Self-Supported Tailoring of Nickel Sulfide/CuCo Nanosheets into Hierarchical Heterostructures for Boosting Urea Oxidation Reaction

Abstract

Electro-oxidation of urea (UOR) in alkaline medium is one of the most effective alternative ways of producing green hydrogen, as the oxidation potential in UOR is less and thermodynamically more favorable than conventional water oxidation. The development of cost-effective materials in catalyzing UOR is recently seeking more attention in the research hotspot. Suitably modifying the Ni-based catalysts towards active site creation and preventing surface passivation is much important in this context, following which we reported the synthesis of Ni₃S₂ (NS) supported with CuCo (CC) bimetallic (NSCC). A simple hydrothermal route for NS synthesis and the electrodeposition method for CuCo (CC) deposition is adapted in a self-supported manner. The NS and CC catalysts exhibited sheet-like morphology, as confirmed by SEM and TEM analysis. The bimetallic CC deposition prevented the surface passivation of nickel sulfide (NS) over oxygen evolution reaction (OER) and improved the charge-transfer kinetics. The NSCC catalyst catalyzed UOR in an alkaline medium, which required a lower potential of 1.335 V vs. RHE to attain the current density of 10 mAcm⁻², with a lower Tafel slope value of 131 mVdec⁻¹. In addition, a two-electrode cell setup is constructed with an operating cell voltage of 1.512 V for delivering 10 mAcm⁻² current density. This study illustrates the new strategy of designing heterostructure catalysts for electrocatalytic UOR.

1. Introduction

The escalating demand for energy in terms of green and clean has propelled the development of sustainable energy production by means of scientific research [1,2,3]. Hydrogen energy, having high-energy density, is considered to be clean and green and has become the crucial element in future renewable energy production technologies, which are environmentally benign with zero carbon emissions [4,5]. Although there are different methods like photocatalytic, electrocatalytic, thermochemical, steam-methane reforming (SMR), etc., available for hydrogen production, the one method with a superior technology readiness level (TRL) next to SMR is electrocatalytic water splitting (EWS), as it gives out hydrogen with maximum efficiency and zero carbon emissions, unlike SMR [6,7]. But, in traditional water splitting, the high-energy input for splitting water (cell voltage is 1.23 V theoretically, ~1.45 V experimentally) limits its extensive implementation in this regard. Although there is a wide variety of electrocatalysts being designed and developed, they still struggle with high-energy inputs and high operating expenses. The anodic counterpart of the EWS, which is the oxygen evolution reaction (OER), has sluggish kinetics as it involves 4e⁻ transfer, and the water in the liquid phase must be converted into gaseous oxygen, thus requiring extra energy as the entropy changes with thermodynamic limitations [8,9]. Hence, researchers have looked for alternate counterpart anodic reactions, suitable for hydrogen energy, like oxidation of smaller organic molecules, e.g., urea, hydrazine, aldehydes, and methanol [10,11,12]. Potentially, the urea oxidation reaction (UOR) has garnered significant interest in this regard, as UOR happens at 0.37 V (theoretical potential), which requires less energy input than OER, offering the combined benefits of energy-efficient hydrogen generation and the treatment of urea-laden effluent [13,14,15,16]. The presence of urea, which is a human metabolite and a by-product of nitrogen fertilizer production, is common in wastewater from industrial processes and effluent from agricultural operations [17,18]. The electrocatalytic breakdown of urea has the potential to increase the effectiveness of the usage of urea resources while also addressing the problems associated with environmental degradation. The UOR is characterized by a complex mechanism as it involves the transfer of six electrons, as the following equation shows, and the sluggish reaction kinetics provides a substantial obstacle to the achievement of high catalytic efficiency.

$$\mathrm{UOR}: CO{(N{H}_2)}_2+{6OH}^{-}\to N_2+{5H}_{2}O+{6e}^{-}{E}_{anode}=0.37\mathrm{V}\mathrm{v}\mathrm{s}.\mathrm{R}\mathrm{H}\mathrm{E}$$

(1)

$$\mathrm{HER}: {6H}_{2}O+{6e}^{-}\to {3H}_2\uparrow +{6OH}^{-}{E}_{cathode}=0\mathrm{V}\mathrm{v}\mathrm{s}.\mathrm{R}\mathrm{H}\mathrm{E}$$

(2)

As a result, the development of high-performance electrocatalysts that can speed up the kinetics of UOR and enhance the efficiency of hydrogen evolution has emerged as a fundamental priority in the growth of this technology [19,20,21].

