One-step Calcination Method Research Articles

Novel red mud-based FeS2 composite used as an effective heterogeneous catalyst for the degradation of levofloxacin: Preparation, application and degradation mechanism

Red mud (RM), as industrial waste, was considered as the base material in this study. A heterogeneous catalyst of RM based-FeS2 (RM-FeS2) was prepared using a simple one-step calcination method. RM-FeS2, as an effective activator of peroxymonosulfate (PMS), was utilized in the levofloxacin (LVF) degradation progress. The effect of the preparation conditions on crystal structure and catalytic activity of RM-FeS2 was investigated. The systematic characterizations indicated that the surface area, electrical conductivity and the number of Fe(II) sites of RM were improved after compounding with FeS2. According to the investigation of catalytic performance of RM-FeS2, approximately 87% of LVF (10 mg/L) was degraded in 60 min with the reaction conditions: [RM-FeS2] = 0.2 g/L, [PMS] = 1 mmol/L and initial pH of 6.2. The RM-FeS2 possessed excellent stability and reusability. ·OH, SO4•−, 1O2 and Fe(Ⅳ) were the dominant active species in RM-FeS2/PMS system. Several possible degradation pathways of LVF were proposed. The toxicity of the treated LVF solution was effectively reduced in the RM-FeS2/PMS system. In a word, this study not only realized the resource utilization of RM, but also presented a novel perspective for the effective degradation of organic pollutants in wastewater.

Piezoelectric assisted boosting photocatalytic hydrogen evolution over a finely prepared Pt/TiO2/g-C3N4 composite system using lactic acid as sacrificial agent

A one-step calcination method was employed to fabricate a new TiO2/g-C3N4(TCN) composite catalyst. The therein TiO2 nanoparticles with good dispersion were synthesized through a sol-gel method and followed by additional heat treatment. The ultra-thin and flat g-C3N4(CN) nanosheets were synthesized by calcining a mixture of urea and melamine. The obtained TCN exhibited significantly excellent performance, especially when 3 wt% Pt was added and lactic acid (HL) was used as a sacrificial agent, achieving a rate of 32.5 mmol/h/g. This improvement can be attributed to the uniform dispersion of nano TiO2 particles on g-C3N4, the flat ultra-thin layer structure of CN, and the constructed heterojunctions between two, which promote the separation of photogenerated electron-hole pairs. Measurements of PL and photocurrent response confirmed enhanced efficiency in interface charge separation and transfer. Additionally, it demonstrated lower internal resistance in EIS tests. Notably, owing to the piezoelectric properties of CN, when the reaction liquid was subjected to additional ultrasonic treatment, the hydrogen production rate further increased to 43.57 mmol/h/g and 2.9 mmol/h/g, respectively, in simulated sunlight and visible light response. The piezoelectric effect of CN induced by ultrasound regulated the bandgap width of the catalysts, broadening their response to visible light.

Deep mineralization of bisphenol A via Cu–Mn spinel oxide nanospheres anchored N-doped carbon activated peroxymonosulfate

Fenton-like technology can efficiently remove recalcitrant pollutants, but developing catalytic oxidation system for deep mineralization of pollutants remains a challenge. Therefore, Cu–Mn spinel oxide nanospheres anchored N-doped carbon (CMO/NC) was prepared by a one-step calcination method and used to activate peroxymonosulfate (PMS) for efficient mineralization of bisphenol A (BPA). With the use of 0.5 g/L CMO/NC and 0.2 g/L PMS, the added BPA (50 mg/L) was completely degraded and deeply mineralized (nearly 95.2 %) in 9 min. The apparent first-order degradation rate constant k was 0.557 min−1, which was 61.9, 6.2 and 2.5 times than those in the systems of N-C/PMS (0.009 min−1), CuO/NC/PMS (0.09 min−1) and Mn3O4/NC/PMS (0.22 min−1). A comparison between the catalytic performances of CMO/NC catalysts prepared by changing the dosage of urea confirmed the catalysis synergism between Cu–Mn spinel oxides and N-C. A further comparison between the catalytic performances of CMO/NC catalysts prepared by varying the Cu/Mn molar ratio of the precursors showed that the synergy between Cu and Mn sites promoted the catalytic activity, with a synergistic effect factor of 1.8. XPS and H2-TPR characterizations proved that strong Cu-Mn interaction caused Mn species easier to donate electrons to PMS and Cu species easier to accept electrons from PMS. The degradation pathway and intermediate toxicity suggested that the system did not produce secondary pollution. Based on the results of EPR and capture experiments confirming that 1O2 was the major active species, a mechanism on PMS activation was proposed. Through investigations of continuous flow BPA wastewater removal, the influence of coexisting anions and catalyst cycling stability, it was clearly demonstrated that the present system had broad application prospects.

