High Cathodic Current Density Research Articles

Porous Ni–Fe–Cr electrocatalyst for the oxygen and hydrogen evolution reaction via facile one-step electrodeposition

A high-performance bifunctional Ni–Fe–Cr electrocatalyst with a coral reef-like porous structure was fabricated by facile one-step electrodeposition at a high cathodic current density of 8 A/cm2 for 30 min in an optimal electrodeposition bath containing 80 g/L CrCl3 and 1 M NH4Cl. The highly porous Ni–Fe–Cr electrocatalyst exhibits extremely low overpotential of 234 mV for oxygen evolution reaction (OER) and 13 mVRHE for hydrogen evolution reaction (HER) in 1 M KOH at a current density of 10 mA/cm2, respectively. The excellent performance of the Ni–Fe–Cr electrocatalyst can be attributed to the modulation of the electronic structure due to the incorporation of Cr enhanced performance capabilities of the porous Ni–Fe–Cr originate from the increased electrochemical active surface area (ECSA), which is 22 times larger than that of thin Ni–Fe–Cr. Moreover, the catalyst exhibits high stability towards the OER and HER in an alkaline solution for 36 h. This work offers a facile synthesis method by which to create a highly porous Ni–Fe–Cr electrocatalyst by electrodeposition and a strategy for increasing the catalytic activity by controlling the pore size.

Electrochemical evaluations of reduced graphene oxide for efficient counter electrode in dye-sensitized solar cell

The design and development of an alternative counter electrode (CE) using graphene-based low-cost material for the dye-sensitized solar cell (DSSC) is the major motivation of the current research to replace the traditional platinum counter electrode. Herein, we prepared reduced graphene oxide (rGO) and investigated it for an efficient CE in DSSC. The structural and morphological properties of rGO are analyzed using FESEM, TEM and Raman techniques. The performance of I3- reduction on the CE is characterized by the EIS Nyquist plot, cyclic voltammetry, and the Tafel curve. The measured electrochemical results suggested that rGO CE has a lower charge transfer resistance (Rct), higher cathodic current density (Jrd), and higher Tafel slope as compared to graphene oxide (GO) CE, revealing that rGO CE has good catalytic activity towards the I3- reduction.

Influence of applied magnetic field in an air-breathing microwave plasma cathode

The air-breathing electric propulsion concept refers to a spacecraft in very-low Earth orbit (VLEO) ingesting upper atmospheric air as propellant for an electric thruster. This compensates atmospheric drag and allows the spacecraft to maintain its orbital altitude, removing the need for on-board propellant storage and allowing an extended mission duration which is not limited by propellant exhaustion. There is a need for development of a robust, high current density and long life cathode (or neutralizer) for air-breathing electrostatic thrusters as conventional thermionic hollow cathodes are susceptible to oxygen poisoning. An Air-breathing Microwave Plasma CAThode is proposed to overcome this issue through the use of a microwave plasma discharge, producing an extracted current in the order of 1 A with 0.1 mg s−1 of air. In this paper, the effect of varying magnetic-field strength and topology is investigated by using an electromagnet coil, which reveals a significantly different behaviour for air compared to xenon. The extracted current with xenon increases by 3.9 times from the zero-field value up to a peak around 150 mT magnetic-field strength at the antenna, whereas an applied field does not increase the extracted current with air at nominal conditions. A non-zero magnetic-field with air is however beneficial for current extraction at reduced neutral densities. A distinct increase in extracted current is identified at low bias voltages with air for a field strength of around 50 mT at the internal microwave antenna, consistent across varying field topologies. The effect of a lowered magnetic-field strength in the orifice region is investigated through the use of a secondary coil, resulting in an extracted current increase of 25% for a relaxation from 6 mT to 1 mT, and demonstrating the beneficial impact of a locally reduced field strength on electron extraction.

