Copper Foam Research Articles

Achieving Long Cycle Life of Zn-Ion Batteries through Three-Dimensional Copper Foam.

Metallic zinc anodes in aqueous zinc-ion batteries (ZIBs) suffer from dendritic growth, low Coulombic efficiency, and high polarization during cycling. To mitigate these challenges, current collectors based on three-dimensional (3D) commercial copper foam (CCuF) are generally preferred. However, their utilization is constrained by their thickness, low electroactive surface area, and increased manufacturing expenses. In this study, the synthesis of cost-effective current collectors with exceptionally large surface areas designed for ZIBs that can be cycled hundreds of times is reported. A zinc-coated CuF anode (Zn/CuF) was prepared with a 3D porous CuF current collector produced by the dynamic hydrogen bubble template (DHBT) method. Electrochemically generated copper foam could be obtained within seconds while offering a thickness as low as 30-40 μm (CuF5 achieved a thickness of ∼38 μm in 5 s) via the DHBT method. The excellent electrical conductivity and open pore structure of the 3D porous copper scaffold ensured the uniform deposition/stripping of Zn during cycling. During the 500 h Zn deposition/stripping process, the as-synthesized CuF5 current collector offered fast electrochemical kinetics and low polarization as well as a relatively high average Coulombic efficiency of 99% (at a current density of 5 mA cm-2 and a capacity of 1 mAh cm-2). Furthermore, the symmetric cell exhibited low voltage polarization and a stable voltage profile for 1000 h at a current density of 0.1 mA cm-2. In addition, full cells containing the Zn/CuF anode coupled with an as-synthesized α-MnO2 nanoneedle cathode in aqueous electrolyte were also prepared. Capacities of 266 mAh g-1 at 0.1 A g-1 and 94 mAh g-1 at 2 A g-1 were achieved after 200 charge/discharge cycles with a stable Coulombic efficiency value close to 99.9%.

Heat transfer analysis of subcooled flow boiling in copper foam helical coiled heat exchanger – A pore-scale numerical study

High performance thermal energy systems are crucial in fulfilling the growing demand of thermal energy. Consequently, numerous heat transfer enhancements have been proposed. Some of the promising methods are boiling flow heat transfer, helical coiled tube and metal foam insert. Although the performance of each strategy has been extensively studied, based on our literature review, the effectiveness of combining these strategies has not been investigated. This missing information may impede further development of efficient heat transfer systems. This study is therefore performed to investigate subcooled flow boiling heat transfer in helical tube with copper foam insert. A high-resolution three-dimensional pore scale model that considers the shape, porosity and pore density of the metal foam is developed and validated against the published experimental results. Using the model, the effect of inlet temperature, mass flux, wall heat flux, porosity, pore density and half-filled metal foam are studied. The results suggest that operating parameters have mild effects on the heat transfer performance. In contrast, porosity and pore density show significant influence in heat transfer coefficient and pressure drop. It has also been found that total heat transfer surface area and base area are better in characterizing heat transfer in pore-scale level than porosity and pore density at pore-scale level. Moreover, implementing metal foam at outer half of the tube is observed to offer slightly better heat transfer than implementing it at the inner side by around 4.8%. Overall, this study indicates that helical metal foam tubes offer the best performance at mass flux of 200 kg/m2∙s with performance index of 0.72, while straight tubes with 0.90 porosity has the highest performance index of 0.66. Empirical correlations to relate dimensionless parameters to the Nusselt number and friction factor is generated. Finally, the model developed in this study can serve to provide guidelines for the upcoming studies in boiling in metal foam structure and assist in designing metal foam heat exchangers.

