Oxygen-rich Functional Groups Research Articles

Pre-Oxidation-Tuned Oxygen and Nitrogen Species of Porous Carbon as an Advanced Electrocatalyst of the Oxygen Reduction Reaction for Flow Zn–Air Batteries

The co-engineering of defects and N doping is highly important for the development of advanced metal-free carbon-based electrocatalysts for the oxygen reduction reaction (ORR). It remains a great challenge to efficiently tune the doped nitrogen species, and the role of oxygen species is often overlooked. Here, a facile strategy is developed for fabricating three-dimensional oxygen and nitrogen codoped porous carbon (ONPC) via air pre-oxidation, followed by carbonization. The optimal catalyst, i.e., ONPC-300, mainly contains pyridinic N and graphitic N species with oxygen-rich functional (ketone C═O) groups and has an enhanced specific surface area, superhydrophilic surface structure, and abundant defect sites for ORR, which endows it with excellent ORR performance, as evidenced by a half-wave potential of 0.862 V and high long-term stability over 100 h in an alkaline medium. Density functional theory (DFT) calculations reveal that ketone C═O groups can optimize the adsorption energy of intermediates and decrease the energy barrier for the rate-determining steps, thus promoting the ORR activity. A flow Zn–air battery using ONPC-300 as the cathode shows outstanding performance, including a remarkable peak power density of 258.5 mW cm–2, high discharge stability over 180 h, and an ultralong cycle life exceeding 800 h.

Regulation of Electrocatalytic Behavior by Axial Oxygen Enhances the Catalytic Activity of CoN4 Sites for CO2 Reduction.

Recent studies have found that the existence of oxygen around the active sites may be essential for efficient electrochemical CO2 -to-CO conversion. Hence, this work proposes the modulation of oxygen coordination and investigates the as-induced catalytic behavior in CO2 RR. It designs and synthesizes conjugated phthalocyanine frameworks catalysts (CPF-Co) with abundant CoN4 centers as an active source, and subsequently modifies the electronic structure of CPF-Co by introducing graphene oxide (GO) with oxygen-rich functional groups. A systematic study reveals that the axial coordination between oxygen and the catalytic sites could form an optimized O-CoN4 structure to break the electron distribution symmetry of Co, thus reducing the energy barrier to the activation of CO2 to COOH*. Meanwhile, by adjusting the content of oxygen, the proper supports can also facilitate the charge transfer efficiency between the matrix layer and the catalytic sites. The optimized CPF-Co@LGO exhibits a high TOF value (2.81 s-1 ), CO selectivity (97.6%) as well as stability (24h) at 21mAcm-2 current density. This work reveals the modulation of oxygen during CO2 RR and provides a novel strategy for the design of efficient electrocatalysts, which may inspire new exploration and principles for CO2 RR.

Tailoring the transesterification activity of MgO/oxidized g-C3N4 nanocatalyst for conversion of waste cooking oil into biodiesel

As a prospective heterogeneous catalyst for transesterification, magnesium oxide (MgO) has long been regarded as a possible candidate. Pure MgO, on the other hand, has a narrow range of applications because of its small surface area and short catalytic lifetime. To overcome these problems, in this work, graphitic carbon nitride (g-C3N4) with higher oxygen doping levels was applied to construct a noteworthy, persistent, and carbon-modified MgO catalyst. The molar ratios of urea to melamine and the mass ratios of oxidized g-C3N4 to MgO in the preparation step are two effective parameters, which were optimized with the Response Surface Methodology (RSM). The significant increase in oil conversion was attained by incorporating O@g-C3N4 nanoparticles composed of urea to melamine at a molar ratio of 2:1 in MgO at a mass percentage of 16.7. O@g-C3N4 had an outstanding effect on the immobilization of oxygen-rich functional groups on the MgO-based catalyst and an increase in the surface area. Also, the effects of transesterification parameters and their interactions on oil conversion were explored using the RSM, and then reusability tests were carried out using the fine-tuned parameters. The prepared catalysts were characterized using a variety of methods, including Field-Emission Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (FESEM-EDS), Fourier Transform Infrared (FTIR) spectroscopy, Temperature Programmed Desorption of CO2 (CO2-TPD), Brunauer-Emmett-Teller (BET) analysis, and powder X-Ray diffraction, in order to determine their basicity, morphology, and composition. The optimum biodiesel yield of 98.80% was attained at 99.6 °C for 133 min with a catalyst quantity of 5.9 wt% and a methanol to oil molar ratio of 14.6. The stability and lifespan of the as-optimized catalyst (OCN2MgO(0.2)) were confirmed over four consecutive cycles. It can be concluded that this solid catalyst could be used to convert low-cost waste cooking oil into biodiesel in a single step.

