Photodegradation Ratio Research Articles

Curcumin-loaded food-grade nano-silica hybrid material exhibiting improved photodynamic effect and its application for the preservation of small yellow croaker (Larimichthys polyactis)

Two types of curcumin-loaded food-grade nano-silica (F-SiO2) hybrid materials were successfully synthesized using the rotary evaporation method (F-SiO2@Cur) and the adsorption method (Cur@F-SiO2). The microstructure and spectral analyses confirmed that the curcumin in F-SiO2@Cur was loaded within the nanopores in a non-aggregate form rather than being adsorbed onto the surface (Cur@F-SiO2). Additionally, F-SiO2@Cur exhibited remarkable water solubility (1510 ± 50.33 µg/mL) and photostability (a photodegradation ratio of only 59.22 %). Importantly, F-SiO2@Cur obtained a higher capacity for the generation of singlet oxygen (1O2) compared to control groups. Consequently, F-SiO2@Cur-mediated photodynamic inactivation (PDI) group attained the highest score in sensory evaluation and the best color protection effect in PDI experiment of small yellow croaker (Larimichthys polyactis) at 4 °C. Moreover, F-SiO2@Cur could effectively controlled total volatile basic nitrogen (TVB-N) content, pH, and total viable count (TVC), thereby prolonging the shelf life. Therefore, F-SiO2@Cur-mediated PDI is an effective fresh-keeping technology for aquatic products.

Doping rare earth cations with an additional chemical reduction synergistically weakened the photocatalytic performance of ceria.

Chemical reducing or rare earth cations (RE) doping was normally employed to promote the photocatalytic performance of ceria, aimed to evaluate their cooperation influences, ceria was obtained by decomposing homogenously RE (RE = La, Sm, and Y)-doped CeCO3OH in H2. XPS and EPR results evidenced that the excess oxygen vacancies (OVs) were formed in RE-doped CeO2 compared to the un-doped ceria. However, all the RE-doped ceria unexpectedly showed an impeded photocatalytic activity towards to methylene blue (MB) photodegradation. The 5% Sm-doped ceria had the best MB photodegradation ratio of 81.47% after 2-h reaction in all RE-doped samples, which was lower than that of 87.24% for the un-doped ceria. After doping RE cations and chemical reducing, the band gap of ceria were almost narrowed, while the PL spectra and photo-electro characterizations indicated that the separation efficiency of photo-excited e-/h+ (electrons/holes) was reduced. The RE dopants and formed excess OVs including inner and surface OVs was proposed to promote the recombination of e-/h+ which further hindered the generation of active species of ·O2- and ·OH, and finally weakened the photocatalytic activity of ceria.

Au nanoparticles modified HNTs/g-C3N4/CdS composite for highly efficient CO2 photoreduction and tetracycline degradation

In this research, Au nanoparticles (NPs) modified HNTs/g-C3N4/CdS composite (HCAC-3) photocatalyst was prepared for highly-efficient photocatalytic reaction. SEM and TEM results confirmed that the g-C3N4 was uniformly wrapped on the surface of HNTs, and Au and CdS NPs were also loaded on the surface of the HNTs/g-C3N4 composite. Photo-electrochemistry tests and density functional theory calculation results showed that the introducing Au NPs speeds up the photo-electric conversion and separation ratio of photogenerated carriers inside the catalyst. Additionally, the CO2 photoreduction experiments showed that the yields of CO and CH4 with HCAC-3 catalyst after 4 h irradiation with UV-Vis light were about 55.4 and 8.6 μmol/g, respectively, which were about five times the performance of HNTs/g-C3N4 composite and the HCAC-3 has great photocatalytic stability. Besides, the photodegradation experiment of tetracycline aqueous solution showed that the HCAC-3 composite has excellent photodegradation activity. After 120 min, the tetracycline photodegradation ratio of HCAC-3 was about 87.4%, which is about 2.2 times higher than that of HNTs/g-C3N4 composite. Finally, the synergistic effect of g-C3N4/CdS type II heterojunction and the LSPR effect of Au NPs were investigated and determined as the main reasons for the improvement of the photocatalytic performance of the g-C3N4-based catalyst.