Insights on the efficiency and contribution of single active species in photocatalytic degradation of tetracycline: Priority attack active sites, intermediate products and their toxicity evaluation

Photocatalysis has been proven to be an excellent technology for treating antibiotic wastewater, but the impact of each active species involved in the process on antibiotic degradation is still unclear. Therefore, the S-scheme heterojunction photocatalyst Ti3C2/g-C3N4/TiO2 was successfully synthesized using melamine and Ti3C2 as precursors by a one-step calcination method using mechanical stirring and ultrasound assistance. Its formation mechanism was studied in detail through multiple characterizations and work function calculations. The heterojunction photocatalyst not only enabled it to retain active species with strong oxidation and reduction abilities, but also significantly promoted the separation and transfer of photo-generated carriers, exhibiting an excellent degradation efficiency of 94.19 % for tetracycline (TC) within 120 min. Importantly, the priority attack sites, degradation pathways, degradation intermediates and their ecological toxicity of TC under the action of each single active species (·O2−, h+, ·OH) were first positively explored and evaluated through design experiments, Fukui function theory calculations, HPLC-MS, Escherichia coli toxicity experiments, and ECOSAR program. The results indicated that the preferred attack sites of ·O2− on TC were O20, C7, C11, O21, and N25 atoms with high f+ value. The toxicity of intermediates produced by ·O2− was also lower than those produced by h+ and ·OH.

Synthesis of carbon nitride nanosheets with N vacancies boosted by S doping for photocatalytic efficient killing of E. coli under visible light

To address the problem of bacterial contamination in drinking water, we synthesized non-metallic photocatalysts for the inactivation of Escherichia coli in drinking water. In this paper, S-g-C3N4 (S-g-CN) composite nanomaterials were synthesized via a one-step calcination method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and transmission electron microscopy (TEM) analyses confirmed the successful synthesis of S-g-CN with N vacancies. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy analyzed the layered morphology and chemical structure of g-C3N4 before and after modification. Optical characterization revealed significantly enhanced light absorption, electron-hole separation efficiency, and carrier mobility in the modified samples. Bactericidal assays demonstrated that under visible light, 0.3 % S-g-CN nanomaterials exhibited superior bactericidal effects against E. coli compared to unmodified g-C3N4. Furthermore, 0.3 % S-g-CN demonstrated excellent degradation of Rhodamine B (RhB) under various conditions (pollutant concentration, pH, and catalyst dosage). Recyclability studies over three cycles confirmed the catalyst's stability and reusability.

Economical, one-pot, and green synthesis of plant-based carbon quantum dots for efficient visible-light photocatalytic dye degradation and water purification

BackgroundGreen, in-situ, one-pot, facile, and economical synthesis of efficient photocatalysts to destroy emerging aqueous contaminants is essential. MethodBiocompatible carbon quantum dots (CQDs) photocatalysts were successfully synthesized from a plant source called garden thyme as a low-cost precursor by one-step calcination method. CQDs were synthesized in both pure form and co-doped with fluorine and boron indicating size of <10 nm and favorable quantum yield of 40%. Four key factors including synthesis temperature, synthesis time, fluorine and boron weight ratios, and CQDs size were investigated on removal rates of organic pollutant Rhodamine B (RhB). Significant findings10%F-10%B co-doped CQDs with synthesized at 400 ºC for 5 h with a size of <10 nm, showed the highest photocatalytic RhB degradation performances of 86.1% and 89% within 40 and 60 min, respectively. This improved performance was originated from synergetic influences of quantum size, co-doping, promising quantum yield, and great visible light harvesting, that satisfactorily separated and transported light-created electron-hole pair. Trapping experimental data approved that hydroxyl radicals were dominant reactive species that oxidized RhB on F,B co-doped CQDs catalysts upon visible light radiation. Overall, CQDs could be easily synthesized as a green and super-cheap photocatalyst and would be effective for wastewater treatments.