Selective laser sintering of functionalized carbon nanotubes and inorganic fullerene-like tungsten disulfide reinforced polyamide 12 nanocomposites with excellent fire safety and mechanical properties

More effective and safe fire prevention solutions for polymer derivatives are necessary to address rising environmental and health concerns. In this study, the novel and simple chemically modified multi-walled carbon nanotubes (H-CNT) and PEGylated inorganic fullerene tungsten sulphide (P-IF-WS2) reinforced PA12 nanocomposites are synergistically prepared via selective laser sintering (SLS). The PA12/H-CNT/IF-WS2 nanocomposites show a wider sintering window than blank PA12. The formed hydrogen bond network of inter-chain contacts and compatibility in PA12/H-CNT/P-IF-WS2 matrix is proved. Furthermore, a dense carbon layer is developed by further dehydrating the oxygen-rich functional groups on the surface of H-CNT and P-IF-WS2 during carbonization at high temperatures. The PA12/H-CNT/P-IF-WS2 nanocomposites fabricated by incorporating hydrogen and carbon bonds in the PA12-based nanocomposites demonstrate good fire safety, thermal, and mechanical properties. The significant reduction in total heat release (20.14%), peak heat release (38.9%), and total smoke emission (22.6%) showed the improved fire safety of PA12. The H-CNT and P-IF-WS2 nanofillers also enhanced the mechanical (tensile and dynamic mechanical) capabilities. This technique of introducing nano-additives to SLS samples changes offers a practical, long-lasting, and effective way to improve the flame retardancy of laser-sintered polymer nanocomposites.

Novel Fe/N co-doping biochar based electro-Fenton catalytic membrane enabling enhanced tetracycline removal and self-cleaning performance

Designing a highly-active electro-Fenton (EF) catalytic membrane without the additional chemicals and iron sludge formation was a challenge for antibiotics treatment. In this study, we constructed Fe/N co-doping biochar (Fe-g-C3N4/biochar) based ultrafiltration membranes for degradation of tetracycline (a common antibiotic) and membrane fouling control under electro-assistance. The results showed that membranes presented high electro-Fenton catalytic activity because the presence of rich oxygen functional groups (high C–O/CO ratio) and nitrogen species (pyridinic N and pyrrolic N) promoted H2O2 generation and accelerated Fe(III)/Fe(II) cycle. Moreover, H3PO4 activation of biochar endowed the EF catalytic membrane with higher electrocatalytic activity, while it was opposite using biochar with higher pyrolysis temperature (600–700 °C). In particular, owing to the oxidative degradation by electro-generated •OH and •O2−, Fe-g-C3N4/ABC-600/Graphite/PVDF (600 represented the pyrolysis temperature) membrane presented 100% tetracycline removal within 0.749 min of residence time, excellent self-cleaning performance (flux recovery = 100%) at neutral pH and low energy consumption (0.199 W h/L) for the reclamation of synthetic municipal wastewater effluent. In addition, membrane self-cleaning mechanism was closely related to the synergy between partial mineralization and reduced fouling potential of foulants. Besides, the EF membrane also exhibited good reusability and stability, which was promising to apply in antibiotics removal.