Electrodeposited kochia scoparia-shaped Te film: Controlled synthesis and enhanced visible-light photocatalytic performance

Recently Te film is precisely designed to degrade organic pollutants under visible light irradiation owing to its suitable photoelectrochemical properties. Here, various nanostructured Te films are synthesized via a facile electrodeposition method. Different concentration of cetyltrimethylammonium bromide (CTAB) is added into electrolytic solution, and a novel kochia scoparia-shaped morphology with excellent photocatalytic activity is successfully synthesized. The as-fabricated kochia scoparia-shaped Te film is explored in detail via many analytical methods. The results show that as-synthesized kochia scoparia-shaped nanostructure has better crystallinity, enhanced light absorption ability, lower intensity in PL spectra, favorable photogenerated carrier transport and a significantly enhanced photodegradation ratio of methylene blue (MB), as compared to the feather-shaped Te film. The removal rates can reach up to 95.5 % on the degradation of MB in 60 min. In addition, the kochia scoparia-shaped Te film also shows good repeatability and stability without an apparent inactivation under visible light irradiation during four repeated photocatalytic processes. Furthermore, a possible reaction mechanism of higher MB degradation efficiency in the film is also proposed and discussed according to the ESR results. This work supplies a worthy reference for developing highly capable and reusable photocatalysts for eliminating various pollutants.

Collaborative influence of morphology tuning and RE (La, Y, and Sm) doping on photocatalytic performance of nanoceria.

Tuning morphology and doping additional rare earth (RE) cations are potential techniques to promote the photocatalytic performance of ceria (CeO2), evaluating the collaborative effects of morphology and RE dopants is significant for producing high active ceria-based catalysts. So in this work, cubic, polyhedral and rod-like nanoceria doped with 10mol % La (lanthanum), Y (yttrium), or Sm (samarium) were synthesized by a facile template-free hydrothermal method. Phases, morphologies, oxygen vacancies (OVs) concentration, energy band structure, photo-carriers separation/recombination, and photodegradation ratio toward methylene blue (MB) dye of as prepared ceria were studied. Results show that doped CeO2 maintains a similar morphology structure with un-doped sample and the band gap narrows slightly. Y-doped nanoceria, with an improved separation and a reduced recombination of photo-excited electrons (e-) and holes (h+), owns a higher MB photodegradation ratio than that of samples doping with La or Sm, which is measured as 79.04, 84.43, and 85.59% for Y-doped cubic, polyhedral, and rod-like CeO2. The collaborative influence of morphology tuning and RE (La, Y, and Sm) doping on photocatalytic performance of nanoceria includes the effects of doped elements and the formation of OVs. The elevation of OVs concentration as well as the separation efficiency of photo-generated e-/h+ are suggested to further enhance the photocatalytic performance of ceria.

0D/1D Co3O4 quantum dots/surface hydroxylated g-C3N4 nanofibers heterojunction with enhanced photocatalytic removal of pharmaceuticals and personal care products

Graphitic carbon nitride (g-C3N4) is a promising candidate for photocatalytic degradation of emerging environmental contaminants, pharmaceuticals and personal care products (PPCPs). To improve the photodegradation performance of pure g-C3N4, the construction of different heterostructures, surface modification and morphology engineering could be considered. However, the surface of g-C3N4 is usually difficult to modify due to fewer functional groups on its surface. In this work, surface hydroxylated g-C3N4 nanofibers were prepared by NaOH treatment (NTCN), and then went through an in-situ growth method to obtain 0D/1D Co3O4-NTCN nanocomposites. Hydrolysis can effectively modify the surface of g-C3N4 to make it rich in hydroxyl and reduce the number of amino groups, which is conducive to photocatalytic activity. Surface hydroxylation of NTCN was confirmed by FTIR and XPS. Structurally, Co3O4-NTCN has a unique 0D / 1D structure, which has not been reported much on photocatalysts based on carbon nitride, providing a large surface area and short diffusion distances and resulting in more exposure to the light and the effective transfer of interfacial photogenerated charge from the interior to the surface. The photodegradation ratio of TC, DCF and MT can reach 97.3% TC, 88.9% and 63.2% within 60 min respectively. DFT calculation is used to illustrate the band structure and separation and migration of photoinduced charges of Co3O4-NTCN composites. Radicals trapping test demonstrate O2⋅− and ⋅OH are the major radicals, and a possible Z-scheme mechanism is proposed.

