Emerging strategies in the sustainable removal of antibiotics using semiconductor-based photocatalysts

• Yunus Ahmed,
• Keya Rani Dutta,
• Parul Akhtar,
• Md. Arif Hossen,
• Md. Jahangir Alam,
• Obaid A. Alharbi,
• Hamad AlMohamadi and
• Abdul Wahab Mohammad

Beilstein J. Nanotechnol. 2025, 16, 264–285, doi:10.3762/bjnano.16.21

• highly effective in degrading high-strength organic and refractory chemicals [26]. Photocatalyst-based AOPs represent a promising strategy for eliminating antibiotics from polluted water, providing several advantages over other oxidation techniques. By utilizing light energy to activate catalysts, these

• . General mechanisms of the photocatalysis process Three fundamental steps can be identified in semiconductor photocatalysis for the breakdown of antibiotics in contaminated water, that is, photon absorption, excitation, and reaction [54][55]. When a photocatalyst absorbs photons with energy higher than its

• bandgap, electrons (e−) in the valence band (VB) transition to the conduction band (CB), resulting in the formation of holes (h+) in the VB (photocatalyst + hν → photocatalyst + h+ + e−) [54][55]. Afterwards, the electrons and holes are effectively separated and move toward the surface of the

Clays enhanced with niobium: potential in wastewater treatment and reuse as pigment with antibacterial activity

• Silvia Jaerger,
• Patricia Appelt,
• Mario Antônio Alves da Cunha,
• Fabián Ccahuana Ayma,
• Ricardo Schneider,
• Carla Bittencourt and
• Fauze Jacó Anaissi

Beilstein J. Nanotechnol. 2025, 16, 141–154, doi:10.3762/bjnano.16.13

• /bjnano.16.13 Abstract Bentonite clay sourced from the Guarapuava region, Brazil, was modified with niobium oxide (BEOx) and niobium phosphate (BEPh) to act as an adsorbent and photocatalyst in the remediation of wastewater containing methylene blue (MB) dye. Additionally, colored materials were evaluated

• photocatalyst to treat MB dye solutions and reuse this material as a hybrid pigment. Considering the semiconductor properties of niobium and the high capacity of the clay to remove pollutants from wastewater, we proposed in this research to use the niobium-modified clay as an adsorbent and photocatalyst to

TiO₂ immobilized on 2D mordenite: effect of hydrolysis conditions on structural, textural, and optical characteristics of the nanocomposites

• Marina G. Shelyapina,
• Rosario Isidro Yocupicio-Gaxiola,
• Gleb A. Valkovsky and
• Vitalii Petranovskii

Beilstein J. Nanotechnol. 2025, 16, 128–140, doi:10.3762/bjnano.16.12

• similarly leads to the formation of TiO2. TiO2 is a well-known photocatalyst whose efficiency depends on a number of factors, including the crystalline phase, particle size, and degree of crystallinity. The most active phase of TiO2 is considered to be anatase. Its nanoparticles usually show higher

• efficiency than the bulk phase, but the bandgap of anatase particles smaller than 10 nm is very sensitive to their size [14]. One of the disadvantages of such free photocatalyst nanoparticles is the limitation of mass transfer between solid and liquid phases. From this perspective, the problem of

Characterization of ZnO nanoparticles synthesized using probiotic Lactiplantibacillus plantarum GP258

• Prashantkumar Siddappa Chakra,
• Aishwarya Banakar,
• Shriram Narayan Puranik,
• Vishwas Kaveeshwar,
• C. R. Ravikumar and
• Devaraja Gayathri

Beilstein J. Nanotechnol. 2025, 16, 78–89, doi:10.3762/bjnano.16.8

• photocatalyst and 20 ppm of MB dye was exposed to UV light in order to initiate photodegradation. Measurements were taken at 15 min intervals to track the reduction in MB dye concentration. UV–visible spectrophotometry was used to measure the absorbance at 663 nm. Under UV irradiation, the photodegradation of

Mn-doped ZnO nanopowders prepared by sol–gel and microwave-assisted sol–gel methods and their photocatalytic properties

