Charge Transfer Rate Research Articles

The Influence of Oxidized Imino-Allantoin in the Presence of OXOG on Double Helix Charge Transfer: A Theoretical Approach.

The genome is continuously exposed to a variety of harmful factors that result in a significant amount of DNA damage. This article examines the influence of a multi-damage site containing oxidized imino-allantoin (OXIa) and 7,8-dihydro-8-oxo-2'-deoxyguanosine (OXOdG) on the spatial geometry, electronic properties, and ds-DNA charge transfer. The ground stage of a d[A1OXIa2A3OXOG4A5]*d[T5C4T3C2T1] structure was obtained at the M06-2X/6-D95**//M06-2X/sto-3G level of theory in the condensed phase, with the energies obtained at the M06-2X/6-31++G** level. The non-equilibrated and equilibrated solvent-solute interactions were also considered. Theoretical studies reveal that the radical cation prefers to settle on the OXOG moiety, irrespective of the presence of OXIa in a ds-oligo. The lowest vertical and adiabatic ionization potential values were found for the OXOG:::C base pair (5.94 and 5.52 [eV], respectively). Conversely, the highest vertical and adiabatic electron affinity was assigned for OXIaC as follows: 3.15 and 3.49 [eV]. The charge transfers were analyzed according to Marcus' theory. The highest value of charge transfer rate constant for hole and excess electron migration was found for the process towards the OXOGC moiety. Surprisingly, the values obtained for the driving force and activation energy of electro-transfer towards OXIa2C4 located this process in the Marcus inverted region, which is thermodynamically unfavorable. Therefore, the presence of OXIa can slow down the recognition and removal processes of other DNA lesions. However, with regard to anticancer therapy (radio/chemo), the presence of OXIa in the structure of clustered DNA damage can result in improved cancer treatment outcomes.

Polydopamine-Anchored Cellulose Nanofiber Flexible Aerogel with High Charge Transfer as a Substrate for Conductive Materials.

In order to obtain a flexible aerogel substrate for conductive materials used in the electrode, polydopamine-anchored cellulose nanofiber (PDA@CNF) was introduced into a polyethylene imine-poly(vinyl alcohol) (PEI-PVA) cross-linking network which used 4-formylphenylboronic acid (4FPBA) as bridge. The incorporation of rigid CNF as a structural scaffold effectively improved the pore architecture of the aerogel, potentially providing substantial advantages for the infiltration and deposition of conductive materials. Additionally, the outstanding stability and flexibility exhibited by the aerogel in aqueous solutions suggest its significant potential for applications in flexible electrodes. Furthermore, electrochemical experiments showed that the rapid pathway formed between PDA and PEI could enhance the charge-transfer rate within the aerogel substrate. It is anticipated that such an enhancement would significantly benefit the electrochemical attributes of the electrode. Inspired by mussels, our introduced PDA-anchored rigid CNF into flexible polymer networks to fabricate aerogel substrates for electrode materials. This study would contribute to the development and utilization of flexible electrodes while reducing carbon footprint in energy production and conversion processes.

Ti2NTx MXene/rGO nanocomposites: Optical tunning, functional bonding and electrochemical analysis for supercapacitor electrode application

Ti2NTx MXene/rGO nanocomposites were prepared via a two-step chemical etching and reduction method. TEM confirmed the stacked multilayer structure with an average interplanar spacing of 0.2 nm and the formation of Ti2NTx/rGO QDs of size from 0.14 to 0.33 nm. The absorption of Ti2NTx MXene/rGO composites decreased from 5.59 to 4.53 eV with increasing rGO concentration due to quantum confinement and microstructural rearrangement of Ti2NTx MXene within the rGO network. Cyclic voltammetry showed a specific capacitance (Cp) of 47.6–247F/g at 5 mV/s in −0.2–0.8 V. Galvanostatic charge–discharge resulted in Cp of 329.14–1203.86F/g at 1 A/g in 1 M H2SO4. The highest capacitive retention of 84.3 % was observed after 5000 cycles for Ti2NTx MXene. Electrochemical impedance spectra revealed that the charge transfer rate was maximum in (Ti2NTx)0.50/rGO0.50 due to the lowest RCT of 7.23 Ω. From the corrosion test, the Icorr ranged from 3.73 to 5.79 µA, and the Vcorr ranged from −0.008 to 0.26 V in the Ti2NTx MXene/rGO composites. Ti2NTx MXene/rGO composite showed remarkable electrochemical properties in acid electrolytes, such as high Cp and corrosion resistance, making them intriguing materials for supercapacitor electrode application.