Although noble metals efficiently catalyze oxidation and reduction reactions, due to their restricted worldwide geological deposits and unreasonably high cost of implementation and procurement, the use of noble metals electrocatalysts (Ire and Ru) has been severely limited, which led the ultimate development of affordable catalysts, which are cost-effective and earth-abundant for UOR in alkaline medium [22,23]. Though UOR is more thermodynamically feasible than OER, the 6e⁻ transfer process involving the multistep conversion reaction still lacks an efficient catalyst to accelerate the reaction rate. Ni-based enzymes are highly active towards urea decomposition but still suffers from the competitive urea adsorption to oxygen adsorption, which increases the UOR overpotential and reduces the selectivity of urea [24,25,26,27,28,29]. Designing a new catalyst is one of the possible approaches to speed UOR rate, along with the minimization of overpotential. Sheet-like morphology is highly desirable for anodic reactions because the sheet-like morphology has the ability to expose plentiful active sites on the crystal facets surfaces and provide electrochemical stability. More specifically, sulfides of Ni have been thoroughly exploited for electrocatalytic applications, having the ability to modify their electronic structure and dimensions tuning into various morphologies [30,31]. Nickel sulfides (Ni_xS_y) with sheet-like morphology are known to possess promising UOR activity as the unpaired d-electrons in Ni atoms may establish a σ bond with the urea through C- or N- coordination [32]. Furthermore, different phases of Ni_xS_y like NiS, NiS₂, Ni₃S₂, Ni₇S₆, and Ni₉S₈ may be developed; Ni₃S₂ is earth-abundant, easy to synthesize in a single step, stable at high basic pH, and has a stable crystal-plane arrangement among all its non-stoichiometric forms. Various researchers [33,34,35,36,37,38] report that Ni₃S₂ in sheet-like morphology has been discussed for its supreme catalytic behavior. Sengeni et al. (2024) synthesized Ni₃S₂ via a self-supported manner on Ni foam with prior oxidation of the substrate, adapting a simple hydrothermal technique at basic pH [39]. The catalyst exhibited supreme oxidation activity of hydrazine, methanol, glucose, and water, demonstrating it is a multifunctional anode [39]. Liu et al. (2021) performed UOR with Ni₃S₂ sheet-embedded NiP particles by a one-step thermal treatment, which resulted in the nickel sulfide sheets with ~100 nm thickness [40]. However, the single-phase Ni-based catalysts generally suffer from deactivation and agglomeration, leading to lower stability and with fewer active sites [20]. Another issue in Ni-based catalysts is that under applied oxidation potentials, the surface sites of Ni become oxidized, which passivates over time due to the competing OER [41]. Hence, to mitigate the internal strain over successive electrochemical processes and to preserve activity, forming a heterostructure with a highly stable metal during gas bubble generation is essential [42,43]. Copper (Cu) is highly stable and flexible, stress-inert, and a good current collector [44,45,46]. But Cu is non-selective towards urea, which forces its application along with cobalt (Co). Introducing Co would positively shift the anodic peak current densities due to the earlier onset of the Co²⁺/Co³⁺ redox couple and perhaps cause positive changes in the electro-oxidation onset potential [47,48]. This would even prevent the surface passivation of Ni sites.

Keeping this in mind, a simple facile electrodeposition technique is adapted to synthesize CuCo bimetallic. At first, Ni₃S₂ sheets are synthesized in a self-supported manner on Ni foam utilizing hydrothermal sulfurization, with thiourea as the source, KOH as the pH regulator, and Ni foam as the activator. The sheets seemed to be thin, wrinkled, and homogeneously formed. The CuCo is subsequently deposited onto the Ni₃S₂ sheets, creating hierarchical heterostructures for facilitating urea adsorption, charge-transfer, and stability and for preventing competitive OER. The heterostructure formation is confirmed from XRD, SEM, and TEM studies, and the electrochemical UOR activity has been demonstrated in further studies. An asymmetric fuel cell is constructed with this catalyst, and the overall cell activity is studied with extended stability.