Physicochemical Properties of UV-Irradiated, Biaxially Oriented PLA Tubular Scaffolds

PLA and its blends are the most extensively used materials for various biomedical applications such as scaffolds, implants, and other medical devices. The most extensively used method for tubular scaffold fabrication is by using the extrusion process. However, PLA scaffolds show limitations such as low mechanical strength as compared to metallic scaffolds and inferior bioactivities, limiting their clinical application. Thus, in order to improve the mechanical properties of tubular scaffolds, they were biaxially expanded, wherein the bioactivity can be improved by surface modifications using UV treatment. However, detailed studies are needed to study the effect of UV irradiation on the surface properties of biaxially expanded scaffolds. In this work, tubular scaffolds were fabricated using a novel single-step biaxial expansion process, and the surface properties of the tubular scaffolds after different durations of UV irradiation were evaluated. The results show that changes in the surface wettability of scaffolds were observed after 2 min of UV exposure, and wettability increased with the increased duration of UV exposure. FTIR and XPS results were in conjunction and showed the formation of oxygen-rich functional groups with the increased UV irradiation of the surface. AFM showed increased surface roughness with the increase in UV duration. However, it was observed that scaffold crystallinity first increased and then decreased with the UV exposure. This study provides a new and detailed insight into the surface modification of the PLA scaffolds using UV exposure.

One stone two birds: Pitch assisted microcrystalline regulation and defect engineering in coal-based carbon anodes for sodium-ion batteries

Coal-based carbons with abundant resources and low cost are regarded as promising anode materials for sodium‐ion batteries (SIBs). However, their ordered carbon microstructure and abundant surface defects often result in low Na-storage capacity and poor initial coulombic efficiency (ICE). Herein, we propose a simple vapor deposition strategy to synthesize coal-based carbons coated with pitch-based soft carbon layer (PCLC) for potential use as anodes for SIBs. The deposition of pitch-based volatile species allows for an efficient cross-linking reaction between hydroxyl‑containing volatile species and oxygen-rich functional groups of coal, thus generating a disordered inner-phase microcrystalline structure with dominant pseudo-graphitic phase in coal-derived carbon. Meanwhile, the exterior soft carbon coating layer substantially reduces surface defects and increases the electrical conductivity of coal-based carbon. Unlike the pristine lignite coal pyrolytic carbon which exhibited a Na-storage capacity of 290.2 mAh g−1 and ICE of 59.9%, the optimal PCLC (PCLC-1) delivered a higher reversible capacity of 312.2 mAh g−1 and a much-improved ICE of 85.3%. In addition, the PCLC-1 electrode also demonstrated excellent cycle stability with 93.4% retention after 1,000 cycles. When coupled with O3-NaNi1/3Fe1/3Mn1/3O2 cathode, PCLC-1 as an anode in a full cell configuration achieved a high energy density of 220.9 Wh kg−1 with excellent cycling and rate performance. The proposed work offers a unique insight into modulating the microcrystalline structure and surface chemistry of high-performance coal-based carbon anode materials for commercial SIBs.

A facile approach for the synthesis of ceramic filters for methyl orange, chromium and lead removal from water

The provision of safe drinking water is still a challenge in rural communities of low-income countries, partly due to the high cost of modern filtration systems. As a result, people often collect and use water without treatment, thereby compromising their health. Readily available material and waste products may provide a solution for drinking water challenges. Therefore, this study investigated the application of optimized ceramic filters for the removal of methyl orange, lead and chromium from water. The filter properties were fine-tuned by optimizing the compression pressure and content of macadamia nutshell (used as porogen) to obtain satisfactory flow rates and high pollutant removal. The raw material and resultant filters were characterized for chemical composition as well as filtration properties using various techniques. The best-performing filter had a flux of 289 L/m2h and removed methyl orange (40%), turbidity (95–98%), chromium (III) (40%) and lead (II) (71%). Improvement in filtration performance was attributed to an increase in filter porosity and hydrophilicity due to the presence of oxygen-rich functional groups. The proposed filter fabrication method is environmentally friendly, facile, cost-effective, less time-consuming and does not require expertise to reproduce. The performance of the filters is comparable to other filters reported in the literature and they are easy to maintain and are reusable.