Synthesis by design and application to desalination of VO2/CTAB-Ti3C2 capacitive deionization electrode

As an emerging technology in capacitive deionization (CDI), flow-electrode capacitive deionization (FCDI) has attracted much attention due to its unlimited electrosorption capacity and continuous operation. Like CDI, carbon is generally chosen as the electrode material for FCDI at this stage, but conventional carbon materials have limited desalination capacity due to the double electric layer. The two-dimensional layered material MXene has been gradually applied to CDI due to its unique structure and physicochemical properties. However, the van der Waals forces exist between the MXene layers, and the layered structure of MXene is susceptible to stacking, while exhibiting an obvious swelling behavior in aqueous solution, thus affecting its desalination performance. Herein, we report a designed VO2/CTAB-Ti3C2 heterostructure synthesised by a simple hydrothermal method. The addition of VO2 can alleviate the lamellar structure buildup of Ti3C2 and improve the desalination performance of Ti3C2. On the other hand, Ti3C2 can be used as a conductive substrate for VO2, which improves the charge transfer rate of VO2, prevents VO2 agglomeration, and provides more contact surfaces for ion intercalation. Compared with the pure VO2 and Ti3C2 electrodes, the composite electrode has a good desalination performance, and its desalination reaches 1041.5 mg g−1 at 1.2 V. Therefore, this VO2/CTAB-Ti3C2 hybrid material is expected to be used as an electrode material for flow capacitive deionization.

Ni nanoparticles embedded in multi-channel carbon nanofibers: Self-supporting electrodes for bifunctional catalysis of hydrogen and oxygen evolution reactions

Nitrogen-doped carbon nanofibers with multi-channels loaded with nanoscale nickel particles (Ni-MNCNF) were achieved by the combination of coaxial electrospinning and pyrolysis. Which was used as a self-supporting electrode for electrochemical hydrogen and oxygen evolution reactions. The multi-channels of the fiber facilitated the fast mass transfer as well as endowed it with more exposed active sites. In addition, nanoscale Ni crystals were dispersed evenly on the fiber walls due to the confinement effect of carbon materials. Furthermore, carbon nanofibers provided an excellent conductive network, which expedited the charge transfer rate and further enhanced catalytic activity. At a current density of 10 mA cm−2, the overpotentials for the hydrogen evolution reaction (HER) were only 65 mV and 203 mV in alkaline and acidic electrolytes, respectively, and the overpotential for the oxygen evolution reaction (OER) was 193 mV in an alkaline electrolyte, promoting its potential industrial applications and reducing the negative impact on the environment. This research presented a strategy for designing self-supporting transition metal-based catalysts with superior activity.

Biogenic synthesis of CuO/ZnO nanocomposite from Bauhinia variegate flower extract for highly sensitive electrochemical detection of vitamin B2

