A highly efficient A-site deficient perovskite interlaced within two dimensional MXene nanosheets as an active electrocatalyst for hydrogen production

We report a unique composite of La_0.4Sr_0.4Ti_0.9Ni_0.1O_3-δ (LSTN) nanoparticles interlaced with two dimensional Ti₃C₂T_x (MXene) nanosheets, providing high conductivity. LSTN heterostructure synthesized by the sol-gel method produces a large oxygen vacancy and creates a variable valence state while, MXene synthesized from Hydrofluoric acid (HF) treatment resulted in a highly hydrophilic and conductive surface, thereby enhancing the charge transferability. For OER, the LSTN/MXene 66.67% electrode exhibits a benchmark of 10 mA cm^?2 at a potential of 1.56 (V vs RHE) in 1 M KOH. It has exhibited the lowest Tafel slope of 44 mV dec^?1 and highest mass activity (60 mA g^?1 @ 1.59 V) due to quicker ions diffusion and increased available exposed area. Moreover, the efficient LSTN/MXene 66.67% electrode showed good long-term durability during a 24 h stability test at a current density of 100 mA cm^?2. The strong interfacial interaction and high charge transfer among LSTN nanoparticles and 2D MXene nanosheets not only provide good structural strength to the composite but also improves the redox activity of LSTN/MXene 66.67% catalyst towards OER. This work provides improved conductive properties of perovskite by developing a composite of perovskite and MXene, that has significantly enhanced electrochemical properties of the catalyst by undergoing fast kinetics.     

Effects of phosphotungstic acid on performance of phosphoric acid doped polyethersulfone-polyvinylpyrrolidone membranes for high temperature fuel cells

Heteropoly acids have been employed to increase the proton conductivity of phosphoric acid (PA) doped polymer membranes for high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). In this work, we develop a new composite membrane based on phosphotungstic acid (PWA) doped polyethersulfone-polyvinylpyrrolidone (PES-PVP) matrix, forming PWA/PES-PVP composite membrane for HT-PEMFCs. The homogeneous distribution of PWA on the PES-PVP membrane enhances its mechanical strength. In addition, there is a strong interaction between PWA and PA that is confirmed experimentally by the attenuated total reflectance Fourier Transform Infrared spectroscopy and semi-empirical quantum mechanics calculation. This enhances not only the PA uptake but also the proton conductivity of the PWA/PES-PVP composite membrane. ¹H nuclear magnetic resonance spectroscopy results elucidate that the high proton conductivity of the PA doped PWA/PES-PVP membranes is due to their higher proton content and mobility compared to the pristine PA doped PES-PVP membrane. The best results are observed on the PES-PVP composite membrane with addition of 5 wt% PWA, reaching proton conductivity of 1.44 × 10^?1 S cm^?1 and a peak power density of 416 mW cm^?2 at 160 °C and anhydrous conditions. PWA additives increase the proton conductivity and cell performance, demonstrating significantly positive effects on the acid-base composite membranes for high temperature polymer electrolyte membrane fuel cell applications.     

Robust proton exchange membrane for vanadium redox flow batteries reinforced by silica-encapsulated nanocellulose

High ion selectivity and mechanical strength are critical properties for proton exchange membranes in vanadium redox flow batteries. In this work, a novel sulfonated poly(ether sulfone) hybrid membrane reinforced by core-shell structured nanocellulose (CNC-SPES) is prepared to obtain a robust and high-performance proton exchange membrane for vanadium redox flow batteries. Membrane morphology, proton conductivity, vanadium permeability and tensile strength are investigated. Single cell tests at a range of 40–140 mA cm⁻² are carried out. The performance of the sulfonated poly(ether sulfone) membrane reinforced by pristine nanocellulose (NC-SPES) and Nafion® 212 membranes are also studied for comparison. The results show that, with the incorporation of silica-encapsulated nanocellulose, the membrane exhibits outstanding mechanical strength of 54.5 MPa and high energy efficiency above 82% at 100 mA cm⁻², which is stable during 200 charge-discharge cycles.     

