摘要 : The CeO2/BiOI/g-C3N4 composites were synthesized by solvothermal and ultrasonic stirring method. The composition, microstructure and optical properties of the material were characterized by XRD, SEM, TEM and UV-Vis DRS. The obtained CeO2/BiOI/g-C3N4 has tighter interface structure, good light response property, uniform phase distribution and high degree of crystallization. Photocatalytic degradation experiments showed that under visible light(λ>420 nm), the photocatalytic degradation efficiency of CeO2/BiOI/g-C3N4 (Ce/Bi molar ratio was 2∶1, and g-C3N4 mass fraction was 5%) for RhB was 71%, which was 7 times that of pure CeO2 and 10 times that of pure BiOI. The sample remained high photocatalytic efficiency after four cycles, revealing its good circulatory stability. Finally, the photocatalytic mechanism of the composites was introduced. It was clear that the real active substances in the photocatalytic experiment were holes and superoxide radicals.

摘要 : 4-Chlorophenol (4-CP) is one of the water pollutants with high toxicity and low biodegradability. Accurate detection against 4-CP is of great value to maintain human life. A photoelectrochemical (PEC) sensor based on three-dimensional carbon-rich carbon nitride (named 3D-CN) material was proposed for monitoring 4-CP from water environment. 3D-CN material was prepared by a low-temperature supramolecular self-assembly combined with thermal-polymerization strategy. 3D and carbon rich structure endow 3D-CN material with significantly extended π-conjugated system and enhanced charge mobility, which not only easily activates inherent π → π electronic transition, but also awakens n → π electronic transition in 3D-CN material. The n → π electronic transition can further extend the absorption band edge, results into excellent PEC performance of 3D-CN material. The constructed PEC 4-CP sensor showed excellent selectivity, stability, reproducibility, and accuracy for actual water sample detection. Furthermore, the sensor provided a wide detection range (1.6–3200 μg L –1 ) and a low limit detection (0.53 μg L –1 ). This work proposes a new idea for the development of graphitic carbon nitride (g-C 3 N 4 ) materials with high PEC performance by introducing a synergistic regulation strategy of carbon rich and 3D structure, and broadens the application of g-C 3 N 4 -based materials in the field of PEC sensors.

摘要 : Simultaneous detection of dihydroxybenzene isomers including hydroquinone (HQ), catechol (CC), and resorcinol (RS) is significant for water quality control as they are highly toxic and often coexist. However, it is a great challenge to realize their accurate and simultaneous detection due to their similarity in structure and properties. Herein, an electrochemical flexible strip with single-atom cobalt (SA-Co/NG) was constructed through high-resolution electrohydrodynamic (EHD) printing for dihydroxybenzene isomer's simultaneous detection. Results showed that the provided SA-Co/NG strip exhibited excellent sensing performance with reliable repeatability, reproducibility, long-term stability, and flexibility. Linear ranges of 0.50–31 745 μM, 0.50–5909 μM, and 0.50–153.5 μM were achieved for HQ, CC, and RS, respectively, with a detection limit of 0.164 μM. Based on the experimental data, the mechanism concerning SA-Co/NG catalytic activity towards HQ can be deduced, starting from the combination of Co and OH− in water, followed by the formation of Co–OH-dihydroxybenzene, and finally leading to O–H bond dissociation to generate benzoquinone. As for CC or RS, pyridinic N or CO synergistic with a single Co atom catalyzes their oxidation. Besides, the printed flexible SA-Co/NG strip further demonstrates the accurate and simultaneous detection of HQ, CC, and RS in textile wastewater, proposing a powerful practical application.

摘要 : The sudden outbreak of coronavirus disease (COVID-19) triggered by SARS-CoV-2 infection has created a terrifying situation around the world. The spike protein of SARS-CoV-2 can act as an early biomarker for COVID-19. Therefore, controlling the spread of COVID-19 requires a low-cost, fast-response, and sensitive monitoring technique of spike protein. Herein, a photoelectrochemical (PEC) immunosensor for the detection of spike protein was constructed using the nanobody and an Mn (Ⅱ) modified graphitic carbon nitride (Mn/g-C3N4). The introduction of atomically dispersed Mn (Ⅱ) can accelerate the effective transfer and separation of photogenerated electron-hole pairs, which significantly boosts PEC performance of g-C3N4, thereby improving the detection sensitivity. As a recognition site, nanobody can achieve high-affinity binding to the spike protein, leading to a high sensitivity. The linear detection range of the proposed PEC immunosensor was 75 fg mL-1 to 150 pg mL-1, and the limit of detection was calculated to be 1.22 fg mL-1. This stable and feasible PEC immunosensor would be a promising diagnostic tool for sensitively detecting spike protein of SARS-CoV-2.

摘要 : Nitrogen-coordinated single-atom manganese in multi-dimensional nitrogen-doped carbon electrocatalysts (Mn–NC) were successfully constructed by combining two-dimensional nanosheets and one-dimensional nanofibers. The Mn–NC exhibited excellent oxygen reduction reaction catalytic activity with a half-wave potential of 0.88 V, which is higher than the 0.85 V of Pt/C.