Utilizing Ragone framework for optimized phase change material-based heat sink design in electronic cooling applications

This study explores the latent thermal energy storage potential of an organic phase change material with porous copper foam and its applicability in electronic cooling under varying heat load conditions. The organic phase change material, n-eicosane, is known for its inherently low thermal conductivity of 0.15 W/mK, rendering it vulnerable during power spikes despite its abundant latent heat energy for phase transition from solid to liquid. Porous copper foams are often integrated into n-eicosane to enhance the composite's thermal conductivity. However, the volume fraction of the phase change material in the porous foam that optimally improves the thermal performance can be dependent on the boundary condition, the cut-off temperature, and the thickness. A finite difference numerical model was developed and utilized to ascertain the energy consumption for the composite of n-eicosane with two kinds of porous copper foam with varying porosity under different heat rates, cut-off temperatures, and thickness. In addition, the results are compared with a metallic phase change material (gallium), a material chosen with a similar melting point but significantly high thermal conductivity and volumetric latent heat. For validation of the numerical model and to experimentally verify the effect of boundary condition (heat rate), experimental investigation was performed for n-eicosane and high porosity copper foam composite at varying heat rates to observe its melting and solidification behaviors during continuous operation until a cut-off temperature of 70 °C is reached. Experiments reveal that heat rate influences the amount of latent energy storage capability until a cutoff temperature is reached. For broad comparison, the numerical model was used to obtain the accessed energy and power density and generate thermal Ragone plots to compare and characterize pure gallium and n-eicosane - porous foam composite with varying volume fractions, cutoff temperature, and thickness under volumetric and gravimetric constraints. Overall, the proposed framework in the form of thermal Ragone plots effectively delineates the optimal points for various combinations of heat rate, cut-off point, and aspect ratio, affirming its utility for comprehensive design guidelines for PCM-based composites for electronic cooling applications

Ice templated honeycomb-like porous copper foam to improve the anisotropic thermal transfer property of phase change composites

This study explores the use of copper foam (CF) as a thermally conductive scaffold for phase change materials (PCMs), enhancing shape stability. Employing the ice template method (ITM), we fabricate a CF with a low-density, honeycomb structure and anisotropy from flake copper powders. The resulting phase change composites (PCCs), infused with paraffin wax (PW), showcase high thermal conductivity and shape retention compared to pure PW, with anisotropic heat flow due to directional channels in the CF. With a 34.4 wt% filling ratio, the PCCs achieve axial and lateral thermal conductivities of 2.85 W m−1 K−1 and 1.51 W m−1 K−1, respectively, and a thermal storage enthalpy of 158.18 J g−1. This work presents a novel method for advanced thermal energy storage and management, indicating the promise of ITM-derived CF in high-performance PCCs for diverse applications.

In Situ Determination of the Potential Distribution within a Copper Foam Electrode in a Zinc‐Air/Silver Hybrid Flow Battery

AbstractThis work describes a novel methodology for measuring the potential distribution within the porous copper foam electrode of a zinc‐air/silver hybrid (ZASH) flow battery by using local potential probes. The suitability of dynamic hydrogen electrodes (DHEs) and a quasi‐reference electrode as probes is evaluated, with the latter chosen in view of stability. Liquid and solid‐phase potentials are recorded at varying applied current densities over multiple charge‐discharge cycles. Various zinc structures are found within specific overpotential ranges, with moss‐like structures appearing between 7.8 mV and 13.2 mV and the desired boulder structures in the range of 22 mV to 100 mV. Regardless of the current density, the highest liquid‐phase potentials are always measured in the outermost region of the porous foam near to the separator. In practice, this means that increasing the thickness of the copper foam over about 5 mm does not provide significant performance benefits. Conversely, solid‐phase potentials across the copper foam remain nearly uniform, resulting in negligible effects on local overpotential. The presented technique provides unique insights into the behavior of porous electrodes in electrochemical energy conversion technologies, facilitating the determination of the optimal properties for maximum efficiency, such as electrode thickness.

Enhanced Heat Transfer in Thermoelectric Generator Heat Exchanger for Sustainable Cold Chain Logistics: Entropy and Exergy Analysis

This study investigates the application of thermoelectric power generation devices in conjunction with cold chain logistics transport vehicles, focusing on their efficiency and performance. Our experimental results highlight the impact of thermoelectric module characteristics, such as thermal conductivity and the filling thickness of copper foam, on the energy utilization efficiency of the system. The specific experimental setup involved a simulated logistics cold chain transport vehicle exhaust waste heat recovery thermoelectric power generation system, consisting of a high-temperature exhaust heat exchanger channel and two side cooling water tanks. Thermoelectric modules (TEMs) were installed between the heat exchanger and the water tanks to use the temperature difference and convert heat energy into electrical energy. The analysis demonstrates that using high-performance thermoelectric modules with a lower thermal conductivity results in better utilization of the temperature difference for power generation. Additionally, the insertion of porous metal copper foam within the heat exchanger channel enhances convective heat transfer, leading to an improved performance. Furthermore, the study examines the concepts of exergy and entropy generation, providing insights into the system energy conversion processes and efficiency. Overall, this research offers valuable insights for optimizing the design and operation of thermoelectric generators in cold chain logistics transport vehicles to enhance energy utilization and sustainability.

