Semiconductor Catalyst Research Articles

Exploring and Leveraging the basic principle for molecular reduction catalysis of biorenewables, CO2, and plastics using light, electric and heat energy

Biorenewable energy and chemicals hold great promise for a greener, more sustainable future. Biomass is organic materials that can be used to generate electricity and gas in the form of bioenergy. Catalysis is required to convert the biomass into a useful form. At the Saito Research Group in the Noyori Laboratory at the Graduate School of Science, Nagoya University, Japan, Professor Susumu Saito and the team are engaged in the design and development of catalysts for exactly this. In one line of research, the team is developing upcycling catalysts for highly oxidised chemical compounds (HOCs). The idea is that these catalysts can be used to quickly and efficiently synthesise high-value-added organic molecules from carbon resources. In another project, the researchers are exploring organic synthesis based on one electron transfer from H2 or H2O using molecular and semiconductor photocatalysis. One electron (radical) species (OES) such as hydrogen atom (H•) can be produced from the homolytic cleavage of chemical bonds of H2 or H2O, occurring by visible/near-UV light energy inducing photo-excited states of tailored homogeneous and heterogeneous (semiconductor) catalysts. These OESs can be used in addition reactions and H-abstraction reactions to generate carbon-centred radical species and achieve artificial photosynthesis directed toward selective organic synthesis (APOS). A key focus for the team is on molecular metal catalysis. They designed novel (PNNP)M catalysts, with the PNNP representing two-phosphine and two-nitrogen coordinative atoms and the M representing metals, from which they derived robust reduction/dehydration catalysts with catalytic activity that can be sustained for a long period of time under visible light, electric and heat energy.

Anti-Oxidant and Anti-Microbial Activities of [ZnO: CoO/ Eugenol] and [ZnO: Fe2O3/ Eugenol] Nanocomposites

Metal oxide nanocomposites (MONCs) manufacturing is increasingly gaining popularity. The primary cause of this is the broad range of applications for such materials, which include fuel cells, photovoltaics, cosmetics, medicine, semiconductor packing materials, water treatment, and catalysts. Due to their size, stability, high surface area, catalytic activity, simplicity in fabrication, and selectivity for particular reactions. The MONCs with various morphologies have been created by physical, chemical, and biological processes, such as sol-gel, hydrothermal, co-precipitation, solvothermal, and microwave irradiation. Eugenol (4-allyl-2-methoxyphenol) is a major component of clove essential oil and it was found in various plant groups, has been widely utilized, and famously stated to have a variety of important biological activities. It is a good starting material for the synthesis of a wide variety of derivatives with different activity. Due to the presence of many functional groups in its structure, including allyl (-CH2-CH=CH2), phenol (-OH), and methoxy (-OCH3). The eugenol was taken with metal oxides (zinc cobalt oxides ZnO: CoO) to synthesis [ZnO: CoO/ Eug] and (zinc ferric oxides ZnO: Fe2O3) to synthesis [ZnO: Fe2O3/ Eug] as nanocomposites by hydrothermal method and characterization the compounds using: (FT-IR, AFM, SEM, EDX, XRD) techniques. Then, they tested their biological activities through antimicrobial and antioxidant.

Integration of 2D graphene oxide/zinc oxide nanohybrid for enhancement adsorption and photodegradation of organic pollutants

The band gap plays a critical role in determining the photocatalytic efficiency of semiconductor catalysts. Zinc oxide (ZnO) photocatalysts have gained significant attention in sustainable energy and environmental pollution remediation. However, despite its potential, ZnO photocatalytic performance has been hindered by its wide band gap and rapid charge carrier recombination. Numerous techniques have been created to tackle this problem, including doping, nanostructuring, creating oxygen defects, surface modification, and utilizing hybrid nanomaterials. The ZnO and ZnO@GO with different GO contents were synthesized using uncomplicated co-precipitation and solid-state reaction techniques. The ZnO@GO possesses bandgap (Eg) values of 2.5 eV, which is advantageous for achieving more significant photocatalytic activity compared to the unadorned ZnO with Eg values of 3.24 eV. This study investigated the effectiveness of the synthesized catalysts in treating methylene blue (MB) dye through visible light-induced photoreaction. The ZnO@GO nanohybrid exhibited remarkable performance, achieving a decomposition rate of 98.4 % for MB within a 22-minute timeframe. The rate constant of 0.1343 min−1 is significantly greater than that of the unadorned ZnO 0.0448 min−1. Graphene oxide (GO) plays a crucial role in the photocatalytic process by facilitating the gathering and transportation of electrons. This enhancement generates reactive oxygen species and hydroxyl radicals, effectively breaking down MB. The scavenger test results provided compelling evidence that the degradation of MB primarily occurred due to the presence of hydroxyl radicals, which were identified as the most active species in this process.

