Nitrogen-doped Nanoporous Carbon Research Articles

Efficient CO2 capture by ZIF-8-derived in-situ nitrogen-doped nanoporous carbon with ultra-high selectivity and stability

Global warming and the increasing frequency of extreme weather caused by the gradual increase in CO2 concentration in the atmosphere are urgent issues that must be addressed. In this study, ZIF-8-derived in-situ nitrogen-doped porous carbon materials were prepared through one-step pyrolysis of ZIF-8. The synthesis was gradually optimized by exploring different pyrolysis temperatures to determine the optimal ZIF-8-derived porous carbon for CO2 adsorption. The CO2-adsorption capacity of ZIF-8–800 reached 5.22 and 6.19 mmol g−1 at 25 ℃ and 0 ℃ (1 bar), respectively. After five cycles, its CO2-adsorption capacity decreased by only about 1.7 %. Moreover, the CO2/N2 selectivity at 1 bar was as high as 21.2 (48.9 at 0.05 bar), and the isothermal adsorption heat was also within a moderate range (31 kJ mol−1). The superior CO2 adsorption performance was found to originate from the comprehensive effect of the three-dimensional pore structure that combined reasonably coordinated micropores, mesopores, and macropores, as well as some specific favorable N/O groups. The results indicate the broad application prospects of ZIF-8-Ts in CO2 capture and separation and provide new ideas for the sustainable application of novel MOF-derived porous carbon materials.

Molecular simulation using transfer-learned potentials for the disordered nanoscale structure of nitrogen-doped nanoporous carbons

Machine learning (ML)-based molecular dynamics (MD) simulations of the formation of a class of N-doped nanoporous carbons are performed to assess their disordered partially graphitized nanoscale structure. The study is motivated by the effectiveness of so-called nitrogen assembly carbons (NACs) for catalysis applications. Benchmark simulations for pure-C disordered graphitic systems reveal the importance of reliably capturing the vdW component of the potentials in order to accurately describe the tendency for layering of disordered graphene-like sheets. In our modeling, this is achieved by a transfer learning strategy incorporating features of the energetics from the optB88-vdW DFT functional into potentials initially trained with a less expensive functional, thereby providing a superior description of the pure-C systems. Generation from MD simulations of realistic partially graphitized structures is significantly more challenging for N-doped versus for pure C systems. However, such structures are achieved by a tailored MD simulation protocol mimicking the experimental synthesis process and in particular incorporating an annealing and subsequent quenching stages. Simulated PXRD patterns effectively reproduce the features of experimental observations for NACs, including the appearance of a prominent but broad (002) peak at around 25∘, and the development of another weaker feature associated with in-layer ordering of mixed C-N graphene-like sheets.

Thermochemical Activation of Wood with NaOH, KOH and H3PO4 for the Synthesis of Nitrogen-Doped Nanoporous Carbon for Oxygen Reduction Reaction.

Carbonization of biomass residues followed by activation has great potential to become a safe process for the production of various carbon materials for various applications. Demand for commercial use of biomass-based carbon materials is growing rapidly in advanced technologies, including in the energy sector, as catalysts, batteries and capacitor electrodes. In this study, carbon materials were synthesized from hardwood using two carbonization methods, followed by activation with H3PO4, KOH and NaOH and doping with nitrogen. Their chemical composition, porous structure, thermal stability and structural order of samples were studied. It was shown that, despite the differences, the synthesized carbon materials are active catalysts for oxygen reduction reactions. Among the investigated carbon materials, NaOH-activated samples exhibited the lowest Tafel slope values, of -90.6 and -88.0 mV dec-1, which are very close to the values of commercial Pt/C at -86.6 mV dec-1.

Rapid solar-driven atmospheric water-harvesting with MAF-4-derived nitrogen-doped nanoporous carbon

A MOF-derived nanoporous carbon (NPCMAF-4-800) with multiple N-doped sites, considerable porous characteristics and inherent photothermal properties demonstrated a superior water-production rate under a relatively arid climate.

