Aero-ZnS prepared by physical vapor transport on three-dimensional networks of sacrificial ZnO microtetrapods

• Veaceslav Ursaki,
• Tudor Braniste,
• Victor Zalamai,
• Emil Rusu,
• Vladimir Ciobanu,
• Vadim Morari,
• Daniel Podgornii,
• Pier Carlo Ricci,
• Rainer Adelung and
• Ion Tiginyanu

Beilstein J. Nanotechnol. 2024, 15, 490–499, doi:10.3762/bjnano.15.44

• nanocomposite components with respect to the HOMO and LUMO molecular orbitals of organic compounds subjected to photocatalytic degradation [18][44]. Specific photocatalytic properties of the aero-ZnS materials prepared by physical vapor transport have not been investigated in this paper. However, preliminary

• results suggest their suitability for the photocatalytic degradation of tetracycline. Nevertheless, focused investigations are needed concerning the optimization of the phase composition of the prepared materials for specific photocatalytic applications. Additional investigations of the surface states are

Photocatalytic degradation of methylene blue under visible light by cobalt ferrite nanoparticles/graphene quantum dots

• Vo Chau Ngoc Anh,
• Le Thi Thanh Nhi,
• Le Thi Kim Dung,
• Dang Thi Ngoc Hoa,
• Nguyen Truong Son,
• Nguyen Thi Thao Uyen,
• Nguyen Ngoc Uyen Thu,
• Le Van Thanh Son,
• Le Trung Hieu,
• Tran Ngoc Tuyen and
• Dinh Quang Khieu

Beilstein J. Nanotechnol. 2024, 15, 475–489, doi:10.3762/bjnano.15.43

• /GQDs nanoparticles. Magnetic properties, morphology, structure, and fluorescence of the nanocomposites were studied, and the photocatalytic degradation of methylene blue as a dye model and the mechanism of methylene degradation were also addressed. Experimental Materials Cobalt(II) nitrate hexahydrate

• first-order kinetic model is widely employed to assess the kinetic data of photocatalytic degradation. This model is as follows: where Ct and C0 are the MB concentration at the beginning and at the time t, respectively; k1 is the first-order kinetic rate constant. The slope of the linear plot of vs t

• provides the value of k1. The values of k1, along with others from the literature, are presented in Table 3. However, because the reactions were conducted under different conditions, the comparison is arbitrary. To clarify the mechanism of MB photocatalytic degradation, 10 mM isopropyl (IPA), potassium

New application of bimetallic Ag/Pt nanoplates in a colorimetric biosensor for specific detection of E. coli in water

• Azam Bagheri Pebdeni,
• Mohammad N. AL-Baiati and
• Morteza Hosseini

Beilstein J. Nanotechnol. 2024, 15, 95–103, doi:10.3762/bjnano.15.9

• ], photocatalytic degradation and bactericidal action [21], sensors and biosensors [22][23][24][25], and as electrocatalysts [26]. Aptamers are single-stranded DNA or RNA oligonucleotides that attach to their targets with great affinity and specificity. Aptamers have high stability in a variety of environments and

Titania nanoparticles for photocatalytic degradation of ethanol under simulated solar light

• Evghenii Goncearenco,
• Iuliana P. Morjan,
• Claudiu Teodor Fleaca,
• Florian Dumitrache,
• Elena Dutu,
• Monica Scarisoreanu,
• Valentin Serban Teodorescu,
• Alexandra Sandulescu,
• Crina Anastasescu and
• Ioan Balint

Beilstein J. Nanotechnol. 2023, 14, 616–630, doi:10.3762/bjnano.14.51

• describes the photocatalytic degradation of ethanol vapors under simulated solar light and low oxygen concentration using TiO2 nanoparticles obtained by laser pyrolysis. The final products are CO2, H2O, and H2. The average particle sizes are between 15 and 22 nm with anatase being the predominant

Conjugated photothermal materials and structure design for solar steam generation

• Chia-Yang Lin and
• Tsuyoshi Michinobu

Beilstein J. Nanotechnol. 2023, 14, 454–466, doi:10.3762/bjnano.14.36

• membranes with hydrophobic photothermal material particles. Over the past years, various types of SSG membranes have been studied [37][39][45][54][56][57]. These SSG membranes can be applied to, for example, seawater desalination and photocatalytic degradation by utilizing the photothermal and separation

