Costate Research Articles

The State of CO and CO2 Ices in the Kuiper Belt as Seen by JWST

JWST has shown that CO2 and CO are common on the surfaces of objects in the Kuiper Belt and have apparent surface coverages even higher than that of water ice, though water ice is expected to be significantly more abundant in the bulk composition. Using full Mie scattering theory, we show that the high abundance and the unusual spectral behavior around the 4.26 μm ν 1 band of CO2 can be explained by a surface covered in a few micron thick layer of ∼1–2 μm CO2 particles. CO is unstable at the temperatures in the Kuiper Belt, so the CO must be trapped in some more stable species. While hydrate clathrates or amorphous water ice are often invoked as a trapping mechanism for outer solar system ices, the expected spectral shift of the absorption line for a CO hydrate clathrates or trapping in amorphous ice is not seen, nor does the H2O abundance appear to be high enough to explain the depth of the CO absorption line. Instead, we suggest that the CO is created via irradiation of CO2 and trapped in the CO2 grains during this process. The presence of a thin surface layer of CO2 with embedded CO suggests volatile differentiation driving CO2 from the interior as a major process driving the surface appearance of these mid-sized Kuiper Belt objects, but the mechanisms that control the small grain size and depth of the surface layer remain unclear.

Solution of the maximum distillate on a batch distillation column by a Pseudo-Newton method

This paper presents a new algorithm for the solution of the maximum distillate problem based on Pontryagin's maximum principle. Four cases of study were analyzed with the algorithm. The first case is a literature problem where the column uses twenty trays to distillate ten components, the second case is a binary mixture with no ideal behavior, the third case is a quaternary mixture, and the last case is a reactive mixture. In all cases, the desired purity was settled as a final constraint. The solution algorithm found the optimal control faster than results reported in literature concerning the CPU time.The batch distillation process is modeled by using a rigorous model with no constant volatility. The proposed algorithm uses the Hamiltonian function to reformulate the maximum distillate problem. Then, the optimal control is solved by a Broyden–Fletcher–Goldfarb–Shanno algorithm. The solution procedure of the indirect approach required the forward integration of the states, the integration of the co-state equations backward in time, and the control input is the distillate flow rate which is parameterized. The binary batch distillation column uses six stages, and the maximum recovery is 95% of the light component with a 95% mol percent on the accumulator. The multicomponent batch distillation column uses 17 stages, and the recovery of the lightest component in the product is 90% mol percent. The reactive case reached 80% conversion.

Probing the incoherent admixture of low and high-spin states of Co in (LaPr)CoO3 perovskite: focus on structural phase transitions

We report the mixed valence and intermediate spin-state (IS) transitions in Pr substituted LaCoO3 perovskites in the form of bulk and nanostructures. Various compositions (x) of La1−x Pr x CoO3 (0 ⩽ x⩽ 0.9) were synthesized using the sol–gel process under moderate heat treatment conditions (600 °C). The structural analysis of these compounds reveals a phase crossover from the monoclinic phase (space group, s.g.: I2/a) to an orthorhombic one (s.g.: Pbnm), and a rhombohedral phase (s.g.: R-3c) to an orthorhombic one (s.g.: Pnma) in the bulk and nanostructures, respectively, for the composition range 0 ⩽ x⩽ 0.6. Such a structural transformation remarkably reduces the Jahn–Teller distortion factor ΔJT: 0.374 → 0.0016 signifying the dominant role of the IS state (S Avg = 1) of trivalent Co ions in the investigated system. Magnetization measurements reveal the ferromagnetic (FM) nature of bulk LaCoO3 along with a weak antiferromagnetic (AFM) component coexisting with an FM component. This coexistence results in a weak loop-asymmetry (zero-field exchange-bias effect ∼134 Oe) at low temperatures. Here the FM ordering occurs due to the double-exchange interaction (J EX /k B∼ 11.25 K) between the tetravalent and trivalent Co ions. Significant decrease in the ordering temperatures was noticed in the nanostructures (T C ∼ 50 K) as compared to the bulk counterpart (∼90 K) due to the finite size/surface effects in the pristine compound. However, the incorporation of Pr leads to the development of a strong AFM component (J EX/k B ∼ 18.2 K) and enhances the ordering temperatures (∼145 K for x = 0.9) with negligible FM correlations in both bulk and nanostructures of LaPrCoO3 due to the dominant super-exchange interaction: Co3+/4+‒O‒Co3+/4+. Further evidence of the incoherent mixture of low-spin (LS) and high-spin (HS) states comes from the M–H measurements which yields a saturation magnetization of M S ∼ 275 emu mol−1 (under the limit of 1/H → 0) consistent with the theoretical value of 279 emu mol−1 corresponding to the spin admixture: 65% LS + 10% IS of trivalent Co along with 25% of LS Co4+ in the bulk pristine compound. A similar analysis yields: Co3+ [30% LS + 20% IS] + Co4+ [50% of LS] for the nanostructures of LaCoO3, yet the Pr substitution decreases the spin admixture configuration. The Kubelka–Munk analysis of the optical absorbance results in a significant decrease in the optical energy band gap (E g:1.86 → 1.80 eV) with the incorporation of Pr in LaCoO3 which corroborates the above results.

