An interfacial C-S bond bridged S-scheme ZnS/C3N5 for photocatalytic H2 evolution: Opposite internal-electric-field of ZnS/C3N4, increased field strength, and accelerated surface reaction.

An interfacial C-S bond bridged ZnS/C3N5 heterojunction was constructed for photocatalytic H2 evolution. Different from traditional type-II ZnS/C3N4 heterojunction, the electron transfer followed S-scheme pathway, due to opposite internal-electric-field (IEF) directions in these two heterojunctions. The C-S bond formation was carefully investigated, and they were susceptive to the preparation temperatures. In photocatalytic reaction, C-S bond was functioned as the "high-speed channel" for electron separation and transfer, and the IEF strength in ZnS/C3N5 was 1.86 × 108 V/m, 2.6 times higher than that in ZnS/C3N4. Moreover, the C-S bond also altered the surface molecular structure of ZnS/C3N5, and hence the surface reaction was accelerated via improving H2O adsorption and activation behaviors. Benefiting from the S-scheme pathway, enhanced IEF strength, and accelerated surface reaction, the photocatalytic H2 production over ZnS/C3N5 reached up to 20.18 mmol/g/h, 3.2 and 2.5 times higher than those of ZnS/C3N4 and ZnS/C3N5-300 without C-S bond.

Preparation of double-yolk egg-like nanoreactor: Enhanced catalytic activity in Fenton-like reaction and insight on confinement effect.

Peroxymonosulfate (PMS)-based Fenton-like reaction is an effective technique for the pollutant degradation, and the Co-based metal organic frameworks displayed the excellent activity for the PMS activation. Nevertheless, how to further improve the catalytic activity, suppress the leaching of toxic cobalt ions, and realize the rapid separation were still challenges for practical application. In this work, a novel solution was proposed: encapsulating Fe3O4 and Prussian blue analogue (PBA) into the polypyrrole (PPy) shell and constructing a "double-yolk egg-like" Fe3O4/PBA@PPy as a nanoreactor. In Fe3O4/PBA@PPy-10, the catalytic performance was remarkably enhanced with the help of confinement effect, and the degradation rate (0.38 L·min·mol-1) was 5.1 times than that of reference Fe3O4/PBA-10 (0.074 L·min·mol-1). In addition, the concentration of leached cobalt ions was reduced to only 0.174 mg/L by the protective function from the PPy shell. Moreover, the nanoreactor could be magnetically separated from the reaction solution due to the encapsulation of Fe3O4 nanospheres, and 84.5% of activity still preserved after the 4th cycle. The main active species involved in Fe3O4/PBA@PPy-10 system was 1O2, while that in reference Fe3O4/PBA-10 system was OH. Electron spin resonance analysis and radical trapping experiment revealed that the different catalytic mechanisms were attributed to the confinement effect inside the hollow cavity. This work not only presents a feasible way to prepare rarely-reported double-yolk egg-like nanoreactor, but also provides a new insight to solve the bottlenecks in Fenton-like reaction.

Partially oxidized MXenes-derived C-TiO2/Ti3C2 coupled with Fe-C3N4 as a ternary Z-scheme heterojunction: Enhanced photothermal and photo-Fenton performance.

Photo-Fenton reaction combining the photocatalytic reaction and Fenton reaction showed excellent degradation performance. However, it highly demanded the catalysts to display outstanding activity in these two reactions. Herein, Fe-doped carbon nitride/MXenes-derived C-TiO2/Ti3C2 (Fe-C3N4/Ti3C2/C-TiO2) was prepared via two steps: Fe-C3N4 and Ti3C2 were assembled via face-to-face attachment, following by in-situ partial oxidation of Ti3C2 to C-TiO2. DFT predicted a Z-scheme charge transfer routine via metallic Ti3C2 as bridge, which was verified by EPR and radical trapping experiments. Additionally, PDOS calculation revealed the charge density around the doped-Fe atoms was remarkably increased, leading to better H2O2 activation, which was experimentally confirmed by high yield of •OH. Moreover, Fe-C3N4/Ti3C2/C-TiO2 possessed the high photothermal effect to accelerate the surface reaction. By taking advantage of these merits, the degradation rate of Fe-C3N4/Ti3C2/C-TiO2 was at least 4.2 times higher than the reference catalysts. Our work provided an insight toward the g-C3N4/TiO2-based photo-Fenton catalysts with high performance.