Bismuth-based nanostructured photocatalysts for the remediation of antibiotics and organic dyes

• Akeem Adeyemi Oladipo and
• Faisal Suleiman Mustafa

Beilstein J. Nanotechnol. 2023, 14, 291–321, doi:10.3762/bjnano.14.26

• photocatalytic degradation of organic dyes and antibiotics in water. The general synthesis of nanometre-sized photocatalytic materials based on bismuth employing energy-efficient techniques is examined. A critical review is also given of ways to improve the photocatalytic activity of the photocatalysts. An

• photocatalyst showed a maximum photocatalytic degradation activity of 90% under visible-light irradiation in 1 h, which is higher than the 52% achieved by pure CdS under the same conditions. The improved photocatalytic degradation efficiency is attributed to the surface plasmon resonance effect, doped Bi3+ ions

• light, and simulated sunlight. Several Bi-based photocatalysts are visible-light-driven because of the bandgap, making them useful in a variety of situations. The solution pH value is a critical parameter when it comes to the photocatalytic degradation of textile dyes and antibiotics. The point of zero

Non-stoichiometric magnetite as catalyst for the photocatalytic degradation of phenol and 2,6-dibromo-4-methylphenol – a new approach in water treatment

• Joanna Kisała,
• Anna Tomaszewska and
• Przemysław Kolek

Beilstein J. Nanotechnol. 2022, 13, 1531–1540, doi:10.3762/bjnano.13.126

• the organic compounds are discussed, as well as their influence on the degradation reaction rates. The degradation efficiency in photocatalytic processes was higher for DBMP (98%) than for phenol (approximately 50%). This proves the high efficiency of magnetite in the photocatalytic degradation of

• SEM reveals the maximum size of the particles. The catalytic activity of commercially available M1 and M2 was evaluated through the photocatalytic degradation of phenol and DBMP. The photocatalytic activity was compared with the efficiency of ozonolysis. The photocatalytic efficiency is improved by

• the reduction process to the photocatalytic degradation of DBMP. Figure 7 shows the degradation efficiency regarding phenol and DBMP. Phenol degradation reached approx. 65% after 60 min of ozonation whereas the degradation of DBMP was 95%. This is related to the ionic forms of these compounds under

LED-light-activated photocatalytic performance of metal-free carbon-modified hexagonal boron nitride towards degradation of methylene blue and phenol

• Nirmalendu S. Mishra and
• Pichiah Saravanan

Beilstein J. Nanotechnol. 2022, 13, 1380–1392, doi:10.3762/bjnano.13.114

• gas chromatograph coupled with a mass spectrometer (GC–MS, Thermo Fisher Scientific) by taking aliquots at 150 min and 330 min. The photocatalytic degradation and mineralization efficiencies were calculated by utilizing the following equations [19]: where Abs(0) symbolizes the initial absorbance, Abs

• modified boron nitride Photocatalytic study Figure 7a–g depicts the adsorption and photocatalytic degradation performance of MBN-80 towards MB (20 ppm) and phenol (10 ppm) accomplished through LED irradiation. Specifically, it removed 78.87% of MB (20 ppm solution) which was further enhanced to 93.83% in

• other hand, the photocatalytic degradation of phenol demonstrated a removal rate of 0.0015 min−1 with 48.56% removal and a mineralization efficiency of 20.17%. The AQE for phenol/H2O2 system was found to be at 2.67%. A negligible removal percentage in the order of 4% for MB and 6% for phenol over a

Recent trends in Bi-based nanomaterials: challenges, fabrication, enhancement techniques, and environmental applications

• Vishal Dutta,
• Ankush Chauhan,
• Ritesh Verma,
• C. Gopalkrishnan and
• Van-Huy Nguyen

Beilstein J. Nanotechnol. 2022, 13, 1316–1336, doi:10.3762/bjnano.13.109

• photocatalysts in eco-friendly applications on a large scale. Bi-based nanomaterials as semiconductor photocatalysts are one of the study’s primary goals, as is the use of Bi-based nanomaterials for wastewater treatment, hydrogen generation, and photocatalytic degradation. Fabrication methods, reliability