Prototype experiments of the low voltage mineral deposition technology as eco-friendly solution for improving the sustainability of offshore platforms at the end of their production life

Several oil and gas offshore platforms are approaching the end of their production life, thus requiring sounding sustainable management solutions. This study aimed to improve the current knowledge on the low voltage mineral deposition technology as an eco-friendly strategy to protect offshore platforms from corrosion and to create suitable substrates for the colonization and growth of sessile marine organisms, thus minimizing environmental impact due to metal release, supporting biodiversity and increasing ecological sustainability. To do so, experimental prototype structures were installed in the Ligurian Sea (NW Mediterranean Sea) with the aim to simulate the sub-merged parts of offshore platforms and to analyze over time (up to ca. 6 months), elemental and chemical composition, growth rates and corrosion protection ability of the minerals deposited on steel substrates, through the alkalization induced by cathodic polarization of the metal. The influence of operational (applied current density) and natural environmental parameters on the deposition process was investigated. Results of this experiment revealed that in general the mineral deposits were mainly composed by aragonite (CaCO 3 ) and brucite (Mg(OH) 2 ) and, more specifically, the amount of the latter prevails a little bit on the amount of the former. This result is most likely related to high cathodic polarization current densities reached during the experimentation. Despite brucite is expected to worsen the physical–mechanical​ characteristics of the mineral deposits, the overall deposits were able to protect to a certain extent the electrified steel material from corrosion. After about 6 months of induced mineral deposition, the layer over the steel reached the maximum thickness of about 2.4 mm, following a non-linear trend as a function of time, whereas the deposition rates ranged from 20.0 to 50.3 μ m d −1 , in relation with the applied current densities. At the same time, a positive relationship of the deposit grow rates with seawater temperature has been observed. Overall, the outcomes reported in this study provide new elements for the application of low voltage mineral deposition technology in temperate seas and pave the way for defining the best operating conditions to protect steel structures from corrosion and support biodiversity, thus contributing to the sustainability of the natural capital. • Offshore platform decommissioning is a complex issue, deserving attention. • Mineral induced deposition on steel structures represents an eco-friendly strategy. • Modulation of cathodic current densities plays a crucial role on mineral accretion. • The obtained mineral deposits were found as a promising solution against corrosion. • This investigation shows the role of key parameters controlling mineral deposition.

Intimate triple phase interfaces confined in two-dimensional ordered mesoporous carbon towards high-performance all-solid-state lithium-sulfur batteries

All-solid-state lithium-sulfur battery (ASSLSB) is one of the most promising next-generation energy storage devices while confronting great challenges for practical applications, in particular the sluggish reaction kinetics of the insulating active materials, less solid-solid contact, and insufficient electronic/ionic conduction networks within cathode layer. Herein, a two-dimensional (2D) ordered mesoporous carbon (OMC) framework is developed and serves as an advanced host for active material Li2S and solid electrolyte Li6PS5Cl (LPSC), forming a mixed conductive nanocomposite with 5 orders and 12 orders of magnitude increase in ionic and electronic conductivities compared with Li2S, respectively. The ordered mesoporous in OMC provide confined space for the intimate contact between nanosized Li2S and LPSC, which are favorable for continuous lithium-ion transport and increasing Li2S utilization. Benefiting from these merits, the ASSLSBs employing Li2S/OMC/LPSC nanocomposite achieve high reversible capacity and excellent cyclic performance at both high current density and high cathode loading.

Zero-Compression, Laminar Electron Beams From Convex Cathodes in Uniform Magnetic Fields

The need for enhanced performance of high-power RF vacuum electron devices has led to the investigation of multiple-beam, sheet beam, and annular beam configurations. A key issue with such devices is the magnetic field shaping required producing high-power, laminar beams. Field shaping is difficult when Pierce-type gun geometries are employed. The development of high current density cathodes makes the necessary beam power achievable without compression. Such cathodes can operate within a uniform magnetic field yielding advantages for both single and distributed-beam RF devices. However, the quality of the resulting beams presents problems. A project to optimize beam quality in zero-convergence electron guns was undertaken by Calabazas Creek Research, Inc. (CCR) and North Carolina State University (NCSU). The surprising result was that high-quality electron beams can be generated in uniform magnetic fields using convex (dome)-shaped cathodes. The underlying physics involves perturbation of the beam cyclotron motion by a nonadiabatic radial electric field impulse. This article examines this physical mechanism and extends the initial result to additional diode and beam geometries.

