•A novel heterogeneous electro-Fenton catalyst Fe2Co1/NPC was successfully synthesized.•The system was effective for degradation of multiple organic pollutants.•Fe2Co1/NPC catalyst exhibited good ...stability and reusability in four consecutive runs.•Satisfactory performance in treatment of various real water matrix was achieved.•The associated mechanism and possible tetracycline degradation pathways were proposed.
Developing efficient heterogeneous electro-Fenton (hetero-EF) catalysts for degradation of organic pollutants has triggered great interests. In this work, a novel hetero-EF catalyst, Fe/Co bimetallic nanoparticles embedded in MOF-derived nitrogen-doped porous carbon rods (Fe2Co1/NPC), was successfully synthesized in a facile manner for effective degradation of multiple organic pollutants including tetracycline (TC), chloramphenicol, ciprofloxacin, diclofenac sodium and sulfamethoxazole. Particularly, the Fe2Co1/NPC hetero-EF system achieved TC removal ratio of 91% within 60 min and mineralization efficiency of 90.3% within 240 min under neutral conditions, and exhibited good stability and reusability in consecutive cycling tests with low leaching of iron and cobalt. The mechanism exploration indicated that TC was primarily oxidized by •OH and •O2– radicals, and the synergistic effects of nitrogen-doped porous carbon support and optimized Fe/Co bimetallic species endowed Fe2Co1/NPC with high catalytic performance in a wide pH range. The possible pathways for the mineralization of TC were also deduced. Furthermore, the Fe2Co1/NPC hetero-EF system achieved satisfactory performance in the treatment of real water matrix including tap water, river water and urban wastewater, suggesting its good application prospect.
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Herein, a twisty C‐TiO2/PCN (CNT) Step‐scheme (S‐scheme) heterojunction is fabricated and applied to degrade ciprofloxacin (CIP) with the assistance of ultrasonic vibration and visible light ...irradiation. The nitrogen‐rich twisty polymeric carbon nitride (PCN) can not only induce a non‐centrosymmetric structure with enhanced polarity for a better piezoelectric effect but also provide abundant lone pair electrons to promote n→π* transition during photocatalysis. Its hybridization with C‐TiO2 particles can construct S‐scheme heterojunction in CNT. During the piezo‐photocatalysis, the strain‐induced polarization electric field in the heterojunction can regulate the electron migration between the two components, resulting in a more effective CIP degradation. With the synergistic effect of ultrasonic vibration and visible light irradiation, the reaction rate constant of CIP degradation by CNT increases to 0.0517 min−1, which is 1.86 times that of photocatalysis and 6.46 times that of ultrasound. This system exhibits a stable CIP decomposition efficiency under the interference of various environmental factors. In addition, the in‐depth investigation found that three pathways and 12 major intermediates with reduced toxicity are produced after the reaction. Hopefully, the construction of this twisty CNT S‐scheme heterojunction with enhanced piezo‐photocatalytic effect offers inspiration for the design of environmentally functional materials.
A novel C‐TiO2/PCN (CNT) composite is designed for piezo‐photocatalytic ciprofloxacin (CIP) degradation. The twisty structure, n→π* electronic transition, and Step‐scheme heterojunction of CNT can respectively give rise to the promotion of piezoelectricity, light utilization, and charge separation, leading to much more efficient CIP degradation during the piezo‐photocatalysis than individual photocatalysis or piezocatalysis.
The good performance of base metal phosphides as alternative catalysts for hydrogen evolution has attracted great attention. However, phosphorus-hydrogen bonds (P-Hads) are easily formed on the ...surface of metal phosphides, which will severely inhibit hydrogen evolution reaction (HER). Herein, we propose a universal strategy to improve the HER activity of metal phosphides by modulating the surface electron densities. The iron modulated Fe0.29Co0.71P nanosheet arrays exhibit an overpotential of 74 mV at 10 mA cm−2 and a Tafel slope of 53.56 mV dec−1, which are close to the performance of noble metal catalysts in alkaline condition. The electronic interactions between cobalt and phosphorus are modulated after iron doping, resulting in more positively charged Co, which can promote adsorption and activation of H2O molecules and will weaken P-Hads bonds formed on the catalyst surfaces. Therefore, Fe0.29Co0.71P can optimize the adsorption and desorption of H atoms, and can promote both Volmer and Heyrovsky steps of HER. In addition, the electron density modulation of catalytic sites also improves the OER catalytic performance of Fe0.29Co0.71P. The overall water splitting electrolyzer assembled by Fe0.29Co0.71P/Ni-foam exhibits a lower cell voltage (1.59 V/10 mA cm−2), compared to that (1.61 V/10 mA cm−2) of the IrO2//Pt/C electrolyzer.