• the improved photocatalytic activity of the Fe-doped Bi2WO6 compound. When exposed to visible light, Fe-doped Bi2WO6 exhibited photocatalytic degradation rates that were 11.9 and 8.0 times higher than those of pristine Bi2WO6. This material was also found to be superior to the majority of modified

• photodegradation of RhB under visible light. Their research also revealed that 15% SnO2 precursor solution was the most effective concentration for achieving a photocatalytic degradation efficiency of 80% after 180 min of exposure to visible light. Photogenerated holes were found to be responsible for the

Green synthesis of zinc oxide nanoparticles toward highly efficient photocatalysis and antibacterial application

• Vo Thi Thu Nhu,
• Nguyen Duy Dat,
• Le-Minh Tam and
• Nguyen Hoang Phuong

Beilstein J. Nanotechnol. 2022, 13, 1108–1119, doi:10.3762/bjnano.13.94

• of 10 °C/min. The zeta potential was measured by analyzing 0.1 g of ZnO in 10 mL of water using a Malvern ZetasizerPro. The solid UV–vis DRS was carried out using a JASCO V550 UV–vis spectrometer. Photocatalytic degradation reaction The photocatalytic degradation of a dye solution under visible and

• ), indicating that ZnO NPs are negatively charged and stable in aqueous solution. Photocatalytic degradation of dyes The photocatalytic degradation of ZnO NPs was evaluated through the degradation of methylene blue and methyl orange under visible and UV light and the degradation efficiency was calculated via

• NPs The mechanism of photocatalytic degradation and E. coli antibacterial activity by ZnO NPs is illustrated in Figure 11. When ZnO is irradiated with visible or UV light whose energy is equal or greater than the bandgap of ZnO, the electrons from the VB of ZnO NPs are excited to the CB generating

Spindle-like MIL101(Fe) decorated with Bi₂O₃ nanoparticles for enhanced degradation of chlortetracycline under visible-light irradiation

• Chen-chen Hao,
• Fang-yan Chen,
• Kun Bian,
• Yu-bin Tang and
• Wei-long Shi

Beilstein J. Nanotechnol. 2022, 13, 1038–1050, doi:10.3762/bjnano.13.91

• . The intermediate products were analyzed by liquid chromatography–mass spectrometry (LC–MS), and a possible photocatalytic degradation path of CTC was proposed. This work provides a new perspective for the preparation of efficient MOF-based photocatalysts. Keywords: Bi2O3; chlortetracycline; metal

• –metal charge transfer (LMCT). For this reason, these MOFs are considered as emerging semiconductor-like photocatalysts and attention is growing toward these materials [26][27][28][29]. In 2007, Garcia and coworkers have first reported photocatalytic degradation of phenol by using MOF-5 as a

• experiment and electron spin resonance (ESR) experiment suggest that the electron transfer path between Bi2O3 and MIL101(Fe) accords with the Z-type transfer mechanism. The possible photocatalytic degradation pathways were investigated via the analysis of the intermediate products in the degradation process

Solar-light-driven LaFe_xNi_1−xO₃ perovskite oxides for photocatalytic Fenton-like reaction to degrade organic pollutants

• Chao-Wei Huang,
• Shu-Yu Hsu,
• Jun-Han Lin,
• Yun Jhou,
• Wei-Yu Chen,
• Kun-Yi Andrew Lin,
• Yu-Tang Lin and
• Van-Huy Nguyen

Beilstein J. Nanotechnol. 2022, 13, 882–895, doi:10.3762/bjnano.13.79

• decompose the methylene blue molecules. Accordingly, the synthesis condition of pH 0, calcination temperature at 700 °C, and Fe/Ni ratio = 7/3 could form LaFe0.7Ni0.3O3 perovskite oxides as highly efficient photocatalysts. Moreover, various conditions during the photocatalytic degradation were verified

• various photocatalysts prepared at pH 0 or pH 7 The standard concentration of MB aqueous solution was prepared at 20 ppm. Various LaFexNi1−xO3 perovskite oxides prepared at pH 0 were examined for dark adsorption and photocatalytic degradation. First, dark adsorption was not significant for all perovskite

• photocatalytic degradation [54]. Accordingly, different pH values of solution using LaFe0.7Ni0.3O3 perovskite oxides prepared at pH 0 were examined for photocatalytic degradation. Thus, the MB aqueous solution was adjusted to pH 1.5, 3.5, and 5.5. The performance of the photocatalytic Fenton degradation was