Enhanced proton conductivity of Nafion membrane with electrically aligned sulfonated graphene nanoplates

To increase the conductivity of proton exchange membranes in the membrane thickness direction, a novel mixed matrix membrane of Nafion ionomer and sulfonated graphene nanoplates (sGNP) with aligned proton channels is prepared with the assistance of an electric field. A high voltage alternative electric field is applied to a casting solution consisting of Nafion ionomer, sGNP, N, N-dimethylformamide (DMF), and p-xylene (PX) while evaporating the solvents. The sGNP, naturally attracting the ionic groups of Nafion ionomer to their vicinity, is polarized and rotated under the electric field, leaving aligned proton channels in the solidified membrane. The trans-plane proton conductivity of the mixed matrix membrane can reach 0.155 S cm^?1 at 80 °C and 100% RH, an increase of 48% as compared with the conventional cast Nafion membrane. Accordingly, the peak power output of H₂/O₂ fuel cell with the mixed matrix membrane increases by 15%, reaching 440 mW cm^?2 at 80 °C.     

Immobilizing imidazolium ionic liquid in flexible proton exchange membranes to modify microstructure fracture

The imidazolium ionic liquid of (Kevlar/bmimCl/SEBS)₅ membrane was immobilized in flexible proton exchange membranes (PEMs) with the spin coating technology. In the prepared (Kevlar/bmimCl/SEBS)₅ membrane, the imidazolium ionic liquid of 1-butyl-3-methylimidazolium chloride (bmimCl) functioned as glue to modify the microstructure fracture from the stretching operation through occupying the cracks. The proton conduction resistance was reduced with the well-ordered distribution of components in the multilayered microstructure. Although the doped phosphoric acid (PA) molecules charged the proton conductivity, the imidazolium cations of bmim⁺ could participate in the proton conduction through the formation of continuous proton conduction channels. In this research, the folding and stretching operations exerted the negligible effect on microstructure and property of the prepared PEMs. Besides the modification of bmimCl, the deformation of polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SBES) molecular chains and Kevlar nanofibers in the stretching operation contributed to maintain the stable microstructure. The stretching and folding operations led to slight variation on the membrane property. Specifically, the proton conductivities were respectively 3.21 × 10^?2 S/cm and 4.16 × 10^?2 S/cm at 160 °C, which were even superior to 2.77 × 10^?2 S/cm of the pristine membranes. Furthermore, the tensile stress values of the folding and stretching membranes can reach (18.9 ± 1.19) MPa and (32.6 ± 2.63) MPa.     

Phosphoric acid doped composite proton exchange membrane for hydrogen production in medium-temperature copper chloride electrolysis

A copper chloride (CuCl) electrolyzer that constitutes of composite proton exchange membrane (PEM) that functions at medium-temperature (>100 °C) is beneficial for rapid electrochemical kinetics, and better in handling fuel pollutants. A synthesized polybenzimidazole (PBI) composite membrane from the addition of ZrO₂ followed with phosphoric acid (PA) is suggested to overcome the main issues in CuCl electrolysis, including the copper diffusion and proton conductivity. PBI/ZrP properties improved significantly with enhanced proton conductivity (3 fold of pristine PBI, 50% of Nafion 117), superior thermal stability (>600 °C), good mechanical strength (85.17 MPa), reasonable Cu permeability (7.9 × 10⁻⁷) and high ionic exchange capacity (3.2 × 10⁻³ mol g⁻¹). Hydrogen produced at 0.5 A cm⁻² (115 °C) for PBI/ZrP and Nafion 117 was 3.27 cm³ min⁻¹ and 1.85 cm³ min⁻¹, respectively. The CuCl electrolyzer efficiency was ranging from 91 to 97%, thus proven that the hybrid PBI/ZrP membrane can be a promising and cheaper alternative to Nafion membrane.     

A highly proton conductive membrane based on hydrolyzed NbCl5 and phytic acid

It is vital to choose economical and environmentally friendly proton conductive materials to improve the performance of proton exchange membranes, which occupies a unique position in proton exchange membrane fuel cells. This paper reports a new proton conductive nanocomposite, that was named NbO₂(OH)-PA prepared from phytic acid (PA) and NbCl₅. NbO₂(OH)-PA showed an excellent proton conductivity of 135 mS cm⁻¹ at 85 °C and 97% relative humidity. In addition, NbO₂(OH)-PA was combined with sulfonated poly (ether ketone) (SPEEK) in different proportions to form proton conductive membranes, that are labeled SPEEK-x NbO₂(OH)-PA. SPEEK-0.9% NbO₂(OH)-PA exhibited the best proton conductivity of 0.17 S cm⁻¹ at 80 °C in water. This work may provide new ideas for improving proton conductivity of membranes through simple methods.     