A simple and green method to prepare non-typical yolk/shell nanoreactor with dual-shells and multiple-cores: Enhanced catalytic activity and stability in Fenton-like reaction.

Nowadays, non-typical yolk/shell structure has drawn much attentions due to the better catalytic performance than traditional counterparts (one yolk/one shell). In this study, ZIF-67 @Co2SiO4/SiO2 yolk/shell structure was prepared in one-step at room temperature, in which ZIF-67 was served as the hard-template, H2O was served as etchant and tetraethyl orthosilicat was served as the raw material for Co2SiO4/SiO2. After calcination, the non-typical CoxOy @Co2SiO4/SiO2 yolk/shell nanoreactor with Co2SiO4/SiO2 dual-shells and CoxOy multiple-cores was obtained. On the one hand, more active sites were exposed on multiple-cores surface and better protection were provided by dual-shells. On the other hand, the sheet-like Co2SiO4 inner shell not only extended the travel path and retention time of pollutants trapped in cavity, but also separated the multiple-cores from aggregation. Therefore, the nanoreactor displayed the outstanding catalytic activity and recyclability in Fenton-like reaction. Metronidazole (20 mg/L) was completely degraded after 30 min, rhodamine B (50 mg/L) and methyl orange (20 mg/L) were removed even within 5.0 min. Catalytic mechanism indicated that 1O2 greatly contributed to the pollutant degradation. This paper presented a simple, versatile, green and energy-saving method for non-typical yolk/shell nanoreactor, and it could inspire to prepare other catalysts with high activity and stability for environmental remediation.

SEAttle-based Research of Chinese Herbs for COVID-19 Study: A Whole Health Perspective on Chinese Herbal Medicine for Symptoms that may be Related to COVID-19.

INTRODUCTION: East Asian Medicine (EAM) is a Whole System medicine that includes Chinese herbal medicine (CHM). Chinese herbal medicine has been utilized to reduce symptom burden in infectious disease, with notable theoretical reformulations during pandemics of the 3rd, 13th, and 17th centuries. Today, Licensed Acupuncturists trained in CHM have utilized it to treat symptoms and sequelae of COVID-19. However, little is known about its use or efficacy by the public and health practitioners. Understanding and evaluating whole medicine systems of healthcare is inherently complex; there is international consensus for a descriptive, pragmatic approach. We are conducting a feasibility pilot study using a prospective, pragmatic, observational design using Whole Health and Whole Person perspectives. The complexity of COVID-19 reflects the impact on multiple homeoregulatory systems and provides a unique opportunity to assess the impact of interventions such as EAM on whole health. Observation of these EAM encounters will provide valuable qualitative and quantitative data on the interface of an extant Whole System medicine with a novel complex illness as a precursor to a randomized clinical trial. METHODS: This ongoing study observes a CHM clinic offering telehealth consultations to a diverse patient population since April, 2020. Patients who report symptoms potentially related to COVID-19 disease are consented for standardized collection and analysis of demographic and clinical data from each clinical encounter. RESULTS: To date, 61 patients engaged in 195 consultations (mean 3.3) with 49 reporting symptom resolution sufficient to complete treatment, and 4 withdrawals. Just over half (62%) were female, with an average age of 45.7 years. A wide variety of CHM formulas and EAM dietary and lifestyle modifications were provided. DISCUSSION: Adequate recruitment and retention suggest feasibility of the intervention and data collection. The rich dataset may facilitate the construction of Whole Health models of CHM's clinical impact, as well as integrative inquiry into CHM's effects on symptoms.

Internal-electric-field induced high efficient type-I heterojunction in photocatalysis-self-Fenton reaction: Enhanced H2O2 yield, utilization efficiency and degradation performance.