Core-shell ZnO@CoO nitrogen doped nano-composites as highly sensitive electrochemical sensor for organophosphate pesticides detection

Core-shell ZIF-8@ZIF-67 was synthesized by growing a cobalt-based ZIF-67 on a ZIF-8 seed particle. Herein, through selective etching of the ZIF-8@ZIF-67 core and subsequent direct carbonization, core-shell hollow ZnO@CoO nitrogen-doped nanoporous carbon (HZnO@CoO-NPC) nanocomposites were prepared. HZnO@CoO–NPCs possessed a high nitrogen content, large surface area, high degree of graphitization and excellent electrical conductivity, all of which were attributed to successfully integrating the unique advantages of ZIF-8 and ZIF-67. HZnO@CoO–NPCs were used to assemble acetylcholinesterase (AChE) biosensors for organophosphorus pesticides (OPs) detection. The low detection limit of 2.74 × 10−13 M for chlorpyrifos and 7.6 × 10−15 M for parathion-methyl demonstrated the superior sensing performance. The results showed that the electrochemical biosensor constructed by HZnO@CoO-NPC provided a sensitive and efficient electrochemical strategy for OPs detection.

Nitrogen-doped lignin-derived porous carbons for supercapacitors: Effect of nanoporous structure

Lignin-derived carbon electrode materials for supercapacitors can be prepared from industrial lignin with a high carbon content and a rich benzene ring structure. However, the capacitive performance is significantly affected by the nanoporous structure of the lignin-derived carbon. In this study, three nitrogen-doped nanoporous carbons were prepared using alkali lignin as a carbon source to examine the effect of different nanopore distributions on the electrochemical performance. Carbon activated by ZnC2O4 (PLC-Zn) had a hierarchical porous structure composed of nanosheets, endowing it with a combined ability to store charge and transfer ions. The specific capacitance of PLC-Zn reached a maximum of 254F/g at 0.5 A/g, surpassing that obtained by the microporous-dominated carbon activated by K2CO3 (PLC-K) and mesoporous-dominated carbon obtained by SiO2 template method (PLC-Si). This study provides theoretical guidance for the preparation of excellent lignin-derived carbon electrode materials.

Effective CO2 capture by in-situ nitrogen-doped nanoporous carbon derived from waste antibiotic fermentation residues

It is of great environmental benefit to rationally dispose of and utilize antibiotic fermentation residues. In this study, oxytetracycline fermentation residue was transformed into an in-situ nitrogen-doped nanoporous carbon material with high CO2 adsorption performance by low-temperature pyrolysis pre-carbonization coupled with pyrolytic activation. The results indicated the activation under mild conditions (600 °C, KOH/OC = 2) was able to increase micropores and reduce the loss of in-situ nitrogen content. The developed microporous structure was beneficial for the filling adsorption of CO2, and the in-situ nitrogen doping in a high oxygen-containing carbon framework also strengthened the electrostatic adsorption with CO2. The maximum CO2 adsorption reached 4.38 mmol g−1 and 6.40 mmol g−1 at 25 °C and 0 °C (1 bar), respectively, with high CO2/N2 selectivity (32/1) and excellent reusability (decreased by 4% after 5 cycles). This study demonstrates the good application potential of oxytetracycline fermentation residue as in-situ nitrogen-doped nanoporous carbon materials for CO2 capture.

Ruthenium/Ruthenium oxide hybrid nanoparticles anchored on hollow spherical Copper-Cobalt Nitride/Nitrogen doped carbon nanostructures to promote alkaline water splitting: Boosting catalytic performance via synergy between morphology engineering, electron transfer tuning and electronic behavior modulation

Exploring bi-functional electrocatalysts with excellent activity, good durability, and cost-effectiveness for electrochemical hydrogen and oxygen evolution reactions (HER and OER) in the same electrolyte is a critical step towards a sustainable hydrogen economy. Three main features such as high density of active sites, improved charge transfer, and optimized electronic configuration have positive effects on the electrocatalyst activity. In this context, understanding structure–composition–property relationships and catalyst activity is very important and highly desirable. Herein, for the first time, we present the design and fabrication of novel MOF-derived ultra-small Ru/RuO2 nanoparticles doped in copper/cobalt nitride (CuCoN) encapsulated in nitrogen-doped nanoporous carbon framework (NC) (Ru/RuO2/CuCoN@NC). For the synthesize of this nanocomposite, firstly bimetallic Cu-Co/MOF hollow nanospheres are prepared via a facile emulsion-based interfacial reaction method and used as the template for Ru ion doping (Ru-doped Cu-Co/MOF). Then, Ru-doped Cu-Co/MOF precursor during the carbonization/nitridation/cooling process converted to the Ru/RuO2/CuCoN@NC nanocomposite. Benefiting from the desirable compositional and structural advantages of more exposed active sites, optimized electronic structure, and interfacial synergy effect, Ru/RuO2/CuCoN@NC hollow nanosphere electrocatalyst demonstrates striking catalytic performances under alkaline conditions with a current density of 10 mA cm−2at low overpotentials of 41 mV for HER and 231 mV for OER, respectively. Moreover, as a bifunctional electrocatalyst for overall water splitting, a two-electrode device needs a voltage of 1.51 V to reach a current density of 10 mA cm−2. Comprehensive electrochemical studies show that the excellent electrocatalytic performance of the Ru/RuO2/CuCoN@NC hollow nanosphere could be attributed to the improved physical and chemical properties such as desirable compositional, catalysts uniform dispersion, structural advantages of more exposed active sites, optimized electronic structure, high electrical conductivity, and interfacial synergy effect. This work paves a novel avenue for constructing robust bifunctional electrocatalyst for overall water splitting.