Role of UV irradiated Nafion in power enhancement of hydrogen fuel cells

The influence of optimum UV ray exposure of pristine Nafion polymer membranes on the improvement of proton conductivity and hydrogen fuel cell performance has been examined. Nafion membranes with thickness 183  μm (117), 90  μm (1035), 50  μm (212) and 25  μm (211) were irradiated with ultraviolet rays with doses in the range 0–250 mJ cm^?2 and their proton conductivities have been measured with standard method. The Nafion membranes have also been studied by measuring their water uptake, swelling-ratios and porosity using standard procedures. Hydrogen fuel cells with dual serpentine microchannels with active area 1.9 x 1.6 cm^-2 were assembled with anode gas diffusion layer, Nafion membrane, cathode gas diffusion layer and other components. An external humidifier was used to humidify hydrogen for the fuel cell. The experimental Results have shown an increase in the value of Nafion proton conductivity with an optimum UV irradiation which depends on the thickness of Nafion membrane: the optimum doses for peak proton conductivity were 196mJ/cm^?2 for Nafion 117, 190mJ/cm^?2for Nafion 1035, 180mJ/cm^?2 for Nafion 212 and 160mJ/cm^?2 for Nafion 211. This enhancement of proton conductivity is because of the optimal photo-crosslinking of –SO₃H groups in Nafion. This causes optimum pore-size in Nafion thereby facilitating increased proton-hopping between –SO₃H sites in Nafion. Hydrogen fuel cells were developed with pristine as well as with optimal UV irradiated Nafion with thicknesses of 90 and 50  μm. The polarization plots obtained for these devices showed an increase in power densities approximately by a factor of 1.8–2.0 for devices with optimally UV irradiated Nafion. These results indicate that optimal UV irradiation of Nafion is an excellent technique for enhancing power output of hydrogen fuel cells.     

Facile synthesis of MWO4 (M=Co,Ni, Zn and Cu) nanoarrays for efficient urea oxidation

Urea electrolysis is an attractive strategy for hydrogen evolution, which can reduce the environmental pollution caused by urea-rich wastewater. It is important to note that catalytic performance depends on the electron cloud density configuration around different metals of the same type of material. Herein, a series of well-tuned MWO₄ (M = Co, Ni, Zn and Cu) nanoarrays was in site grown on Ni foam substrates using a single-step hydrothermal process for the first time. It is worth mentioning that as prepared NiWO₄ electrode significantly improves urea oxidation activity with an applied voltage of 1.36 V at 100 mA cm^?2, which is lower than that of CoWO₄ (1.37 V@100 mA cm^?2), ZnWO₄ (1.38 V@100 mA cm^?2) and CuWO₄ (1.42 V@100 mA cm^?2). Experimental and theoretical calculations demonstrate that the superior activity of the electrodes is mainly attributed to the optimal urea adsorption energy, fast electron transfer rate, more active site exposure, lower impedance and better conductivity of the material.     

Amino acid-functionalized metal organic framework with excellent proton conductivity for proton exchange membranes

Proton conduction is a ubiquitous fundamental phenomenon in biological systems. Biology has solved the problem of energy-related proton conduction, in which the exposed amino acids in the protein ordered channels play a key role in proton conduction. In this contribution, amino acids (glutamate, lysine, and threonine) were attached to metal organic framework (MOF) nanoparticles, which were incorporated into sulfonated polysulfone matrix forming bio-proton channels for the nanocomposite membranes. It is shown in the results that the amino acid-functionalized MOF can help to enhance the proton conductivity and the proton exchange membrane with glutamate-functionalized MOF demonstrate excellent proton conductivity of 0.212 S cm^?1 at 80 °C and 100% relative humidity. Meanwhile, the methanol permeability coefficient of the nanocomposite membrane is reduced to 5.8 × 10^?7 cm² s^?1. The nanocomposite membranes demonstrate excellent proton conductivity, dimensional stabilities, water absorption, and resistance to methanol performance. Therefore, this material is promising for fuel cells.     