2. Results

The crystalline nature and the phase purity of all the electrocatalysts is determined from the powder Xray diffraction pattern (PXRD). From the PXRD pattern Figure 1a, all the catalysts showed sharp peaks attributed to the crystalline nature of the material. Specifically, all the self-supported catalysts showed diffraction peaks at 2θ values 44.39°, 51.78°, and 76.3°, corresponding to the hkl planes (111), (200), and (220), respectively, which is attributed to the metallic Ni foam (NF) peaks matching with the reference pattern ICDD 03-065-0380. Apart from these, the hydrothermally sulfurized nickel sulfide catalyst (NS) has diffraction peaks at 2θ values 21.76°, 31.1°, 37.7°, 44.35°, 49.72°, and 55.3°, whose planes match the nickel sulfide in the heazlewoodite phase, Ni₃S₂ (space group: R32(155); reference pattern: ICDD 01-071-1863) [37]. The reduced intensity of metallic Ni foam peaks is due to the fact that during the hydrothermal sulfurization process at 120 °C, in the presence of potassium hydroxide, Ni atoms from the Ni foam react with the hydrolyzed thiourea, resulting in the formation of Ni₃S₂. The chrono-potentiometric deposition of Cu and Co revealed the presence of bimetallic CuCo (CC) with the metallic Cu phase at the 2θ = 43.6° (111) plane, as highlighted in the Figure 1b and the amorphous Co phase. The absence of Co peak further confirms that the cobalt present on NF exists to be amorphous along with metallic Cu. This might be ascribed to larger positive reduction potential of the Cu redox pair relative to the Co redox pair [49]. In the copper cobalt bimetallic electrodeposited onto the nickel sulfide catalyst (NSCC), the distinctive reflections of Ni₃S₂ were evident in the PXRD pattern, and still, the lack of any diffractions matching with Co and the lack of any change in the 2θ location of metallic Cu suggest that Co metal was deposited in an amorphous state.

The morphology of the synthesized self-supported electrocatalysts is demonstrated by Field-Emission Scanning Electron Microscopy (FE-SEM) images. Figure S1 depicts the FE-SEM images of NS, which show the thin wrinkled sheet-like morphology of Ni₃S₂ being grown homogeneously on the surface of the Ni foam. At 120 °C, the S²⁻ ions is liberated from the hydrolyzed thiourea and nucleates with the Ni ions on the surface of the Ni foam in the presence of KOH. As the time proceeds, the nucleation of Ni₃S₂ occurs, and the liberation of NH₃ gas occurs simultaneously during the Ostwald ripening process, creating in situ defects, thus depicting thin wrinkled sheet-like morphology [39]. Figure 2a–c shows the FE-SEM images of the electrodeposited CC catalyst showing flower-like morphology, which is composed of two-dimensional (2D) nanosheets with a uniform coverage on the Ni foam. Similarly, in the heterostructure NSCC Figure 2d–f, when the CC catalyst is deposited onto the NS sheets, the flower-like morphology is opened and deposited as sheets on the wrinkled sheets of NS catalyst, thus confirming the formation of the hierarchical heterostructures.

Furthermore, as shown by the SEM images, thin wrinkled sheets of NSCC are visible in the transmission electron microscopy (TEM) image in Figure 3a. The heterointerface between NS and CC was successfully constructed, as seen from the high-resolution transmission electron microscopy image (HRTEM) in Figure 3b–d, which shows interplanar crystal spacings of 0.28 nm and 0.204 nm that are indexed to the respective hkl planes (110) and (020) of the Ni₃S₂ and (111) plane of metallic Cu with the d value 0.212 nm, which are found to be in good agreement with the PXRD results. Furthermore, the presence of all elements Ni, S, Cu, and Co is ascertained from the TEM energy-dispersive X-ray spectroscopy (TEM-EDX) (Figure 3e) depicting the presence of all the elements in the NSCC electrocatalyst.