TiO2/carbonaceous nanocomposite from titanium-alginate coordination compound

TiO2-based materials have been developing rapidly as eco-friendly photocatalysts, but the inherent defects limited their application, such as rapid recombination of photogenerated electrons and wide bandgap. To obtain high-efficient TiO2/carbonaceous photocatalysts (TiO2/C), we prepared the nanocomposite by carbonizing titanium alginate coordination compound and studied their photocatalytic performance against methylene blue (MB) under simulated sunlight irradiation. The resultant nanocomposites were characterized by FT-IR, XPS, XRD, SEM-EDS, TG-DTG, UV-DRS, and N2 adsorption-desorption analysis. The carbon mainly existed in the outer layer of TiO2/C composites, contributing to the optical sensibilization. As a result, the degradation efficiency of sample TiO2/C-20 to MB could reach 97.47% within 15 min under simulated sunlight. The samples also possessed high stability, proved by the 0.72% reduction in photodegradation ratio after five cyclic tests. The present study proved the feasibility of preparing photocatalyst from titanium-alginate coordination compound and provided an extensible approach for preparing high-efficiency photocatalysts from a polysaccharide-based coordination compound.

Insight into the Contributions of Surface Oxygen Vacancies on the Promoted Photocatalytic Property of Nanoceria.

Oxygen vacancies (OVs) have critical effects on the photoelectric characterizations and photocatalytic activity of nanoceria, but the contributions of surface OVs on the promoted photocatalytic properties are not clear yet. In this work, we synthesized ceria nanopolyhedron (P-CeO2), ceria nanocube (C-CeO2) and ceria nanorod (R-CeO2), respectively, and annealed them at 600 °C in air, 30%, 60% or pure H2. After annealing, the surface OVs concentration of ceria elevates with the rising of H2 concentration. Photocatalytic activity of annealed ceria is promoted with the increasing of surface OVs, the methylene blue photodegradation ratio with pure hydrogen annealed of P-CeO2, C-CeO2 or R-CeO2 is 93.82%, 85.15% and 90.09%, respectively. Band gap of annealed ceria expands first and then tends to narrow slightly with the rising of surface OVs, while the valence band (VB) and conductive band (CB) of annealed ceria changed slightly. Both of photoluminescence spectra and photocurrent results indicate that the separation efficiency of photoinduced electron-hole pairs is significantly enhanced with the increasing of the surface OVs concentration. The notable weakened recombination of photogenerated carrier is suggested to attribute a momentous contribution on the enhanced photocatalytic activity of ceria which contains surface OVs.

Homogenously Rare-Earth-Ion-Doped Nanoceria Synthesis in KOH-NaOH Molten Flux: Characterization and Photocatalytic Property

Homogeneously rare-earth (RE=La, Sm and Y) ions doped CeO2 nanoparticles (NPs) with enhanced photocatalytic performance were synthesized by a facile KOH-NaOH molten flux method. XRD, TEM, EDS mapping and XPS results demonstrate that RE cations have been successfully doped into the CeO2 lattice, which leads to the lattice expansion/shrinking, and more oxygen vacancies are generated after RE ions doping. The UV-Vis DRS and PL spectra indicate that RE-doped CeO2 samples have slightly narrower band gaps and significantly reduced photo-generated electron-hole recombination rates. 5% RE ions doped CeO2 NPs show excellent photocatalytic performances and the photodegradation ratio of methylene blue (MB) increases from 71.63% of undoped CeO2 to 76.35%, 77.51% and 77.37% for 5%-La, 5%-Sm and 5%-Y-doped CeO2 NPs, respectively. The obviously reduced recombination rate of e−/h+ pairs after RE ions doping may be the critical factor for the enhanced photocatalytic performance.

Self-assembly of structured CeCO3OH and its decomposition in H2 for a novel tactic to obtain CeO2- with excellent photocatalytic property