Binary active sites of nickel–iron alloy bonded in nitrogen-doped carbon nanocage for robust durability and low polarization zinc-air batteries

The industrialization of rechargeable metal-air batteries, especially zinc-air batteries (ZABs), is greatly limited to the low efficiency, high polarization, and short lifetime of oxygen catalysts (both oxygen reduction reaction and oxygen evolution reaction), which still faces challenges. Herein, a novel efficient bifunctional electrocatalyst based on binary active sites engineering of NiFe alloy embedded in hierarchical nanoporous nitrogen-doped carbon nanocage (NiFe@NC) is successfully synthetized by pyrolysis of urea and Prussian blue analogues coated with polydopamine. Profiting from strong synergetic between NiFe alloy and nitrogen-doped carbon, abundant Fe/Ni–N–C bond, this unique hierarchical yolk-core-shell structure provides an integration of superior OER and ORR property, half-wave potential of 0.86 V for ORR and a small overpotential of 277 mV at 10 mA cm−2 for OER in O2-saturated 0.1 M KOH. Consequently, the liquid ZABs based on the electrocatalyst exhibits a high open-circuit voltage of 1.50 V, a low-polarization voltage of 0.68 V after 370 h at 10 mA cm−2, as well as superior stability for up to 750 h (10 mA cm−2) and 450 h (20 mA cm−2). This work provides a reference significance to the research and development of high-performance rechargeable ZAB catalysts.

Zeolitic imidazolate frameworks derived Co-Zn-nanoporous carbon-sulfide material for supercapacitors

To synthesize porous carbon-based electrodes for supercapacitors, a bimetallic strategy is used from zeolitic imidazolate frameworks (ZIFs), i.e., ZIF-67 and ZIF-8 are used for derived carbon material. The synthesized electrode comprises two metals, nitrogen and nanoporous carbon with sulfur, which have precisely controlled specific surface area, porosity, and graphitization degree. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) methods are used to explore the electrochemical behavior of the prepared materials using three-electrode configurations in an electrolyte solution (2 M KOH). By combining the consequences of sulfur and bimetal, the prepared specimens performed exceptionally well. The modified final ZIF-derived bimetallic sulfide exhibited an enhanced specific capacitance value of 815 F/g at a scan rate of 2 mV/s. According to the findings, the modified composite has very little resistance to charge transfer, a fast frequency response time, and an improved specific capacitance value. The composite's coulombic efficiency remains at 83.9% after 5000 cycles. The final composite's outstanding performance is due to its nitrogen-doped nanoporous carbon nature/structure and bimetallic derived sulfide composition.

Wood and Black Liquor-Based N-Doped Activated Carbon for Energy Application

Fuel cells, batteries and supercapacitors are critical to meet the rising global demand for clean, sustainable energy. Biomass-derived activated carbon can be obtained with tailored properties to fulfil the extensive need for low-cost, high-performance, catalyst and electrode materials. To investigate the possibility of nanoporous nitrogen-doped carbon materials as catalysts in fuel cells and electrodes in lithium-ion batteries, biomass precursors were thermochemically activated with NaOH at 800 °C, nitrogen was introduced using dicyandiamide and doping was performed at 800 °C. The chemical composition, porous structure, texture and electrochemical properties of the obtained materials change depending on the biomass precursor used. It has been found that the most promising precursor of the obtained materials is wood char, both as an oxygen reduction catalyst in fuel cells, which shows better properties than the commercial 20% Pt/C catalyst, and as an anode material in Li-ion batteries. However, catalysts based on black liquor and hybrid material have comparable properties with commercial 20% Pt/C catalyst and can be considered as a cheaper alternative.