Hierarchical Bi₂WO₆/TiO₂-nanotube composites derived from natural cellulose for visible-light photocatalytic treatment of pollutants

• Zehao Lin,
• Zhan Yang and
• Jianguo Huang

Beilstein J. Nanotechnol. 2022, 13, 745–762, doi:10.3762/bjnano.13.66

• photocatalytic reduction of Cr(VI), while hydroxyl radicals and reactive holes contributed to the photocatalytic degradation of rhodamine B. Keywords: biomimetic synthesis; cellulose; nanoarchitectonics; nanocomposite; nanotubes; photocatalysis; pollutants; Introduction The direct emission of untreated

• ), EDTA-2Na (0.1 M), and p-BQ (5.0 mM) were also put into the initial RhB pollutant solution to capture •OH, h+, and •O2− species, respectively, generated during the photocatalytic degradation of RhB. Results and Discussion Structural characterization As shown in Figure 1, the Bi2WO6/TiO2-NT

• response to the visible spectral region. Besides, under visible light irradiation, Bi2WO6/TiO2-NT composites show better photocatalytic degradation activities than that of g-C3N4/TiO2-NT composites. Based on these cellulose-derived nanocomposites, structure–activity relationships between photocatalytic

Zinc oxide nanostructures for fluorescence and Raman signal enhancement: a review

• Ioana Marica,
• Fran Nekvapil,
• Maria Ștefan,
• Cosmin Farcău and
• Alexandra Falamaș

Beilstein J. Nanotechnol. 2022, 13, 472–490, doi:10.3762/bjnano.13.40

• when used as a SERS substrate. The self-cleaning ability of ZnO alone or ZnO–noble metal-based nanostructured substrates has been shown under UV or visible irradiation via the photocatalytic degradation of the organic molecules attached to the substrate [8][34][53]. For instance, [75] presented Au

• -coated roughened ZnO nanostructures, which enabled photocatalytic degradation of adsorbed analytes and the reuse of the substrate. Also, [73] demonstrated the self-cleaning ability of ZnO–Au nanostructures under UV irradiation. The rhodamine 6G adsorbed on Ag–ZnO–Au film showed a fast photocatalytic

• remove the analyte. Figure 5 shows the disappearance of the SERS signals of rhodamine 6G after UV irradiation and the possibility to reuse the substrate for several cycles [32]. It appears that the photocatalytic degradation depends on the geometrical configuration of the ZnO–metal nanocomposites, as

A comprehensive review on electrospun nanohybrid membranes for wastewater treatment

• Senuri Kumarage,
• Imalka Munaweera and
• Nilwala Kottegoda

Beilstein J. Nanotechnol. 2022, 13, 137–159, doi:10.3762/bjnano.13.10

• 50% glycerol. 97% of the dye removal efficiency of the membrane was maintained even after five consecutive adsorption/desorption cycles [79]. Hou et al. added the photoactivity of TiO2 into a hybrid membrane of PVA, PAA, and carboxyl-functionalized GO to degrade organic dyes by photocatalytic

• degradation. The membrane displayed an efficient photocatalytic capacity for MB, CR, and RhB [80]. Although TiO2 is abundant and inexpensive, it only converts to UV part of sunlight, which is only 5% of the solar energy. This makes the use of TiO2 impractical. To counter this drawback Liu and co-workers

Tin dioxide nanomaterial-based photocatalysts for nitrogen oxide oxidation: a review

• Viet Van Pham,
• Hong-Huy Tran,
• Thao Kim Truong and
• Thi Minh Cao

Beilstein J. Nanotechnol. 2022, 13, 96–113, doi:10.3762/bjnano.13.7

• co-photocatalysts, including inorganic and organic semiconductors, is a practical approach to enhance the charge transfer efficacy for the photocatalytic process. The photocatalytic degradation of NOx over SnO2 as a host photocatalyst is reported to be considerably enhanced after the combination with

• ]. Huy et al. [38] hydrothermally synthesized SnO2 NPs adhering to TiO2 nanotubes (SnO2/TNTs) via a facile one-step method for the photocatalytic abatement of NO under visible light (Figure 9). At a NO concentration of 450 ppb in a continuous flow, SnO2/TNTs yields a photocatalytic degradation of NO of