Preparation of a silver ferrite-assisted tungsten oxide nanocomposite for efficient sonocatalytic degradation of organic pollutants activated by PMS followed by toxicity evaluation

Sonocatalytic technology combined with ultrasonic irradiation with semiconductor catalyst has attracted much attention to address environmental issues.

Research advances on conjugated microporous polymer-derived photocatalysts toward solar-to-hydrogen production

Photocatalytic hydrogen evolution (PHE) is a sustainable energy technology that directly produces green and renewable hydrogen fuel from water under the drive of solar energy, achieving the conversion from solar energy to hydrogen energy, while the critical mission toward highly efficient PHE is to develop efficient and durable semiconductor catalysts. In this context, the newly-emerged conjugated microporous polymers (CMPs) have been considered as prospective candidates for efficient PHE due to their low density, good light absorption, high surface area, permanent microporous, and wide availability of synthesis methods. In particular, their molecular customizability and modifiability enable the effective encoding of desirable light-harvesting moieties and photo-catalytically active units into the conjugated polymer backbone for high-performance PHE. Herein, this review provides a brief summary on the latest advancements based on CMP-derived photocatalysts for PHE. First, the synthesis methods, reaction routes, and photoactive units of CMP photocatalysts are elucidated. Subsequently, the feasible methods regarding how to improve the PHE performance of CMPs by expanding light absorption, improving the separation and transport of photogenerated carriers, and promoting surface reactions are put forward. Finally, potential challenges and future prospects for CMP-derived photocatalysts are also discussed.

Enhanced photocatalytic CO2 conversion over 0D/2D CsPbBr3/BiOCl S-scheme heterojunction via boosting charge separation.

The stable contact of heterogeneous interfaces and the substantial exposure of active sites are crucial for enhancing the photocatalytic performance of semiconductor catalysts. However, most reported two-dimensional (2D)/2D CsPbBr3 and BiOCl heterostructures are fabricated using electrostatic self-assembly methods, which exhibit significant deficiencies in precise interface quality control and effective active site exposure. In this study, we fabricate a zero-dimensional (0D)/2D CsPbBr3/BiOCl heterojunction via a two-step calcination method, achieving an efficient direct S-scheme configuration. Optimizing interfacial contact and band alignment between CsPbBr3 quantum dots and BiOCl nanosheets enhances cross-plane charge transfer, promoting superior charge separation. This 0D/2D CsPbBr3/BiOCl heterojunction exhibits enhanced carrier mobility and high conversion rates without cocatalysts or sacrificial agents. The mechanism underlying the accelerated S-scheme charge transfer is comprehensively elucidated through a combination of analytical techniques and density functional theory (DFT) calculations. This study offers a novel approach for managing charge carrier segregation and mobility in CO2 reduction photocatalysts.

Metal oxide-based photocatalysts for the efficient degradation of organic pollutants for a sustainable environment: a review.