Metal–Organic Framework@Polyacrylonitrile-Derived Potassiophilic Nanoporous Carbon Nanofiber Paper Enables Stable Potassium Metal Anodes

Potassium (K) metal is a promising anode for potential low-cost and high-energy-density K-ion batteries. However, its application is hampered by serious dendrite growth and large volume change. Herein, a Co nanoparticle-embedded nitrogen-doped nanoporous carbon nanofiber paper is prepared by carbonizing the electrospun fiber paper of metal–organic framework (MOF) nanoparticles and polyacrylonitrile, which displays a high potassiophilicity due to the incorporation of Co nanoparticles and N doping. As a three-dimensional host, excellent electrochemical performance is demonstrated for the K metal anode with a high average Coulombic efficiency of 98.75% for 400 cycles and a long lifespan of 1300 h in symmetric cells. Furthermore, enhanced electrochemical performance with good cycling stability and rate capability is achieved in full cells that are paired with organic cathodes. Our findings highlight a promising strategy for fabricating high-performance K metal anodes using MOF-based materials.

In situ simultaneous chemical activation and exfoliation of carbon quantum dots for atmospheric adsorption of H2S and CO2 at room temperature

Herein, novel nitrogen-doped nanoporous carbons possessing 2.63 at.% N and high porosity were prepared using nitrogen-rich carbon quantum dots (N-CQDs) via a facile chemical activation. To this end, after performing the hydrothermal process on the raw materials, chemical activation was carried out by various KOH/N-CQDs ratios (2:1 to –4:1), resulting in unique micro-mesoporous structures (i.e., HNAC samples). In this approach, a large surface area (1477 m2g−1) and pore volume (1.05 cm3g−1) were obtained, where the micropore volume was increased by decreasing the KOH/N-CQDs ratio, activation time and augmenting the activation temperature, that caused considerable adsorption at 1 bar. It is worth mentioning that mesopores could be generated by condition optimization that led to higher adsorption at high pressure. Due to their large surface area and high nitrogen loading, the HNAC samples demonstrated excellent H2S and CO2 adsorption capacity at ambient conditions (9.28 mmolg−1 for H2S and 4.28 mmolg−1 for CO2 at 1 bar and 25 °C) and at higher pressures (18.0 mmolg−1 for H2S and 6.20 mmolg−1 for CO2 at 10 bar and 25 °C). According to the significant performance of the prepared nanosorbents along with stable cyclic adsorption-desorption performance, the HNACs are proposed as promising adsorbents with outstanding adsorption.

Decoration of silver nanoparticles on nitrogen-doped nanoporous carbon derived from zeolitic imidazole framework-8 (ZIF-8) via in situ auto-reduction.

We discovered an in situ auto-reduction method to embed silver nanoparticles onto a nanoporous carbon (NC) derived from the zeolitic imidazole framework-8 (ZIF-8), without any requirement of the reducing agents. The detailed analysis demonstrated the formation of Ag NPs by the replacement of the metallic Zn residue in the NC with Ag ions. The synthesized Ag@NC exhibited a superior catalytic activity toward the reduction reaction of 4-nitrophenol into 4-aminophenol.

Controllable synthesis of nitrogen-doped porous carbon from metal-polluted miscanthus waste boosting for supercapacitors

High-value reclamation of metal-polluted plants involved in phytoremediation is a big challenge. In this study, nitrogen-doped nanoporous carbon with large specific area of 2359.1 m2 g−1 is facilely fabricated from metal-polluted miscanthus waste for efficient energy storage. The synergistic effect of KOH, urea and ammonia solution greatly improve the nitrogen quantity and surface area of the synthesized carbon. Electrodes fabricated with this carbon exhibit the excellent capacitance performance of 340.2 F g−1 at 0.5 A g−1 and a low combined resistance of 0.116 Ω, which are competitive with most of previously reported carbon-based electrodes. In addition, the as-obtained carbon electrode shows a high specific capacitance retention of over 99.6% even after 5000 cycles. Furthermore, the symmetric supercapacitor fabricated using the synthesized carbon achieves a superior energy density of 25.3 Wh kg−1 (at 400 W kg−1) in 1 mol L−1 Na2SO4 aqueous solution. This work provides an efficient route to upcycle metal-polluted plant waste for supercapacitor applications.

