Efficient Proton Transfer and Charge Separation within Covalent Organic Frameworks via Hydrogen-Bonding Network to Boost H2O2 Photosynthesis.

Photocatalytic synthesis based on the oxygen reduction reaction (ORR) has shown great promise for H2O2 production. However, the low activity and selectivity of 2e- ORR result in a fairly low efficiency of H2O2 production. Herein, we propose a strategy to enhance the proton-coupled electron transfer (PCET) process in covalent organic frameworks (COFs), thereby significantly boosting H2O2 photosynthesis. We demonstrated that the construction of a hydrogen-bonding network, achieved by anchoring the H3PO4 molecular network on COF nanochannels, can greatly improve both proton conductivity and photogenerated charge separation efficiency of COFs. Thus, COF@H3PO4 exhibited superior photocatalytic performance in generating H2O2 without sacrificial agents, with a solar-to-chemical conversion efficiency as high as 0.69%. Results indicated that a much more localized spatial distribution of energy band charge density on COF@H3PO4 led to efficient charge separation, and the small energy barrier of the rate-limiting step from *OOH to H2O2 endowed COF@H3PO4 with higher 2e- ORR selectivity.

Peroxymonosulfate and peroxydisulfate activation by fish scales biochar for antibiotics removal: Synergism of N, P-codoped biochar.

Social development is accompanied by technological progress, which commonly leads to the expansion of pollution As an essential resource of modern medical treatment, antibiotics have become a hot topic in the aspect of environmental pollution. In this study, we first used fish scales to synthesize N, P-codoped biochar catalyst (FS-BC) as peroxymonosulfate (PMS) and peroxydisulfate (PDS) activator to degrade tetracycline hydrochloride (TC). At the same time, peanut shell biochar (PS-BC) and coffee ground biochar (CG-BC) were prepared as reference materials. Among them, FS-BC exhibited the best catalytic performance due to the excellent defect structure (ID/IG = 1.225) and the synergism of N, P heteroatoms. PS-BC, FS-BC and CG-BC achieved degradation efficiencies of 86.26%, 99.71% and 84.41% for TC during PMS activation and 56.79%, 93.99% and 49.12% during PDS, respectively. In both FS-BC/PMS and FS-BC/PDS systems, non-free radical pathways involved singlet oxygen (1O2), surface-bound radicals mechanism and direct electron transfer mechanism. Structural defects, graphitic N and pyridinic N, P-C groups and positively charged sp2 hybridized C adjacent to graphitic N were all critical active sites. FS-BC has the potential for practical applications and development because of its robust adaptation to pH and anions and stable re-usability. This study not only provides a reference for biochar selection, but also suggests a superior strategy for TC degradation in the environment.

Highly Enhanced Photocatalytic Performances of Composites Consisting of Silver Phosphate and N-Doped Carbon Nanomesh for Oxytetracycline Degradation.

Photocatalytic technology based on silver phosphate (Ag3PO4) has excellent potential in removing antibiotic pollutants, but the low separation rate of photogenerated hole-electron pairs restricts the application of the photocatalyst. In this study, it was found that the combination of nitrogen-doped carbon (NDC) with carbon defects and Ag3PO4 can significantly enhance the photocatalytic ability of Ag3PO4. After it was exposed to visible light for 5 min, the photocatalytic degradation efficiency of oxytetracycline (OTC) by the composite photocatalyst Ag3PO4@NDC could reach 100%. In addition, the structure of NDC, Ag3PO4, and Ag3PO4@NDC was systematically characterized by SEM, TEM, XRD, Raman, and EPR. The XPS results revealed intense interface interaction between Ag3PO4 and NDC, and electrons would transfer from Ag3PO4 to the NDC surface. A possible mechanism for enhancing the photocatalytic reaction of the Ag3PO4@NDC composite catalyst was proposed. This study provides a highly efficient visible light catalytic material, which can be a valuable reference for designing and developing a new highly efficient visible light catalyst.

Carbon nanotube-based materials for persulfate activation to degrade organic contaminants: Properties, mechanisms and modification insights.

Removal of harmful organic matters from environment has great environmental significance. Carbon nanotube (CNT) materials and their composites have been demonstrated to possess excellent catalytic activity towards persulfate (PS) activation for the degradation of organic contaminants. Herein, detailed information concerning the function, modification methods and relevant mechanisms of CNT in persulfate-based advanced oxidation processes (PS-AOPs) for organic pollutant elimination has been reviewed. The activation mechanism of PS by CNT might include radical and nonradical pathways and their synergistic effects. The common strategies to improve the stability and catalytic capability of CNT-based materials have also been put forward. Furthermore, their practical application potential compared with other catalysts has been described. Finally, the challenges faced by CNT in practical application are clearly highlighted. This review should be of value in promoting the research of PS activation by CNT-based materials for degradation of organic pollutants and the corresponding practical applications.

Construction of Bi2WO6/CoAl-LDHs S-scheme heterojunction with efficient photo-Fenton-like catalytic performance: Experimental and theoretical studies.

The photo-Fenton-like catalytic process has shown great application potential in environmental remediation. Herein, a novel photo-Fenton-like catalyst of Bi2WO6 nanosheets decorated hortensia-like CoAl-layered double hydroxides (Bi2WO6/CoAl-LDHs) was synthesized via hydrothermal process. The optimized Bi2WO6/CoAl-LDHs composite performed the high-efficiency photo-Fenton-like catalytic performance for oxytetracycline (OTC) removal (98.47%) in the mediation of visible-light and H2O2. The comparative experiment, technical characterization and density functional theory calculation results indicated that the efficient photo-Fenton-like catalytic performance of Bi2WO6/CoAl-LDHs was attributed to the synergistic action of the Fenton-like process of cobalt ions in CoAl-LDHs, an internal electric field and the S-scheme heterojunction form between Bi2WO6 and CoAl-LDHs, which could significantly promote the active substance formation and the photocatalytic process in the catalytic system. This study will stimulate the new inspiration of designing the efficient catalytic system for environmental remediation and other fields.