenda (BETA) for Inclusive Growth. Despite the slow pace, small and medium-sized enterprises (SMEs) are now adopting these policies to reduce their environmental footprint. However, there is limited documentation on how these practices affect their economic performance. Hence, this study aimed at examining stakeholders' perceptions on the influence of adopting energy efficiency practices on the economic performance of selected manufacturing SMEs in Nakuru County. The study was guided by the ecological modernization theory (Win-Win principle). An explanatory sequential mixed-method research design was employed, targeting SME proprietors in the manufacturing sector with a sample size of 76 respondents. Descriptive and inferential statistics (linear regression) was used to analyze quantitative data, while content analysis was used to analyze qualitative data. The study found out that SMEs largely adopted the use of energy-efficient bulbs and turned off lights when not in use. However, they used solar lighting as an energy efficiency practice to a lesser extent because they consider this practice expensive. The study also found that stakeholders perceived that energy efficiency practices adopted had a significant influence on the economic performance of selected manufacturing SMEs. This finding implied that energy efficiency practices adopted by manufacturing SMEs would have an influence on SMEs economic performance. This study recommends that the government, both national and county should sensitize the SMEs as well as allocate financial and technical resources to support SMEs implement and upscale their energy efficiency practices within their operations. The focus of energy efficiency practices should be on those that reduce production costs and enhance competitiveness such as those that improve SMEs customer base

Advanced understanding of the natural forces accelerating aging and release of black microplastics (tire wear particles) based on mechanism and toxicity analysis

Currently, tire wear particles (TWPs), a typical type of black microplastics (MPs), are frequently overlooked as the major source of MPs in aquatic environments. TWPs are widely distributed and exhibit complex environmental behaviors. However, how natural forces affect the aging and release behavior of TWPs at the nano(micro)scale remains inadequately explored. This study systematically investigated the aging behavior and mechanism of TWPs under the action of simulated natural light and high-temperature in both dry and wet environments, as well as the effect of aging treatment on the released leachate. The findings demonstrated that aging treatment significantly altered the physicochemical properties of TWPs, including chain scission and surface oxidation, and facilitated the release of heavy metals and organic additives in the meantime. In particular, the leaching concentration of Zn exhibited a positive linear relationship with exposure time. In the thermal-aging process, the oxidation of TWPs was primarily caused by superoxide anion (O2•−). During the photo-aging exposure, TWPs exhibited heightened electron-donating capacity, resulting in the formation of more O2•− and singlet oxygen (1O2) to attack TWPs. Moreover, the analysis of leachate produced under light and high-temperature conditions suggested that heavy metals exerted low ecological risks in water. Nonetheless, the photo-aging process enhanced the toxicity of released leachate to L929 cells, which could be attributed to highly toxic additive transformation products (such as HMMM-411 and 6PPD-Q) and more heavy metals. These findings shed light on the fate of TWPs and the ecological risks posed by aged TWPs in aquatic environments.

Dual-functional paper-like evaporator for boosting interfacial evaporation synchronized with organic pollutant degradation

Solar-driven interfacial evaporation is a sustainable method to produce freshwater, but volatile organic compounds (VOCs) inevitable accumulate in the condensed water, causing secondary pollution. Herein, paper-like photothermal evaporators were constructed by fixing zeolitic diazoate frameworks-8 derived N-doped carbon with different morphologies on the interwoven cellulose nanofibrils (CNFs) membranes for simultaneous steam generation and organic pollutant degradation. The results showed that the evaporator incorporated porous N-doped carbon with rhombic dodecahedron (NC-RD) into CNFs membranes not only increases the roughness to achieve broad spectrum solar absorption, but also capable of ensuring continuous evaporation of water, and maintaining a sufficient water supply. The NC-RD/CNFs membranes exhibit the high evaporation rate of 1.46 kg·m−2·h−1 under one sun. Meanwhile, N-doped carbon enable photothermal-synergistic peroxymonosulfate (PMS) activation to promote the generation of abundant 1O2 and O2∙– for degradation of methylene blue, tetracycline and phenol. Furthermore, the solar-vapor conversion efficiency and the evaporation rate are stable in a simulated seawater environment with 15 wt% NaCl solution. Importantly, an outdoor NC-RD/CNFs-based device was constructed, which realizes a high evaporation rate of 0.659 kg∙m−2∙h−1 under natural light irradiation for 10 h. The present study highlights that the NC-RD/CNFs membranes successfully coupled interfacial evaporation with PMS based-advanced oxidation processes to provide a subtlety strategy to solve the problem of VOCs accumulation in the evaporation process.