Nanocomposites formed by combination of urchin like NiS with Ni-nanoparticles/N-doped nanoporous carbon, derived from nickel organic framework, and decorated with RuO2 nanoparticles: Construction and kinetics for hydrogen evolution reaction

Fabrication of active, stable, and cost effective electrocatalysts, as alternative cathodes to Pt or Pt-based materials for catalytic hydrogen production, is important for different industrial purposes, such as hydrogen therapy in medicine, syntheses in pharmaceutical and nutrient, and clean carbon-free energy carrier in industry.Herein, construction, characterization and examination of an efficient electrocatalyst for hydrogen evolution reaction (HER) in alkaline media is reported. The catalyst system is based on nanocomposites formed of urchin-like nickel sulfide incorporated with nickel nanoparticles and nitrogen doped-nanoporous carbon, and decorated electrochemically with ruthenium (IV) oxide on the glassy carbon electrodes, leading to GCE-NiS/Ni/NNPC/RuO2 system.Physicochemical characteristics of the prepared composite systems are studied by several surface, solution and electrochemical methods, from which the system is characterized.Then, electrocatalytic activity of the GCE modified with the composite, is studied for the HER by means of the steady-state linear sweep voltammetry (LSV), polarization curves (Tafel plots), and electrochemical impedance spectroscopy (EIS). The obtained data are analyzed by using appropriate equivalent circuit models, from which the HER kinetics are quantitatively determined.The results revealed that the electrode modified with the prepared composite, GCE-NiS/Ni/NNPC/RuO2, is an efficient electrocatalyst for the HER in alkaline solution, where an overpotential of −82.54 mV at the current density of 20 mA cm‒2 (η20 =− 82.54 mV) with Tafel slope of 49.88 mV dec‒1 is observed. These activities are very close to those obtained on Pt-based electrode materials. The origin of the enhancement in the HER activity can be attributed to (i) the high surface area of the urchin-like structure along with nanoporous carbon, and (ii) the synergistic chemical coupling effects between the NiS, Ni/NNPC and RuO2nanoparticles.

High-performance flexible hybrid-supercapacitor enabled by pairing binder-free ultrathin Ni–Co–O nanosheets and metal-organic framework derived N-doped carbon nanosheets

High-rate electrochemical hybrid supercapacitors (HSCs) have attracted great scientific attention due to the expectation of the battery-level energy density and super long life as electrochemical double-layer capacitors. But in reality, the rational design of HSCs with a balanced capacity of positive and negative electrodes with high-rate capability is still a great challenge. Herein, a unique strategy is applied by pairing the binder-free NiCo2O4 ultrathin nanosheets supported on carbon fiber paper (Ni–Co–O@CFP) as cathode and metal-organic-framework (MOF) derived nanoporous nitrogen-doped carbon nanosheets (NPC) as an anode to fabricate the hybrid supercapacitor (NCO||NPC-HSC). The specific capacitance of the Ni–Co–O@CFP electrode reaches 2038 F g−1 (339 mAh g−1) at 1.5 A g−1 with capacitance retention of 93.65% after 5000 charge-discharge cycles at a high current density of 20 A g−1. The as-fabricated NCO||NPC-HSC exhibited excellent electrochemical properties in PVA/KOH hydrogel electrolyte with highly flexible characteristics. The NCO||NPC-HSC can work under the extended potential window of 0.0–1.6 V and reach at a high specific capacitance of 201 F g−1 at 0.55 A g−1, providing ultra-high energy density of 69 Wh kg−1 at a power density of 840 W/kg, which is substantially higher than values reported for symmetric and asymmetric supercapacitors based on the NiCo2O4 till date. Moreover, the NCO||NPC-HSC demonstrated the negligible change in performance while bent at different states. Overall, our NCO||NPC-HSC exhibits exceptionally good cycling performance over 20,000 cycles (>90% capacitance retention). Interestingly, three NCO||NPC-HSC devices connected in series can power 16 green color light-emitting-diodes (LEDs, 2 V) for more than 2 min, demonstrating its fusibility as a practical energy storage device.

