Effective degradation of phenol by activating PMS with bimetallic Mo and Ni Co-doped g C3N4 composite catalyst: A Fenton-like degradation process promoted by non-free radical 1O2.

The application of bimetal supported graphite phase carbon nitride in activated peroxymonosulfate (PMS) process has become a research hotspot in recent years. In this study, 8-g C3N4/Mo/Ni composite catalyst material was successfully prepared by doping Mo and Ni in graphite phase carbon nitride. The bimetallic active sites were formed in the catalyst, and PMS was activated by the metal valence Mo6+/Mo4+ and Ni2+/Ni(0) through redox double cycle to effectively degrade phenol. When pH was neutral, the degradation rate of 20 mg/L phenol solution with 8-g C3N4/Mo/Ni (0.35 g/L) and PMS (0.6 mM) could reach 95% within 20 min. The degradation rate of 8-g C3N4/Mo/Ni/PMS catalytic system could reach more than 90% within 20min under the condition of pH range of 3-11 and different anions. Meanwhile, the degradation effects of RhB, MB and OFX on different pollutants within 30min were 99%, 100% and 82%, respectively. Electron spin resonance and quenching experiments showed that in 8-g C3N4/Mo/Ni/PMS system, the degradation mechanism was mainly non-free radicals, and the main active species in the degradation process was 1O2. This study provides a new idea for the study of bimetal supported graphite phase carbon nitride activation of PMS and the theoretical study of degradation mechanism.

The calcium alginate-immobilized Co-g-C3N4 composite microspheres as an efficient mediator to activate peroxymonosulfate for degrading organic pollutants.

Poor water stability and difficult separation severely limited the application of Co-based catalysts in persulfate activation. Herein, for the first time, the calcium alginate-immobilized Co-g-C3N4-2 composite microspheres were prepared by a feasible method. Notably, embedding Co ion into g-C3N4 can improve its specific surface area and electrochemical activities. More significantly, as-prepared Co-g-C3N4-2 microsphere presented excellent catalytic performance in PMS activation for the degradation of TC. For the activation mechanisms of PMS over Co-g-C3N4-2 microspheres, the calcium alginate microspheres could mediate the direct electron transfer between TC and PMS, while both radical and nonradical pathways were involved in the activation of PMS over Co-g-C3N4-2. Meanwhile, SO4•-, OH•, O2•- and 1O2 were major reactive oxygen species formed in the Co-g-C3N4-2 microsphere/PMS system. Proposed Co-g-C3N4-2 microsphere/PMS system still exhibited great degradation ability towards TC over a wide pH range, and co-existing anions had weak influence on TC degradation over Co-g-C3N4-2 microsphere/PMS system. Moreover, the construction of Co-g-C3N4-2 microspheres not only avoided the release of metal ion from catalyst, but also provided convenience for the recovery of catalyst. In short, current work shared some novel insights into the application of heterogeneous catalysis in persulfate activation for wastewater treatment.

Porous P, Fe-doped g-C3N4 nanostructure with enhanced photo-Fenton activity for removal of tetracycline hydrochloride: Mechanism insight, DFT calculation and degradation pathways.

This study fabricated an efficient P and Fe co-doping graphitic carbon nitride catalyst (Fe- CN/P) by thermal polymerization of melamine, FeCl3, and 2-hydroxyphosphonoacetic acid (HPAA) mixture. The Fe-CN/P catalyst exhibited much better tetracycline hydrochloride (TCH) degradation performance than that of single doping and neat CN. Various characterizations indicated that the introduction of HPAA significantly increased the specific surface area of CN and improved charge separation as well as transfer efficiency. Based on Fe 2p XPS analysis and indirect determination of hydroxyl radical (·OH) content, the separated photogenerated electrons accelerated the reduction of Fe(III) and activated photo-Fenton reaction, resulting in more ·OH species generation. The effect of pH value, catalyst dosages, H2O2 concentration, the type of cations and anions as well as water matrices on the degradation of TCH by Fe-CN/P was systematically investigated. The main degradation pathways of TCH were proposed according to the LC-MS intermediates detection and DFT calculation. The results indicated that reactive oxide species (ROS) were more likely to attack the atoms with high Fukui index (f0). This work provides new ideas for adjusting the morphology and electronic structure of CN to enhance its photo-Fenton catalytic activity.

Signal-on photoelectrochemical immunoassay mediated by the etching reaction of oxygen/phosphorus co-doped g-C3N4/AgBr/MnO2 nanohybrids.

We designed a signal-on photoelectrochemical (PEC) immunoassay for the sensitive monitoring of prostate-specific antigen (PSA) based on the etching reaction of hydrogen peroxide (H2O2) toward oxygen/phosphorus co-doped graphitic C3N4/AgBr/MnO2 nanosheets (OP-g-C3N4/AgBr/MnO2). Initially, glucose oxidase (GOX)-labeled detection antibodies were introduced into the capture antibody-coated microplate with a sandwich-type immunoreaction in the presence of PSA. Then, the as-generated H2O2 from the decomposition of glucose by GOX etched the manganese dioxide (MnO2) nanosheets into manganese ions (Mn2+), thereby causing the exposure of the underlying OP-g-C3N4/AgBr. Meanwhile, H2O2 could be also used as an electron scavenger, and restrain the recombination of the electron-hole pairs of OP-g-C3N4/AgBr. Two advantages of H2O2 enhanced the photocurrent synergistically. Under optimum conditions, the PEC immunoassay showed high sensitivity toward target PSA within a dynamic working range of 0.05-50 ng mL-1 with a limit of detection of 17 pg mL-1. In addition, our system possessed high specificity, favorable selectivity, and good stability. Relative to commercialized PSA ELISA kits, the accuracy of our strategy was acceptable. More importantly, our strategy can be easily extended to screen other biomarkers by controlling the corresponding antibodies.

In Situ Preparation and Analysis of Bimetal Co-doped Mesoporous Graphitic Carbon Nitride with Enhanced Photocatalytic Activity.

A novel photocatalyst of mesoporous graphitic carbon nitride (g-C3N4) co-doped with Co and Mo (Co/Mo-MCN) has been one-pot synthesized via a simple template-free method; cobalt chloride and molybdenum disulfide were used as the Co and Mo sources, respectively. The characterization results evidently indicate that molybdenum disulfide functions as Mo sources to incorporate Mo atoms in the framework of g-C3N4 and as a catalyst for promoting the decomposition of g-C3N4, resulting in the creation of mesopores. The obtained Co/Mo-MCN exhibited a significant enhancement of the photocatalytic activity in H2 evolution (8.6 times) and Rhodamine B degradation (10.1 times) under visible light irradiation compared to pristine g-C3N4. Furthermore, density functional theory calculations were applied to further understand the photocatalytic enhancement mechanism of the optical absorption properties at the atomic level after Co- or Mo-doping. Finite-difference time-domain simulations were performed to evaluate the effect of the mesopore structures on the light absorption capability. The results revealed that both the bimetal doping and the mesoporous architectures resulted in an enhanced optical absorption; this phenomenon was considered to have played a critical role in the improvement in the photocatalytic performance of Co/Mo-MCN.