Abstract In this work, various new-observed structured CeCO3OH were synthesized by a self-assembly hydrothermal method, and a novel tactic to produce CeO2-x with excellent photocatalytic activity by decomposing CeCO3OH in H2 was proposed and identified. By controlling the synthetic conditions, almond-like, subglobose shape and hollow-sphere of CeCO3OH, 3D-broom-like of Ce2O3·2CO2·nH2O (n = (1–2)), and sheet-like of Ce2(CO3)3·6H2O were synthesized. The crystal growth and formation of the cerium carbonate compounds were carefully studied using XRD, SEM and TEM. TG, thermodynamic calculation and in-situ XRD were employed to reveal the decomposition behavior of almond-like CeCO3OH in air, Ar and H2. The results show that the decomposition temperatures of CeCO3OH in Ar and H2 are higher than that of in air, and suggest that Ce2O3 has a low thermodynamic stability during the decomposition of CeCO3OH in Ar and H2, and Ce3+ will be mostly oxidized by H2O firstly and then by both of H2O and CO2. The ceria samples obtained by decomposing from CeCO3OH in different atmosphere maintain indistinguishable shape and particle size. The XPS, Raman spectra and ESR results indicate that the one obtained in H2 has the richest surface oxygen vacancies (OVs), narrowest band gap of 3.12 eV, lowest intensity in PL spectra and a significantly enhanced photodegradation ratio of methylene blue. The MB photodegradation ratio after 120 min reaction with the catalysts of CeO2-Air, CeO2-Ar and CeO2-H2 is 43.14%, 54.43% and 73.41%, with a calculated reaction rate constant of 0.00539, 0.00652 and 0.01097 min-1, respectively. The offered novel tactic of decomposing CeCO3OH in H2 is an efficient and facile technique for active CeO2-x production.

Optimal rare-earth (La, Y and Sm) doping conditions and enhanced mechanism for photocatalytic application of ceria nanorods

Morphological tuning or additional cation doping is one of the potential and simple methods to enhance the photocatalytic properties of ceria, in which rare-earth element doped ceria nanorods (CeO2-RE NRs) are expected to be a promising photocatalyst with high activity. But the optimal doping conditions, including the variety and concentration of RE elements are ambiguous, and the contribution of doped RE ions to the enhancement of photocatalytic activity needs to be further studied. In this work, we doped La, Y and Sm with a wide range of 0%–30% into CeO2 NRs, and investigated the phase, morphology, band gap, oxygen vacancy concentration, PL spectra and photocatalytic activity variation under different doping conditions. All synthesized CeO2-RE NRs possessed a good nanorod morphology except the 15 and 30% Y-doped samples. The energy band gaps of the synthesized samples changed slightly; the 10% CeO2-RE NRs with the narrowest band gaps possessed the higher photocatalytic performance. The most outstanding photocatalyst was found to be the 10% Y-doped CeO2 NRs with a methylene blue photodegradation ratio of 85.59% and rate constant of 0.0134 min−1, which is particularly associated with a significant higher oxygen vacancy concentration and obviously lower recombination rate of photogenerated e−/h+ pairs. The doped RE ions and the promotion of oxygen vacancy generation impede the recombination of photogenerated carriers, which is proposed as the main reason to enhance the photocatalytic property of CeO2.

Surfactant‐assisted hydrothermal synthesis of NaTaO 3 nanotubes with enhanced photodegradation activity

The morphology of photocatalysts plays an important role in their photocatalytic activity. Here, a novel sodium tantalum trioxide (NaTaO3) nanotube photocatalyst was hydrothermally synthesised with the assistant of Na dodecyl sulphate (SDS) surfactant. The as-synthesised NaTaO3 nanotubes presented an enhanced light absorption, compared with NaTaO3 nanocubes prepared without the addition of SDS. By using rhodamine B (RhB) as organic pollutants model, the NaTaO3 nanotubes exhibited a 96.2% of photodegradation ratio after 80 min ultraviolet light irradiation, which was much higher than NaTaO3 nanocubes and commercial P25. The cycle degradation results revealed that NaTaO3 nanotubes had an excellent photochemical stability. The active species trapping experiment suggested that the dominating active species were hydroxyl radicals and superoxide radicals, rather than holes.

Preparation, Structural, and Photocatalytic Properties of Boron-Doped Bismuth Oxybromide Nanoplatelets Combined with a First-Principle Study