MOFs-derived S-scheme ZnO/BiOBr heterojunction with rich oxygen vacancy for boosting photocatalytic CO2 reduction

In this paper, a MOFs-derived S-scheme ZnO/BiOBr heterojunction photocatalyst was constructed by a one-step calcination method. It was found that the dodecahedral ZnO was well attached to the BiOBr hollow rods in ZnO/BiOBr composites, which could simultaneously introduce oxygen vacancies and enhance interfacial interactions. The photocatalytic CO2 reduction results exhibited that ZnO/BiOBr, without adding any sacrificial agent and photosensitiser, produced CO and CH4 at rates of 21.13 μmol·g−1·h−1 and 2.2 μmol·g−1·h−1 under simulated sunlight, with a CO selectivity of 74.34 %, which was 6.35 and 4.07 times higher than that of the original BiOBr as well as the original ZnO 4.14 and 1.98 times, respectively. The optimised ZnO/BiOBr has excellent photocatalytic CO2 reduction performance. The ZnO/BiOBr photocatalyst has excellent stability after 5 cycles. The unique heterostructures and matched energy band potentials between ZnO and BiOBr provided close interfacial contacts, a large number of active sites and effective charge transferred for photocatalytic CO2 reduction. Furthermore, the mechanism of photocatalytic CO2 reduction for S-scheme ZnO/BiOBr heterojunction was also proposed. Therefore, the MOFs-derived ZnO/BiOBr composites had the potential to be used as photocatalyst for CO2 reduction, providing a rational design idea for solar energy-driven CO2 conversion of MOFs-structured photocatalysts.

Cu inanchored MnO/carbonaceous frameworks trigger peroxymonosulfate activation for enrofloxacin degradation: ROS generation and pollutant attacking processes

Despite Fluoroquinolone antibiotics (FQs) removal in peroxymonosulfate (PMS) activation have been widely researched and the outstanding degradation performance have been gained, the detailed processes by which reactive oxygen species attack pollutants have not been adequately studied. In this study, a Cu/MnO catalyst is anchored onto carbonaceous frameworks using a one-step calcination method for investigation. Benefiting from the sp2 unsaturated carbon as well as the synergistic effect between Cu2+/Cu+/Cu and Mn3+/Mn2+ bimetallic redox electron pairs, the prepared Cu/MnO anchored on carbonaceous frameworks catalyst (4CuMn/C-800) material possesses excellent enrofloxacin (ENR) removal performance, where 85.52 % of ENR is degraded in 80 mins, and maintains relatively high catalysis performance even in the various reaction conditions (reaction pH, reaction temperature, existing anions etc.). The analysis reveals the 1O2 and •O2-, as the dominate ROS, continuously attack the specific active sites of ENR molecules until they are mineralized. In detail, the generated •O2- mainly attacks the piperazine ring, while the formed 1O2 assaults the quinolone group of ENR. By combining density functional theory (DFT) calculations with LC-MS analysis, we propose four distinct pathways for ENR degradation in the 4CuMn/C-800/PMS system. In summary, this study offers a novel and practical approach to design metal/metal oxide/carbon catalysts and enhances our understanding of the mechanisms behind ROS-driven PMS activation.