Photocatalytic degradation is a highly efficient technique for eliminating organic pollutants such as antibiotics, organic dyes, toluene, nitrobenzene, cyclohexane, and refinery oil from the environment. The effects of operating conditions, concentrations of contaminants and catalysts, and their impact on the rate of deterioration are the key focuses of this review. This method utilizes light-activated semiconductor catalysts to generate reactive oxygen species that break down contaminants. Modified photocatalysts, such as metal oxides, doped metal oxides, and composite materials, enhance the effectiveness of photocatalytic degradation by improving light absorption and charge separation. Furthermore, operational conditions such as pH, temperature, and light intensity also play a crucial role in enhancing the degradation process. The results indicated that both high pollutant and catalyst concentrations improve the degradation rate up to a threshold, beyond which no significant benefits are observed. The optimal operational conditions were found to significantly enhance photocatalytic efficiency, with a marked increase in degradation rates under ideal settings. Antibiotics and organic dyes generally follow intricate degradation pathways, resulting in the breakdown of these substances into smaller, less detrimental compounds. On the other hand, hydrocarbons such as toluene and cyclohexane, along with nitrobenzene, may necessitate many stages to achieve complete mineralization. Several factors that affect the efficiency of degradation are the characteristics of the photocatalyst, pollutant concentration, light intensity, and the existence of co-catalysts. This approach offers a sustainable alternative for minimizing the amount of organic pollutants present in the environment, contributing to cleaner air and water. Photocatalytic degradation hence holds tremendous potential for remediation of the environment.

Efficient hydrogen evolution from degenerate-doped p-type WS2 electrocatalysts over a wide pH range

The degenerate doping strategy shows a beneficial effect on improving the electrochemical hydrogen evolution reaction (HER) performance of Ir-doped WS2 semiconductor catalysts in 0.5 M H2SO4, 1 M Na2SO4, and 1 M KOH electrolytes.

Dual functionality of the BiN monolayer: unraveling its photocatalytic and piezocatalytic water splitting properties.

To achieve scalable and economically viable green hydrogen (H2) production, the photocatalytic and piezocatalytic processes are promising methods. The key to successful overall water splitting (OWS) for H2 production in these processes is using suitable semiconductor catalysts with appropriate band edge potentials, efficient optical absorption, higher mechanical flexibility, and piezoelectric coefficients. Thus, we explore the bismuth nitride (BiN) monolayer using density functional theory simulations, revealing intriguing catalytic properties. The BiN monolayer is a semiconductor with an indirect electronic bandgap (Eg) of 2.08 eV and displays excellent visible light absorption (approximately 105 cm-1). Detailed analyses show that the band edges satisfy the redox potential for photocatalytic OWS via biaxial strain engineering and pH variation. Notably, the solar to hydrogen conversion efficiency (ηSTH) for the BiN monolayer can reach 17.18%, which exceeds the 10% efficiency limit of photocatalysts for economical green H2 production. The obtained in-plane piezoelectric coefficient of e11 = 16.18 Å C m-1 is superior to widely studied 2D materials. Moreover, the generated piezopotential under oscillatory strain stands at 28.34 V, which can initiate the water redox reaction via the piezocatalytic mechanism. This originates from the mechanical flexibility coupled with higher piezoelectric coefficients. The result highlights the BiN monolayer's potential application in photocatalytic, piezocatalytic, and photo-piezo-catalytic OWS.

Dual-functional, highly efficient CaIn2S4/PDA@SnO2 photocatalyst with Z-Scheme for photocatalytic hydrogen production from water splitting and organic pollutant degradation

Heterojunction can be used to develop semiconductor catalysts with high photocatalytic activity. In this work, a Z-Scheme CaIn2S4(CIS)/PDA@SnO2 photocatalyst was successfully synthesized. Firstly, SnO2 hollow nanospheres were prepared by hydrothermal method. On this basis, SnO2 hollow nanospheres wrapped by polydopamine (PDA) were obtained via self-polymerization of dopamine. Finally, the CIS/PDA@SnO2 composites were synthesized via a one-step oil bath method. The heterojunction has successfully achieved effective separation of electron-hole pairs. PDA acted as a photosensitizer and an electron transfer medium in the heterojunction. Multiple characterization techniques such as XRD, SEM, TEM, BET, XPS, PL, UV–vis DRS, EPR and photoelectrochemical measurements were used for material structure and performance analysis. The photocatalytic performance of the photocatalysts was tested by photocatalytic hydrogen production from water splitting and RhB solution degradation. A flower-like close contact between CaIn2S4 and PDA@SnO2 interfaces can be obviously observed via SEM and TEM images. The band gap energies (Eg) of CaIn2S4 and PDA@SnO2 are 2.06 eV and 3.74 eV. CaIn2S4/PDA@SnO2-1(CPS-1) exhibits stronger light absorption together with lower transfer resistance compared to other samples. CPS-1 showed excellent photocatalytic hydrogen production and RhB degradation performance. Furthermore, the results of active species capture experiments, Mott-Schottky curve, XPS measurement and other tests show that it is logical to use the Z-Scheme charge mobility process to explain the better photocatalytic activity of the CIS/PDA@SnO2 composite. This work will present an efficient option for the fabrication of Z-Scheme heterojunctions and possibly further develop a new avenue for the control of the structure of semiconductor photocatalysts.