Variation in the dielectric and magnetic characteristics of multiferroic LuFeO3 as a result of cobalt substitution at Fe sites

Due to its electrical, magnetic, and optical characteristics, LuFeO3 (LFO) has caught the scientific community's interest. In this study, the powders of LFO, LuFe0.95Co0.05O3, and LuFe0.90Co0.10O3 samples were prepared by using the well-known solid-state approach. The crystalline structure of the fabricated samples was examined by an X-ray diffractometer (XRD). It was found that the samples display secondary phases such as Lu2O3, Lutetium Tetraoxodiferrate, and Wüstite. It was shown by scanning electron microscope (SEM) that particle size decreases with Co doping. X-ray photoelectron spectroscopy (XPS) determined oxidation states for Fe and Co. It was presented that Fe has a mixture of 2 + and + 3 valance states in the LFO sample. Although LuFe0.95Co0.05O3 has only the 3 + state, LuFe0.90Co0.10O3 sample has coexisting metallic and 3 + states. The conductivity and dielectric constant of the undoped LFO sample were higher than those of Co doped LFO samples. A decrease in both the dielectric constant and conductivity was associated with a lack of Fe2+ ions and lattice distortions. Furthermore, it was argued that several conduction models must be developed to explain the conduction process in the analyzed samples. Magnetic experiments using a vibrating sample magnetometer (VSM) revealed that Co doping raises Mr values. We discuss that this increase in Mr values could be related to i) variations in the inclined angles of Fe3+ moments and ii) the growth of magnetocrystalline anisotropy's energy.

Particle Swarm Optimization-based co-state initialization for low-thrust minimum-fuel trajectory optimization

In this paper, Particle Swarm Optimization with energy-to-fuel continuation is proposed for initializing the co-state variables for low-thrust minimum-fuel trajectory optimization problems in the circular restricted three-body problem. Particle Swarm Optimization performs a search of the solution space by minimizing the weighted sum of squares of the two-point boundary-value problem final boundary condition residuals for the minimum-energy problem. Next, an energy-to-fuel homotopy is employed to transition the minimum-energy trajectory to a minimum-fuel trajectory, starting from the generated guess. The proposed methodology is applied to two low-thrust transfer problems in the Earth–Moon system: a transfer from a geostationary transfer orbit to an L1 halo orbit, and a transfer from an L2 halo orbit to an L1 halo orbit. The resulting minimum-fuel trajectories are validated with the literature. It is demonstrated that the methodology can successfully generate guesses for the initial co-state variables which converge to a solution for both scenarios. A strategically chosen particle swarm size is shown to improve the efficiency of the methodology. The proposed approach is of simple implementation, can be easily extended to other trajectory optimization problems, facilitates the discovery of multiple candidate trajectories, and does not require a user-provided guess, all of which are advantageous features for the preliminary phase of mission design.

NiSe2-CoSe2 with a Hybrid Nanorods and Nanoparticles Structure for Efficient Oxygen Evolution Reaction

Hetero-structure induced high performance catalyst for oxygen evolution reaction (OER) in the water splitting reaction has received increased attention. Herein, we demonstrated a novel catalyst system of NiSe2-CoSe2 consisting of nanorods and nanoparticles for the efficient OER in the alkaline electrolyte. This catalyst system can be easily fabricated via a low-temperature selenization of the solvothermal synthesized NiCo(OH)x precursor and the unique morphology of hybrid nanorods and nanoparticles was found by the electron microscopy analysis. The high valence state of the metal species was indicated by X-ray photoelectron spectroscopy study and a strong electronic effect was found in the NiSe2-CoSe2 catalyst system compared to their counterparts. As a result, NiSe2-CoSe2 exhibited high catalytic performance with a low overpotential of 250 mV to reach 10 mA·cm-2 for OER in the alkaline solution. Furthermore, high catalytic stability and catalytic kinetics were also observed. The superior performance can be attributed to the high valence states of Ni and Co and their strong synergetic coupling effect between the nanorods and nanoparticles, which could accelerate the charge transfer and offer abundant electrocatalytic active sites. The current work offers an efficient hetero-structure catalyst system for OER, and the results are helpful for the catalysis understanding.