Insights of the adsorption mechanism of ketamine on 3D hierarchically porous carbon: Characterization, experiment and simulation calculation

Psychoactive substances can irreversibly harm human health and threaten ecologic environment after entering the environment. 3D hierarchically porous carbon obtained from magnetic biochar/metal–organic framework (MBC/MOF) has been successfully prepared by changing ZIF-8 and waste biomass ratio. Comprehensive characterization results before and after ketamine adsorption showed the possible adsorption mechanisms including chelation, π-π, H-bond interaction and pore filling. Batch experiments have proved chemical and physical adsorption coexist, in which chemisorption was dominant. π-π interaction and H-bond interaction were confirmed by the humic acid and pH experiments, respectively. Further analysis of Molecular Dynamics simulations indicated that the chelation was stronger than the π-π interaction and H-bond interaction. Specifically, the Zn of ZIF-8 in MBC/MOF acted as a chelating site, the π-π interaction occurred between the graphene-like structure of MBC and the benzene ring of ketamine, the hydrogen bonding interaction was found between the oxygen-rich functional groups of MBC/MOF and the oxygen atoms of ketamine (OH···O). Anion, cation, leaching and cycle experiments indicated the MBC/MOF had outstanding anti-interference ability, high reusability, excellent stability and safety. These findings will broaden the applications of metal organic framework and magnetic biochar in the field of pollutants adsorption.

Hydrothermally etching commercial carbon cloth to form a porous structure for flexible zinc-ion hybrid supercapacitors

A novel modification method of hydrothermal treatment in acidic potassium chlorate solution is proposed here to etch directly the commercial carbon cloth (CC) surface to produce a porous structure with oxygen-rich functional groups and a large specific surface area (OCC). Following that, an in-situ polypyrrole coating is deposited on OCC (PPy@OCC) to improve conductivity and electrochemical stability. The assembled zinc-ion hybrid supercapacitors (Zn-HSCs) used the PPy@OCC sample as the cathode and Zn foil as the anode, and they demonstrated excellent electrochemical properties. The device has a capacity retention of 92 % after 10,000 cycles at a current density of 20 mA cm−2 and an area capacity of up to 4.74 mAh cm−2 at a current density of 0.5 mA cm−2. It also has a high surface energy density of 4740 Wh cm−2 and a high peak surface power density of 20.23 mW cm−2. When the Zn foil is replaced as the anode to flexible Zn-HSCs by electrodeposited Zn on CC (Zn@CC), the remarkable volume energy density (27.22 mWh cm−3) and flexibility are demonstrated, implying that the prepared PPy@OCC is an ideal electrode for high-performance flexible Zn-HSCs.

Ecofriendly surface modification of cotton fabric to enhance the adhesion of CuO nanoparticles for antibacterial activity

ABSTRACT The present study employs a facile and environmentally cleaner plasma technology to induce adhesion between the cotton fabric and CuO nanoparticles. The oxygen plasma pre-treatment of cotton fabric was performed using DC glow discharge plasma for different plasma treatment times (5, 10 and 15 min) with constant pressure and power. The untreated and plasma treated cotton fabrics were analysed by contact angle, AFM, XPS, XRD, FESEM and elemental mapping analysis. From the AFM results, it is observed that the surface roughness of treated fabric increases with plasma treatment time. XPS analysis reveals that the oxygen plasma treatment introduces oxygen-rich functional groups on the surface which provides the adhesion property of cotton fabric. The 15 min oxygen plasma treated cotton fabric is optimised to coat the CuO nanoparticles based on the AFM and XPS analyses. Furthermore, the CuO nanoparticles coated plasma treated cotton fabric are analysed for antibacterial test and a significant antibacterial activity was identified for gram-positive and gram-negative bacteria.

Fenton oxidation of biochar improves retention of cattle slurry nitrogen.