Inclined solar interface evaporation system with downward steam generation for efficient desalination and salt crystallization positioning

Solar-driven Interfacial Vapor Generation (SIVG) has been recognized as a potentially effective method of converting seawater into potable freshwater resources. In this work, we employed a straightforward approach to cultivate CuS and polypyrrole on copper foam as an solar absorber, while sterilized face towels served as water an evaporation interface and water transport sites. An inclined steam blocking evaporator with a salt-out part that attracts salt aggregation was ingeniously designed to improve the salt-resistant performance. Even in 15 wt% brine, the evaporation equipment maintained a stable and high evaporation rate, with an average evaporation rate of about 1.588 kg m−2 h−1 under 1 solar illumination. More particularly, in order to improve the water collection rate, a beveled condensers placed at the bottom of the steam blocking evaporator was customized, so as to shorten the steam condensation path and achieve internal water collection. Therefore, the water collection rate of the evaporator is as high as 2.238 kg m−2 h−1 and water collection efficiency is 85.90 %. Additionally, the evaporation device can effectively purify heavy metal ions and organic matter. This study can provide a new idea for the design and performance improvement of solar interfacial vapor generation and water collection device.

Explosion behavior of nonuniform hydrogen/methane/air mixtures in the presence of copper foam

The effect of copper foam on the explosion characteristics of nonuniform hydrogen/methane/air mixtures with different hydrogen volume fractions (φ) and diffusion times (DT) was investigated in a closed duct. Copper foams with different PPIs (pores per inch): 0 PPI, 20 PPI, 40 PPI, and 60 PPI were used, where 0 PPI refers to the case where there is no copper foam in the duct. The results show that a triple flame is observed in nonuniformly mixed hydrogen/methane/air mixtures after the hemispherical flame and finger flame stage, rather than the traditional plane flame and successive tulip flames. Upstream of the copper foam, the presence of the copper foam has no effect on the flame evolution process in uniformly mixed hydrogen/methane/air mixtures but affects the shape of the triple flame in nonuniformly mixed gas. The flame front develops numerous folds and cellular structures after it through the copper foam, and the flame velocity and overpressure increase rapidly. When the PPI of the copper foam is increased, the flame downstream of the copper foam becomes more disordered and irregular, and the maximum flame velocity and maximum overpressure initially increase and then decrease with increasing PPI. The maximum flame velocity and maximum overpressure are obtained in uniform and nonuniform hydrogen/methane/air mixtures when copper foams with 20 PPI and 40 PPI are used, respectively. The results provide experimental evidence for preventing and controlling hydrogen/methane fuel explosions.

Performance of Co9S8/Cu2S@LDH nanowires prepared by dual sulfur sources to promote oxygen evolution performance

Hydrogen production through water electrolysis is an effective method for obtaining clean energy. The oxygen evolution reaction plays a key role in the process of water electrolysis, and the development of efficient and stable oxygen evolution electrocatalysts is crucial to improve the efficiency of hydrogen production. This paper presents the preparation of Co9S8/Cu2S@LDH nanowire catalysts on copper foam using thiourea and sodium sulfide as dual sulfur sources by a hydrothermal method combined with electrochemical deposition. The composition, structure, and performance of the catalysts were investigated using characterization methods of XRD, SEM, Raman, and electrochemical analyses. Also, the mechanism of thiourea's role in the process of sulfurization of dual sulfur sources was also revealed. The results indicate that the introduction of thiourea facilitates the generation of the active center CoOOH and improves the catalytic efficiency of oxygen precipitation with a low overpotential of 199 mV at 10 mA/cm2 in 1.0 M KOH electrolyte. Additionally, the LDH deposited in the outer layer effectively prevents the oxidation of Co9S8/Cu2S and improves the catalyst's stability. Therefore, the prepared Co9S8/Cu2S@LDH nanowire catalyst exhibits high oxygen evolution reaction (OER) catalytic activity and stability in alkaline electrolyte, making it a promising OER catalyst.