In this study, we report the preparation of bio-inspired binary CuO/ZnO nanocomposite (bb-CuO/ZnO nanocomposite) via the biological route using Bauhinia variegata flower extract following hydrothermal treatment. The prepared bb-CuO/ZnO nanocomposite was electrophoretically deposited (EPD) on indium tin oxide (ITO) substrate to develop bb-CuO/ZnO/ITO biosensing electrode which is employed for the determination of vitamin B2 (Riboflavin) through electrochemical techniques. Physicochemical assets of the prepared bb-CuO/ZnO nanocomposite have been extensively evaluated and make use of different characterization techniques including powder XRD, FT-IR, AFM, SEM, TEM, EDX, XPS, Raman, and TGA. Electrochemical characteristics of the bb-CuO/ZnO/ITO biosensing electrode have been studied towards vitamin B2 determination. Furthermore, different biosensing parameters such as response time, reusability, stability, interference, and real sample analysis were also estimated. From the linear plot of scan rate, charge transfer rate constant (Ks), surface concentration of electrode (γ), and diffusion coefficient (D) have been calculated, and these are found to be 6.56 × 10−1 s−1, 1.21 × 10−7 mol cm−2, and 6.99 × 10−3 cm2 s−1, respectively. This biosensor exhibits the linear range of vitamin B2 detection from 1 to 40 μM, including sensitivity and limit of detection (LOD) of 1.37 × 10−3 mA/μM cm2 and 0.254 μM, respectively. For higher concentration range detection linearity is 50–100 μM, with sensitivity and the LOD of 1.26 × 10−3 mA/μM cm2 and 0.145 μM, respectively. The results indicate that the bio-inspired nanomaterials are promising sustainable biosensing platforms for various food and health-based biosensing devices.

Efficiency and mechanistic insights of photocatalytic decomposition of tetracycline and rhodamine B utilizing Z-scheme g-C3N4/SnWO4 heterostructures under visible light irradiation

The hydrothermal approach was used in the design and construction of the SnWO4 (SW) nanoplates anchored g-C3N4 (gCN) nanosheet heterostructures. Morphology, optical characteristics, and phase identification were investigated. The heterostructure architect construction and successful interface interaction were validated by the physicochemical characteristics. The test materials were used as a photocatalyst in the presence of visible light to break down the antibiotic tetracycline (TC) and the organic Rhodamine B (RhB). The best photocatalytic degradation efficiency of TC (97%) and RhB (98%) pollutants was demonstrated by the optimized 15 mg of gCNSW-7.5 in 72 and 48 min, respectively, at higher rate constants of 0.0409 and 0.0772 min−1. The interface contact between gCN and SW, which successfully enhanced charge transfer and restricted recombination rate in the photocatalyst, is responsible for the enhanced performance of the gCNSW heterostructure photocatalyst. In addition, the gCNSW heterostructure photocatalyst demonstrated exceptional stability and reusability over the course of four successive testing cycles, highlighting its durable and dependable function. Superoxide radicals and holes were shown to be key players in the degradation of contaminants through scavenger studies. The charge transfer mechanism in the heterostructure is identified as Z-scheme mode with the help of UV–vis DRS analysis. Attributed to its unique structural features, and effective separation of charge carriers, the Z-scheme gCNSW-7.5 heterostructure photocatalyst exhibits significant promise as an exceptionally efficient catalyst for the degradation of pollutants. This positions it as a prospective material with considerable potential across various environmental applications.

Measurement of interfacial charge transfer rate during visible light CO2 reduction under bias voltage conditions

The study of photogenerated electron transfer pathway and time scale in photoelectrocatalysis is the key factor to improve the efficiency of light energy utilization. At present, the reduction of CO2 by visible light is one of the hotspots of research, but it is difficult to determine the reduction reaction and mechanism. Therefore, we use electrochemical in situ growth technology to prepare Bi2(MoO4)3, and then use photoelectrocatalytic method to reduce CO2. The results show that the rate of charge transfer at the interface is about 10−18 cm4/s in the reduction of CO2 by visible light under bias voltage, and the catalyst can react stably for 10 h. This provides a way to optimize the photogenerated electron transfer model and to design the catalysts for the reduction of carbon dioxide under visible light.

Cobalt telluride regulated by nickel for efficient electrooxidation of 5-hydroxymethylfurfural

Replacing the anodic oxygen evolution reaction (OER) in water splitting with 5-hydroxymethylfurfural oxidation reaction (HMFOR) can not only reduce the energy required for hydrogen production but also yield the valuable chemical 2,5-furandicarboxylic acid (FDCA). Co-based catalysts are known to be efficient for HMFOR, with high-valent Co being recognized as the main active component. However, efficiently promoting the oxidation of Co2+ to produce high-valent reactive species remains a challenge. In this study, Ni-doped CoTe (CoNiTe) nanorods were prepared as efficient catalysts for HMFOR, achieving a high HMFOR current density of 65.3 mA cm−2 at 1.50 V. Even after undergoing five successive electrolysis processes, the Faradaic efficiency (FE) remained at approximately 90.7 %, showing robust electrochemical durability. Mechanistic studies indicated that Ni doping changes the electronic configuration of Co, enhancing its charge transfer rate and facilitating the oxidation of Co2+ to high-valent CoO2 species. This work reveals the effect of Ni doping on the reconfiguration of the active phase during HMFOR.