Herein, a type-I phosphorus-doped carbon nitride/oxygen-doped carbon nitride (P-C3N4/O-C3N4) heterojunction was designed for photocatalysis-self-Fenton reaction (photocatalytic H2O2 production and following Fenton reaction). In P-C3N4/O-C3N4, the photoinduced charge carriers were effectively separated with the help of internal-electric-field near the interface, ensuring the high catalytic performance. As a result, the production rate of H2O2 in an air-saturated solution was 179 µM·h-1, about 7.2, 2.5, 2.5 and 2.1 times quicker than that on C3N4, P-C3N4, O-C3N4, and phosphorus and oxygen co-doped C3N4, respectively. By taking advantage of the cascade mode in photocatalysis-self-Fenton reaction, H2O2 utilization efficiency was remarkably improved to 77.7%, about 9.0 times higher than that of traditional homogeneous Fenton reaction. Befitting from the superior yield and utilization efficiency, the degradation performance of P-C3N4/O-C3N4 was undoubtedly superior than other photocatalysts. This work well addressed two bottlenecks in traditional Fenton reaction: source of H2O2 and their low utilization efficiency, and the findings were beneficial to understand the mechanism and advantage of the photocatalysis-self-Fenton system in environmental remediation.

A stable lanthanum-based metal-organic framework as fluorescent sensor for detecting TNP and Fe3+ with hyper-sensitivity and ultra-selectivity.

A new Lanthanum-based luminescent metal-organic framework, {[La(H2O)4(HL)]·H2O} (1), has been successfully synthesized by employing 3,3',5,5'-azodioxybenzenetetracarboxylic acid (H4L) as a rigid organic linker through the solvothermal reactions. 1 exhibits a two-dimensional (2D) layered structure and a three-dimensional (3D) supramolecular structure is formed by hydrogen bonds between the layers. Stability studies indicate that 1 has good chemical stability and thermostability. Meanwhile, the Ksv values for TNP is 4.61 × 104 M-1 with the LOD of 4.13 × 10-6 M and the Ksv value for Fe3+ is 1.22 × 104 M-1 with the LOD of 1.72 × 10-5 M, respectively, which demonstrated that 1 exhibits high sensitivity and excellent selectivity for the detection of TNP and Fe3+via fluorescence quenching. Significantly, 1 shows high regenerability after five recycling progress for sensing Fe3+. The possible mechanisms associated with the luminescent quenching are discussed in detail through some relevant experiments and tests, as well as the DFT calculations. Based on the above excellent properties of 1, it will have extremely potential to be used as a dual functional sensor for both detecting TNP and Fe3+ in aqueous solution, simultaneously.

Z-scheme Fe2(MoO4)3/Ag/Ag3PO4 heterojunction with enhanced degradation rate by in-situ generated H2O2: Turning waste (H2O2) into wealth (•OH).

Ag3PO4-based photocatalysts have been deeply studied in environmental remediation; however, two problems limited their further application: photocorrosion and quenching effect by in-situ generated H2O2. To addressed these two questions simultaneously, Fe2(MoO4)3 was coupled with Ag3PO4 to construct Z-scheme Fe2(MoO4)3/Ag/Ag3PO4 heterojunction driven by internal-electric-field. The rhodamine B degradation rate of heterojunction was 254 and 7.0 times higher than those of Fe2(MoO4)3 and Ag3PO4, respectively. The outstanding photoactivity was due to the high visible-light harvest, low interface resistance, high separation efficiency of charge carriers, long lifetime of hole (h+) and electron (e-), well-preserved oxidation potential of h+, and especially photocatalytic produced H2O2 inside the system. The in-situ generated H2O2 was fully activated to be •OH on the Fe2(MoO4)3 surface via a Fenton reaction, leading to the elimination of quenching effect on h+ and e-, and generation of more •OH. Additionally, in Z-scheme heterojunction, e- transferred from Ag3PO4 to Fe2(MoO4)3, avoiding the accumulation on Ag3PO4 surface, and hence suppressing the photocorrosion. As a result, 91.2% of degradation efficiency remained after 5 cycles. This paper provides a new method to simultaneously increase the degradation rate by utilizing the in-situ generated H2O2 and improve the stability of Ag3PO4 via constructing a Z-scheme heterojunction.

MoS2/FeS Nanocomposite Catalyst for Efficient Fenton Reaction.