Nitrogen (N) losses during fertilization with livestock slurry, mainly in the form of ammonia (NH3 ), can cause environmental problems and reduce fertilizer efficiency. Leonardite, which is characterized by oxygen-rich functional groups and low pH, has been found to decrease losses of slurry N. However, leonardite, as a byproduct of open-cast lignite mining, is not a renewable resource. The objective of this study was to modify biochar by chemical surface oxidation in order to find a sustainable but similarly effective substitute for leonardite. Biochar was produced from spruce sawdust in a pyrolysis oven at a maximum temperature of 610°C. Then the biochar was oxidized using the Fenton reaction, with a ratio of Fe2+ /H2 O2 of 1:1,000, as a source of highly reactive HO· radicals to introduce oxygen-rich functional groups to the biochar surface. The ammonium (NH4 + ) adsorption capacity of biochar, oxidized biochar, and leonardite was tested in ammonium sulfate [(NH4 )2 SO4 ] solution, pH-adjusted (NH4 )2 SO4 solution, and cattle slurry. The results showed that biochar had the highest total NH4 + adsorption of 1.4mg N g-1 in (NH4 )2 SO4 solution, whereas oxidized biochar had the highest reversible NH4 + adsorption of 0.8mg N g-1 . In the pH-adjusted ammonium solution, all materials reduced NH3 emissions by ≥90%, and oxidized biochar reduced NH3 emissions by 99.99%. In contrast, leonardite reduced NH3 emissions the most in cattle slurry, and oxidation of biochar increased the reduction in NH3 emissions from 22 to 67% compared with non-oxidized biochar. In conclusion, biochar oxidized by means of the Fenton reaction greatly decreased NH3 emissions by increased adsorption of NH4 + in cattle slurry compared with non-oxidized biochar, indicating the great potential of oxidized biochar for reducing N losses during slurry application.

Laser-derived porous carbon as a metal-free electrocatalyst for oxygen evolution reaction

We introduce a metal-free, high-surface-area N-containing carbon material prepared via single-step laser-induced carbonization of polyimide films as an electrocatalyst for oxygen evolution reaction (OER), which obviates the need for a loading substrate. Our inexpensive and scalable one-step fabrication process yields porous carbon films with a high atomic ratio of pyridinic and pyrrolic N functional groups. The material is activated by inducing additional oxygen-rich functional groups, resulting in more electrochemically active sites and less charge transfer resistance for superior electrocatalytic performance. The activated laser-carbon exhibits an excellent catalytic activity towards OER with an overpotential of 470 mV at a current density of 10 mA cm−2, which is much lower compared to other metal-free electrocatalysts. This multifunctional carbon material has an immense potential for the fabrication of lightweight water electrolyzers as well as in the designing of electrode for flexible solid-state metal-air batteries.

Carbon dots derived from frankincense soot for ratiometric and colorimetric detection of lead (II)

We report a simple one-pot hydrothermal synthesis of carbon dots from frankincense soot. Carbon dots prepared from frankincense (FI-CDs) have narrow size distribution with an average size of 1.80 nm. FI-CDs emit intense blue fluorescence without additional surface functionalization or modification. A negative surface charge was observed for FI-CDs, indicating the abundance of epoxy, carboxylic acid, and hydroxyl functionalities that accounts for their stability. A theoretical investigation of the FI-CDs attached to oxygen-rich functional groups is incorporated in this study. The characteristics of FI-CDs signify arm-chair orientation, which is confirmed by comparing the indirect bandgap of FI-CDs with the bandgap obtained from Tauc plots. Also, we demonstrate that the FI-CDs are promising fluoroprobes for the ratiometric detection of Pb2+ ions (detection limit of 0.12 μM). The addition of Pb2+ to FI-CD solution quenched the fluorescence intensity, which is observable under illumination by UV light LED chips. We demonstrate a smartphone-assisted quantification of the fluorescence intensity change providing an efficient strategy for the colorimetric sensing of Pb2+ in real-life samples.

Iron-tungsten oxides modified oxygen-rich carbon nitride with defects S-scheme heterojunction for boosting photo-Fenton like removal of pollutants