Homogeneous distribution of highly dispersed Pt species over O and P co-doped g-C3N4 and its superior photocatalytic H2 evolution activity

In this study, we synthesized O and P co-doped graphitic C3N4 (OPCN) materials by a one-step calcination method and prepared Pt/OPCN photocatalysts for the photocatalytic H2 evolution reaction. Among the Pt/OPCN catalysts with various O and P contents, Pt/OPCN2 exhibited the highest H2 evolution rate of 2198 μmol·g−1 (AQE = 7.33 %), which was 1.65 times higher than that of Pt/CN (1330 μmol·g−1). Moreover, Pt/OPCN2 demonstrated excellent photocatalytic properties, such as suitable band gap (2.50 eV) for visible light and efficient charge separation of photoexcited electron–hole pairs, which was confirmed by ultraviolet-visible spectroscopy, electrochemical impedance spectroscopy, photoluminescence spectroscopy, and time-resolved photoluminescence measurements. Fundamentally, the Pt species effectively interacted with neighboring PO and CO functional groups that optimally located on defective OPCN2, resulting in a homogeneous formation of highly dispersed PtO evenly distributed over Pt/OPCN2, as confirmed by X-ray photoelectron spectroscopy, high-angle annular dark-field scanning transmission electron microscopy, and density functional theory calculations. However, excessive O and P contents of OPCN3 damaged the morphological structure of g-C3N4, inducing a poor interaction between the Pt species and OPCN3 and forming isolated Pt nanoparticles, resulting in the low photocatalytic activity of Pt/OPCN3.

Facile synthesis of Al-g-C3N4/Bi2S3 with enhanced for CO2 cycloaddition reaction performance

In this paper, a high specific surface area lamellar heterogeneous composite catalyst (MCN) was synthesized for the cycloaddition reaction of CO2 and epoxides. MCN is doped aluminum with high catalytic activity in Bi2S3 and g-C3N4 with photocatalytic activity, and it was prepared by a facile one-step calcination method. This catalyst achieved 88 % and 97 % conversion and selectivity for the cycloaddition reaction of epichlorohydrin and CO2 with no change in yield after five cycles. In addition, the two compositions of Bi2S3 and g-C3N4 in MCN resulted in enhanced light absorption of the catalyst, thus providing some photothermal performance. This paper provides an idea for the design of bifunctional catalysts with Lewis acid-base.

Efficient photocatalytic removal of ciprofloxacin through in-situ growth of g-C3N4 on the surface of clinoptilolite

Natural mineral clinoptilolite has many advantages such as porous structure, stability, low price, environmental protection, and simple modification process, making it an ideal choice for wastewater treatment materials. Loading photocatalysts on the surface of zeolite can effectively exert adsorption degradation synergy in wastewater treatment, improve pollutant removal and mineralization capabilities, and further reduce the harm of wastewater to the environment. In this work, g-C3N4 was in-situ grown on the surface of clinoptilolite using a one-step calcination method for efficient photocatalytic removal of the pollutant ciprofloxacin from water. In-situ growth of g-C3N4 on clinoptilolite enables the catalyst to have strong adsorption capacity for pollutants. At the same time, the large specific surface area and extended photo-generated carrier lifetime make the composite photocatalyst exhibit excellent visible light adsorption degradation ability. The CN/CLI-60 with the best photocatalytic performance showed a removal rate of over 90 % of ciprofloxacin within 60 min, much higher than pure g-C3N4 and clinoptilolite. In addition, the pH value, pollutant concentration, catalyst quantity, and cycle stability have all been investigated to evaluate the practical application potential of this catalyst. This work can provide industrial guidance for the rational design of low-cost and high-efficiency photocatalysts using natural clinoptilolite.

Utilising bauxite residue (red mud) to construct Z-type heterojunction for formaldehyde degradation