The electrochemical measurements were performed in a three-electrode cell-setup, having Hg/HgO as the reference electrode, Pt wire as the counter electrode, and the synthesized self-supported catalysts as the working electrode, in an electrolyte of 1.0 M KOH +0.5 M Urea. To test the electrochemical activity of the electrocatalysts, Linear Sweep Voltammetry (LSV) is performed in an anodic oxidation potential window. In 1.0 M KOH, all the catalysts performed OER having an onset overpotential greater than ~1.5 V. As seen from the Figure 4a, the overpotential required to reach the current density of 10 mAcm⁻², for NSCC, NS, CC, and NF, is 308, 328, 337, and 357 mV, respectively. When 0.5 M urea is added into the electrolytic system, the required potential of the catalysts to reach the current density of 10 mAcm⁻² gets reduced to 1.335 V, 1.356 V, 1.4 V, and 1.383 V vs. RHE for NSCC, NS, NF, and CC, respectively. This enhanced activity of the NSCC and NS for UOR is attributed to the presence of Ni atoms, which catalyze the formation of active species NiOOH in alkaline medium. Additionally, NF exhibits a hump in the Figure 4b. after ~1.5 V, which is not observable in other electrocatalysts. The appearance of a small hump often occurs in Ni-based catalysts, due to the surface passivation of UOR owing to the competing OER at elevated potentials. Nonetheless, the catalysts electrodeposited on Ni foam exhibited no surface passivation, as shown by the absence of peak current [50,51]. This minimization of surface passivation is because the Ni atoms have been sulfurized to nickel sulfide, and the heterostructure formed between NS sheets and CC creates numerous UOR electrochemical active sites, increasing the electrochemical surface area (ECSA) manifesting for improved UOR activity by requiring lower potentials, as shown in the comparative LSV and bar chart (Figure 4c,d).

Meanwhile, to elucidate the kinetics of the mechanistic pathways, a Tafel plot is constructed from the LSV at catalytic turn-over conditions. In 1.0 M KOH, NF catalyst demonstrates lower the Tafel slope of 149.2 mVdec⁻¹, followed by NS (158 mVdec⁻¹), NSCC (161 mVdec⁻¹), and CC (175.2 mVdec⁻¹), as seen from Figure 5a. This trend is the most reliable as the presence of Ni accelerates the OER pathway through the facile formation of NiOOH species, unlike in CC and NSCC catalysts. In the presence of urea, as shown in Figure 5b, the urea adsorption is spontaneous in CC catalysts, and the heterostructure formation between the sheets of CC and NS results in the lower Tafel slope values for NSCC (131 mVdec⁻¹), NS (149 mVdec⁻¹), NF (178 mVdec⁻¹), and CC (260 mVdec⁻¹).

Electrochemical Impedance Spectroscopy (EIS) was carried out for all the catalysts, and the charge-transfer rate was evaluated. The Nyquist plot in 1.0 M KOH (Figure 6a) gives out charge-transfer resistance (R_ct) values in the order 1.302 Ω >1.35 Ω > 2.28 Ω > 2.9 Ω, respectively, for NSCC, NS, CC, and NF. In 0.5 M urea from Figure 6b, the R_ct values become 3.17 Ω for NF, 1.08 Ω for NS, 1.93 Ω for CC, and 1.227 Ω for NSCC, which seems to be in good agreement with the R_ct values from Bode-absolute impedance plots (Figure S2). Though the R_ct value of NSCC is hardly lower than that of NS, the kinetics and activity of the NSCC from the LSV and Tafel slopes suggest that the heterointerface formed between the wrinkled sheets of NS and CC intrinsically activates the catalyst towards the formation of numerous active sites. To support this, Bode-phase angle plots were constructed, which shows that all the catalysts exhibit phase shift values of less than <45°, which is significant for charge-transfer characteristics. In KOH, NS gives out lower phase shift θ values of 9°, whereas for NSCC θ = 10.6° (Figure 6c). The same response occurs in the presence of 0.5 M urea (Figure 6d), but on keen observation, the RC time constant (τ) value is increasing in the order of NF < NS < CC < NSCC, confirming that the time taken to charge the electrode surface to 63.2% is increasing, which directly indicates the improved ECSA [52]. Despite this, the ECSA is deciphered from the C_dl method. Cyclic voltammograms (CVs) are being recorded at increasing scan-rates from 100–200 mVs⁻¹ in the non-Faradaic region, unlike for the anodic and cathodic current densities, for which a linear plot is constructed. The slope of the linear plot against their respective scan-rates gives a double-layer capacitance (2C_dl) value where, from the CVs at different scan-rates for NF, NS, CC, and NSCC (Figure S3), a linear plot is deciphered in Figure 7a,b. The highest 2C_dl value for NSCC 78.4 mFcm⁻² supports the extension of ECSA due to the formation of heterostructures NS and CC having individual 2C_dl values of 1.2 mFcm⁻² and 31.7 mFcm^−2, respectively.