Optimal Control of Vaccination for Dengue Fever in SIR Model

According to data from The Indonesian ministry of health, many of individuals suffere dengue fever until may 2023 in Indonesia. To reduce its cases, in this article, a single of control strategy of vaccination for infected human by dengue fever has been proposed. To obtain the optimal control, the SIR model has been modificated with single control and the new objective function has been made before the Pontryagin minimum principle is used in this article. According to the differential equation in the model of the dengue fever and the objective function, we made the Hamiltonian equation. Then, from it, the state equation, costate equation, and stationary condition has been made from the Hamiltonian equation so we obtained the optimal control in vaccination. In the end of this article, we did the numerical simulation using the sweep forward-backward method. Through numerical simulation, we find that the control succeed to reduce the infected human by dengue fever and also increase human recovery from this desease. Futhermore, the control of vaccination for infected human should be implemented not only in this mathematical model but also into real life to decrease the dengue fever case.

Exploration and Application of the Self-Optimization Phenomenon of a Trimetal-Based MOF Electrocatalyst in the Oxygen Evolution Reaction

Metal–organic frameworks (MOFs) have emerged as a promising class of catalysts due to their large specific surface area, high porosity, and dispersed metal sites. However, the inherent low electrical conductivity of organic ligands limits their application as electrocatalysts. Herein, we constructed a trimetal FeCoNi MOF/NF catalyst for oxygen evolution reaction (OER) on nickel foam substrates by electrodeposition and hydrothermal methods. The FeCoNi MOF/NF catalyst shows a unique self-optimization phenomenon, which originates from the increase in the pore structure on the topography, the increase in the valence state of Co and Ni ions, and the formation of crystalline/amorphous interfaces. The self-optimizing stabilized FeCoNi MOF/NF has excellent electrocatalytic performance, which achieves a low overpotential of 267 mV at the current density of 10 mA cm–2 in 1 M KOH with a small Tafel slope of 37.6 mV dec–1. The self-optimization transformation process proposed in this work provides a new insight for the understanding and application of the active center of MOFs during the OER catalytic process.

Deciphering structural changes in LiNixMnyCozO2 cathodes of Li ion batteries during cycling: Experimental and theoretical investigations

Layered oxide material LiNixMnyCozO2 is emerging out as promising cathode for new generation of Li-ion batteries, especially as power sources for electric vehicles and plug-in hybrid vehicles. In this work, structural and electronic changes occurring in LiNixMnyCozO2 (LNMC) cathode materials during charge/discharge cycle of the battery is studied over a wide composition range using in-situ X-ray diffraction (XRD) and in-situ X-ray absorption spectroscopy (XAS) techniques. While in-situ XRD measurements decipher the overall structural changes during the charging/discharging cycles, in-situ element specific XAS measurements reveal site specific information on electronic and local structural changes. It has been found that for the LNMC samples the major charge compensation at the metal site during charging or Li ion de-intercalation is achieved by oxidation of Ni2+ ions without significant change in the oxidation state of Co or Mn ions. It is also found that local structure around Ni undergoes reversible change during charging and discharging cycles whereas local structure around Co or Mn sites show no significant change. Moreover, it has been found that local structural changes at Ni sites in the samples with higher Ni concentrations are much less compared to that in the samples with lower Ni concentrations during charging/discharging cycles, the result being corroborated by ab-initio theoretical simulations also. This is a new finding and would have significant implications in determining the optimum composition of LNMC electrodes of Li ion batteries for commercial applications.