Highly efficient photocatalytic hydrogen generation of PtPdy nanoframe/2D-CdS: Shape-controlled preparation and property modulation

This work focuses on the structure design of Pt-based alloys, and their influences on 2D-CdS semiconductor photocatalyst in hydrogen (H2) generation reaction from water-splitting under visible light, using traditional experimental techniques and DFT calculations as Pd concave nanocube (Pd CNCs) as a template, PtPdx alloy with cuboctahedron core-shell structure (PtPdx NPs) and cuboctahedron nanoframe (PtPdy NFs) were successfully synthesized via wet chemical routes. The structure of Pt-based alloys was certified by XRD, HRTEM, XPS, and ICP. The Pt-based co-catalysts were photo-deposited on 2D-CdS in an aqueous solution of (NH4)2SO3 while the reaction for photo-generating of H2 occurred. The obtained photocatalysts show excellent activity towards hydrogen generation, i.e., in ascending order, Pd CNCs/2D-CdS (46.1 mmol/h/g) < PtPd1.8 NPs/2D-CdS (55.4 mmol/h/g) < PtPd0.2 NFs/2D-CdS (71.7 mmol/h/g, QE=61.46%, λ=420 nm). Photoelectrochemical tests, ESR, and work functions results indicate that PtPd0.2 NFs have excellent photoelectrochemical performance, the longest lifetime of electrons, and the highest work function, respectively. Moreover, DFT calculations unveil that PtPd0.2 has the largest surface energy and the lowest activation energy ΔGH* which results in the fast charge transfer rate at the PtPd0.2/2D-CdS interface. This work offers a novel thought into the structural design of Pt-based co-catalysts applied in photocatalytic hydrogen generation from water-splitting.

Preparation and electrocatalytic oxygen evolution of bimetallic phosphates (NiFe)2P/NF

Abstract The energy and environmental crisis pose a great challenge to human development in the 21st century. The design and development of clean and renewable energy and the solution for environmental pollution have become a hotspot in the current research. Based on the preparation of transition metal phosphates, transition metals were used as raw materials, Prussian blue-like NiFe(CN)6 as a precursor, which was in situ grown on nickel foam (NF) substrate. After low temperature phosphating treatment, a bimetallic phosphide electrocatalyst (NiFe)2P/NF was prepared on NF substrate. Using 1 mol·L−1 KOH solution as a basic electrolyte, based on the electrochemical workstation of a three-electrode system, the electrochemical catalytic oxygen evolution performance of the material was tested and evaluated. Experiments show that (NiFe)2P/NF catalyst has excellent oxygen evolution performance. In an alkaline medium, the overpotential required to obtain the catalytic current density of 10 mA·cm−2 is only 220 mV, and the Tafel slope is 67 mV·dec−1. This is largely due to: (1) (NiFe)2p/NF nanocatalysts were well dispersed on NF substrates, which increased the number of active sites exposed; (2) the hollow heterostructure of bimetallic phosphates promotes the electron interaction between (NiFe)2P and NF, increased the rate of charge transfer, and the electrical conductivity of the material is improved; and (3) theoretical calculations show that (NiFe)2P/NF hollow heterostructure can effectively reduce the dissociation barrier of water, promote the dissociation of water; furthermore, the kinetic reaction rate of electrocatalytic oxygen evolution is accelerated. Meanwhile, the catalyst still has high activity and high stability in 30 wt% concentrated alkali solution. Therefore, the construction of (NiFe)2P/NF electrocatalysts enriches the application of non-noble metal nanomaterials in the field of oxygen production from electrolytic water.