To further investigate its extending activity in the two-electrode setup, a cell is constructed utilizing NSCC (+) as the anode and Pt/C (−) as the cathode, making an electrical circuit in 1.0 M KOH the electrolyte. In the two-electrode cell setup, the net voltage required to carry out the overall reaction of UOR to acquire a current density of 10 mAcm⁻² should be the difference between the cathodic and anodic current densities. Since Pt/C is the cathode and NSCC the anode, the difference should be approximately equal to 1.35 V for UOR and 1.45 V for OER, but practically we observed 1.512 V for UOR and 1.638 V for OER to reach the current density of 10 mAcm⁻² (Figure 7c). To test the durability and stability of the catalyst, the material was subjected to constant current density, and the material NSCC in the two-electrode system was able to deliver a constant current of 25 mAcm⁻² for 23,000 s with the retainment of the activity (Figure 7d and Figure S4).

3. Materials and Method

3.1. Chemicals and Materials Required

Ni foam of 99.9% purity with 1.6 mm thickness was purchased from MTI Corp (Seoul, Republic of Korea). Potassium hydroxide pellets (KOH, extrapure, 85%), ammonia solution (NH₄OH, extrapure AR, 25%), sodium citrate tribasic dihydrate (C₆H₅Na₃O₇.2H₂O, extrapure AR, 99%), cobalt nitrate hexahydrate (Co(NO₃)₂.6H₂O, extrapure, 97%), and cupric nitrate trihydrate (Cu(NO₃)₂.3H₂O, extrapure, 98%) were purchased from Sisco Research Laboratories Pvt. Ltd. (Taloja, Navi Mumbai, India). Thiourea (CH₄N₂S, 99%) was procured from Thermo Fisher Scientific India Pvt. Ltd. (Powai, Mumbai, India). Sodium chloride (NaCl, AR, 99%) was sourced from Pallav Chemicals and Solvents Pvt. Ltd. (Boisar, Mumbai, India). Pt/C and 5% Nafion solution were purchased from Sigma Aldrich (St. Louis, MO, USA), and absolute ethanol (C₂H₅OH, 99.9%) was purchased from Changshu Hongsheng Fine Chemical Co. Ltd. (Changshu, China). Deionized (D.I) water with 18.2 MΩ·cm resistivity was used throughout all the experiments. All chemicals were used as such without any purification.

3.2. Self-Supported Hydrothermal Synthesis of Ni₃S₂ on Ni Foam (NS)

Ni foam (NF) is cut into pieces in the dimensions of 1 cm × 1.5 cm, and it is sonicated in 3.5 M HCl, for about 30 min; then, it is taken out; washed with D.I water, absolute ethanol, and acetone; and dried in vacuum at 40 °C. Simple hydrothermal sulfurization is carried out as per the previous literature [37] with slight modification. Thiourea is taken as the sulfur source, and KOH is taken to activate the NF; as at basic pH, the formation of nickel sulfide in Ni₃S₂ is favored. About 25 mL of the equimolar mixture of the solution containing thiourea and KOH is taken and stirred to make a homogenous solution. The pre-treated NF pieces are added to it. Then the mixture is transferred into a 50 mL Teflon lined stainless-steel autoclave, sealed tightly, and kept in the hot air oven at 120 °C for 7 h. After the completion of hydrothermal treatment, the autoclave is allowed to cool naturally, and then the sulfurized Ni foam (NS) is taken out, washed with distilled water and absolute ethanol, and dried in vacuum at 60 °C for 6 h (Scheme 1). The mass loading of NS/NF after hydrothermal sulfurization is ~2 mg.

3.3. Electrodeposition of CuCo on NS (NSCC)

CuCo (CC) bimetallic is deposited onto the NS electrode following a simple electro-deposition technique [49]. An aqueous solution containing an equimolar mixture of Cu(NO₃)₂·3H₂O, Co(NO₃)₂·6H₂O, 0.28 M NaCl, and 0.016 M trisodium citrate dihydrate is prepared. The role of NaCl is to promote ionic conductivity and trisodium citrate both as complexing and reducing agents. To maintain the pH in a neutral state, 25% ammonia solution is added for regulation. This serves as the electrolytic bath for the deposition with constant stirring using a rice pellet at a constant current density of −150 mAcm⁻². NS is the working electrode (WE), Ag/AgCl is the reference electrode (RE), and graphite rod is used as the counter electrode (CE). The deposition is carried out for 600 s. After 600 s, the foam turned black, indicating the successful deposition of CC bimetallic onto the NS electrode (NSCC). After electrodepositing, the total mass of the NSCC is approximately 4 mg.