Stability and optimal control analysis for studying the transmission dynamics of a fractional-order MSV epidemic model

In this research paper, we study the transmission dynamics of the maize streak virus disease in agriculture using fractional calculus. Our fractional-order model (FOM) consists of fractional differential equations within Caputo fractional derivative (CFD). Further, we investigate the mathematical analysis of this FOM such as the positivity and boundedness of the projected solutions, compute the control reproduction number (Rc) by the next-generation matrix method, examine the local stability by using Routh–Hurwitz conditions and global stability by using fractional LaSalle’s invariance principle for all possible equilibrium points. A sensitivity analysis is conducted on the parameters integrated into Rc to evaluate how accurately the parameter estimation fits. Additionally, we present further numerical results on the FOM to demonstrate the obtained analytical results. Then, we formulate the fractional optimal control problem (FOCP) depending on the suggested FOM with three control efforts u1, u2 and u3 called respectively, prevention, quarantine and insecticide chemical. Also, we study this FOCP analytically to derive the fractional necessary optimality conditions (NOCs) based on a kind of Pontryagin’s maximum principle. After that, we solve these fractional NOCs numerically where the state and co-state variables are subject to the left CFD. We present various strategies with different combinations of suggested controls to examine the best strategy for decreasing the transmission of MSV in maize plants, where each one of these strategies is able to reduce the maize streak disease (MSD) at the period of control time. We perform simulations of outcomes using MATLAB by developing the forward–backward sweep method utilizing the fractional Euler method. Moreover, some figures are presented to show the impact of both control interventions, change in weight factors and fractional order within the suggested strategies. We can observe that the fractional order plays a significant role in limiting the spread of MSD where the obtained results illustrated that the MSD can be reduced through the suggested FOM, which has a notable influence on plant epidemiology.

Peeling of Finite-Length Plates From an Elastomeric Foundation: A 1D Cylindrical Bending Solution

Abstract Quasi-static peeling of a finite-length, flexible, horizontal, one-dimensional (1D) plate (strip, thin film) from a horizontal, thin, elastomeric layer (foundation) is considered. The displaced end of the plate is subjected to an upward deflection or to a rotation. The top of the interlayer is perfectly bonded to the plate, and its lower surface is bonded to a rigid, flat substrate. A transversality (debonding) condition is derived for peeling, based on the common fracture mechanics approach. Whereas debonding from a Winkler foundation can be expressed in terms of the displacement (or equivalently the foundation stress2) at the bond termination, the sixth-order formulation required for elastomeric foundations involves a more complex debonding criterion. Transversality relationships are used to describe this limit state (here the onset of debonding) in terms of co-state variables, herein the deflection and slope at the peel front. In the analysis, bending is assumed to be paramount, linear Kirchhoff–Love (classical) plate theory is used to model the deformation, and therefore displacements are assumed to be small. The foundation is linearly elastic and incompressible. The effects of the work of adhesion, the length of the plate, and the initial nonbonded length of the plate are investigated. The results are compared to those for a Winkler foundation. By replacing the shear modulus of the interlayer by viscosity, and displacements by their time derivatives, the results are expected to apply to viscous liquid interlayers as well.

Dissociation dynamics of anionic carbon monoxide in dark states.

A resonant system consisting of an excess electron and a closed-shell atom or molecule, as a temporary negative ion, is usually in doublet-spin states that are analogous to bright states of photoexcitation of the neutral. However, anionic higher-spin states, noted as dark states, are scarcely accessed. Here, we report the dissociation dynamics of CO- in dark quartet resonant states that are formed by electron attachments to electronically excited CO (a3Π). Among the dissociations to O-(2P) + C(3P), O-(2P) + C(1D), and O-(2P) + C(1S), the latter two are spin-forbidden in the quartet-spin resonant states of CO-, while the first process is preferred in 4Σ- and 4Π states. The present finding sheds new light on anionic dark states.

Covalent triazine framework featuring single electron Co2+ centered in intact porphyrin units for efficient CO2 photoreduction

Covalent triazine frameworks (CTFs) are porous materials constructed by the trimerization of aromatic nitriles. They have frequently been utilized in heterogeneous catalysis due to rich nitrogen sites, excellent stability and porosity. In the past decade, many methods have been developed to synthesize CTFs, however, the roles of structural differences of CTFs synthesized by different methods in catalytic performance remain unclear. Herein, we synthesized two Co porphyrin-based CTFs using same porphyrin monomer by different approaches. CTF-TfOH-Co formed by trifluoromethanesulfonic acid vapor catalysis retains original porphyrin units, and Co (active catalytic sites) feature single electrons. In contrast, CTF-ZnCl2-Co synthesized by the ionothermal method no longer preserves the original porphyrin units, and the Co sites have no single electrons. CTF-TfOH-Co exhibits efficient photocatalytic activity for CO2 reduction with a CO yield rate of 2562.8 μmol g-1h−1, which greatly exceeds that of CTF-ZnCl2-Co. Those results highlight that the integrity of the porphyrin units and the electronic state of Co significantly are vital to their photocatalytic performance. Steady-state photoluminescence tests confirm that CTF-TfOH-Co has a better ability to separate photogenerated electron-hole pairs than CTF-ZnCl2-Co, which accounts for its superior photoreduction performance.