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•Fe-doping modulates the surface electron densities and improves the intrinsic activity of catalyst.•Fe-doping promotes both Volmer and Heyrovsky steps of HER.•Fe-doping can optimize the adsorption energies of the OER intermediates.•Reasonable mechanism for the enhanced electrocatalytic activity was well explained.
The full utilization of solar energy has attracted great attention in the photocatalysis and environmental pollutant control. In this study, the local surface plasmon resonance effect of Ag ...nanoparticles (Ag NPs) with the upconversion property of nitrogen-doped graphene quantum dots (N-GQDs) was first combined for the formation of ternary Ag/N-GQDs/g-C3N4 nanocomposites. The prepared material presents enhanced full-spectrum light response ability, even in near-infrared (NIR) light. The experiment results disclosed that the 0.5% N-GQDs and 2.0% Ag NPs co-doped g-C3N4 show the highest photocatalytic activity, achieving 92.8 and 31.3% removal efficiency under full-spectrum light and NIR light irradiation, respectively, which was three-fold than that of pristine g-C3N4. The boosted photocatalytic activity can be attributed to the synergistic effect among the g-C3N4, N-GQDs, and Ag NPs. The g-C3N4 nanosheets can serve as the reaction matrix and support for the dispersion of N-GQDs and Ag NPs, inhibiting their agglomeration. The existence of Ag NPs and N-GQDs can promote the light absorption and transfer ability, leading to the generation of more photoinduced charges. Simultaneously, N-GQDs and Ag NPs can efficiently transfer and reserve electrons, which can accelerate the photoinduced electrons’ migration, inhibiting the recombination. The comprehensive effect of the reasons mentioned above resulted in the unique photocatalytic activity of the prepared Ag/N-GQDs/g-C3N4 nanocomposites. This study provides a new strategy for the formation of highly efficient photocatalysts with broad-spectrum light response ability and the potential for realistic wastewater pollution control.
This work presents a novel hexagonal boron nitride (h-BN) based self-powered photoelectrochemical (PEC) aptasensor for ultrasensitive detection of diazinon (DZN) with excellent photoelectric ...conversion efficiency. It was the first time that h-BN based materials were applied to PEC aptasensor, in which the construction of Z-scheme heterojunction of h-BN and graphitic carbon nitride (CN) via doping sulfur into h-BN was innovatively proposed. Meanwhile, Au nanoparticles (AuNPs) were utilized for the surface plasmon resonance (SPR) effect and the formation of new recombination centers. The charge transfer mechanism was expounded and verified by the electron spin resonance (ESR) spin-trap technique. The proposed PEC aptasensor for determination of DZN exhibited a wide linear range from 0.01 to 10000 nM and a low detection limit of 6.8 pM with superb selectivity and remarkable stability. Moreover, the constructed PEC aptasensor performed well with excellent recoveries in three different real samples. This work illustrated that PEC aptasensor is a promising alternative to conventional analytical technologies for the detection of DZN and other organophosphorus (OP) pesticides. The designing ideas of the proposed h-BN based material can provide a foothold for the innovative construction of photoactive materials for PEC bioanalysis.
•h-BN based photoactive materials were first applied to PEC aptasensor.•The proposed h-BN based material enhanced photoelectric conversion efficiency.•The designing ideas of the h-BN based material via element doping and Z-scheme heterojunction was innovatively proposed.•Self-powered PEC aptasensor for DZN detection was proposed with superb selectivity and remarkable stability.
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•Unique C3N5/C3N4 homojunction (AT-CN) have been fabricated.•Metal-free AT-CN homojunction showed enhanced visible-light-driven PMS activation.•The built-in field in AT-CN ...homojunction can facilitate the charge transfer.•Both experiment and simulation was employed to unveil the reaction mechanism.
Photocatalytic activation of PMS is a potential advanced oxidation process in refractory wastewater purification. Herein, a C3N5/C3N4 homojunction (AT-CN) catalyst as an efficient photocatalyst for PMS activation is reported, which owns interlaced band structure, high-efficiency charge transfer, and PMS activation capability. This homojunction structure is demonstrated to be highly efficient in charge transfer and separation. As experimental result, the reaction rate constants of atrazine in AT-CN/PMS/Vis system increased to 2.9-fold and 7.4-fold, compared with C3N4/PMS/Vis and C3N5/PMS/Vis system. The photocatalytic activation of PMS for atrazine removal efficiency reached 97 % within 60 min (under pH = 3). The band structure, the charge density difference, the PMS adsorption behavior of AT-CN, and the activation pathways of PMS have been studied through the DFT calculation. According to experimental and DFT simulation, the AT-CN homojunction not only suppress the charge recombination via built-in electric field, but also exhibited a better PMS activation capability. In brief, this study through the combination of experiment and simulation is providing more inspiration for designing appropriate nonmetal homojunction in the photo-activated PMS process.