Improved proton conduction of sulfonated poly (ether ether ketone) membrane by sulfonated covalent organic framework nanosheets

A type of sulfonated covalent organic framework nanosheets (TpPa-SO₃H) was synthesized via interfacial polymerization and incorporated into sulfonated poly (ether ether ketone) (SPEEK) matrix to prepare proton exchange membranes (PEMs). The densely and orderly arranged sulfonic acid groups in the rigid skeleton of the TpPa-SO₃H nanosheets, together with their high-aspect-ratio and well-defined porous structure provide proton-conducting highways in the membrane. The doping of TpPa-SO₃H nanosheets led to an increased ion exchange capacity up to 2.34 mmol g^?1 but a 2-folds reduced swelling ratio, remarkably mitigating the trade-off between high IEC and excessive swelling ratio. Based on the high IEC and orderly arranged proton-conducting sites, the SPEEK/TpPa–SO₃H–5 membrane exhibited the maximum proton conductivity of 0.346 S cm^?1 at 80 °C, 1.91-folds higher than the pristine SPEEK membrane. The mechanical strength of the composite membrane was also improved by 2.05-folds–74.5 MPa. The single H₂/O₂ fuel cell using the SPEEK/TpPa–SO₃H–5 membrane presented favorable performance with an open voltage of 1.01 V and a power density of 86.54 mW cm^?2.     

Enhanced proton conduction in zirconium phosphate/ionic liquids materials for high-temperature fuel cells

This work reports the synthesis of high temperature proton conductors based on zirconium phosphate and imidazolium-based ionic liquids. This material is evaluated for high temperature proton exchange membrane fuel cells applications operating at 200 °C. The characterization results show high proton conductivity, enhanced water uptake properties, changes in structure, and exfoliation in zirconium phosphates crystal layers upon the introduction of the ionic liquid. The proton conductivity results demonstrate that there is an optimum amount of ionic liquid that can be introduced into zirconium phosphates to enhance its conductivity beyond which, the conductivity starts to decrease. At the optimum conditions, the addition of ionic liquids enhances the proton conductivity of the zirconium phosphates material by orders of magnitude. The results show a high proton conductivity the order of 10^?2 S cm^?1 at room temperature and high anhydrous proton conductivity of 10^?4 S cm^?1 at 200 °C. These findings indicate that the zirconium phosphate-ionic liquid material has a great potential as solid proton conductors for fuel cells applications operating at elevated temperatures.     

Assimilation of highly porous sulfonated carbon nanospheres into Nafion matrix as proton and water reservoirs

A unique form of carbon nanospheres possessing an immense number of micropores and pendant surface sulfonic acid groups was synthesized and used as an effective filler to enhance proton transfer in Nafion^® membrane at elevated temperatures. The synthesis of the filler involved the formation of polypyrrole nanoparticles and pyrolysis of them to generate carbon nanospheres (CN). Alkaline etching was then carried out to create the porous structure, and the resulting porous carbon nanospheres were then sulfonated to attain the sulfonated porous carbon nanospheres (sPCN, 1300 m²/g, 6.9 mmol-SO₃H/g). Dispersion of a substantially small amount of sPCN in a Nafion matrix brought about a cross-adsorption between the hydrophilic side-chain of Nafion molecules and sPCN. This causes the formation of a cross-linking network with sPCN junctions. The scope of this network, however, decreased with the increase in the sPCN loading from 1 to 2 wt% due to a reduction in extent of the cross-adsorption. The sPCN loading of 1 wt% reached the highest crosslinking degree that displayed the maximum enhancement on proton transport. It can be attributed to the role of the sPCN crosslinking junctions in keeping moisture and supplying protons. The characterizations of glass transition behaviour, hydrophilic microenvironments, and proton conductivity under low humidity levels reflected the impact of crosslinking extent. In the single H₂-PEMFC test at 70 °C using dry H₂/O₂, 1 wt%-sPCN Nafion composite membrane manifested a power density of 571 mW/cm² as compared to the pristine Nafion membrane that showed uppermost value of 388 mW/cm².     