Dielectric and anti-reduction properties of BaTiO3-based ceramics for MLCC application

BaTiO3 ceramics doped with different contents of Co2O3(abbreviated as (1-x) BT-xCo2O3) and (1-x) BaTiO3-xBiCoO3(abbreviated as (1-x) BT-xBC) ceramics were prepared via conventional solid-state process and sintered in reducing atmosphere. The main crystal phase of both ceramic samples was characterized by X-ray diffraction (XRD), which was perovskite structure. Compared with (1-x) BT-xCo2O3, (1-x) BT-xBC ceramic samples were dense with uniform microstructure confirmed by scanning electron microscopy (SEM). The 0.95BT-0.05BC ceramics had good dielectric properties, with ε25°C = 2670, tanδ = 0.012, and resistivity was 1.71 × 1011 Ω cm at 25°C, meeting the X7S standard for multilayer ceramic capacitor (MLCC) applications. The mechanism of improved anti-reduction property of (1-x) BT-xBC ceramics was studied by X-ray photoelectron spectroscopy (XPS) and thermally stimulated depolarization current (TSDC) techniques. The XPS results showed that there were two valence states of Co in 0.95BT-0.05BC and 0.95BT-0.05Co2O3 ceramics, indicating that the introduction of Co can improve anti-reduction property of BT-based ceramics. The TSDC revealed the formation of defect dipoles [2CoTi’−Vo▪▪], which was considered to be the cause for the improvement in anti-reduction property.

Minimum-fuel low-thrust trajectories to the Moon

An approach to solve the problem of optimizing multi-revolution thrust limited trajectories with constant exhaust velocity between the Earth orbit and the orbit around the Moon is considered. An indirect approach is used to solve the lunar trajectory optimization problem, based on the application of the Pontryagin's maximum principle and continuation method. At all segments of the trajectory, the gravities of the Earth, the Moon and the Sun are taken into account. The trajectory to the Moon is divided into geocentric and selenocentric segments, which are connected at the libration point EML1 of the Earth-Moon system. To ensure the choice of the optimal relation between the angular distance and the transfer duration of each segment, the problem of optimizing the trajectory with a fixed angular distance and free time of flight is considered. Solving a sequence of optimization problems for the limited power trajectory, the minimum-thrust trajectory and the minimum-fuel trajectory avoids the need to choose an initial guess for unknown initial costate variables. The numerical examples of optimizing the multi-revolution low-thrust transfers from the highly elliptical orbit around the Earth to the circular orbit around the Moon are given.

Monitored recurrence of a one-parameter family of three-state quantum walks

Monitored recurrence of a one-parameter set of three-state quantum walks on a line is investigated. The calculations are considerably simplified by choosing a suitable basis of the coin space. We show that the Polya number (i.e. the site recurrence probability) depends on the coin parameter and the probability that the walker is initially in a particular coin state for which the walk returns to the origin with certainty. Finally, we present a brief investigation of the exact quantum state recurrence.

Fe-doped Co3O4 anchored on hollow carbon nanocages for efficient electrocatalytic oxygen evolution

In this work, a Fe-doped Co3O4 OER electrocatalyst supported by an N-doped hollow nanocage carbon framework (Fe-Co3O4/NC) was successfully prepared by anion exchange and annealing in an air atmosphere strategy. XRD and HRTEM characterizations confirm that Fe the incorporation of Fe into the lattice of Co3O4. XPS characterization clarifies that the valence state of Co increases after the introduction of Fe, which originates from the electrons transfer from Co2+/Co3+ to Fe3+ and is induced by the valence electron configuration of cations. It simulates Co sites in-situ derived into CoOOH active species during the OER process, which is confirmed by the HRTEM and XPS characterization after the OER stability test. Electrochemical performance tests show that the Fe-Co3O4/NC electrocatalyst only exhibits 275 mV overpotential to achieve a current density of 10 mA/cm2 and stably maintains for 20 h at 100 mA/cm2. Together with 20% Pt/C electrocatalyst, the composed two-electrode system only needs 2.041 V applied potential to achieve 100 mA/cm2 for total water splitting in a self-made membrane electrode device, which has industrial application prospects.