In this work, we propose a modified sol–gel route to obtain boron-doped BiOBr nanoplatelets and investigate its photocatalytic performance. The prepared materials were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectroscopy (UV–Vis DRS), Raman spectroscopy, nitrogen adsorption–desorption measurements, X-ray photoelectron spectroscopy (XPS), steady-state photoluminescence emission, and time-resolved fluorescence decay spectra, respectively. In addition, the photocatalytic activity of the prepared samples was evaluated using model pollutants (Orange G, Rhodamine B dye and ciprofloxacin (CIP)) under simulated visible light irradiation (λ > 440 nm). The photo-degradation ratio of Orange G (OG), Rhodamine B (RhB) and CIP was ~91.0–96.0% after only 110, 180, and 60 min photocatalytic reaction by using B-doped BiOBr as catalyst, revealing that it had an excellent visible-light photocatalytic activity. In the tenth recycle, the degradation ratio of B‑doped BiOBr for CIP decomposition still reached to 80.0%. The outstanding photocatalytic activity was mainly contributed to the slowing down of recombination of electron–hole pairs. A first principle calculation on the electron band structures and density of states was also presented. The calculated band–gap (Eg) of B‑BiOBr (2.13 eV) was smaller than that of the neat BiOBr (2.77 eV), which are compared with the experimental values; Eg for B-BiOBr and neat BiOBr are 2.80 and 2.29 eV, respectively. The results of first principles calculations indicating B doping can decrease the band–gap energy of BiOBr effectively and improve its practical visible-light energy utilization. These conclusions are consistent with experimental results.

Preparation of nano-TiO2@polyfluorene composite particles for the photocatalytic degradation of organic pollutants under sunlight

In the tetrabutyl titanate solution via a sol-gel method, the nano-TiO2@polyfluorene composite particles were successfully prepared from the polyfluorene particles which were obtained by grinding fluorene with FeCl3 through the solid-state oxidative coupling reaction. The morphology and optical properties of the composite particles were characterized by scanning electronmicroscope, high resolution transmission electron microscopy, X-ray photo electron spectrometer, X-ray diffractometer, UV–visible diffuse reflectance spectroscopy, photoluminescence spectra and so on. The composite particles presented excellent photocatalytic activity on the degradation of triphenylmethane dyes, such as malachite green and rhodamine B under sunlight or under visible light. The photocatalytic reusability was investigated up to six successive cycles and the composite particles still retained their high activity of photodegradation ratio for malachite green. The mechanism of photocatalysis has been were discussed. The high surface area and effective photoinduced electrons and holes of TiO2@polyfluorene led to the enhanced photocatalytic activity. Consequently, the nano-TiO2@polyfluorene composite particles can be employed as an efficient photocatalyst to treat the organic pollutants.

Ni/ZnO heterostructured microspheres: electronic structure engineering for enhanced photocatalytic activity

Wurtzite ZnO is one of benchmark photocatalysts for the decomposition of organic pollutants. The wide band gap of about 3.4 eV, however, hinders its application in photocatalysis, which requires the electronic structure engineering to reduce the band gap for the enhancement of its optical absorption. Herein, a sodium citrate-assisted hydrothermal route is reported to prepare uniform Ni/ZnO heterostructured microspheres. The ZnO microspheres with the size of about 2.5 μm are assembled by ZnO nanosheets decorated by Ni nanoparticles of about 3 nm. The Ni/ZnO heterostructures provide enhanced surface activity, which is not only resulted from the larger surface area, but also caused by the formation of mid-gap-like electronic states in the heterostructures. Besides, it can promote the separation of the excited charges. Therefore, the Ni/ZnO microspheres deliver a significantly enhanced photodegradation ratio of 93% towards the probe organic pollutant of rhodamine B in comparison with that of bare wurtzite ZnO samples (degradation ratio of 72%). Density functional theory studies reveal that the Ni/ZnO heterostructures can improve the optical absorption of ZnO by forming mid-gap-like electronic states.

Flower-like structured Fe3O4−MQDs/Bi2WO6/GNs heterojunction with high-efficiently charge transfer for organic contaminants degradation

Abstract A novel flower-like ternary Fe3O4-magnetic quantum dots / Bi2WO6/ Graphene nanosheet (Fe3O4−MQDs/Bi2WO6/GNs) composite was successfully prepared by a facile one-pot hydrothermal method. The prepared samples were characterized by XRD, FTIR, UV–vis, SEM, HRTEM, EDS, BET and VSM technologies. Compared with the Bi2WO6 and Fe3O4/Bi2WO6, the Fe3O4/Bi2WO6/GNs catalyst exhibited higher photodegradation ratio of 98.2% for methylene blue (MB) and 90% for Tetracycline hydrochloride (TC) within 210 min irradiation at pH 7, and stability over 80% even after six cycles. Characterization results showed that the enhanced photocatalytic activity was mainly due to the strong interactions of MQDs/Bi2WO6 heterojunction and high specific surface area. A possible photocatalytic degradation mechanism was proposed on the basis of the identified intermediates. Furthermore, the Fe3O4/Bi2WO6/GNs composite could be easily recovered from the reaction system under an external magnetic field owing to its sufficient magnetism, therefore which has certain potential applications in water treatment process.