Cost effective dye sensitized solar cell based on novel Cu polypyrrole multiwall carbon nanotubes nanocomposites counter electrode

In order to replace Pt CE in dye sensitized solar cell (DSSC) with simple and low cost, copper polypyyrol functionalized multiwall carbon nanotubes (Cu-PPy-FWCNTS) nanocomposite CE was fabricated by two step electrodeposition method on the stainless-steel substrate. The surface morphology, electrical conductivity, electrochemical properties of Cu-PPy-FWCNTS nanocomposite CE electrodes were observed by using verity of techniques such as scanning electron microscopy, a four-probe method and electrochemical workstation. The Fourier transform infrared (FTIR) spectroscopy confirms the presence of FMWCNTS into PPy-FMWCNTS nanocomposite and XRD analysis verified the Cu nanostructures had come into being. The cyclic voltammogram and Tafel polarization measurement demonstrated that solution processed Cu-PPy-FWCNTS nanocomposites CE had smaller charge transfer resistance Rct (4.31 Ω cm2) and higher electrocatalytic performance for I3−/I− redox solution. Finally, the photovoltaic efficiency of DSSC assembled with Cu-PPy-FWCNTS nanocomposite CE and Platinized CE were compared. The results revealed that the photovoltaic efficiency of DSSC with Cu-PPy-FWCNTS nanocomposites CE reached (7.1%), which is superior to Platinized CE (6.4%). The higher photovoltaic efficiency of the Cu-PPy-FMWCNTS film is due to copper nanostructures that lead to higher cathodic current density (2.35 mA/cm2). The simple fabrication method, excellent electrocatalytic and photovoltaic properties permit the Cu-PPy-FWCNTS nanocomposites credible alternative CE to save the cost of DSSC.

High-performance electrocatalytic and cationic substitution in Cu2ZnSnS4 as a low-cost counter electrode for Pt-free dye-sensitized solar cells

Herein, we report the synthesis of quaternary chalcopyrite sulfide semiconductors Cu2MSnS4 (M = Zn, Ni, Co, Mn, Fe) by a hydrothermal process. The formation of kesterite structure was confirmed by XRD. XPS analysis confirmed the composition of Cu–(Zn, Ni, Co, Mn, Fe)–Sn–S. Morphologies of the hierarchical structures were characterized. Hall measurements revealed that the Zn was replaced with Ni which exhibited higher carrier density and lower resistivity. Cyclic voltammetry measurements showed peak-to-peak separation (Epp) value of Cu2NiSnS4 about 268 mV, which was smaller than that of Cu2ZnSnS4, and a higher cathodic current density (Ic) of 0.000334 mA cm−2 compared to those of Pt. This indicated that the electrocatalytic activity of Cu2NiSnS4 was better for the I−/I3− redox reaction, with a long-term stability for 250 cycles.

Mechanism of the Electrochemical Deposition of a CoNiFe Alloy

Heating the chloride electrolyte to a temperature of 70°C ensures the normal codeposition of the components of the CoNiFe alloy as a result of the discharge of single-charged iron and cobalt species (Fe2+Cl-)+ and (Co2+Cl-)+, respectively and double-charged Ni2+ ions at a high cathode current density. The chloride electrolyte obtained with filtration and pH correction by hydrochloric acid provides the electrochemical deposition of CoNiFe films with a CCo:CNi:CFe ratio of 1:1:1. The mechanism of the abnormal deposition of Co, Fe and Ni occurs due to the incomplete ionization of atoms and differences in ion mobility. Based on the experimental results of CoNiFe films, an electrochemical deposition mechanism is proposed. In contrast to the well-known in the literature, the phenomena occurring in the volume of electrolyte, including transmission of ions, with the determining effect is the mobility and formation of positive ions on the anode. CoNiFe films are produced without mechanical stresses, with a uniform structure and with high magnetic parameters without a high burn temperature. Electrochemical deposition when the charge of ions in the electrolyte is taken into account allows to obtaining a reproducible electrochemical deposition of CoNiFe films.

Electrochemical Relithiation for Direct Regeneration of LiCoO2 Materials from Spent Lithium-Ion Battery Electrodes

Increased generation of spent lithium-ion batteries (LIBs) has driven the exploration of new methods for reusing and/or recycling LiCoO₂ cathode materials. Herein, an electrochemical relithiation method was proposed to directly regenerate LiCoO₂ cathode materials using the waste LiₓCoO₂ electrode as a base. It was shown that Li⁺ was successfully inserted into the waste LiₓCoO₂ electrode, and this relithiation process became faster with either a higher Li₂SO₄ concentration or a higher cathodic current density. The XRD analysis confirmed that the peak positions of the relithiation products were consistently close to those of a standard LiCoO₂ material. The crystal structure of the relithiation products was restored with a post-annealing process. The activation energy for electrochemical relithiation (Eₐ) was estimated at 22 kJ mol–¹, and the constant of equilibrium constant k₀ was determined as 1.35 × 10–⁶ cm s–¹. The relithiation process was controlled by the charge transfer process when the Li₂SO₄ concentration was high (e.g., 1, 0.8, and 0.5M), and a lower concentration at 0.01–0.3 M led to a diffusion control pattern. The electrode made of the regenerated LiCoO₂ materials had a charge capacity of 136 mAh g–¹, close to that of the commercial LiCoO₂ electrode (140 mAh g–¹). A potential mechanism of electrochemical relithiation was proposed involving lithium defects, relithiation, and crystal regeneration.