• /TNTs and pointed out the existence of •O2− and •OH radicals as critical factors in the photocatalysis process [38]. These results demonstrated that the SnO2 NPs could be both a host or an auxiliary material for the NO photocatalytic degradation. Besides the coupling with semiconductor oxides such as

Unravelling the interfacial interaction in mesoporous SiO₂@nickel phyllosilicate/TiO₂ core–shell nanostructures for photocatalytic activity

• Bridget K. Mutuma,
• Xiluva Mathebula,
• Isaac Nongwe,
• Bonakele P. Mtolo,
• Boitumelo J. Matsoso,
• Rudolph Erasmus,
• Zikhona Tetana and
• Neil J. Coville

Beilstein J. Nanotechnol. 2020, 11, 1834–1846, doi:10.3762/bjnano.11.165

• et al. [27] observed an improved photocatalytic degradation of rhodamine blue dye in the presence of rattle-type TiO2@void@SiO2 nanostructures. They attributed the improved photoactivity to the ease of dye molecules to access the TiO2 active sites through the void space between the core and the shell

• recombination, leading to faster charge transport and photodegradation. Typically, the photocatalytic degradation efficacy of TiO2 depends on the surface area and metal-ion doping on the surface. Metal-ion doping of TiO2 influences its interfacial charge-transfer properties [51]. Differences in

• ) was used for evaluation of the photocatalytic properties. The photocatalytic degradation efficiency was estimated from the equation D% = (C0 − C/C0) × 100% (where C0 is the initial concentration and C is the concentration of MV solution after UV irradiation at a time t) [48][84]. After the catalyst

Nanocasting synthesis of BiFeO₃ nanoparticles with enhanced visible-light photocatalytic activity

• Thomas Cadenbach,
• Maria J. Benitez,
• A. Lucia Morales,
• Cesar Costa Vera,
• Luis Lascano,
• Francisco Quiroz,
• Alexis Debut and
• Karla Vizuete

Beilstein J. Nanotechnol. 2020, 11, 1822–1833, doi:10.3762/bjnano.11.164

• photocatalytic activity [20]. Since the photocatalytic degradation of organic molecules using a metal oxide photocatalyst is a heterogeneous process, it is obvious that efficiency and overall catalytic performance are strongly correlated to the number of active sites on the catalyst surface area and, thus, to

• radicals are the main active species in photocatalytic degradation reactions [22]. The addition of silver nitrate (AgNO3, 2 mM) to the photocatalytic reaction leads to an improvement of the overall efficiency resulting in a complete degradation of RhB after 240 min (Figure 12). This is explained by the

• sized particles. This behavior can be attributed to a low concentration of surface defects and low local strain. The photocatalyst proved to be stable under visible-light irradiation as it could be reapplied successfully in five successive photocatalytic degradation experiments without loss of

Cu₂O nanoparticles for the degradation of methyl parathion

• Juan Rizo,
• David Díaz,
• Benito Reyes-Trejo and
• M. Josefina Arellano-Jiménez

Beilstein J. Nanotechnol. 2020, 11, 1546–1555, doi:10.3762/bjnano.11.137

• bacteria are used for the degradation of MP, whereas photocatalytic degradation needs photons in the form of UV light and chemical degradation utilizes chemical species, such as copper(I) oxide (Cu2O) NPs in this work. Cu2O is widely known for its photocatalytic activity [29][30][31][32][33]. However

• similar results. Likewise, degradation experiments in the darkness were also performed giving identical results to those under daylight thus photocatalytic degradation was ruled out. Instrumentation UV–vis electronic absorption spectra were acquired on an Ocean Optics CHEM-2000 spectrophotometer equipped

Effect of Ag loading position on the photocatalytic performance of TiO₂ nanocolumn arrays

• Jinghan Xu,
• Yanqi Liu and
• Yan Zhao

Beilstein J. Nanotechnol. 2020, 11, 717–728, doi:10.3762/bjnano.11.59

• spectra and (c,d) bandgaps of the different samples. Photocatalytic activity for the degradation of MB: (a) UV–vis absorption spectra for the photocatalytic degradation of MB in the presence of AFT1 sample, (b) photocatalytic degradation rate of MB by different samples and pure MB under UV–vis light, (c

Preparation, characterization and photocatalytic performance of heterostructured CuO–ZnO-loaded composite nanofiber membranes