Constructing a Z-scheme Heterojunction of Egg-Like Core@shell CdS@TiO₂ Photocatalyst via a Facile Reflux Method for Enhanced Photocatalytic Performance.

A well designed and accurate method of control of different shell thickness and electronic transmission in a Z-scheme core@shell system is conducive to obtaining an optimum photocatalytic performance. Herein, the Z-scheme heterojunction of egg-like core@shell CdS@TiO2photocatalysts with controlled shell thickness (13 nm, 15 nm, 17 nm, 22 nm) were synthesized by a facile reflux method, and the CdS@TiO2 structure was proved by a series of characterizations. The photodegradation ratio on methylene blue and tetracycline hydrochloride over the 0.10CdS@TiO2 composites with TiO2 shell thickness of 17 nm reached 90% in 250 min and 91% in 5 min, respectively, which was almost 9.8 times and 2.6 times than that of TiO2 and CdS on rhodamine B respectively under visible light. Besides, the higher total organic carbon removal ratio indicated that most of the pollutants were degraded to CO2 and H2O. The Z-scheme electronic transfer pathway was studied through radical species trapping experiments and electron spin resonance spectroscopy. Moreover, the relationship between shell thickness and photocatalytic activity demonstrated that different shell thickness affects the separation of the electron and holes, and therefore affected the photocatalytic performance. In addition, the effects of pollutants concentration, pH, and inorganic anions on photocatalytic performance were also investigated. This work can provide a novel idea for a well designed Z-scheme heterojunction of core@shell photocatalysts, and the study of photocatalytic performance under different factors has guiding significance for the treatment of actual wastewater.

Facile synthesis of ultrathin red phosphorus nanosheets with excellent photocatalytic performances

Ultrathin red phosphorus nanosheets (N-RP) have been first attempt synthesized through thermal decomposition reaction. N-RP exhibits a higher surface area compared to that of hydrothermal treatment red phosphorus (HT-RP). The crystal violet (CV) dye solution photodegradation ratio of N-RP is 94.5% in 40 min, higher than that with HT-RP only 38.0% under visible light irradiation.

Dy(III) Doped BiOCl Powder with Superior Highly Visible-Light-Driven Photocatalytic Activity for Rhodamine B Photodegradation.

Dy-doped BiOCl powder photocatalyst was synthesized A one–step coprecipitation method. The incorporation of Dy3+ replaced partial Bi3+ in BiOCl crystal lattice system. For Rhodamine B (RhB) under visible light irradiation, 2% Dy doped BiOCl possessed highly efficient photocatalytic activity and photodegradation efficiency. The photodegradation ratio of RhB could reach 97.3% after only 30 min of photocatalytic reaction; this was more than relative investigations have reported in the last two years. The main reason was that the 4f electron shell of Dy in the BiOCl crystal lattice system can generate a special electronic shell structure that facilitated the transfer of electron from valance band to conduction band and separation of the photoinduced charge carrier. Apart from material preparation, this research is expected to provide important references for RhB photodegradation in practical applications.

Utility of Solid-State UV/Vis Spectra on the Evaluation of Photostability of Indomethacin Crystals.

Evaluating the stability of drugs over ranges of various environmental conditions is necessary to ensure the quality of the drug throughout the shelf life. In this study, we used indomethacin, which is well known as a photosensitive drug, and evaluated the photostability of prepared crystals. HPLC analysis revealed that all the indomethacin crystals were degraded by light exposure. However, the indomethacin crystals involving solvates had different degrees of photodegradation and different solid-state UV/Vis spectra. The value of the absorption integral in the UVA range related closely to the photodegradation of indomethacin crystals involving solvates. Therefore, it is easy to compare the photosensitivity among the crystals without actual analytical data, by use of a suitable analytical method and using light exposure samples. Moreover, it is possible to predict the value of photodegradation ratio from the solid-state UV/Vis spectra of indomethacin crystals. Therefore, this method may provide key information for selecting the most appropriate crystal form of photosensitive drugs.