Thermal Conversion of Triazine-Based Covalent Organic Frameworks to Nitrogen-Doped Nanoporous Carbons and Their Capacitor Performance

Abstract Nanoporous carbons with well-defined pore structures are promising for advanced energy applications. Herein, we fabricate nitrogen-doped porous carbons via direct carbonization of a triazine-based covalent organic framework (TACOF1) that acts as both intrinsic template and carbon/nitrogen source. The carbonized TACOF1 forms porous carbon that has a large surface area (1194 m2 g−1) comprised of high volumes of micro- and meso-pores (0.58 cm3 g−1 and 0.44 cm3 g−1, respectively) with a narrow size distribution. In addition, nitrogen doping of the graphitic carbons is uniformly achieved. A thermal analysis along with evolved gas investigation reveals that chemical processes, including N2 gas release and graphitization, vary pore texture formation in the resultant carbons with strong dependence on carbonization temperature. Such structural difference of the carbonized TACOF1 changes electrochemical capacitor behavior. The carbonized TACOF1 synthesized at 800 °C is found to show good capacitive performance due to its nitrogen-doped porous structures.

Deep eutectic solvent promoted tunable synthesis of nitrogen-doped nanoporous carbons from enzymatic hydrolysis lignin for supercapacitors

Dual functional deep eutectic solvent (DES) generated by the complexation of choline chloride and ZnCl2 was applied as both soft template and nitrogen source for the preparation of nanoporous carbons from sustainable lignin resource. Urea was purposely introduced as an additional nitrogen source as well as porogen. The diverse carbons were obtained by thermal treatment of the physical mixtures under N2 atmosphere in one-step. Physico-chemical characterization of the resultant carbons demonstrated that the presence of urea plays a key role in the formation of abundant micropores. With the incorporation of urea into the DES-templated system, the pore structure dominated by small mesopores evolved to a desirable micro-mesoporous hierarchical texture and exhibited a broccoli-like morphology. It has been demonstrated that the broccoli-like carbons exhibit enhanced electrochemical performance when used as electrodes in supercapacitors ascribed to the synergistic effect between rational micro-mesoporous structure and excellent nitrogen-doping efficiency (ca. 4–10 wt%).

Construction of Ni@Pt/N-doped nanoporous carbon, derived from pyrolysis of nickel metal organic framework, and application for HER in alkaline and acidic solutions

Owing to the growing significance of hydrogen as a non-polluting fuel, design and construction of low-cost, efficient and highly stable electrocatalysts are required for its production by means of water electrolysis. Herein, a general strategy is introduced to fabricate a new type of electrocatalysts based on bimetallic core@shell structure formed on nitrogen-doped nanoporous carbon for electrocatalytic hydrogen evolution reaction (HER). Accordingly, a nickel metal organic framework, Ni‒MOF, synthesized by using benzene-1,3,5-tricarboxylic acid (H3BTC) as the carbon source and 2-methyl-imidazole as the carbon and nitrogen source, is employed, and the nickel/nitrogen−doped nanoporous carbon composite, Ni/NNPC system, is synthesized by the direct carbonization of Ni‒MOF system, i.e. annealing the system in argon atmosphere without using any carbon precursor additive. Then, the outer layers of nickel in Ni/NNPC system are replaced by Pt via galvanic reaction to synthesize the nanostructured system, Ni metal core@Pt thin layer shell, Ni@Pt/NNPC. The step-by-step synthesis of the system and formation of core@shell was supported by several surface analysis techniques. The fabricated materials were transferred onto a glassy carbon (GC) electrode and studied for the HER. The electrochemical results revealed a large electrocatalytic activity for the GCE/Ni@Pt/NNPC system toward the HER in both alkaline and acidic media, compared with GCE, GCE/Ni−MOF and GCE/Ni/NNPC. Tafel slopes of 43.78 and 46.73 mV dec−1, and overpotentials of −33.80 and −76.32 mV (vs RHE) at 20 mA cm−2 (η20) were observed on GCE/Ni@Pt/NNPC electrode in the alkaline and acidic media, under the same conditions, respectively. The observed activity is attributed to (i) the increased electrochemically active surface area, (ii) the cooperative action or synergistic effect between the Pt thin layer shell and the Ni metal core as well as between the Ni@Pt nanoparticles and the NNPC platform, and (iii) effective pore structures of the Ni@Pt/NNPC system.