Construction of MOF-derived hollow sugar gourd-like Ni-Co-S@NiMoO4•xH2O nanocage arrays for efficient solar-powered overall water splitting

In situ growth of nanoarrays on conductive substrates is an efficient strategy for designing electrocatalysts. However, preparing array with excellent catalytic activities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains a challenge. Here, we construct a novel hollow sugar gourd-like Ni-Co-S@NiMoO4·xH2O/NF nanocage array through MOF derivation strategy for stable solar-driven overall water splitting. Due to the hollow core–shell structure and multi-component advantages, the Ni-Co-S@NiMoO4·xH2O/NF presents high density of active sites and fast charge transfer rate. Therefore, Ni-Co-S@NiMoO4·xH2O/NF exhibits attractive electrocatalytic activity in alkaline electrolytes for HER (90 mV@10 mA cm−2) and OER (208 mV@10 mA cm−2, 245 mV@100 mA cm−2). The corresponding two-electrode electrolytic cell demonstrates small cell voltage (1.515 V @ 10 mA cm−2) and shows durability over 50 h at 10 mA cm−2, exhibiting excellent overall water splitting performance. It is worth noting that the solar-assisted electrolysis cell reaches a high solar-to-hydrogen (STH) conversion rate of 19.4 %. The construction of this unique hollow structure gives a fascinating method for improving the HER and OER performance of transition metal sulfide electrocatalysts.

Construction of La2O3/AgCl S-scheme heterojunction with interfacial chemical bond for efficient photocatalytic degradation of bisphenol A

The formation of interfacial chemical bonds in S-scheme heterostructure is a crucial factor to realize efficient interfacial charge transfer. High-energy mechanical ball-milling is an effective method to form interfacial chemical bonds. In this work, an S-scheme La2O3/AgCl heterojunction catalyst was designed and prepared by ball-milling method. XPS, FTIR and Raman measurements showed that La-Cl chemical bond was formed at the interface of La2O3 and AgCl and an S-scheme charge transfer path mechanism existed in the La2O3/AgCl composite. The results of electrochemistry, photo-electrochemistry, capture experiments, free radical measurement and EPR verified that the S-scheme heterojunction and the interfacial La-Cl bond significantly accelerated the charge transfer rate between La2O3 and AgCl, and enhanced the photocatalytic capability of the composite catalysts. The degradation rate of bisphenol A by La2O3/AgCl heterojunction composite (LA50) reached 99 % in 20 min, and it also had excellent anti-interference ability and cycling stability. The toxicity of the degradation intermediates of bisphenol A was much less than itself, as calculated by TEST simulation. This work provided a promising strategy for improving the performance of S-scheme heterojunction catalysts by introducing interfacial chemical bonds as charge transfer channels.

Time-dependent synthesis of tungsten disulfide for flexible supercapacitors

Tungsten disulfide (WS2) with various nanostructures was synthesized for times ranging from 6 to 72 h, using a simple and easy hydrothermal technique, for high-performance supercapacitor applications. The synthesized WS2 for 24 h (WS2–24), among other synthesized WS2, exhibited flower-like structures, composed of numerous nanosheets, demonstrating superior electrochemical properties in terms of electrochemical surface area, charge transfer resistance, specific capacitance, and rate capability. In addition, WS2–24 was coated on a flexible activated carbon cloth substrate to make flexible electrodes and assemble a flexible symmetric supercapacitor with a gel electrolyte. The flexible supercapacitor exhibited a specific capacitance of 262.5 F g−1 at 1 A g−1 with an energy density of 23.6 Wh kg−1 and a power density of 802 W kg−1. It also showed excellent capacitance retention of 94.5 % and a Coulombic efficiency of 86.4 % after 5000 cycles. The remarkable electrochemical properties of the synthesized WS2 materials highlight them as highly effective active materials for high-performance supercapacitor electrodes.