Phosphorus-doped nickel selenides nanosheet arrays as highly efficient electrocatalysts for alkaline hydrogen evolution

Earth-abundant transition-metal dichalcogenides are considered as promising electrocatalysts to accelerate the hydrogen evolution reaction （HER）. Among them, the pyrite nickel diselenide (NiSe₂) has been received special attention due to its low cost and high conductivity, but it suffers a poor HER performance in alkaline media possibly attributed to its inadequate hydrogen adsorption free energies. Here, we report a novel P-doped NiSe₂ nanosheet arrays anchored on the carbon cloth with an obviously optimized HER performance. The catalyst only needs a low overpotential of 86 mV at a current density of 10 mA cm^?2 and a Tafel slop of 61.3 mV dec^?1，as well as maintains a long-term durability for 55 h in 1.0 M KOH, which is superior to the pristine NiSe₂ (135 mV@10 mA cm^?2) and most recently reported non-noble metal electrocatalysts. The XRD, EDS, TEM and XPS results validated the successful doping of P element into NiSe₂ nanosheet, while the density functional theory (DFT) calculation demonstrated the P doping can optimize the electronic structures and the hydrogen adsorption free energy of NiSe₂. This work thus opens up new ways for rationally designing high-efficient HER electrocatalysts and beyond.     

UiO-66-NH2 functionalized cellulose nanofibers embedded in sulfonated polysulfone as proton exchange membrane

Metal–organic frameworks (MOFs) exhibit high proton conductivity, thermal stability, and offer immense flexibility in terms of tailoring their size. Owing to their unique characteristics, they are desirable candidates for proton conductors. Nevertheless, constructing ordered MOF proton channels in proton exchange membranes (PEMs) remains a formidable challenge. Herein, blend nanofibers of cellulose and UiO-66-NH₂ (Cell–UiO-66-NH₂) obtained via the electrospinning process were embedded in a sulfonated polysulfone matrix to obtain high-performance composite PEMs with an orderly arrangement of UiO-66-NH₂. Comprehensive characterization and membrane performance tests reveal that composite membrane with 5 wt% (nominal) UiO-66-NH₂ have revealed high proton conductivity of 0.196 S cm^?1 at 80 °C and 100% relative humidity. Meantime, the composite membrane exhibits a low methanol permeability coefficient (~5.5 × 10^?7 cm² s^?1). Moreover, the composite membrane exhibits a low swelling ratio (17.3%) even at 80 °C. The Cell–UiO-66-NH₂ nanofibers exhibit strong potential for use as a proton-conducting nanofiller in fuel-cell PEMs.     

Pentadentate Copper(II)-amidate complex as a precatalyst for electrocatalytic proton reduction

Electrochemical reduction studies of a mononuclear Cu(II) complex bearing a pentadentate amidate ligand under both aqueous and non-aqueous media revealed the deposition of a heterogeneous film on the electrode. The heterogeneous film was grown on an FTO working electrode by control potential electrolysis (CPE) at ?0.9 V vs. NHE for 3 h (pH 3.0, phosphate buffer). Characterization of the electrodeposited film by SEM, EDX and XPS indicates the preferential formation of Cu₂O. The FTO/Cu₂O cathode, thus formed, exhibits electrocatalytic proton reduction in acidic aqueous medium (pH 3.0) with 95% Faradaic efficiency at moderate overpotential (η = 320 mV at onset). The overpotential required to reach 1 mA/cm² is 530 mV. The FTO/Cu₂O cathode maintained a current density of 2.5 mA cm^?2 for a period of 3 h and showed stability after 200 scan cycles.     

High temperature proton exchange porous membranes based on polybenzimidazole/ lignosulfonate blends: Preparation,morphology and physical and proton conductivity properties

Porous polybenzimidazole (PBI) based blend membranes were prepared by adding different amounts of lignosulfonate (LS) in the presence of LiCl salt. The morphology characteristics of the PBI/LS blends were investigated by FT-IR, atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses. The relation between the membrane morphology and membrane proton conductivity was studied. Results showed that LS content has a significant influence on the membrane morphology. High amount of LS in the blend created micro-pores within the membrane where increase in the LS content up to 20 wt% resulted in membranes containing pores with a mean diameter of about 0.8 μm. The resulting PBI/LS (0–20 wt%) membranes indicated high PA doping levels, ranging from 3 to 16 mol of PA per mole of PBI repeat units, which contributed to their unprecedented high proton conductivities of 4–96 mS cm⁻¹, respectively, at 25 °C. The effect of temperature on the proton conductivity of blends was also investigated. The results showed that by rising the temperature, the proton conductivity increases in PBI/LS blends. In the blend containing 20 wt% LS, proton conductivity increased from 98 mS cm⁻¹ at 25 °C to 187 mS.cm⁻¹at 160 °C which can be considered as an excellent candidate for use in both high and low temperature proton exchange membrane fuel cells.     