Owning to excellence of photocatalytic persulfate (PS)-based oxidation processes in pollutant removal, the iron-tungsten oxides modified oxygen-rich carbon nitride with defects (ITOs/OCNv) S-scheme heterojunction composites were successfully prepared, and the photo-Fenton like system (Vis/ITOs/OCNv/PS) was constructed to degrade antibiotic pollutants. Results indicated that the ITOs/OCNv composites exhibited large specific surface area and rich porous structure. In addition, the in-situ introduction of oxygen-rich functional groups and lots of N and O vacancy defects in the composites enhanced the absorption of visible light (Vis) and the electron transfer. Importantly, the formed S-scheme heterojunction improved the separation of photogenerated carriers. The degradation efficiencies of sulfamethazine (SMZ) and ciprofloxacin (CIP) in the optimal Vis/5% ITOs/OCNv/PS system were 99.6 % and 99.5 %, which were 1.69 and 2.34 times that of Vis/5% ITOs/OCNv system (SMZ 58.9 % and CIP 42.6 %) after 40 min, respectively. Results of quenching experiments showed that the main active species were h+, 1O2 and O2− for SMZ and CIP degradation. Moreover, this system exhibited better anti-interference of water substrates and applicability in actual water body. The degradation pathways of CIP were proposed by combining density functional theory calculation with intermediate analysis. Moreover, the ecotoxicities of CIP and its products were evaluated comprehensively. The system showed better broad-spectrum degradation of pollutants, including sulfamethoxazole, atrazine, sulfadimethoxine and bisphenol A, which would provide a new insight for persistent pollutant removal.

Reversible Oxygen-Rich Functional Groups Grafted 3D Honeycomb-Like Carbon Anode for Super-Long Potassium Ion Batteries

Studies have found that oxygen-rich-containing functional groups in carbon-based materials can be used as active sites for the storage performance of K+, but the basic storage mechanism is still unclear. Herein, we construct and optimize 3D honeycomb-like carbon grafted with plentiful COOH/C = O functional groups (OFGC) as anodes for potassium ion batteries. The OFGC electrode with steady structure and rich functional groups can effectively contribute to the capacity enhancement and the formation of stable solid electrolyte interphase (SEI) film, achieving a high reversible capacity of 230 mAh g−1 at 3000 mA g−1 after 10,000 cycles (almost no capacity decay) and an ultra-long cycle time over 18 months at 100 mA g−1. The study results revealed the reversible storage mechanism between K+ and COOH/C = O functional groups by forming C-O-K compounds. Meanwhile, the in situ electrochemical impedance spectroscopy proved the highly reversible and rapid de/intercalation kinetics of K+ in the OFGC electrode, and the growth process of SEI films. In particular, the full cells assembled by Prussian blue cathode exhibit a high energy density of 113 Wh kg−1 after 800 cycles (calculated by the total mass of anode and cathode), and get the light-emitting diodes lamp and ear thermometer running.

A widely applicable method to stabilize nanoparticles comprising oxygen-rich functional groups

Colloidal stability of nanoparticle suspensions is fundamental to apply nanomaterials in functional devices and to develop new methodologies in nanoscience. Herein, a versatile method is described to disperse and stabilize various solids with technological applications in pharmaceutical industry, batteries and fuel cells, dye sensitized solar cells, pigments and coatings. The method is based on the use of Zr(IV) hydroxo-complexes that interact with carboxylic- and hydroxo- functional groups at the solid-liquid interfaces of active pharmaceutical ingredients (API), carbon black (CB) and Pt-CB, metal oxide and metal oxy-hydroxide nanoparticles. The colloidal stability is assessed via sedimentation analysis, electrophoretic measurements, ultraviolet-visible spectroscopy (UV–Vis), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and isothermal titration calorimetry (ITC). The effect of the anion and pH are studied in depth. Finally, the current work enables liquid phase length and diameter characterization of rod-like goethite (α-FeOOH) particles without relying on tedius counting the particles from electron micrographs.

Room temperature NH3 sensing properties and humidity influence of Ti3C2Tx and Ag-Ti3C2Tx in an oxygen-free environment