Promoting Piezocatalytic H2 O2 Production in Pure Water by Loading Metal-Organic Cage-Modified Gold Nanoparticles on Graphitic Carbon Nitride.

Piezocatalytic hydrogen peroxide (H2 O2 ) production is a green synthesis method, but the rapid complexation of charge carriers in piezocatalysts and the difficulty of adsorbing substrates limit its performance. Here, metal-organic cage-coated gold nanoparticles are anchored on graphitic carbon nitride (MOC-AuNP/g-C3 N4 ) via hydrogen bond to serve as the multifunctional sites for efficient H2 O2 production. Experiments and theoretical calculations prove that MOC-AuNP/g-C3 N4 simultaneously optimize three key parts of piezocatalytic H2 O2 production: i) the MOC component enhances substrate (O2 ) and product (H2 O2 ) adsorption via host-guest interaction and hinders the rapid decomposition of H2 O2 on MOC-AuNP/g-C3 N4 , ii) the AuNP component affords a strong interfacial electric field that significantly promotes the migration of electrons from g-C3 N4 for O2 reduction reaction (ORR), iii) holes are used for H2 O oxidation reaction (WOR) to produce O2 and H+ to further promote ORR. Thus, MOC-AuNP/g-C3 N4 can be used as an efficient piezocatalyst to generate H2 O2 at rates up to 120.21 μmol g-1 h-1 in air and pure water without using sacrificial agents. This work proposes a new strategy for efficient piezocatalytic H2 O2 synthesis by constructing multiple active sites in semiconductor catalysts via hydrogen bonding, by enhancing substrate adsorption, rapid separation of electron-hole pairs and preventing rapid decomposition of H2 O2 .

Promoting Piezocatalytic H2O2 Production in Pure Water by Loading Metal‐Organic Cage‐Modified Gold Nanoparticles on Graphitic Carbon Nitride

AbstractPiezocatalytic hydrogen peroxide (H2O2) production is a green synthesis method, but the rapid complexation of charge carriers in piezocatalysts and the difficulty of adsorbing substrates limit its performance. Here, metal‐organic cage‐coated gold nanoparticles are anchored on graphitic carbon nitride (MOC‐AuNP/g‐C3N4) via hydrogen bond to serve as the multifunctional sites for efficient H2O2 production. Experiments and theoretical calculations prove that MOC‐AuNP/g‐C3N4 simultaneously optimize three key parts of piezocatalytic H2O2 production: i) the MOC component enhances substrate (O2) and product (H2O2) adsorption via host–guest interaction and hinders the rapid decomposition of H2O2 on MOC‐AuNP/g‐C3N4, ii) the AuNP component affords a strong interfacial electric field that significantly promotes the migration of electrons from g‐C3N4 for O2 reduction reaction (ORR), iii) holes are used for H2O oxidation reaction (WOR) to produce O2 and H+ to further promote ORR. Thus, MOC‐AuNP/g‐C3N4 can be used as an efficient piezocatalyst to generate H2O2 at rates up to 120.21 μmol g−1 h−1 in air and pure water without using sacrificial agents. This work proposes a new strategy for efficient piezocatalytic H2O2 synthesis by constructing multiple active sites in semiconductor catalysts via hydrogen bonding, by enhancing substrate adsorption, rapid separation of electron‐hole pairs and preventing rapid decomposition of H2O2.