• Cristina Maria Vlăduț,
• Crina Anastasescu,
• Silviu Preda,
• Oana Catalina Mocioiu,
• Simona Petrescu,
• Jeanina Pandele-Cusu,
• Dana Culita,
• Veronica Bratan,
• Ioan Balint and
• Maria Zaharescu

Beilstein J. Nanotechnol. 2024, 15, 1283–1296, doi:10.3762/bjnano.15.104

• preparation and provide a comparative analysis of Mn-doped ZnO powders synthesized using SG and MW. By doing so, the authors intend to further the understanding of how these preparation methods influence the properties and effectiveness of Mn-doped ZnO as a photocatalyst. The study emphasizes detailed morpho

• photocatalyst for organic pollutant degradation but also underscore the importance of optimizing synthesis methods to enhance efficiency and reduce energy consumption. These advancements are crucial for addressing pressing environmental challenges and pave the way for more sustainable approaches to water

Photocatalytic methane oxidation over a TiO₂/SiNWs p–n junction catalyst at room temperature

• Qui Thanh Hoai Ta,
• Luan Minh Nguyen,
• Ngoc Hoi Nguyen,
• Phan Khanh Thinh Nguyen and
• Dai Hai Nguyen

Beilstein J. Nanotechnol. 2024, 15, 1132–1141, doi:10.3762/bjnano.15.92

• massive guidance in synthesizing an efficient photocatalyst for CH4 conversion under mild conditions. Keywords: photocatalysis; photocatalytic CH4 oxidation; p–n heterojunction; TiO2/SiNWs; Introduction Methane (CH4), which can take the form of liquefied natural gas, is one of the crucial sources of

• valuable products such as formaldehyde (HCHO), methanol (CH3OH), and other value-added oxygenates, which serve as essential precursors in various manufacturing and production processes [18][19]. The n-type semiconductor titanium dioxide (TiO2) has been discovered as a potential photocatalyst material

• ) [43][44]. As expected, the crystal orientation of the TiO2/SiNWs catalyst obviously led to the creation of a robust p–n junction photocatalyst. The SEM analysis further confirms the morphological evolution during etching and TiO2 ALD. As revealed in Supporting Information File 1, Figure S1, the

Intermixing of MoS₂ and WS₂ photocatalysts toward methylene blue photodegradation

• Maryam Al Qaydi,
• Nitul S. Rajput,
• Michael Lejeune,
• Abdellatif Bouchalkha,
• Mimoun El Marssi,
• Steevy Cordette,
• Chaouki Kasmi and
• Mustapha Jouiad

Beilstein J. Nanotechnol. 2024, 15, 817–829, doi:10.3762/bjnano.15.68

• several cycles. This finding underscores the advantageous outcomes of intermixing WS2 and MoS2, shedding light on the development of an efficient and enduring photocatalyst for visible-light-driven photodegradation of methylene blue. Keywords: methylene blue; MoS2/WS2 composite; photocatalysis

• cost-effective technology. By harnessing impinging photons, the photocatalytic degradation of pollutants takes place at the interface between the photocatalyst surface and the MB-contaminated electrolyte. The photon energy is the driving force for breaking down the MB compound leading to its removal [9

• optimizing their functionalities to design novel materials and devices with improved PD stability and durability [8][9][10]. Recently, researchers have investigated the use of MoS2 as a photocatalyst for the degradation of MB. They demonstrated that the MoS2–GO compound exhibited interesting PD performances

Green synthesis of biomass-derived carbon quantum dots for photocatalytic degradation of methylene blue

• Dalia Chávez-García,
• Mario Guzman,
• Viridiana Sanchez and
• Rubén D. Cadena-Nava

Beilstein J. Nanotechnol. 2024, 15, 755–766, doi:10.3762/bjnano.15.63

• mineralization of the MB molecule [38]. Other aspects that contribute to the MB degradation are the adsorption capacity of MB on the photocatalyst surface (i.e., CQD) and the specific surface area of the CQDs. All samples (but M3 and M7) presented a similar behavior, increasing their photocatalytic activity when

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

• degradation of methylene blue (MB) under visible light. The catalyst can be recycled with an external magnetic field and displays suitable stability. Also, it was reused in three successive experiments with a loss of efficiency of about 5%. The CF/GQDs are considered as an efficient photocatalyst for MB