The relationship between thermal management methods and hydrogen storage performance of the metal hydride tank

Solid-state hydrogen storage tanks are key equipment for fuel cell vehicles and hydrogen storage. However, the low heat transfer properties of hydrogen storage tanks result in the inability to meet the hydrogen supply requirements of fuel cells. In this study, different thermal management approaches were explored through the design of LaNi5-based solid-state hydrogen storage tanks. We experimentally studied the effects of different internal heat transfer methods, that is, expanded natural graphite (ENG), copper foam, and copper fins on the hydrogen absorption and desorption performance. We also studied the effects of external cooling methods with natural convection, air cooling, and water cooling, respectively. Under the same external cooling method of natural convection, a solid hydrogen storage tank filled with 5 wt.% ENG has similar performance to a tank filled with copper foam. Compared to natural convection, air and water cooling can significantly improve the heating performance of metal hydride (MH) beds by increasing the external heat transfer coefficient. The effect of water cooling is better than that of air cooling, and in these two enhanced performance conditions, the tank filled with copper foam performs better than with ENG. In the case of water cooling, by adding copper fins to a hydrogen storage tank filled with 5 wt.% ENG, the tank was saturated with hydrogen absorption in only 29.4 min, which is 55.6 % shorter than the hydrogen uptake time in a hydrogen storage reactor without copper fins. And its stable hydrogen desorption (1 NL/min) has reached 98.1 % of the total hydrogen released. The results show that the effective thermal conductivity and heat transfer area of metal hydride bed play key roles in improving heat transfer and reaction rate. In addition, heat transfer is more important than mass transfer to improve the performance of the hydrogen storage tank.

An experimental study of the effects of porosity and ratio of fin to channel width on water flow boiling in copper foam fin microchannels

Flow boiling in copper foam fin microchannels (FFMC) has demonstrated better heat transfer performance and flow stability. In this work, systematic experiments are conducted to investigate the effects of structural parameters on flow boiling in five FFMCs with porosities ranging from 0.78 to 0.82 and ratios of fin width to channel width ranging from 0.5 to 2. Five mass fluxes ranging from 68 kg/(m2s) to 408 kg/(m2s) and effective heat fluxes ranging from 2 W/cm2 to 297 W/cm2 are tested. The heat transfer, pressure drop, and flow instability characteristics are analyzed. Generally, the heat transfer in FFMCs follows the “three-zone” model. The heat transfer coefficient first increases with increasing heat flux and then decreases. A “synchronous backflow” phenomenon is observed in FFMCs, which is the direct cause of heat transfer deterioration. Due to the interaction of heat transfer area and the transverse flow resistance through the fins, the heat transfer coefficient increases with decreasing porosity in the low-quality region, while the opposite trend is observed in the high-quality region. The utilization efficiency of the fin area decreases as the fin width increases. An optimal ratio of fin width to channel width exists corresponding to the best heat transfer performance, which equals one in this work. A correlation is developed based on 583 data points considering heat transfer mechanisms in channels and fins. The new correlation predicts the experimental values with a mean absolute percentage error of 9 %, and over 99 % of the data are predicted within a 30 % deviation. A performance evaluation criterion is defined to comprehensively compare the FFMCs, and the FFMC with the porosity of 0.78 demonstrates the best flow boiling performance due to higher heat transfer coefficients and lower pumping powers when the ratio of fin to channel width is equal to one.

Electrocatalytic Conversion of Nitrate Into Ammonia Through Heterogeneous Catalysis of NiMoO4 and Cu/Cu2O