Criteria for Designing Penitentiary Institutions in Light of Modern Penal Policy

This study aimed to identify the design standards of penitentiary institutions in light of modern penal policy. It specifically aimed to identify the criteria for choosing the location of the penal institution. Moreover, it identified the standards for the interior and exterior design of the penal institution. The descriptive analytical approach was used, and the study found that the more the location of the penal institution is not isolated, the more it is in line with modern penal policy. Furthermore, the larger the area of the penal institution is, the more it is in line with modern penal policy. When designing the interior of a penal institution, adequate ventilation, natural lighting, and appropriate temperature are taken into consideration from the environmental standpoint. When designing the internal spaces of a penal institution, the appropriate space for prisoner rooms and dormitory rooms, along with the availability of sanitary facilities in each room, is taken into account. The study recommended making administrative reform and rehabilitation centers in the police force. This can be done by designing and building penitentiary institutions in accordance with modern penal policy

Synergistic design of processable Nb2O5-TiO2 bilayer nanoarchitectonics: enabling high coloration efficiency and superior stability in dual-band electrochromic energy storage

This paper introduces a proof of concept for a dual-band electrochromic (EC) device to modulate solar light transmission across visible and near-infrared regions selectively. EC materials based on ion insertion/extraction mechanisms also present the possibility for energy storage, widening its functionality to the supercapacitor platform. The bi-functional performance of dual-band radiation control and energy storage was achieved by exploiting two earth-abundant metal oxides that could absorb two different spectral regions when electrochemically charged. The bilayer structure was prepared using a one-step hydrothermal method, which produced Nb2O5-TiO2 bilayer on fluorine-doped tin oxide (FTO) conducting glass substrates. The nano-dimensions of the active materials endorse the development of high-transparency thin film under open circuit conditions. The variations in the TiO2 annealing temperature influence the crystallinity and surface morphology of the thin films, which influence the performance of dual-band EC energy storage. The well-optimized NT-500 sample facilitated exclusive electron-charge transport, producing excellent electrochemical performance in dual-band EC and energy storage. A large optical modulation of 80.4 % and 89.8 % at 600 nm and 800 nm (near-infrared) was achieved with an enhanced areal capacitance of 88.1 mF/cm2 and excellent cycling stability after continuous coloring/bleaching cycles for 18,000 s. This paper presents a prototype bi-functional device based on NT-500, which showed independent control and modulation of visible and near-infrared transmittance. Notably, the device retained excellent energy storage performance alongside its advanced optical functionalities. This bilayer nanostructure capitalizes on the inherent electrochemical properties of both materials and introduces novel features that can potentially revolutionize the platform of EC-energy storage.

Novel eco-friendly and easily recoverable bismuth-based materials for capturing and removing polyphenols from water

Olive oil production is one of the most developed Europe's sectors, producing olive oil and undesirable by-products, such as olive mill wastewater (OMWW) and organic waste. OMWW, containing large amounts of compounds (mainly polyphenols, phenols, and tannins), represents a problem. In fact, polyphenols have dual nature: i) antioxidant beneficial properties, useful in many industrial fields, ii) biorefractory character making them harmful in high concentrations. If not properly treated, polyphenols can harm biodiversity, disrupt ecological balance, and degrade water quality, posing risks to both environment and human health. From a circular economy viewpoint, capturing large quantities of polyphenols to reuse and removing their residuals from water is an open challenge. This study proposes, for the first time, a new path beyond the state-of-the-art, combining adsorption and degradation technologies by novel, eco-friendly and easily recoverable bismuth-based materials to capture large amounts of two model polyphenols (gallic acid and 3,4,5-trimethoxybenzoic acid), which are difficult to remove by traditional processes, and photodegrade them under solar light. The coupled process gave rise to collect 98% polyphenols, and to rapidly and effectively photodegrade the remaining portion from water.

Pili annulati under the electron microscope: a case report and literature review.

We report a 32-year-old woman whose hair had exhibited a distinctive pattern of black and white streaks under natural light. She underwent trichoscopic photography and scanning electron microscopy, leading to the identification of pili annulati (PA). Trichoscopic photography revealed that the hair shafts were uniformly thick, with a pattern of alternating light and dark bands resembling beads. The scanning electron micrograph depicted a rough and cracked surface of the hair stem, with many grooves clearly visible. And numerous air bubbles of varying sizes were observed within the hair cortex.

Tailoring Energy Structure of Low‐Toxic Ternary Ag−Bi−S Quantum Dots through Solution‐Phase Synthesis for Quantum‐Dot‐Sensitized Solar Cells

AbstractLow‐toxic multinary semiconductor quantum dots (QDs) showing a photoresponse in a wide wavelength range from visible to near‐IR wavelength regions have been intensively investigated for fabricating efficient solar light conversion systems. Recently, AgBiS2 QDs have attracted much attention for their application to improve the performance of QD solar cells because they have a large absorption coefficient in the visible and near‐IR regions. In this report, we describe solution‐phase preparation of ternary Ag−Bi−S QDs with different sizes and with different Ag/Bi ratios. The average size of resulting spherical Ag−Bi−S QDs was controllable from 2.7 to 8.1 nm by adjusting the reaction temperature from 373 to 473 K, while the Ag fraction of obtained QDs also increased with an increase in particle size. The absorption onset wavelength shifted from 850 to 1200 nm in the near‐IR region as the particle size increased. AgBiS2 QDs with an almost stoichiometric composition, obtained at reaction temperatures of 423 K and 473 K, contained no deep intragap states and exhibited a p‐type semiconductor behavior, while QDs prepared at a reaction temperature of 393 K or lower had non‐stoichiometric Ag‐deficient compositions producing intragap defect states. Sensitized solar cells fabricated with stoichiometric AgBiS2 QDs exhibited a photoresponse in visible and near‐IR wavelength regions, the optimal PCE being 0.74% with AgBiS2 QDs of 6.2 nm in diameter that were prepared at 423 K.