• that the present photocatalyst exhibits no significant loss of activity over three cycles. The CF/GQDs-200 photocatalyst used in the cycling tests was characterised by using XRD before and after the cycling experiments. The result indicates that the as-obtained CF/GQDs-200 does not suffer from

• min). (a) Effects of addition of KI, IPA, KBrO3, and BQ on the visible-light-driven photocatalytic degradation of MB with CF@GQDs; (b) dependence of the chemical oxygen demand on the reaction time. (a) Cyclic photocatalytic degradation experiments of MB with CF/GQDs-200 photocatalyst; (b) XRD pattern

Nanomaterials for photocatalysis and applications in environmental remediation and renewable energy

• Viet Van Pham and
• Wee-Jun Ong

Beilstein J. Nanotechnol. 2023, 14, 722–724, doi:10.3762/bjnano.14.58

• ]. Semiconducting photocatalyst nanomaterials, such as SnO2, TiO2, MoS2, g-C3N4, and Bi-nanostructures have been proven efficient for a range of applications, including organic pollutant removal, NOx degradation, renewable energy production, and waste-to-energy conversion [15][17][18]. Figure 1 shows a general

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

• gas production has been detected for the samples from series “b”, whereas the CO2 evolution was observed for all samples from series “a”. Keywords: ethanol; H2 production; laser pyrolysis; photocatalyst; TiO2 nanoparticles; Introduction Semiconductor materials are widely used, from electronic

• fluorescent compound, namely umbelliferone, was monitored with a Carry Eclipse fluorescence spectrometer, slits set to 10 nm in excitation and emission, λexc = 330 nm. The experimental procedure for photocatalytic tests started with dispersing a uniform layer of 0.01 g of titania photocatalyst nanopowder on

Plasmonic nanotechnology for photothermal applications – an evaluation

• A. R. Indhu,
• L. Keerthana and
• Gnanaprakash Dharmalingam

Beilstein J. Nanotechnol. 2023, 14, 380–419, doi:10.3762/bjnano.14.33

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

• inactivate pathogens. The term “photocatalysis” refers to chemical reactions that use light and a photocatalyst (basically a semiconductor). A few of the requirements that an effective photocatalyst system should satisfy include high sunlight absorption, an appropriate gap (1.5–2.8 eV), long-term charge

• carrier separation, high photo-transporter mobility, appropriate physical and chemical properties, sufficient band alignment to meet the kinetic requirements of the target reaction, and anti-corrosion stability in reactive environments [18][19][20]. Figure 1 depicts the mechanism of the photocatalyst. In

• pair (e− and h+) on the surface of the photocatalyst. Three possibilities exist at this point: (a) The generated charge carriers recombine and generate heat, (b) the generated interfacial charge carriers simultaneously reduce and oxidise contaminants, or (c) the generated charge carrier and an electron

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 available electrons, and, as a result, bromide ions can be released. The results confirm that magnetite is an effective photocatalyst in the degradation of halogenated aromatic pollutants. Keywords: magnetite; ozonolysis; persistent organic pollutants; photocatalysis; water treatment

• solar radiation as an energy source [11]. The photocatalysts are activated by radiation and produce highly reactive photo-induced charge carriers, which can react with the contaminants adsorbed on the surface of the catalyst. Understanding the properties of the photocatalyst material is critical to

• designing an effective photocatalytic process. The factors that influence photocatalytic efficiency include the photocatalyst bandwidth, the recombination rate of photogenerated electron–hole pairs, the use of solar energy, and problems with catalyst degradation. Magnetite is a common auxiliary mineral in

A TiO₂@MWCNTs nanocomposite photoanode for solar-driven water splitting

• Anh Quynh Huu Le,
• Ngoc Nhu Thi Nguyen,
• Hai Duy Tran,
• Van-Huy Nguyen and
• Le-Hai Tran

Beilstein J. Nanotechnol. 2022, 13, 1520–1530, doi:10.3762/bjnano.13.125

• reactions. As a wide-bandgap (ca. 3.2 eV) semiconductor, TiO2 is a promising photocatalyst for degrading a massive range of high-molecular-weight organic pollutants under UV radiation [1]. Because of high specific surface, nanoscale TiO2 as grains or tubes can absorb UV light more substantially than