•The introduction of a methyl group successfully facilitated targeted phosphorus doping in g-C3N4.•The composite oxidation system facilitates the degradation of diverse pollutants.•The precise ...modulation of reactive oxygen species enables tailored degradation of pollutants.•The atomic reactivity of pollutants towards various reactive oxygen species was unveiled.
In the photocatalytic degradation process, constructing a controllable composite oxidation system with radicals and nonradicals to meet the requirement for efficient and selective degradation of diverse pollutants is significant. Herein, a methylated and phosphorus-doped g-C3N4 (NPEA) can exhibit selective radical and nonradical species formation depending on the pH values. The NPEA can spontaneously switch the production of active species according to the pH value of the reaction system, exhibiting steady-state concentrations of ·O2− for 11.83 × 10−2 µmol L−1 s−1 (with 92.7 % selectivity) under alkaline conditions (pH = 11), and steady-state concentrations of 1O2 for 5.18 × 10−2 µmol L−1 s−1 (with 88.7 % selectivity) under acidic conditions (pH = 3). The NPEA exhibits stability and universality in the degradation of pollutants with rate constant for sulfamethazine (k = 0.261 min−1) and atrazine (k = 0.222 min−1). Moreover, the LC-MS and Fukui function demonstrated that the NPEA can tailor degradation pathways for pollutants, achieving selective degradation. This study offers a comprehensive insight into the mechanism of the photocatalytic oxidation system, elucidating the intricate interplay between pollutants and reactive oxygen species.
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•Triazole and pyromellitic diimide modified carbon nitride (TACP) was fabricated;•The thin-walled vesicular TACP can effectively enhance the n → π* electron excitation;•The donor-π-acceptor electron ...structured TACP promoted the separation of photocarriers;•TACP significantly enhanced the photodegradation of atrazine to a 95% removal rate;•Two pathways and 14 intermediates were proposed during atrazine degradation in the system.
Polymeric carbon nitride (PCN) as a competitive non-metal photocatalyst, has been widely applied in water treatment. However, the limited visible-light utilization and high photocarrier recombination rate restrict its photocatalytic efficiency. Herein, triazole and pyromellitic diimide were applied for the bimolecular decoration of polymeric carbon nitride (PCN) to fabricate TA-CN-PDI for the photodegradation of atrazine. The thin-walled vesicular morphology in TA-CN-PDI can enhance the n→π* electron excitation, and the donor-π-acceptor electronic structure can promote the directional movement of photogenerated electrons and holes. The theoretical and experimental results suggested that the vesicular structure and the donor-π-acceptor electronic structure synergistically promoted the photoactivity of the catalyst. Compared to the pristine PCN, the reaction rate constants of atrazine by TA-CN-PDI increased to 6.64-fold, achieving a 95 % removal rate. It was found that1O2, OH, h+, ·O2- were contributed to the ATZ degradation. In addition, mainly 14 intermediates and two pathways were proposed according to the LC-MS analysis. Hopefully, this modification strategy of PCN and its application in ATZ degradation can pave a way for subsequent research on the modification of photocatalysts.
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•Improved activity by synergy of Z-scheme and piezoelectricity was firstly proposed.•The promotion mechanism of piezoelectricity on dual Z-scheme is explained.•The prepared material ...has strong anti-interference ability.•The degradation path of nitenpyram is explained in detail.•The toxicity of NTP’s intermediate products was also analyzed.
A highly active catalyst AgI/Ag3PO4/BaTiO3 with the synergistic effect of photocatalysis and piezoelectricity was prepared, which can remove 100 % of Nitenpyram (NTP) in a wide pH range within 10 min. This piezo-photocatalyst AgI/Ag3PO4/BaTiO3 with dual Z-scheme shows a higher NTP degradation rate than their mono-material and binary composites. The apparent rate constant of AgI/Ag3PO4/BaTiO3 in NTP removal is 2.12 times higher than the second-performing catalyst. In the quenching experiment, h+ and ·O2– were observed to be the main active substance in NTP degradation and the former contributes the most. The dual Z-scheme mechanism and the built-in electric field are both beneficial for the separation of electron-hole pairs, as well as the extension of the photo-generated carrier lifetime. At last, the effect factor experiments proved that the prepared AgI/Ag3PO4/BaTiO3 catalyst owns stable and efficient activity. This work provides novel guidance for the construction of highly efficient and stable piezo-photocatalytic heterojunction catalysts.