Highly selective production of singlet oxygen by manipulating the spin state of single-atom Co–N moieties and electron localization

Singlet oxygen (1O2) is a reactive species with oxidation selectivity that is preferred in advanced oxidation processes. However, the underlying mechanism of 1O2 selective production remain ambiguous. In this study, we demonstrated that electron localization and high spin state of metal active sites favored peroxymonosulfate (PMS) co-adsorption and dissociation, which promoted selective production of 1O2. Under theoretical guidance, single Co atoms anchored on uneven graphite carbon nitride nanosheet (Co-SA/CMN) was fabricated and exhibited the highest 1O2 production selectivity so far with 87.8% of the PMS consumed was converted to 1O2. The Co-SA/CMN/PMS system exhibited remarkable degradation efficiency to multiple organic pollutants, show strong resistance to environmental interference and robust stability at the device level. Co-SA/CMN/PMS oxidation was assessed as a safe and detoxifying technology, the estrogenic activity and toxicity originating from 17β-estradiol (E2) or its degradation by-products were sufficiently removed. These findings deepen the mechanistic understanding of the origins of high 1O2 production selectivity and provide a rational strategy for precisely controlling 1O2 generation in PMS activation.

Impact of non-magnetic Zn2+ doping on the structural, magnetic and magnetocaloric properties of Nd0.5Ca0.5Mn1-xZnxO3 (x = 0, 0.05, 0.10) compounds

Nd0.5Ca0.5Mn1-xZnxO3 (x = 0, 0.05, 0.10) polycrystalline perovskite samples were made using the conventional solid-state reaction method to investigate effects of Zn2+ substitution on the structural and magnetic properties, along with exchange bias and magnetocaloric effects. All the bulk compounds belong to Pnma space group with orthorhombic structure. Both charge ordering temperature (TCO) and antiferromagnetic ordering temperature (TN) decreased with increase in Zn concentration. Thermal irreversibility in magnetization in all Zn doped samples indicate a first-order phase transition. At low temperatures soft ferromagnetic nature was observed from the isotherms (M(H)). Field-induced metamagnetic behavior was observed in low-temperature regions. Increasing exchange bias effect with Zinc doping was observed, which reduces with temperature due to thermal fluctuation. Also magnetocaloric effect (MCE) has been calculated for two temperature regimes, 10–65 K and 150–300 K. As observed in temperature-dependent magnetization plot entropy-change parameter switches from negative (above TCO) to positive (below TCO), accompanied by a change in magnetic correlation from ferromagnetic to antiferromagnetic. However, the magnitude of change in entropy decreases with Zn doping, whereas, the same increases at low-temperature region. The destabilization of the CO state and enhanced disorder by the Zn doping plays role behind this variation in MCE behavior.

Bimetal-organic framework-derived porous CoFe2O4 nanoparticles as biocompatible anode electrocatalysts for improving the power generation of microbial fuel cells

HypothesisThe relatively lower power density of Microbial fuel cells (MFCs), primarily resulting from weak biofilm habitation and sluggish extracellular electron transfer (EET) at the anode interface, limits their practical implementation on a large scale. To address this challenge, porous CoFe2O4 nanoparticles could be used as anode electrocatalysts based on the following considerations: (i) the introduction of CoFe2O4 nanoparticles endows the anode with a rough surface that facilitates biofilm formation; (ii) the positively charged Co and Fe ions improve the interfacial affinity of anodes, enabling rapid immobilization and colonization of negatively bacteria; (iii) the multi-valent metal states of Co and Fe can function as electron shuttles, mediating EET process between biofilm and anode. ExperimentsCoFe2O4 nanoparticles prepared with a bimetal-organic framework (B-MOF) as precursor, were modified to the surface of carbon cloth as the anode of MFCs. FindingsMFCs equipped with CoFe2O4 anode achieved a maximum power density of 1026.68 mW m−2, which was approximately 3.4 times higher than that of the pristine carbon cloth. Additionally, the biofilm density and viability on the anode were enhanced after CoFe2O4 modification. Considering the facile fabrication process and superior electrocatalytic performance, the CoFe2O4 nanoparticles are promising electrocatalysts for high performance and cost-effective MFCs.