The same procedure is adapted for CC synthesis, except the working electrode is pretreated bare NF.

3.4. Preparation of Pt/C Catalytic Ink on NF

About 10 mg of the catalyst is weighed and distributed at a 3:1 ratio of D.I water and absolute ethanol with 15 µL of 5% Nafion solution to an overall volume of 1 mL. To make the catalyst ink-homogeneous, the mixture was ultra sonicated for 30 min. In order to produce the Pt/C on NF, a 100 µL aliquot of the ink was drop-casted onto a prepared NF substrate. The aliquot was then allowed to dry at room temperature for a period of 12 h having a mass loading of ~2 mg.

3.5. Physical Characterization

The crystalline structure and the phase composition of the materials were investigated using powder X-Ray diffractometer (PXRD) with Cu Kα radiation in the 2θ range 5 to 90°, with a continuous scanning of step size 0.02°/2θ, (PANalytical, Malvern, Almelo, The Netherlands). The morphologies and micrographs of the materials were observed by scanning electron microscopy (HR SEM, Thermo Scientific Apreo S, Waltham, MA, USA). Hi-Resolution Transmission Electron Microscopy (HR-TEM) images was taken using JEOL Japan (Tokyo, Japan) and JEM-2100 Plus to study the atom arrangements, defects, and interplanar distances.

3.6. Electrochemical Characterization

Throughout the experiment, a typical three-electrode cell model was used, with Hg/HgO serving as the (RE) and Ni foam serving as the CE for the HER. The pH of the solution was fixed at 14 for OER and 0.5 M urea for UOR. A room temperature screening was performed on the electrochemical experiments using the CHI760E electrochemical workstation. 12.8250223° N, 80.0439124° E was the particular geographic place.

To verify that the working electrode (WE) electrochemically activated, the electrocatalysts were subjected to cyclic voltammetry (CV) for a number of cycles at a scan-rate of 100 mVs⁻¹ against the Open Circuit Potential (OCP). At the lowest possible scan-rate of 5 mVs⁻¹, Linear Sweep Voltammetry (LSV) was performed. For the purpose of interpreting the charge-transfer rate, Electrochemical Impedance Spectroscopy (EIS) was used under catalytic turn-over conditions, with an alternating current (AC) amplitude of 5 mV and a broad frequency range of 0.1 Hz to 100 MHz. Nyquist, Bode-absolute impedance, and Bode phase angle measurements were demonstrated from EIS results. The charge-discharge phenomena were used to study the double layer capacitance (C_dl), which was evaluated by raising the scan rate from 100 to 200 mVs⁻¹ for CV in the non-Faradaic region. Using i-t amperometry, the material’s stability over an extended period of time, was evaluated. Microsoft Excel was used to plot all of the data that was collected by CHI760E, and the graphs were produced using the program.

For the two-electrode system, the synthesized electrode NSCC was taken as the anode (+) connected to the positive terminal and Pt/C on NF as cathode (−) connected to the negative terminal of the circuit. The electrolyte was 1.0 M KOH for OER and 1.0 M KOH + 0.5 M urea for UOR. LSV was carried out in the potential range of 1 to 2.5 V.

4. Conclusions

In this work, we constructed a heterostructure between nickel sulfide and CuCo bimetallic via the hydrothermal method followed by the electrodeposition method. The NS and CC both have sheet-like morphology, exposing a greater number of electro-active species, as confirmed by SEM and TEM. The self-supported catalysts are subjected to OER and UOR, showing a lower potential of 1.335 V vs. RHE for delivering current density, and 10 mAcm⁻² with a reduced Tafel slope value of 131 mVdec⁻¹ for UOR. The charge-transfer kinetics were enhanced, and the surface passivation of nickel sulfide (NS) over oxygen evolution reaction (OER) was avoided by the bimetallic CC deposition. Notably, the catalyst NSCC, when constructed to a two-electrode cell arrangement, Pt/C||NSCC, requires an operating cell voltage of 1.512 V for 10 mAcm⁻². The CuCo deposition mitigated the surface passivation and improved the charge transfer over the thin wrinkled sheets of NS via heterostructure formation. This study creates a synergistic approach for sustainable energy and environmental applications by combining urea-rich wastewater treatment with energy-efficient hydrogen production. The results provide a scalable route to replace traditional energy-intensive water electrolysis and give crucial insights for improving multi-metallic electrocatalysts.