• mesoscale TiO2 [2][3]. This results in an improvement of the photon efficiency of TiO2 nanoparticles. Reducing the dimension of the photocatalyst favors not only a bandgap shift to the visible-light region but, unfortunately, also the recombination of photogenerated electrons and holes (e−/h+), which limits

• ) conversion efficiency of TiO2-based photoanodes (0.2–0.42%) is lower than that of TiO2/CNT anodes (4.4%), which is attributed to a wider bandgap of the TiO2 photocatalyst and the lesser extent of e−/h+ pair recombination [12]. Dai et al. prepared a MWCNTs/TiO2 (MWCNTs = multi-wall carbon nanotubes

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

• approaches to make it as a light-driven nanomaterial owing to its potential capabilities. The light-driven ability of HBN can be achieved through multiple strategies. These include varying the structural morphology, heterojunction formation with a suitable photocatalyst, and doping with heteroatoms. The

• carriers due to appropriate positioning of edge potentials with respect to the synergised photocatalyst [11][12][13]. The process of doping includes introduction of heteroatoms such as sulphur, oxygen, and carbon into the HBN lattice. The doping of oxygen into the HBN lattice results in the generation of

• light photocatalyst. Materials and Methods Chemicals required Boric acid (H3BO3), melamine, glucose, hexagonal boron nitride nanopowder (BET surface area: 19 m−2 g−1), MB, and phenol were purchased from Alfa Aesar and TCI chemicals. All the purchased chemicals were high purity analytical grade reagents

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

• synthesizing and applying a semiconductor photocatalyst have been published in recent years. A survey on bismuth-based nanocomposites with the search keywords "Bismuth-based nanoparticles for environmental remediation" from 2011 to 2021 yields roughly 15,995 articles. This data illustrates the interest of the

• oxides, and binary Bi sulfides. Bismuth oxyhalides are indirect bandgap semiconductors in which photogenerated electrons and holes rarely recombine. BiOX is an excellent photocatalyst, and it is widely applied due to its small bandgap and high electron density, which are easily adjustable by changing the

• purification [31][32][33][34][35]. However, the present report focuses on understanding the role of different Bi-based photocatalysts concerning their synthesis method and enhancement. The mechanism of photocatalysts for different applications has been described for the type or nature of the photocatalyst

Rapid fabrication of MgO@g-C₃N₄ heterojunctions for photocatalytic nitric oxide removal

• Minh-Thuan Pham,
• Duyen P. H. Tran,
• Xuan-Thanh Bui and
• Sheng-Jie You

Beilstein J. Nanotechnol. 2022, 13, 1141–1154, doi:10.3762/bjnano.13.96

• environment, human health, and other biotas. Among the technologies to treat NO pollution, photocatalytic oxidation under visible light is considered an effective means. This study describes photocatalytic oxidation to degrade NO under visible light with the support of a photocatalyst. MgO@g-C3N4

• simple way to synthesize photocatalytic heterojunction materials with high reusability and the potential of heterojunction photocatalysts in the field of environmental remediation. Keywords: g-C3N4; MgO; nitric oxide; photocatalyst; visible light; Introduction The rapid development of industrialization

• -C3N4 could be applied in the future as an excellent photocatalyst with high removal efficiency and low generation of toxic products. FTIR, XPS, and EDS measurements were carried out to confirm the presence of MgO in the MgO@g-C3N4 heterojunctions. Although MgO was difficult to determine in the MgO@g

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

• that the prepared ZnO material excellently removed MB and MO (cinitial = 10 mg/L) with efficiencies of 100% and 82.78%, respectively, after 210 min under UV radiation with a ZnO NP dose of 2 g/L. The photocatalyst activity of the synthesized material was also tested under visible light radiation with

• photocatalysts. ZnO has a higher quantum efficiency than that of TiO2 since it absorbs more energy in the UV region [4][5][6][7]. Furthermore, ZnO is a low-cost photocatalyst with high photocatalytic activity, nontoxicity, light sensitivity, and stability [8][9][10]. The photodegradation of organic substances by

• ] used Citrus aurantifolia extracts to synthesize ZnO NPs with a size range of 50–200 nm. Sangeetha et al. and Gunalan et al. used Aloe vera leaves as a precursor to synthesize ZnO with a size range of 25–45 nm [24][25]. Many studies have synthesized nanosized ZnO for antibacterial and photocatalyst