Novel oxygen vacancy-rich Bi2MoO6-SOVs/MgFe2O4 S-scheme heterojunction piezo-photocatalytic for efficient degradation of norfloxacin and theoretical calculations

Magnetic materials introduced into semiconductor catalysts greatly compensate for the traditional powder catalysts’ disadvantages of difficult recovery and low reuse rate. A series of oxygen vacancy-rich Bi2MoO6-SOVs/MgFe2O4 nanomicrospheres are prepared by stepwise synthesis. By simulating visible light irradiation and ultrasonic co-illumination to degrade norfloxacin (NOR) to evaluate the piezo-photocatalytic performance of the samples, the Bi2MoO6-SOVs/MgFe2O4-15 % has a degradation efficiency of 96.8 % within 30 min and high chemical stability. This method not only improves the limitations of finite free electrons in piezoelectric catalysis but also effectively suppresses the rapid recombination of photogenerated electrons-holes in photocatalysis. To improve the practical application of this catalyst, we also consider the effects of pH, co-existing ions in water and different water matrices on NOR degradation. In situ X-ray photoelectron spectroscopy (ISI-XPS) and density functional theory (DFT) calculations further confirm the existence of an S-scheme charge transfer mechanism and oxygen vacancies (SOVs).

Perovskite Type B-CaTiO3 Coupled with Graphene Oxide as Efficient Bifunctional Composites for Environmental Remediation

To prepare boron doped perovskite CaTiO3 nanocubes coupled with graphene oxide (B-CaTiO3/GO), B-CaTiO3 photocatalyst was initially synthesized by the solvothermal method and subsequently attached on GO by a simple hydrothermal process. The phase structure and optical features of the prepared materials were efficiently characterized by several techniques. The XRD patterns indicated that boron doping could not give rise to lattice disruption of CaTiO3. The results of XPS, HRTEM and Raman measurements revealed that the presence of B-CaTiO3 is anchored on the surface of GO effectively. The morphology of the B-CaTiO3/5GO was nanocube particles. The photocatalytic capacity of B-CaTiO3/GO nanocomposites was determined by investigating the degradation of a model dye, methylene blue (MB). Their degradation performance could be enhanced by altering the ratio between B-CaTiO3 and GO. The most effective GO incorporation is 5 wt%, and at this loading percentage, B-CaTiO3/GO nanocomposite showed improved photocatalytic activity compared with CaTiO3 and B-CaTiO3 photocatalyst, which could be attributed to the synergistic efficacy of the adsorbed MB molecule on the GO followed by their degradation after 180 min of visible light. Additionally, the active species trapping tests confirm the dominant role performed by ·OH and O2·− during the degradation of MB. The presence of HCO3− and Cl− indicated moderate prohibitive effect on the degradation of MB, while NO3− and SO42− negatively affected the catalytic activity in a non-significant way. In brief, the results of this study show that boron doped perovskite-type semiconductor catalysts by combining with graphene has significant efficiency in the removal of MB from aqueous solution, which can be employed as effective photocatalyst materials for the treatment of other organic pollutants.

Construction of Z-scheme heterojunction TiO2-ZnO@Oxygen-doped gC3N4 composite for enhancing H2O2 photoproduction and removal of pharmaceutical pollutants under visible light

In this study, the heterojunction photocatalyst of titanium dioxide-zinc oxide@oxygen-doped graphitic carbon nitride (TiO2-ZnO@OCN (TZ@OCN)) was synthesized using a simple and cost-effective hydrothermal self-assembly process. Characterization of the fabricated materials revealed that the incorporation of TiO2 and ZnO as inherent semiconductors along with the oxygen doping has effectively broadened the absorption spectrum of gC3N4, which can promote the electron generation and provide more active sites for O2 and H+ adsorption. It is noteworthy that the mentioned structure modification resulted in a superior H2O2 production rate among gC3N4-based photocatalysts with up to 3.11 mM.g−1 under visible light irradiation. Moreover, a valence band shifting from 1.57 to 2.91 eV upon doping oxygen atoms also elucidated the participation of active species in the photocatalytic degradation of ciprofloxacin (99.7 %, k = 0.030 min−1) and tetracyline (94.6 %, k = 0.017 min−1), in which superoxide radicals (•O2−) were shown to play a major role in removing the antibiotic. Besides, a Z-scheme heterojunction mechanism is additionally suggested, demonstrating the effectiveness of electron-hole pair splitting in the oxidation of antibiotics. Conclusively, the results show a novel and feasible modification pathway to enhance the photocatalytic activities of gC3N4 and other advanced semiconductor catalysts, especially for eliminating antibiotics and generating H2O2 within aqueous media.