The photocatalytic treatment of pollutants has garnered significant attention owing to its ability to safely and efficiently treat pollutants without secondary contamination. However, the complexity of synthesis methods and the high costs of photocatalysts remain major challenges for the industrial application of this technology. The high content of α-Fe2O3 metal semiconductors in red mud (RM) presents an opportunity for the effective preparation of RM-based α-Fe2O3 composites for catalytic degradation. Graphitic-phase carbon nitride features a similar energy band structure to α-Fe2O3 and demonstrates excellent photocatalytic properties. Herein, we directly prepared a novel Z-scheme-heterojunction g-C3N4/RM composites via a one-step calcination method by reconstructing the interface between RM and melamine. Comprehensive characterisations revealed the formation of a Z-scheme heterojunction between g-C3N4 and α-Fe2O3. This significantly improved the spatial separation of photogenerated carriers, enabling the efficient degradation of formaldehyde. The degradation efficiency reached 63.04% after 2 h of light exposure, and the composites exhibited excellent recyclability. The optical adsorption and photocatalytic properties of this newly developed composite material were significantly enhanced compared with pristine RM, which degraded 26.96% of formaldehyde under similar conditions. This study marks the first application of Z-type heterojunctions constructed from bauxite residue and nonmetallic semiconductors for degrading formaldehyde, an air pollutant. Our work offers new insights into leveraging solid wastes for high-value-added advanced catalytic applications.

Insight on the degradation of P-chlorophenol based on the Co-g-C3N4/diatomite composite photo-Fenton process

The non-metallic photocatalyst g-C3N4 is characterized by non-toxicity and straightforward preparation. Still, the drawbacks of low specific surface area and fast carrier complexation rate limit its practical application in photocatalysis. In this work, Co-doped g-C3N4 was prepared on the surface of diatomite (DE) through a simple one-step calcination method and used to degrade 4-chlorophenol (4-CP). Photocatalytic experiments showed that Co-g-C3N4/DE removed up to 98.7% of 4-CP. The doping of Co could capture the photogenerated electrons, thereby reducing the recombination of photocarriers and accelerating the oxidation–reduction reaction of Co3+/Co2+ and H2O2, promoting the generation of OH. Introducing DE improved the aggregation of g-C3N4 and expanded its surface area. Moreover, the Co-g-C3N4/DE composite material exhibited a low metal leaching rate and good reusability throughout the experiments. In addition, based on DFT calculations, the ROS attack mechanism of 4-CP degradation was speculated and calculated. The final product of 4-CP was found to pose a more minor environmental threat, according to the T.E.S.T. In short, the prepared Co-g-C3N4/DE composite realized the capture of photogenerated electrons and the acceleration of photocatalytic reactions, which are expected to solve the challenges in wastewater treatment.

Isotype heterojunction: tuning the heptazine/triazine phase of crystalline nitrogen-rich C3N5 towards multifunctional photocatalytic applications.

Photocatalytic technology has been well studied as a means to achieve sustainable energy generation through water splitting or chemical synthesis. Recently, a low C/N atomic ratio carbon nitride allotrope, C3N5, has been found to be highly prospective due to its excellent electronic properties and ample N-active sites compared to g-C3N4. Tangentially, crystalline g-C3N4 has also been a prospective candidate due to its improved electron transport and extended π-conjugated system. For the first time, our group successfully employed a one-step molten salt calcination method to prepare novel N-rich crystalline C3N5 and elucidate the effect of calcination temperature on the heptazine/triazine phase. Calcination temperatures of 500 °C (CC3N5-500) and 550 °C (CC3N5-550) lead to crystalline carbon nitride with both heptazine and triazine phases, forming an intimate isotype heterojunction for robust interfacial charge separation. An excellent photocatalytic hydrogen evolution rate (359.97 μmol h-1; apparent quantum efficiency (AQE): 12.86% at 420 nm) was achieved using CC3N5-500, which was 15-fold higher than that of pristine C3N5. Furthermore, CC3N5-500 exhibited improved activity for simultaneous benzyl alcohol oxidation and hydrogen production, as well as H2O2 production (AQE: 9.49% at 420 nm), signifying its multitudinous photoredox capabilities. Moreover, the recyclability tests of the optimal CC3N5-500 on a 3D-printed substrate also showed a 92% performance retention after 4 cycles (16 h). This highlights that crystalline C3N5 significantly augmented the reaction performance for diverse multifunctional solar-driven applications. As such, these results serve as a guide toward the structural tuning of 2D metal-free carbon nanomaterials with tunable crystallinity toward achieving boosted photocatalysis.