AbstractFacilitating equilibrium in the nitrogen cycle, electrochemical nitrate reduction (NitRR) to ammonia stands as a carbon‐free method for ammonia synthesis. Copper‐based catalysts, renowned for NitRR, face a hurdle in supplying sufficient hydrogen radicals (*H) for efficient hydrogenation of NitRR intermediates. Addressing this, NiMoO4 is leveraged as an excellent *H donor, synergistically coupling it with a copper‐based catalyst. The work introduces a high‐performance NiMoO4/CuO nanowire (NW)/Copper foam (CF) catalyst for NitRR, achieving a remarkable Faraday efficiency (FE) of 98.8% and a yield of 0.8221 mmol cm−2 h−1. Operating at −0.2 V versus reversible hydrogen electrode (vs RHE) in an H‐type electrolytic cell, the catalyst demonstrates exceptional stability over 20 h. Additionally, coupling NitRR with an air stripping process enables efficient collection of NH4Cl products, offering a practical avenue for converting waste nitrates into valuable ammonia products. In‐depth in situ electrochemistry and density‐functional theory (DFT) calculations affirm the transformation of CuO into Cu/Cu2O during the electrocatalytic reduction process. Cu/Cu2O catalyzes nitrate conversion to nitrite, while NiMoO4, serving as a *H donor, facilitates deoxidation and hydrogenation of other N intermediates on the Cu/Cu2O surface, effectively driving the reduction of nitrate to ammonia.

Improving vapor condensation via copper foam in capillary-fed photovoltaic membrane distillation

The photovoltaic conversion efficiency of solar cells is significantly constrained by temperature rise. Photovoltaic membrane distillation (PVMD) offers a promising solution for simultaneous solar cell cooling and clean water production. However, the present PVMD system is confronted with the challenge of attaining high cooling efficiency and water production sans reliance on fossil fuels. In this work, a novel and zero-carbon PVMD system is introduced and optimized. One notable improvement is the transportation of feedwater to the backside of the solar cell using capillarity instead of a pumping system. Additionally, a porous copper foam condenser with a rough surface is introduced to the PVMD system. This rough surface creates more nucleation sites for rapid vapor condensation, resulting in a water productivity increase from 0.23 to 0.43 kg m−2 h−1 under 1 sun (=1 kW m−2) irradiation. Furthermore, a 5 cm × 5 cm solar cell demonstrates a temperature decrease from 59.9 to 38.3 °C, accompanied by a voltage enhancement from 2.18 to 2.39 V. This work offers an effective strategy for lowering the operational temperature of solar cells and enhancing the overall utilization efficiency of PVMD devices.

A polyurethane solid–solid phase change material for flexible use in thermal management

Phase change materials (PCMs) have received great attention in thermal management of electronic devices due to their high energy storage density and no need for additional energy supply. Yet the leakage problem after phase change limits their application greatly. In this paper, the block copolymerization was used to prepare a novel solid–solid phase change material (SSPCM) with a melting enthalpy of 90.26 J/g, starting pyrolysis at a temperature of more than 300 °C, and its physicochemical and thermal properties remained basically unchanged after 100 heating/cooling cycles. Notably, this SSPCM has excellent shape stability and can be pressed into phase change film with flexibility, thermally induced self-healing capability and recyclability. Finally, we innovatively combined this SSPCM, copper foam (CF), and polyimide tape (PI) to obtain a composite phase change material (CPCM) with both high thermal conductivity (1.1994 W/m·K) and high electrical insulating properties. Thermal management experiment shows that this CPCM has good thermal management performance and can significantly reduce the temperature rise rate of the simulated CPU. The SSPCM prepared in this study shows great potential for application in thermal management of portable electronic devices and flexible wearable electronic devices.

Refined Pore Structure Design and Surface Modification of 3D Porous Copper Achieving Highly Stable Dendrite‐Free Lithium‐Metal Anode

Abstract3D porous copper is anticipated to serve as an ideal current collector for lithium‐metal anodes (LMAs) owing to its excellent conductivity, huge surface area, and cost‐effectiveness. However, most pertinent studies center around commercial copper foams, where their notable large pore size (150–400 µm) is identified as a primary inducement for dendrite formation and ultimate battery failure. Hence, ensuring the appropriate pore structure in 3D porous copper for achieving highly reversible lithium deposition/stripping process plays a pivotal role in stabilizing LMAs. Herein, the hydrogen bubble template method is employed to fabricate five distinct types of 3D porous copper. Among them, the one with an average surface pore diameter of 25.18 µm and the lowest probability of macropores distribution within the pore walls demonstrates optimal electrochemical performance. To further improve the inherent lithiophobicity of copper, Cu2Se/Cu2O heterostructure nanowires are loaded as kinetic enhanced nucleation sites. Benefiting from the synergistic effect of optimized pore structure and heterostructure nanowires, the Cu2Se/Cu2O@3D Cu composite current collector exhibits excellent dendrite‐free characteristics and outstanding electrochemical performance, showcasing an ultra‐long symmetrical‐cell lifespan of 3000 h at 1 mA cm−2 and stability for 300 h even under 20 mA cm−2.