Optimizing physico-chemical properties of hierarchical ZnO/TiO2 nano-film by the novel heating method for photocatalytic degradation of antibiotics and dye

The design of semiconductor catalysts with excellent photocatalytic properties, stability, recyclability, and good separation for the treatment of polluted water is still challenging. In this paper, the ZnO/TiO2 nano-thin films were fabricated using the magnetron sputtering technique and then heating the underlying ZnO layer and the upper TiO2 layer for their respective optimal heating time, i. e. heating ZnO for 3 h and heating TiO2 for 2 h. The as-prepared films were characterized. The results show that the preferred growth of TiO2 grains along the [001] axis, relatively large specific surface area, and increased amounts of surface oxygen vacancies (OVs) were induced to the heterojunction catalysts through this optimized heating strategy, which boosts the photocatalytic activity of ZnO/TiO2 nano-film. The degradation experiment inndicates that the ciprofloxacin (CIP) removal efficiency can reach 97.3% in 2 h duration, which was higher than that of the samples annealed for the same periods. Meanwhile, the prepared ZnO/TiO2 photocatalytic film exhibited favorable stability of 95.5% degradation efficiency after the fourth run and general applicability for the photodegradation of various contantains, whih removed 99.5% of ofloxacin (OFX) and 77.6% of tetracycline (TC) in 2 h and 94.1% of Rhodamine B (RhB) in 1 h. This work is expected to yields a novel insight into the production of heterojunction photocatalysts with excellen ability for photocatalytic degradation of pollutants in the practical industry.

Enhancing the Photocatalytic Activity by Tailoring an Anodic Aluminum Oxide Photonic Crystal to the Semiconductor Catalyst: At the Example of Iron Oxide

AbstractPhotonic crystals (PhCs) are interesting structures for photocatalytic applications because of their capability of harnessing distinct forms of light–matter interactions within the PhCs. Of all these, overlapping one of the photonic stopband's (PSB) edge with the absorption of the PhC material or adsorbed molecules improves their excitation and generated charge carriers can subsequently induce photocatalytic reactions. The PSB position of anodic aluminum oxide PhCs (AAO‐PhCs) can be easily adjusted by modifying the anodization profile. Herein, AAO‐PhCs are designed to match the band gap of a model semiconductor enabling a general photocatalytic activity enhancement independent of the chemical to be decomposed. Fe2O3, as an example photocatalyst, is coated onto AAO‐PhCs to demonstrate efficient photocatalytic systems by utilizing the slow photon effect. Tailored Fe2O3‐AAO‐PhCs with their PSB edge at 564 nm matching the Fe2O3 band gap exhibit generally enhanced degradation of three different organic dyes while a significant activity decrease is observed when the PSB edge does not overlap with the Fe2O3 absorption. Furthermore, photocatalyst degradation can be reduced down to only 4% activity loss over six consecutive measurements by an ultra‐thin alumina coating.

A handbook for graphitic carbon nitrides: revisiting the thermal synthesis and characterization towards experimental standardization