Enhanced Silicon Anodes with Robust SEI Formation Enabled by Functional Conductive Binder

AbstractThe application of silicon (Si) anode is limited by the drastic volume change of silicon in the lithiation/delithiation process, the repeated formation of the solid electrolyte interface (SEI), and the low intrinsic conductivity. In this work, a small amount of poly (3,4‐ethylenedioxythiophene):poly (styrene sulfonic acid) (PEDOT:PSS) (PP), citric acid (CA), isopropyl alcohol (IPA), and silicon nanoparticles (SiNPs) are mixed and vacuum treated at a specific temperature to obtain silicon‐based anode electrode composite Si@PP@CA. The interphase forms a robust elastic network with hydrogen and chemical bonds, which have good mechanical properties and self‐repairing characteristics. The modified PEDOT:PSS as the conductive medium significantly improves the charge transfer rate. Moreover, the rapid formation of SEI by CA on the surface of SiNPs enhances the structural stability of the material. The electrochemical results show that the capacity of Si@PP@CA composite electrode canretain more than 2200 mAh g−1 after 200 cycles at 0.2 A g−1. It still shows a high capacity retention of 89% even at the current density of 1.0 A g−1 after 2000 cycles. More importantly, such excellent performance can be obtained using an electrode with an active material content of up to 90 wt%, which is essential for practical applications.

Spatial confinement of Co3O4 in hollow carbon sphere to boost peroxymonosulfate activation for effective degradation of organic pollutants

Herein, hollow carbon sphere (HCS) is constructed via hard template method for loading the Co3O4, and obtained catalyst (namely Co3O4/HCS) is then employed to activate peroxymonosulfate (PMS) for the removal of tetracycline (TC). Owing to high specific surface area and good conductivity of HCS, Co3O4 modified with HCS exhibits low interface resistance and fast charge transfer rate. Meanwhile, hollow structure of HCS can provide spatial confinement effect for Co3O4 and accelerate the mass transfer process between Co3O4 and PMS. As predicted, peroxy bond break of PMS over Co3O4/HCS is significantly boosted compared with pure Co3O4, so reaction system can produce more SO4•–, OH•, 1O2 and high-valent metal complexes to conduct TC degradation. Importantly, Co3O4/HCS-mediated electron transfer process between PMS and TC is also involved in TC degradation. As a result, Co3O4/HCS shows excellent performance in TC degradation, and the highest removal efficiency of TC is more than 95 % within 10 min. Benefiting from the protective effect of HCS, only a small amount of Co ion is released from Co3O4/HCS during the reaction process. Besides, Co3O4/HCS possesses good reusability and anti-interference ability. In short, current work provides a promising catalyst for PMS activation to treat wastewater containing antibiotic.

Short-time potentiostatic assisted borate to induce the generation of ultrathin NiFe LDH active phase for industrial-level water oxidation

Self-supported NiFe-based oxygen evolution reaction (OER) catalysts with high activity and durability are essential for the industrialization of green hydrogen. Herein, Boron-interfered NiFe LDH nanosheets (B2-NiFe-(a-10)) with abundant wrinkle structure are prepared by introducing nonmetallic sources into the surface reconstruction of layered double hydroxide (NiFe LDH) through a novel short-time potential constant activation strategy. It enhances interactions with the electrolyte, decreases Arrhenius activation energy (Ea), accelerates efficient charge transfer and O2 escape rate. The as-reconstructed B2-NiFe-(a-10) exhibits outstanding alkaline OER activity with an ultralow overpotential of 290 mV at 100 mA cm−2 and excellent durability (100 h). Additionally, density functional theory calculations further reveal that the interaction optimizes the adsorption of oxygenated intermediates (*OH→*O), induces the center of the d-band toward the Fermi energy level, and lowers the dissociation barrier of H2O. Moreover, the anion-exchange membrane water electrolyzer (AEMWE) achieves a current density of 1 A cm−2 at 1.97 V.

Boosting Electrocatalytic N2 Reduction to NH3 by Enhancing N2 Activation via Interaction between Au Nanoparticles and MIL-101(Fe) in Neutral Electrolytes.