Effect of Metal Foam’s Volume on the Performance of a Double Pipe heat exchanger

The present numerical study aims to explore the effect of metal foam’s volume on the performance of a double-pipe heat exchanger in comparison with a smooth pipe (HXS). It used water as operating fluid at flow rate 2lpm, the outer stainless steel pipe has outer diameter (Do=60mm) and length (L=609.6mm), and inner copper pipe with outer diameter (do=20mm). The numerical simulation was conducted by ANSYS FLUENT 2020 R2 software and open-cell copper foam (CF) with porosity (0.9) was used. The cases considered in the analysis include a heat exchanger with a complete fill of copper foam (HXF), and a partial fill heat exchanger. The latter was made by inserting a complete rings of copper foam baffles (CFB) to decrease volume of a CF. Then, the baffles volumes was increased by increasing the thickness and their number. Three parameters were varied and their influence on performance evaluate criteria (PEC) were investigated. They are pore density (PPI), thickness of baffles (tc), and number of baffles (nob). Results showed that, heat transfer rate (Qave) and the pressure drop (∆p) increased with increase pore density, and well distribution of a CFB increase thermal performance while the pressure drop did not change with use same volume of CF.

Cu3P Nanoarrays Fabricated on Copper Foam Substrates Followed by Coating with CoFe Layered Double Hydroxide Nanosheets as Electrocatalysts for Water Splitting

Cu₃P Nanoarrays Fabricated on Copper Foam Substrates Followed by Coating with CoFe Layered Double Hydroxide Nanosheets as Electrocatalysts for Water Splitting

Preparation of Flower-like Copper Foam Supported Co3O4 Electrocatalyst and Its Hydrogen Evolution Performance

Preparation of Flower-like Copper Foam Supported Co3O4 Electrocatalyst and Its Hydrogen Evolution Performance

Constructing dendritic arrays composed of copper nanowires loaded with polyaniline for efficient nitrate electroreduction to ammonia

The use of electrochemical method to remove nitrate and reduce it to ammonia under mild conditions has attracted widespread attention. In this study, a dendritic structured electrode composed of polyaniline (PANI) modified copper nanowires was designed and synthesized on copper foam (CF) as the electrocatalytic nitrate (NO3-) reduction reaction (NO3-RR) catalyst. The PANI can not only accelerate the migration of electron, but also provide abundant active sites. The optimized sample exhibited an attractive electrocatalytic ability for NO3- reduction to NH3 with conversion rate, faradaic efficiency, and selectivity of 95.1%, 96.1%, and 98.38%, respectively, at −0.89 V vs reversible hydrogen electrode (RHE). This work provides an efficient and convenient solution for solving nitrate pollution and achieving nitrogen cycling.

Dynamics of bulk and surface oxide evolution in copper foams for electrochemical CO2 reduction

Oxide-derived copper (OD-Cu) materials exhibit extraordinary catalytic activities in the electrochemical carbon dioxide reduction reaction (CO2RR), which likely relates to non-metallic material constituents formed in transitions between the oxidized and the reduced material. In time-resolved operando experiment, we track the structural dynamics of copper oxide reduction and its re-formation separately in the bulk of the catalyst material and at its surface using X-ray absorption spectroscopy and surface-enhanced Raman spectroscopy. Surface-species transformations progress within seconds whereas the subsurface (bulk) processes unfold within minutes. Evidence is presented that electroreduction of OD-Cu foams results in kinetic trapping of subsurface (bulk) oxide species, especially for cycling between strongly oxidizing and reducing potentials. Specific reduction-oxidation protocols may optimize formation of bulk-oxide species and thereby catalytic properties. Together with the Raman-detected surface-adsorbed *OH and C-containing species, the oxide species could collectively facilitate *CO adsorption, resulting an enhanced selectivity towards valuable C2+ products during CO2RR.