Graphitic carbon nitrides (g-C3N4s) have continued to attract attention as metal-free, low-cost semiconductor catalysts. Herein, a systematic synthesis and characterization of g-C3N4s prepared using four conventional precursors (urea (U), dicyandiamide (DCDA), semicarbazide hydrochloride (SC-HCl), and thiosemicarbazide (TSC)) and an unexplored one (thiosemicarbazide hydrochloride (TSC-HCl)) is presented. Equal synthesis conditions (e.g. heating and cooling rates, temperature, atmosphere, reactor type/volume etc) mitigated the experimental error, offering fair comparability for a library of g-C3N4s. The highest g-C3N4 amount per mole of the precursor was obtained for D-C3N4 (∼37.85 g), while the lowest was for S-C3N4 (∼0.78 g). HCl addition to TSC increased the g-C3N4 production yield (∼5-fold) and the oxygen content (T-C3N4 ∼ 3.17% versus TCl-C3N4 ∼ 3.80%); however, it had a negligible effect on the level of sulphur doping (T-C3N4 ∼ 0.52% versus TCl-C3N4 ∼ 0.45%). S-C3N4 was the darkest in color (reddish brown), and the band gap energies were S-C3N4(2.00 eV) < T-C3N4(2.74 eV) < TCl-C3N4(2.83 eV) ≤ D-C3N4(2.84 eV) < U-C3N4(2.97 eV). The experimentally derived conduction band position of S-C3N4(−0.01 eV) was closer to the Fermi energy level than the others, attributable to high oxygen atom doping (∼5.11%). S-C3N4 displayed the smallest crystallite size (∼3.599 nm by XRD) but the largest interlayer distance (∼0.3269 nm). Furthermore, BET surface areas were 138.52 (U-C3N4), 22.24 (D-C3N4), 18.63 (T-C3N4), 10.51 (TCl-C3N4), and 9.31 m2 g−1 (S-C3N4). For the first time, this comprehensive handbook gives a glimpse of a researcher planning g-C3N4-based research. It also introduces a novel oxygen-sulphur co-doped g-C3N4 (TCl-C3N4) as a new halogen-free catalyst with a relatively high production yield per mole of precursor (∼24.09 g).

In-situ constructing amidoxime groups on metal-free g-C3N4 to enhance chemisorption, light absorption, and carrier separation for efficient photo-assisted uranium(VI) extraction

The development of inexpensive and efficient semiconductor catalysts for photo-assisted uranium extraction from seawater remains a huge challenge. Herein, we have successfully synthesized amidoxime-rich g-C3N4 (AO-C3N4) by simply amidoximing a cyano-rich precursor for photo-assisted uranium extraction from seawater. The amidoxime groups not only served as the U(VI) binding sites for efficient uranium adsorption, but also significantly improved the visible light absorption capacity and carrier separation efficiency via introducing defect energy level, resulting in the excellent photocatalytic activity for AO-C3N4 towards photo-assisted uranium extraction. In the process of photo-assisted uranium extraction, U(VI) was first adsorbed by the amidoxime groups on the AO-C3N4 and then reduced to U(IV), while (UO2)O2·2H2O and (UO2)O2·4H2O were further formed by the oxidation of U(IV) by superoxide radicals (·O2-). Moreover, the generated reactive oxygen species (ROS) under light endowed AO-C3N4 with outstanding antibacterial properties, preventing the limitation of uranium extraction capacity from marine biofouling.

Iron nanoparticles decorated TiO2 hollow microspheres for boosting degradation of tetracycline in a photo-Fenton catalytic system

The problem of water pollution caused by antibiotic contamination is essential for human health and the ecological environment. In this study, Fe-doped TiO2 (FT-2) photocatalyst with a hollow microsphere structure was fabricated for efficient photocatalytic-Fenton removal of tetracycline (TC) under visible light irradiation. The unique hollow microsphere structure of FT-2, iron doping and oxygen vacancies enhance the photo-Fenton activity and stability of the material. The results showed that the degradation rate of tetracycline in the FT-2 photo-Fenton system at 60 min was 98.18%, with a degradation efficiency of mostly 90% after five successful reuses. The efficient TC degradation activity should be mainly ascribed to the structure of hollow microspheres and oxygen vacancies, resulting in the extended optical light absorption in the visible light region, reduced compound efficiency of electron cavitation pairs, and accelerated separation and migration of photogenerated carriers. In addition, this highly benefits the formation of reactive radicals·O2- and h+ play a key role in the TC degradation in a photo-Fenton reaction system and thus lead to great improvement in TC removal according to the capture experiments and EPR. This study provides an idea for the construction of semiconductor catalysts with oxygen vacancy and doped with transition metal elements for the effective photocatalytic remediation of wastewater containing antibiotic contaminants.