• Wei Fang,
• Liang Yu and
• Lan Xu

Beilstein J. Nanotechnol. 2020, 11, 631–650, doi:10.3762/bjnano.11.50

• , and properties of the CNFMs was investigated, and the optimal process parameters were determined. Then, the CNFMs obtained with optimal process parameters were applied for the photocatalytic degradation of methyl orange. It was found that the CNFMs could be reused to degrade methyl orange at least

• a high photocatalytic activity because of a better charge separation [16][17][18][19][20][21][22]. Liu et al. [23] prepared CuO/ZnO nanocomposites by homogeneous coprecipitation and used them for the photocatalytic degradation of methyl orange. Wei et al. [24] fabricated CuO/ZnO composite nanofilms

• using cathodic co-electrodeposition and observed their photocatalytic performance. Fierro et al. [25] synthesized CuO–ZnO composite catalysts by temperature-programmed reduction and applied them in photocatalytic degradation. Nanocomposites loaded with metal oxide semiconductors have excellent optical

Synthesis and enhanced photocatalytic performance of 0D/2D CuO/tourmaline composite photocatalysts

• Changqiang Yu,
• Min Wen,
• Zhen Tong,
• Shuhua Li,
• Yanhong Yin,
• Xianbin Liu,
• Yesheng Li,
• Tongxiang Liang,
• Ziping Wu and
• Dionysios D. Dionysiou

Beilstein J. Nanotechnol. 2020, 11, 407–416, doi:10.3762/bjnano.11.31

• -type CuO semiconductor is ≈1.2 eV [6]. The application of CuO covers the fields of photocatalytic degradation of organic contaminants [7], photocatalytic reduction of CO2 [8][9], photocatalytic splitting of water [10], etc. Nanoscale CuO has been widely studied owing to its increased surface defects

• the samples were characterized and discussed. The photocatalytic degradation performance of the CuO/tourmaline composite was investigated, and a plausible mechanism was proposed. Experimental Materials The tourmaline sample used in this study was obtained from Hebei province, China. It was crushed and

• clarified by centrifugation for the measurement of absorbance, which can be used to monitor the progress of the photocatalytic degradation reactions. For the durability test, the used photocatalyst was firstly rinsed with ethanol and deionized water by centrifugation, then it was collected by using aqueous

Air oxidation of sulfur mustard gas simulants using a pyrene-based metal–organic framework photocatalyst

• Ghada Ayoub,
• Mihails Arhangelskis,
• Xuan Zhang,
• Florencia Son,
• Timur Islamoglu,
• Tomislav Friščić and
• Omar K. Farha

Beilstein J. Nanotechnol. 2019, 10, 2422–2427, doi:10.3762/bjnano.10.232

• oxygen production and photocatalytic degradation of mustard gas simulant. In contrast to previously reported NU-1000, based on a 1,3,6,8-tetrasubstituted pyrene unit, which required saturation with oxygen to achieve effective high singlet oxygen production, the herein reported NU-400 is effective without

Improved adsorption and degradation performance by S-doping of (001)-TiO₂

• Xiao-Yu Sun,
• Xian Zhang,
• Xiao Sun,
• Ni-Xian Qian,
• Min Wang and
• Yong-Qing Ma

Beilstein J. Nanotechnol. 2019, 10, 2116–2127, doi:10.3762/bjnano.10.206

• photocatalytic degradation performance of all samples was tested with MB as the target pollutant. Figure 7 representatively shows the temporal evolution of the UV–vis spectra during the photodegradation of aqueous MB over the 2-S2 sample (a) and the variation of the MB concentration C/C0 with time in the

BiOCl/TiO₂/diatomite composites with enhanced visible-light photocatalytic activity for the degradation of rhodamine B

• Minlin Ao,
• Kun Liu,
• Xuekun Tang,
• Zishun Li,
• Qian Peng and
• Jing Huang

Beilstein J. Nanotechnol. 2019, 10, 1412–1422, doi:10.3762/bjnano.10.139

• is tightly connected with TiO2 and BiOCl, which mainly acts as a carrier to solve the problem of agglomeration of TiO2 and BiOCl. Photocatalytic activity analysis The photocatalytic degradation of RhB under visible-light irradiation was studied in this work. As shown in Figure 7a, RhB does not self