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

• photocatalyst under UV light irradiation [30]. So far, a large number of MOFs have been shown to exhibit photocatalytic activity in H2 production, organic pollutant degradation, and Cr(VI) and CO2 reduction [26][27][31][32][33]. Among MOF catalysts, MIL101(Fe) is a cage-like structure formed by self-assembly of

• iron and bridged terephthalic acid molecules. It has high hydrothermal stability, low cost, good hydrophilicity, non-toxicity, and environmental friendliness [20][34]. Most importantly, MIL101(Fe) contains abundant iron-oxo (Fe-O) clusters, which makes it a photocatalyst with visible-light response [19

• . Characterization of the as-prepared catalyst The crystalline structure of the prepared photocatalyst was analyzed by X-ray diffraction spectrometry (Empyrean, Panalytical, Holland) with Cu Kα radiation at a scanning speed of 7 °/min. The morphology of the samples was observed by scanning electron microscopy (SEM

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

• : LaFeO3; LaNiO3; methylene blue (MB); perovskite oxides; photocatalyst; Introduction With the advancement of science and technology, the world's population is increasing, leading to the fact that factories are consuming more and more resources. Water inevitably plays a vital role in industrial

• ]. Ti-doped, Mn-doped [30], and Cu-doped [31] LaFeO3 were investigated to conduct a photocatalytic Fenton-like reaction. Jauhar et al. demonstrated that Mn substituting Fe within LaFeO3 with the molar ratio of 0.1–0.5 displayed the effect of being used as a heterogeneous photocatalyst for dye

• understand the effect of the photocatalysis and the Fenton reaction in the degradation reaction, some degradation tests were also carried out as controlling experiments for comparison, including: (1) without adding photocatalyst (No catalyst), (2) without light (No light), and (3) without adding H2O2 (No

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

• 5.0 cm from the quartz tube reactor. The photocatalyst (10.0 mg) was dispersed in the pollutant solution (20.0 mL, 10.0 mg·L−1) and stirred in the dark for 1 h to guarantee the adsorption−desorption equilibrium. Then, the visible light was switched on, and the suspension containing photocatalyst and

• by using the 70%−Bi2WO6/TiO2-NT nanocomposite. After the photocatalytic reaction of the first cycle, the photocatalyst was separated from the pollutant solution, washed with ethanol, and dried at 37 °C under vacuum for 12 h. After that, the photocatalyst was applied to the second cycle of the

• nanocomposite was set as the representative photocatalyst for the exploration of optimal pH values of the Cr(VI) pollutant solution under visible-light irradiation. It was demonstrated that the reduction efficiency of Cr(VI) under the alkaline condition was poor because the newly formed Cr(OH)3 precipitates

Direct measurement of surface photovoltage by AC bias Kelvin probe force microscopy

• Masato Miyazaki,
• Yasuhiro Sugawara and
• Yan Jun Li

Beilstein J. Nanotechnol. 2022, 13, 712–720, doi:10.3762/bjnano.13.63

• modulated external disturbances. Keywords: atomic force microscopy; Kelvin probe force microscopy; photocatalyst; surface photovoltage; titanium dioxide; Introduction Surface photovoltage (SPV) is the change in surface potential caused by light illumination [1][2] and is measured to determine such

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

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

• Thanh District, Ho Chi Minh City, 700000, Viet Nam 10.3762/bjnano.13.7 Abstract Semiconducting SnO2 photocatalyst nanomaterials are extensively used in energy and environmental research because of their outstanding physical and chemical properties. In recent years, nitrogen oxide (NOx) pollutants have

• −, similarly holes react with water to form hydroxyl radicals). Free radicals and strong oxidizing agents react with NOx to produce NO3−, deposited on the photocatalyst surface. The NO3− product formed on the surface of the catalyst can be easily separated for further treatment by washing with water due [11

• morphology [25][26][27][28][29][30]. However, pure SnO2 suffers from some inherent drawbacks that limit its practical applications. With a wide bandgap (3.5–3.7 eV) [31][32], SnO2 can only be excited by UV irradiation. As a typical oxidation photocatalyst with the CB edge energy level, which is not conducive