Constructing highly efficient and ultra-stable (against Temperature, Humidity and Sunlight) luminescent solar concentrators by using dendritic CsPbBr3@SiO2 particles

Conventional perovskite quantum dots (PQDs) suffer long-term stability, further limiting practical application of luminescent solar concentrators (LSCs). In this work, novel dendritic CsPbBr3@SiO2 particles with bright solid-state green light emission and 46 % of photoluminescence quantum yield (PLQY) have first been synthesized via one-step solid-phase calcination method. The dendritic CsPbBr3@SiO2 particles have then been used as fluorescent material for construction of LSCs along with using organosilicon polymers with better compatibility as waveguide materials. Single-layer thin film LSCs and overall curing LSCs are easily prepared by the casting and curing method, exhibiting high external optical efficiency (ηopt) of 7.88 % and 10.92 %, respectively. The maximum internal quantum efficiency (ηint) of thin film LSCs and overall curing LSCs reach 45.09 % and 44.07 %, respectively, while their maximum external quantum efficiency (ηext) of 29.42 % and 34.07 % are obtained, respectively. Importantly, both types of LSCs show excellent stability, maintaining above 92 % of the initial ηopt under high-relative-humidity (RH = 90 %), high-temperature (60 °C) and sunlight exposure conditions for two weeks or room temperature environment for twenty weeks. Moreover, both types of LSCs at optimal conditions have good transparency (>40 % over 515 nm of light wavelength). Otherwise, both types of LSCs have higher ηopt than that of the previous related work.

Synergistic effect between Ni single atoms and Ni nanoparticles for effectively boosting sustainable co-electrolysis of CO2 and hydrazine

The intrinsic performance of single atom catalysts (SACs) to electrochemical CO2 reduction reaction (ECRR) is limited due to the absence of synergistic active sites. Herein, Ni single atom (NiSAs) and Ni nanoparticles (NiNPs) are co-loaded on nitrogen-doped hollow carbon spheres (N-HCSs) by a one-step calcination method, which exhibits high CO selectivity in H-type cell with aqueous solution or an ionic liquid as electrolyte. Particularly, NiSAs-NPs-N-HCSs demonstrate a CO selectivity of 98.98%, yielding an industrial level CO current density of 152.7 mA cm−2 in flow cell. In situ Raman spectroscopy and in situ infrared characterization technology confirm that *COOH and *CO are important intermediates in the ECRR process. Theoretical computations suggest that coexisting NiNPs can reduce the energy barrier of *COOH, thereby improving the ECRR performance, indicating the synergistic effect between NiSAs and NiNPs in the ECRR process. Moreover, NiSAs-NPs-N-HCSs is applied to the membrane electrode assembly system coupling the hydrazine oxidation reaction (HzOR), which can significantly reduce the voltage about 836 mV at 100 mA cm−2.

Novel Z-scheme Nb2O5/C3N5 photocatalyst for boosted degradation of tetracycline antibiotics by visible light-assisted activation of persulfate system

Photocatalytic-assisted activation of persulfate (PDS) is regarded as a promising method for the rapid and efficient degradation of refractory pollutants in the water environment. In this study, a novel Nb2O5/C3N5 (NOCN) p-n heterojunctions composite was created by loading n-type Nb2O5 onto p-type C3N5 via an in-situ facile one-step calcination method. The NOCN/PDS system exhibited excellent performance in degrading tetracycline (TC) antibiotics under visible light and had great cyclic stability. The degradation efficiency of the coupled system reached 95 %, surpassing the pure C3N5 and PDS systems by 3.5 times and 2.4 times, respectively. The degradation rate of target pollutants was improved by the coupled system with the photocatalytic activation of PDS. The photogenerated electrons (e-) in NOCN were able to activate PDS effectively, which facilitated the creation of more reactive species. The Photoluminescence (PL) and other photoelectrochemical data demonstrated that the interfacial charge separation and photoresponsivity were remarkably enhanced in the coupled system. According to Mott-Schooky and electron spin resonance (ESR) characterization, it was confirmed that the reaction mechanism was the Z-scheme charge transfer mechanism based on p-n heterojunctions in the NOCN/PDS system. In addition, LC-MS analyses, TOC monitoring and biotoxicity analyses detected that the target pollutants were degraded to weakly bio-toxic micromolecules. In conclusion, this work provides valuable insights into the application of visible light-activated PDS technology in the degradation of organic pollutants, highlighting its potential for practical implementation.