Ti3C2Tx is a new two-dimensional material with attractive characteristics, but the disadvantage of easy oxidation hinders its practical application. In this paper, single/few-layer Ti3C2Tx (ST) and multilayer Ti3C2Tx (MT) are fabricated from severely oxidized Ti3C2Tx by TMAOH intercalation. Simultaneously most TiO2 nanoparticles are removed. This is a useful path to fabricate Ti3C2Tx with oxygen-rich functional groups by reusing the oxidized Ti3C2Tx. Ag-loaded Ti3C2Tx (AgT) is then successfully synthesized by the self-reduction of AgNO3 on MT. The morphology, surface functional groups, oxidation degree, and oxidation derived defects are characterized by XRD, SEM, TEM, XPS, and FTIR. The gas sensing test results illustrate that MT and AgT are more sensitive to NH3 than ST. These sensors perform best in 40% RH N2 and worst in dry N2, significantly related to humidity. In comparison, AgT exhibits the best humidity resistance due to its minor response degradation from 40% RH N2 to dry N2. The DFT calculation results reveal that with pre-adsorbed H2O, the adsorption capacity of Ti3C2O2 and Ag-Ti3C2O2 for NH3 is considerably enhanced. In the absence of H2O, the adsorption of NH3 by Ag-Ti3C2O2 is much more effective than that of Ti3C2O2, indicating that Ag-Ti3C2O2’s response decays less with humidity changes. The enhanced scattering of carriers by the Ti atom at the adsorption site on the Ti3C2O2 surface also contributes to the gas sensing performance. These simulation results are consistent with the experimental results. In addition, the formation of heterojunction between Ag and Ti3C2Tx is beneficial to improving its gas-sensing response to NH3.

Sustainable and efficient removal of paraben, oxytetracycline and metronidazole using magnetic porous biochar composite prepared by one step pyrolysis

Pharmaceuticals and personal care products (PPCPs) have recently become a cause of growing concern due to their persistence in the human body and in the ecosystem. Therefore, it is important to develop a material with high adsorption capacity in order to effectively remove them. In the present study, magnetic porous biochar (MAGB) obtained from a biomass garlic skin was prepared through a one-step magnetization pyrolysis and was examined via SEM, XRD, Raman, XPS, TG, VSM, and N2 adsorption–desorption analysis. MAGB presents many advantages, such as a high specific surface area, good ferromagnetic properties, and oxygen-rich functional groups. The capacities of MAGB to adsorb paraben, metronidazole, and oxytetracycline have been reported at 415, 287, and 822 mg g−1, respectively, which are more effective than the values recorded for most other adsorbents. Furthermore, MAGB presents a good adsorption capacity after three cycles. The removal mechanisms of PPCPs onto MAGB are attributable to pore adsorption, hydrogen bonding, π-π stacking action, and electrostatic effects. This study demonstrates the applicability of MAGB as a reliable adsorbent, which holds a great potential for the removal of PPCPs from aquatic environments.

Bridge the activity and durability of Ruthenium for hydrogen evolution reaction with the Ru O C link

• In-situ reduced graphene oxide supported Ru nanoparticles is synthesized. • A stable Ru O C interface is established by a simple annealing strategy at 700 ℃. • The introduction of oxygen leads to the electron-deficient of Ru NPs. • The catalyst shows high activity and stability for the hydrogen evolution reaction. Exploring efficient and robust electrocatalysts with low cost for hydrogen evolution reaction (HER) is critical for the practical application of electrochemical water splitting. Ruthenium (Ru)-based catalysts exhibit great potential in HER, whereas the extensive application is largely hampered by the insufficient performance and durability at current stage. In addition, understanding and revealing the activity enhancement mechanism of Ru-based catalysts is still very tempting while challenging. Herein, we use the oxygen-rich functional groups of graphene oxide (GO) to adsorb Ru species and in situ generate reduced graphene oxide supported Ru nanoparticles (NPs) catalysts by annealing (Ru/rGO-700). Ru/rGO-700 exhibits low overpotential of 26 mV at 10 mA cm −2 in alkaline electrolytes, and simultaneously the strong interaction induced by the Ru-O bond between the support and the anchored Ru NPs endows the catalyst a desirable stability, thus the activity of the catalysts barely decays after 50,000 cycles of durability testing. Density functional theory (DFT) calculations demonstrate that the introduction of anionic oxygen leads to the electron-deficient characteristics of Ru NPs, which weakens the Ru-H affinity and accelerates/ or favors water dissociation and hydrogen desorption. In addition, the integrated crystal orbital Hamilton population (ICOHP) confirms that the introduction of electron holes weakens the antibonding interactions between Ru atoms, thus the stability of the catalysts is greatly improved.