摘要 : Photocatalytic degradation of organic pollutants is considered an ideal method to solve the global environmental pollution problem. In this method, photocatalytic materials are regarded as the key factor. As an n-type photocatalytic material, graphitic carbon nitride (g-C3N4) has attracted much attention due to its suitable bandgap, nontoxicity, and high photostability. However, g-C3N4 still has defects such as insufficient visible light absorption, low specific surface area, and easy recombination of photogenerated electron–hole pairs, which lead to the poor photocatalytic performance of g-C3N4. Herein, to solve the above problems, thiourea, lemon juice, and tin chloride pentahydrate are used as precursors, while carbon quantum dots (CQDs) are used as electron mediators, and the third phase SnS2 is introduced by a hydrothermal and ultrasonic composite method. SnS2/CQDs/g-C3N4 composites with Z-type heterojunction are successfully prepared. The results show that the SnS2/CQDs/g-C3N4 has a 2D0D2D structure, which effectively inhibits the recombination of photogenerated electron–hole pairs, making the material have better photocatalytic degradation activity for Rhodamine B (RhB). When the mass ratio of SnS2 is 15%, the photocatalytic degradation efficiency of RhB by the composite reaches the best, which is 87.8%. After four cycles, the photocatalytic degradation efficiency of the 15% SnS2/CQDs/g-C3N4 composite still remains at 82.9%.

摘要 : To solve the problem of water pollution, researchers have proposed a photocatalytic degradation technology, in which the key factor is the development of efficient photocatalytic materials. Graphitic carbon nitride (g-C3N4), an n-type semiconductor, has been widely studied due to its suitable band gap (2.7 eV), low cost, easy preparation, non-toxicity, and high photostability. However, the pure-phase g-C3N4 still has defects such as low specific surface area, insufficient visible light absorption, low charge mobility, few active sites for interfacial reaction, and easy recombination of photogenerated electron–hole pairs, which leads to the lower photocatalytic activity of g-C3N4. Aiming at the problems mentioned above, this paper focus on the synthesis of g-C3N4-based composites with high photocatalytic activity via lemon juice induction method. Thiourea and lemon juice were selected as precursors, and carbon quantum dots (CQDs) as electron mediators were introduced anchoring on the surface of g-C3N4 to build g-C3N4/CQDs with compact interface. The results showed that small-sized CQDs are uniformly distributed on the surface of g-C3N4, and the g-C3N4/CQDs composite has a 2D0D structure, which reduces the recombination of photogenerated electron–hole pairs. The photocatalytic degradation efficiency of 4% g-C3N4/CQDs for RhB reaches the highest data of 90.9%, and the photocatalytic degradation rate is 0.016 min−1, which is about 2.3 times that of g-C3N4. After four cycles of photocatalytic reaction, the photocatalytic degradation efficiency of the material remained at 81.7%. Therefore, the g-C3N4/CQDs synthesized via lemon juice induction has a more stable microstructure, and the charge separation efficiency is greatly improved, which is suitable for practical photocatalytic environmental protection.

摘要 : A highly sensitive and selective photoelectrochemical (PEC) aptasensor was constructed by Ag nanoparticles sensitized bismuth oxyiodide (AgNPs/BiOI) composites for detecting trace chloramphenicol (CAP). Because the sufficient light utilization of AgNPs and high photoelectrons transfer efficiency of BiOI, AgNPs/BiOI composites exhibited dramatically enhanced PEC performance, which is in favor of realizing efficient CAP detection. Attributed to the specific recognition of modified CAP aptamer, the PEC CAP aptasensor based on the aptamer/AgNPs/BiOI/ITO electrodes performed a wide linear range (1 pM − 20000 pM), a satisfactory detection limit (0.4 pM, S/N = 3), and superior selectivity. In addition, the CAP aptasensor possessed favorable stability and reproducibility, promoting further application of CAP trace detection and providing a foothold for ultrasensitive antibiotic detection and environmental monitoring.

摘要 : Photoelectrochemical (PEC) aptasensor is a promising analysis platform with high selectivity and sensitivity. Exploration of photoelectric active material with excellent photoelectric conversion efficiency is the key condition to design a PEC aptasensor with excellent sensitivity. Herein, a PEC aptasensor was designed and constructed by g-C 3 N 4 /Bi 24 O 31 Cl 10 heterojunction as photoelectric active material for realizing sensitive detecting enrofloxacin (ENR) antibiotic. The formation of heterojunction can facilitate separation and transfer of photogenerated carriers and reduce the recombination rate, leading to the enhancement of photocurrent response compared to that of individual semiconductor. The ENR aptamer was introduced as the specific recognition element to realize excellent selectivity of the PEC aptasensor. Because ENR-aptamer complex can block the transfer of charge, the ENR-PEC aptasensor presented the decreased photocurrent response with the increasing of ENR concentration without external voltage. The developed ENR-PEC aptasensor presented excellent sensitivity and selectivity for detecting ENR with a detection range from 0.5 to 100 fM and a low detection limit of 0.167 fM (S/N = 3). The ENR-PEC aptasensor with good reproducibility may be potential for the determination of the actual samples.

摘要 : The regulating active sites of vanadium nitride (VN)–based materials is an effective way to improve their oxygen reduction reaction (ORR) performance, which is expected to effectively solve the problem of sluggish kinetics in the cathode of Zn–air batteries. However, traditional synthesis methods cannot uniformly disperse VN, cause inadequate exposure to the active site, resulting in poor ORR performance. Herein, we successfully prepared a nitrogen–doped carbon supported ultra-small vanadium nitride nanoparticles (VN/NC) by organic group modification combined with rapid calcination strategies. The size of VN nanoparticles is around 5–10 nm. The smaller size can ultimately improve the ORR performance of VN/NC by exposing more active sites. Finally, the half–wave potential of the VN/NC is 0.813 V for ORR. More importantly, the Zn–air batteries assembled with the VN/NC catalyst as the air cathode shows a high power density (115 mW cm −2 ) and a large specific capacity (673 mAh g −1 ). It indicates that this approach can successfully synthesize ultra-small size VN nanoparticles, which is of great significance to the development of efficient air cathode materials for the Zn–air battery.