Electrocatalytic nitrogen reduction reaction (NRR) has attracted much attention as a sustainable ammonia production technology, but it needs further exploration due to its slow kinetics and the existence of competitive side reactions. In this research, xAu/MIL-101(Fe) catalysts were obtained by loading gold nanoparticles (Au NPs) onto MIL-101(Fe) using a one-step reduction strategy. Herein, MIL-101(Fe), with high specific surface area and strong N2 adsorption capacity, is used as a support to disperse Au NPs to increase the electrochemical active surface area. Au NPs, with a high NRR activity, is introduced as the active site to promote charge transfer and intermediate formation rates. More importantly, the strong interaction between Au NPs and MIL-101(Fe) enhances the electron transfer between Au NPs and MIL-101(Fe), thereby enhancing the activation of N2 and achieving efficient NRR. Among the prepared catalysts, 15 %Au/MIL-101(Fe) has the highest NH3 yield of 46.37 μg h-1 mg-1 cat and a Faraday efficiency of 39.38 % at -0.4 V (vs. RHE). In-situ FTIR reveals that the NRR mechanism of 15 %Au/MIL-101(Fe) follows the binding alternating pathway and also indicates that the interaction between Au NPs and MIL-101(Fe) strengthens the activation of the N≡N bond in the rate-limiting process, thereby accelerating the NRR process.

Dual-functional electrocatalyst of defective cobalt-nitrogen-doped porous carbon for enhanced in-situ hydrogen peroxide generation and electro-Fenton tetracycline degradation

Tetracycline hydrochloride (TC) is one of the organic pollutants that can be consistently monitored in the aquatic environment and pose a great threat to the environment. The development of a bifunctional electro-Fenton (EF) catalyst capable of in situ H2O2 production and decomposition to ·OH to degrade the pollutant is an efficient and green approach to deal with antibiotic pollution. The bifunctional catalysts Co, N double doped defective carbon materials were prepared by pyrolysis ball milling method using zeolite imidazolium ester skeleton structural materials (ZIFs) series materials as precursors, which showed more than 80% selectivity to H2O2 and could basically remove TC within 120 min in EF system. Carbon defects and graphitic nitrogen can effectively improve the selectivity and yield of H2O2, while graphitization degree improves the charge transfer rate, the doping of Co and pyridinic-N contribute to the decomposition of H2O2 into ·OH. The active species present in the Co1/Zn1-NPC/EF system is ·OH, and factors such as coexisting ions, humic acid and water quality have little effect on the efficiency of the degradation of TC in the Co1/Zn1-NPC/EF system, whereas Co1/Zn1-NPC electrocatalytic catalyst has excellent stability and stable treatment performance for a wide range of pollutants, as well as being an environmentally friendly green catalyst without metal leaching. Furthermore, the possible pathways and the toxicity hazard of TC degradation were proposed. The bifunctional electrocatalyst prepared in this research provides a novel strategy for the green and efficient treatment of pollutants in wastewater.

Biomass-derived porous carbon with single-atomic cobalt toward high-performance aqueous zinc-sulfur batteries at room temperature

Aqueous zinc-sulfur batteries at room temperature hold great potential for next-generation energy storage technology due to their low cost, safety and high energy density. However, slow reaction kinetics and high activation energy at the sulfur cathode pose great challenges for the practical applications. Herein, biomass-derived carbon with single-atomic cobalt sites (MMPC-Co) is synthesized as the cathode in Zn-S batteries. The catalysis of single-atom Co sites greatly promotes the transform of cathode electrolyte interface (CEI) on the cathode surface, while offering accelerated charge transfer rate for high conversion reversibility and large electrochemical surface area (ECSA) for high electrocatalytic current. Furthermore, the rich pore structure not only physically limits sulfur loss, but also accelerates the transport of zinc ions. In addition, the large pore volume of MMPC-Co is able to relieve the stress effect caused by the volume expansion of ZnS during charge/discharge cycles, thereby maintaining the stability of electrode structure. Consequently, the sulfur cathode maintains a high specific capacity of 729.96 mA h g−1 after 500 cycles at 4 A g−1, which is much better than most cathode materials reported in the literature. This work provides new insights into the design and development of room-temperature aqueous Zn-S batteries.