Prussian blue analogues-derived zero valent iron to efficiently activate peroxymonosulfate for phenol degradation triggered via reactive oxygen species and high-valent iron-oxo complexes

It is of great significance to develop the effective technique to treat phenol-containing wastewater. Herein, Fe-based prussian blue analogues-derived zero valent iron (ZVI) was successfully synthesized by one-step calcination method. Owing to high specific surface area and rich active sites, ZVI-2 possessed excellent performance in charge transfer. Notably, in comparison with conventional ZVI and Fe2+, ZVI-2 can effectively activate peroxymonosulfate (PMS) for achieving rapid degradation of phenol, and the highest removal efficiency of phenol reached 94.9% within 24 min. More importantly, developed ZVI-2/PMS oxidation system with good stability displayed strong anti-interference capability. Interestingly, Fe0 loaded on the surface of ZVI-2 can efficiently break the O–O bond of PMS to generate reactive oxygen species (i.e., SO4•−, OH•, O2•− and 1O2). As main adsorption sites of PMS, the existence of oxygen vacancy promote the formation of high-valent transition metal complexes (namely ZVI-2≡Fe4+=O). Under the combined action of reactive oxygen species and ZVI-2≡Fe4+=O, phenol can be eventually degraded into CO2 and H2O. The possible degradation pathways of phenol were also investigated. Furthermore, proposed ZVI-2/PMS oxidation system displayed great potential for application in the field of wastewater treatment. All in all, current work provided a valuable reference for design and application of Fe-based catalysts in PS-AOPs.

Monoatomic Fe and Pt-Co alloys on NC/Ti4O7 for efficient and durable oxygen reduction

The combination of metal monoatomic with alloys on carbon support facilitates the promising activity in oxygen reduction. However, the alloys still suffer from the degradation of catalyst stability due to carbon corrosion. Herein, the NC/Ti4O7 support was loaded with both monoatomic Fe and Pt-Co alloys using a one-step calcination method. The results indicate that chelation of Fe3+ with α-D-glucose, physical segregation of excess α-D-glucose and binding to N species at high temperatures are essential to increase the loading of monatomic Fe in Fe1/PtCo-NC/Ti4O7. Fe1/PtCo-NC/Ti4O7 demonstrates a half-wave potential of 0.941 V and a mass activity of 3.16 A mgPt -1. This mass activity is as high as 6.87 times that of Fe/PtCo-NC/Ti4O7 (without α-D-glucose during the synthesis, 0.46 A mgPt -1). Meanwhile, Fe1/PtCo-NC/Ti4O7 exhibits a peak power density of 210.5 mW cm-2 and a specific capacity of 771.1 mAh gZn -1 in a zinc-air battery. This dual-substrate strategy provides a new perspective on the multilevel construction of catalysts.

Photothermal-Assisted Photocatalytic Degradation of Tetracycline in Seawater Based on the Black g-C3N4 Nanosheets with Cyano Group Defects

As a broad-spectrum antibiotic, tetracycline (TC) has been continually detected in soil and seawater environments, which poses a great threat to the ecological environment and human health. Herein, a black graphitic carbon nitride (CN-B) photocatalyst was synthesized by the one-step calcination method of urea and phloxine B for the degradation of tetracycline TC in seawater under visible light irradiation. The experimental results showed that the photocatalytic degradation rate of optimal CN-B-0.1 for TC degradation was 92% at room temperature within 2 h, which was 1.3 times that of pure CN (69%). This excellent photocatalytic degradation performance stems from the following factors: (i) ultrathin nanosheet thickness reduces the charge transfer distance; (ii) the cyanogen defect promotes photogenerated carriers’ separation; (iii) and the photothermal effect of CN-B increases the reaction temperature and enhances the photocatalytic activity. This study provides new insight into the design of photocatalysts for the photothermal-assisted photocatalytic degradation of antibiotic pollutants.