Influence of surface condition on the current densities rendering nucleation loop during cyclic voltammetry for electrodeposition of Pd thin films

ABSTRACT Cyclic voltammetry (CV) for Pd electrodeposition on Au from PdCl2+HCl solution between +1.100 and –0.400 V vs Ag/AgCl (3M NaCl) was performed. The CVs exhibit nucleation loop (NL), which can be characterized by higher cathodic current density (j) in the reverse scan rather than that in the forward scan. The reasons for the appearance of NL are investigated by making use of the surface condition of electrode and overpotential (η). Since it is difficult to estimate η during CV, it was obtained by potentiostatic electrodepositions (ED) on the substrates with similar surface conditions as those within NL. These substrates were produced by a potential sweep in (i) forward (FS) and (ii) forward+reverse (RS) scans from open circuit potential up to a representative potential (+0.330 V) within NL. These FS and RS substrates possess partial and significant Pd coverage, respectively. ED at +0.330 V on these substrates shows similar j trends in the initial stages as in NL. η during ED is estimated from the equilibrium potentials and the potential drop due to solution resistance (Rs). Rs is obtained from electrochemical impedance spectroscopy at +0.330 V. The estimated η is higher on RS, supporting higher j during electrodeposition on RS and reverse scan of CV within NL. Electrochemical and morphological analyses suggest that Pd deposition on the FS is nucleation driven whereas that on the RS is growth driven with the surface condition playing an important role in the appearance of NL during CV.

Corrosion and Alloy Engineering in Rational Design of High Current Density Electrodes for Efficient Water Splitting

AbstractAlongside rare‐earth metals, Ni, Fe, Co, Cu are some of the critical materials that will be in huge demand thanks to growth in clean‐energy sector. Herein scrap stainless steel wires (SSW) from worn‐out tires are employed as a support material for catalyst integration in the hydrogen evolution reaction (HER). In addition, SSW by corrosion engineering is exercised as an in situ formed freestanding robust electrode for the oxygen evolution reaction (OER). By superficial corrosion of SSW, inherent active species are unmasked in the form of Ni/FeOOH nanocrystallites displaying efficient water oxidation by reaching 500 mA cm−2 at low overpotential (η500) of 287 mV in 1 m KOH. Similarly, cathode scrap SSW with active (alloy) coatings of MoNi4 catalyzes the HER at η‐200 = 77 mV, with a low activation energy (Ea = 16.338 kJ mol−1) and high durability of 150 h. Promisingly, when used in industrial conditions, 5 m KOH, 343 K, these electrodes demonstrate abnormal activity by yielding high anodic and cathodic current density of 1000 mA cm−2 at η = 233 mV and η = 161 mV, respectively. This work may inspire researchers to explore and reutilize high‐demand metals from scrap for addressing critical material shortfalls in clean‐energy technologies.

On the Nucleation Loop in Cyclic Voltammetry for Electrodeposition of Pd Thin Films

Pd is an excellent catalyst layer for Mg-based thin films for hydrogen storage. Cyclic voltammetry (CV) for Pd deposition on Au in PdCl2+HCl solution between +1.100 and –0.400 V vs Ag/AgCl (3M NaCl) exhibits nucleation loop (NL). NL is characterized by higher cathodic current density (j) in reverse scan versus that in forward scan. This work addresses the question “Why does nucleation loop occur during CV?” using substrate conditions and overpotential (η). Since it is difficult to estimate η during CV, the substrate conditions similar to those within NL are reproduced by potential sweep in (i) forward and (ii) complete forward+reverse scans up to a representative potential (+0.330 V) within NL. These scans produce substrates FS and RS with partial and significant Pd coverage, respectively. Eventual potentiostatic electrodepositions (ED) at +0.330 V on these substrates initially show similar j trends as in NL, replicating Pd deposition during CV. η during ED is estimated by equilibrium potentials and potential drop due to solution resistance (R s) from electrochemical impedance spectroscopy at +0.330 V. The estimated η is higher on RS, supporting higher j during electrodeposition on RS and reverse scan of CV within NL. Electrochemical and morphological analyses together suggest that Pd deposition on FS is nucleation driven; that on RS is growth driven, which help in revealing the metal deposition mechanisms.