Surfactant-assisted synthesis of platinum nanoparticle catalysts for proton exchange membrane fuel cells

High-performance platinum nanoparticle catalysts (Pt–NPCs) remain the most widespread applied electrocatalysts for oxygen reduction reaction (ORR). Here, cetyltrimethylammonium bromide (CTAB), a surface-controlling agent, is introduced to modulate the microstructure and size of Pt nanoparticles (NPs) via a microwave-assisted heating process. The Pt-NPC assisted by 5 wt% CTAB exhibits the highest mass activity (MA) of 0.072 A mg_Pt^?1 and specific activity (SA) of 0.077 mA cm^?2, higher than those of commercial Pt/C (0.023 A mg_Pt^?1 and 0.035 mA cm^?2). Transmission electron microscopy (TEM) results indicate that Pt NPs are uniformly dispersed onto carbon supports with an average size of 2.39 nm. When applied in membrane electrode assembly (MEA), it exhibits the highest power density of 1.142 W cm^?2, which is about 1.24 times larger than that of commercial Pt/C.     

Sulfonated mesoporous benzene-silica-embedded sulfonated poly(ether ether ketone) membranes for enhanced proton conduction and anti-dehydration

In polymer electrolyte fuel cell operation, a decrease in the proton conductivity of the membrane at reduced humidity is a main cause for poor cell performance at high temperature. To alleviate the dehydration of the membrane at high temperature, sulfonated mesoporous benzene-silica (sMBS) particles are embedded in sulfonated poly(ether ether ketone) (sPEEK) membranes. As the sMBS itself is highly sulfonated on both organic and inorganic moieties, the proton conductivity of composite membranes is much higher than that of the pristine sPEEK membrane, and it reaches that of Nafion 117 at a high relative humidity (RH) of 90%. The dehydration rate of the membrane is reduced significantly by the capillary condensation effect of sMBS particles with the nanometer-scale 2-D hexagonal cylindrical pores, and the proton conductivity of the composite membranes, 0.234 × 10⁻¹ S cm⁻¹, is much higher than that of pristine sPEEK membrane, 0.59 × 10⁻³ S cm⁻¹, at a relatively low humidity of 40% RH. This maintenance of high conductivity at low humidity is attributed to the high water-holding capacity of the sMBS proton conductors. The sMBS-embedded sPEEK composite membranes show a much lower methanol permeability of 2–5 × 10⁻⁷ cm² s⁻¹ compared to that of Nafion 117, which is 1.6 × 10⁻⁶ cm² s⁻¹ at room temperature.     

Construction of heterostructure interface with FeNi2S4 and CoFe nanowires as an efficient bifunctional electrocatalyst for overall water splitting and urea electrolysis

The design of high-performance non-noble-metal-based electrocatalysts for electrooxidation reactions involving splitting of water molecule for energy and environmental applications is the need of the hour. In this study, we report the electrocatalytic performance of a nanocomposite catalyst of FeNi₂S₄ nanoparticles/CoFe nanowires supported on nickel foam that was prepared by a simple hydrothermal method. The electrocatalyst has several advantages, such as the nanocomposite structure, relatively high electrical conductivity, and synergistic effect between FeNi₂S₄ and CoFe. These characteristics enhanced the catalytic efficiency of FeNi₂S₄/CoFe electrode, gaining small overpotentials of 380 and 207 mV for oxygen and hydrogen evolution reactions, respectively, at a current density of 100 mA cm^?2. The charge transfer processes are significantly improved by the electron pairs from FeNi₂S₄ and CoFe, as well as by the enhanced active sites at the electrode-electrolyte interface and their bonding interactions. The electrooxidation of urea was also explored, which showed a lower overpotential of 230 mV to reach 100 mA cm^?2 current density. Interestingly, FeNi₂S₄/CoFe was successfully employed as cathode and anode for urea-assisted water electrolysis, utilizing 1.56 V to produce 10 mA cm^?2 current density, which is approximately 160 mV below that for water electrolysis, thus verifying the lower energy consumption during electrolysis. These results indicate that nanoparticle and nanowire composite catalysts can be used for wastewater treatment and green energy production applications.