Nanocomposites containing FeS as catalyst and MoS2 as cocatalyst have been synthesized toward efficient heterogeneous Fenton reaction. The deposition of FeS nanoparticles in situ on the surface of MoS2 nanosheets creates strong contact between the two components and generates a large number of exposed Mo6+ sites and sulfur vacancies, which contribute to the enhanced degradation rate by accelerating Fe3+/Fe2+ cycling and ensuring rapid electron transfer. In addition, the MoS2/FeS nanocomposite catalysts exhibit the best performance at near-neutral conditions (pH 6.5), which solves the challenges in conventional Fenton reactions such as leaching of metal ions, the formation of iron slurry, and the need of adjusting solution pH. Further, the nanocomposite can maintain high efficiency after many recycling experiments. It is believed that the MoS2/FeS nanocomposite represents an efficient heterogeneous Fenton catalyst that can greatly promote the performance of advanced oxidation processes (AOPs) for solving practical environmental issues.

Transforming type-II Fe2O3@polypyrrole to Z-scheme Fe2O3@polypyrrole/Prussian blue via Prussian blue as bridge: Enhanced activity in photo-Fenton reaction and mechanism insight.

Photo-Fenton reaction is a more effective technique for pollutant disposal than photocatalytic reaction. Herein, Fe2O3@polypyrrole/Prussian blue (Fe2O3@PPy/PB) with a hierarchical porous structure was prepared by a reactive-template method. After transforming typical type-II Fe2O3@PPy to Z-scheme Fe2O3@PPy/PB via PB as a bridge, the degradation rate was increased by 1.4 times in photocatalytic reaction and 4.0 times in photo-Fenton reaction due to higher visible-light harvest, enhanced separation efficiency of photoinduced charges, lower interface resistance, and especially well-preserved redox potentials of holes and electrons. Mechanism studies revealed that holes were quenched by H2O2, and this led to •O2- generation and efficient separation of electrons. Meanwhile, O2 was reduced by separated electrons, and this further increased •O2- yield. Therefore, the main radicals changed from hole in photocatalytic reaction to •O2- in the photo-Fenton reaction, leading to an increase as high as 12.1-fold enhancement in the degradation rate. Conversely, only H2O2 participated into photocatalytic reaction using Fe2O3@PPy while O2 was absent, resulting in merely 4.2-fold improvement. This manuscript gives a comprehensive understanding on mechanisms of type-II and Z-scheme heterojunctions in both photocatalytic and photo-Fenton reactions. Obviously, the outcomes are beneficial for designing catalysts with high photo-Fenton activity.

Construction of phosphorus-doped carbon nitride/phosphorus and sulfur co-doped carbon nitride isotype heterojunction and their enhanced photoactivity.

Photocatalysis was one of the most promising techniques for environmental remediation. Exploring photocatalysts with high efficiency, low cost and easy preparation was still an ongoing issue. In this work, phosphorus-doped carbon nitride/phosphorus and sulfur co-doped carbon nitride (P-C3N4/PS-C3N4) isotype heterojunction was prepared by a two-step calcination method. The composite displayed a sheet-like structure with a surface area of 23 m2/g. Compared with pure C3N4, band gaps of P-C3N4 and PS-C3N4 were only slightly modified during the heteroatom-doping process. Therefore, a well-matched band alignment was constructed, which not only improved the separation efficiency of photogenerated electron-hole pairs, but also well preserved the high oxidizability of holes on valance band and good reducibility of electrons on conduction band. Because of the similarity in physicochemical properties, the interface resistance between P-C3N4 and PS-C3N4 was low, which accelerated the electron transfer and prolonged the lifetime of charge carriers. Although the visible-light utilization was somewhat low in comparison with P-C3N4 and PS-C3N4, by taking advantage of above merits, P-C3N4/PS-C3N4 displayed the high photocatalytic activity in rhodamine B degradation, and the reaction rate constant was 0.183 min-1, about 8.7 and 4.0 times higher than those of P-C3N4 and PS-C3N4. Besides high catalytic activity, isotype heterojunction displayed good recyclability, since 95.3% of catalytic activity was maintained after the 5th cycle. The method presented here was facile, economic and environmentally benign, thus it was highly attractive for the application in environmental remediation.