Influence of Current Density on the Microstructure of Carbon-Based Cathode Materials during Aluminum Electrolysis

Sodium expansion plays an important role in cathode deterioration during aluminum electrolysis. In this work, the sodium expansion of semigraphitic cathode material has been measured at various cathodic current densities using a modified Rapoport apparatus. We have studied the microstructural changes of carbon cathodes after aluminum electrolysis using high-resolution transmission electron microscopy (HRTEM). Because of an increasing trend toward higher amperage in retrofitted aluminum reduction cells, an investigation is conducted both at a representative cathode current density (0.45 A/cm2) and at a high cathodic current density (0.7 A/cm2). The results indicate that the microstructures of carbon cathodes can be modified by Joule heating and electrostatic charging with higher current densities during aluminum electrolysis. With the penetration of the sodium and melt, zigzag and armchair edges, disordered carbon, and exfoliation of the surface layers may appear in the interior of the carbon cathode. The penetration of the sodium and melt causes remarkable stresses and strains in the carbon cathodes, that gradually result in performance degradation. This shows that increasing the amperage in aluminum reduction cells may exacerbate the material deterioration of the cathodes.

First-principles study of the electronic properties of graphene nanostructures for high current density cathodes

Graphene is a crystalline allotrope of carbon with 2D properties. Its carbon atoms are densely packed in a nanoscale hexagonal pattern. Graphene has many unusual properties. In this study, the authors study the electronic properties of graphene nanostructures using first-principles or ab initio calculations based on density functional theory as implemented in the Vienna ab initio simulation package in order to explore its applications in field-emission devices. The density of states and work function of graphene nanoribbons are calculated. The work function value is a key parameter in determining the field emission from a cathode surface according to the Fowler–Nordheim theory. For practical applications, the work functions of graphene nanoribbons with different widths and terminating edges, with and without passivation, have been investigated. Specifically, with the decoration of different alkali and alkaline earth metal species, the reduction of the work function has been systematically studied and determined for achieving higher current density emission.

Microwave-Initiated Synthesis of Metal Chalcogenides/Graphene-Catalyst for Enhanced Hydrogen Evolution Reaction

In present days, new types of renewable energy resources are being developed to resolve the world energy crisis. Nanomaterials, such as carbon nanotubes, metal oxides, metal chalcogenides (MCs) and conducting polymers with superior mechanical, thermal and electrical properties, lead to broad applications in composite materials, smart structures, chemical sensors, energy storage and nano-electronic devices. However, the high cost and difficulty in producing large scale, high quality nanomaterials remain challenges. The present work successfully demonstrates the production of MCs on graphene substrate through ultra-fast (60 seconds), facile and energy-efficient microwave-initiated approach. Graphene plays a vital role during the synthesis process by absorbing microwave energy and converting it to heat energy, which facilitates the precursors to react vigorously. Moreover, high specific surface area and conductivity of graphene delivers a favorable conductive network for the uniform growth of MCs, along with rapid charge transfer kinetics. The electrochemical characterizations reveal that the as-produced nanocomposites can be used for hydrogen evolution reaction (HER) to generate useful hydrogen fuel. As an example, the molybdenum disulfide on graphene (MoS2/graphene) composite exhibits superior electrocatalytic activity for the HER in acidic medium, with a low onset potential of only 100 mV and a Tafel slope of 43.3 mV per decade, suggesting the Volmer-Heyrovsky mechanism of hydrogen evolution. Beyond excellent catalytic activity, MoS2/graphene reveals an unusual ability to enhance the accessible active sites during the HER proceeds. This leads to a long cycling stability with a very high cathodic current density, providing the opportunity of practical application for scalable processing. Therefore, this single-step microwave approach can be universally employed to produce other useful MCs (e.g., MoSe2, WS2, WSe2 etc.), that will catalyze substantial development in more widespread uses of MC-based nanocomposites for successful energy applications.

Facile microwave approach towards high performance MoS2/graphene nanocomposite for hydrogen evolution reaction

Low-cost, highly efficient catalysts for hydrogen evolution reaction (HER) are very important to advance energy economy based on clean hydrogen gas. Intensive studies on two-dimensional molybdenum disulfides (2D MoS2) have been conducted due to their remarkable catalytic properties. However, most of the reported syntheses are time consuming, complicated and less efficient. The present work demonstrates the production of MoS2/graphene catalyst via an ultra-fast (60 s) microwave-initiated approach. High specific surface area and conductivity of graphene delivers a favorable conductive network for the growth of MoS2 nanosheets, along with rapid charge transfer kinetics. As-produced MoS2/graphene nanocomposites exhibit superior electrocatalytic activity for the HER in acidic medium, with a low onset potential of 62 mV, high cathodic currents and a Tafel slope of 43.3 mV/decade. Beyond excellent catalytic activity, MoS2/graphene reveals long cycling stability with a very high cathodic current density of around 1000 mA cm−2 at an overpotential of 250 mV. Moreover, the MoS2/graphene-catalyst exhibits outstanding HER activities in a temperature range of 30 to 120°C with low activation energy of 36.51 kJ mol−1, providing the opportunity of practical scalable processing.

Electrocatalytic performance of reduced graphene oxide supported nano-NiZnO2 for oxygen reduction reaction

Development of highly efficient and low-cost electrocatalysts for oxygen reaction is of high importance for the commercialization of fuel cells. In the present study, we synthesized the hybrid of reduced graphene oxide (rGO) supported NiZnO2 nanoparticles (NPs) as highly efficient non-precious-metal electrocatalysts for oxygen reduction reaction (ORR). The NiZnO2 NPs composed of ∼8 nm being relatively well distributed and strongly anchored on rGO. Electrochemical test reveals that the NiZnO2/rGO exhibits excellent electrocatalytic activity towards ORR, in terms of positive onset potential (0.80 V), high cathode current density (3.49 × 10−4), and low H2O2 yield (about 2%). The mechanism analysis shows that it favors the 4-electron pathway for the reduction of oxygen. Furthermore, the NiZnO2/rGO exhibits excellent electrochemical performance in term of durability.

Synthesis of high performing Cu0.31Ni0.69O/rGO hybrid for oxygen reduction reaction in alkaline medium

Abstract In this feature article, Cu0.31Ni0.69O nanoparticles were assembled on reduced graphene nanosheets (Cu0.31Ni0.69O/rGO) by a simple hydrothermal method. The structural characterizations confirm that the synthesized nanoparticles with an average size around 9 nm are densely and uniformly assembled on the reduced graphene oxide (rGO) nanosheets. The electrochemical measurements demonstrate that the as-synthesized Cu0.31Ni0.69O/rGO catalyst exhibits excellent catalytic performance for oxygen reduction reaction with high cathodic current density (2.08 × 10−4 mA/cm2), positive onset potential (−0.21 V), low H2O2 yielding rate (less than 2.5%) and long-term running stability. The rotating disk and rotating ring-disk electrode measurements proved that the oxygen reduction reaction occurs on Cu0.31Ni0.69O/rGO through a high efficient four-electron pathway. The Cu0.31Ni0.69O/rGO nanoparticles shows great potential to be promising noble metal-free catalyst for cathodes of alkaline fuel cells.

Hollow mesoporous nickel dendrites grown on porous nickel foam for electrochemical oxidation of urea

The macroporous nickel foam (NF) with attached hollow mesoporous nickel dendrites (NF@p-Ni) was prepared through electrochemical deposition of copper-nickel dendrites on the NF (NF@CuNi) followed by selective removal of the copper cores. The deposition process under high cathodic current density in an acidic solution favored the formation of hydrogen bubbles which acted as a template for the subsequent growth of macroporous dendritic copper-nickel film with 10 μm scale pores. The copper appeared to play an important part in the growth of dendritic shape and hollow porous structure on the porous and conductive NF framework. In the electrochemical oxidation of urea, the NF@p-Ni electrode could offer abundant electroactive sites and porous channels for increasing the oxidation current density and efficiency compared to the NF@CuNi electrode. The NF@p-Ni electrode featuring macroporous catalyst layer of hollow dendrites on highly conductive NF framework expedited the charge-transfer reaction of urea electrooxidation and the evolution of gaseous products. Thus, the current density and efficiency of NF@p-Ni could reach 141 mA cm−2 and 82%, respectively, higher than those of NF@CuNi (110 mA cm−2 and 72%, respectively) in catalyzing the electrochemical oxidation of urea molecules at 0.60 V versus saturated calomel electrode.