N-doped Carbon Support Research Articles

(Invited) Facile and Scalable Production of an Intermetallic Nanocatalyst for High-Power Proton-Exchange-Membrane Fuel Cell

With universal attention to sustainable development, the eco-friendly generation of energy has been emerging as one of the most important tasks. Proton-exchange-membrane fuel cells (PEMFC) are one of the key solutions to this urgent problem due to their clean energy generation. However, a complicated reaction environment has been limiting its power performance for industrial applications, such as 1) catalytic activity, 2) oxygen mass transfer, and 3) proton conduction at the cathode catalyst layer. To handle all these critical factors, a holistic design and elaborate synthesis of catalyst are imperative without compromising the scalability of synthesis. Here, we present a straightforward but exquisite synthetic approach that addresses the aforementioned practical issues and demonstrate an excellent PEMFC power performance. The crystalline ionic compound ([Co(bpy)3]2+[PtCl6]2-, bpy = 2,2′-bipyridine) enabled a carbon shell-protected growth of intermetallic nanoparticles with N-doping on the entire mesoporous carbon support via a simple thermal annealing process. The overall structure of the catalyst simultaneously tackled the critical issues in PEMFC, including ORR kinetics (by strained Pt-skin surface on intermetallic Pt-Co core), oxygen mass transfer (by high ECSA and mesoporous N-doped carbon support), and proton conduction (by stabilized Co species in intermetallic core and Pt-skin) with desirable durability. This study highlights the importance of meeting all the critical parameters to achieve much higher fuel cell power performance through the development of a facile and scalable production method of catalyst.

Imparting selective polysulfide conversion via geminal-atom moieties in lithium-sulfur batteries

Electrocatalysis in lithium-sulfur (Li–S) chemistry has readily stimulated extensive interests because of its irreplaceable role in realizing high-performance batteries. In this sense, achieving accelerated catalytic conversion of polysulfides is essential for the shuttle inhibition and kinetics promotion. Nonetheless, selective catalysis of sulfur reduction/evolution reaction via precise control over electrocatalytic mediators is still in its infancy. Moreover, specific catalytic role of the active metal center in dual-atom catalyst sites remains relatively unexplored. Herein, we utilize a salt-confined strategy to fabricate FeCo geminal-atom moieties dispersed on N-doped carbon support (FeCo-NC) for Li–S batteries throughout leveraging Fe and Co single-atom species with selective catalysis. The enhanced bidirectional conversion kinetics of polysulfide with the incorporation of Fe and Co atoms are uncovered throughout theoretical simulation and electrokinetic analysis. As a result, the FeCo-NC endows a rechargeable Li–S battery with excellent capacity retention rate of 98.6% after 100 cycles at 0.2 C and cycling stability with a decay rate of 0.033% per cycle over 2000 cycles at 3.0 C. More encouragingly, the assembled Li–S cell at a sulfur loading of 6.7 mg cm−2 can harvest an areal capacity of 7.13 mAh cm−2, signifying the rational design of geminal-atom mediators to dictate selective catalysis behaviors toward practical Li–S batteries.

Synergistic effect of perovskites and nitrogen-doped carbon hybrid materials for improving oxygen reduction reaction

A fundamental understanding of the electrochemical behavior of hybrid perovskite and nitrogen-doped (N-doped) carbon is essential for the development of perovskite-based electrocatalysts in various sustainable energy device applications. In particular, the selection and modification of suitable carbon support are important for enhancing the oxygen reduction reaction (ORR) of non-platinum group metal electrocatalysts in fuel cells. Herein, we address hybrid materials composed of three representative N-doped carbon supports (BP-2000, Vulcan XC-72 and P-CNF) with valid surface areas and different series of single, double and triple perovskites: Ba0.5Sr0.5Co0.8Fe0.2O3−δ, (Pr0.5Ba0.5)CoO3−δ, and Nd1.5Ba1.5CoFeMnO9−δ (NBCFM), respectively. The combination of NBCFM and N-doped BP-2000 produces a half-wave potential of 0.74 V and a current density of 5.42 mA cm−2 at 0.5 V versus reversible hydrogen electrode, comparable to those of the commercial Pt/C electrocatalyst (0.76 V, 5.21 mA cm−2). Based on physicochemical and electrochemical analyses, we have confirmed a significant improvement in the catalytic performance of low-conductivity perovskite catalyst in the ORR when nitrogen-doped carbon with enhanced electrical conductivity is introduced. Furthermore, it has been observed that nitrogen dopants play active sites, contributing to additional performance enhancement when hybridized with perovskite.

Preparation of thiol-decorated Ag nanoparticles on N-doped carbon through resonant acoustic mixing for electrochemical CO2 reduction

The development of electrocatalysts with high selectivity and low overpotentials has been a prominent area of focus in electrochemical CO2 reduction (ECR) research. Supported metal nanoparticle (NP) has been received considerable interest due to the immense potential of remarkable activity, stability, and recyclability in ECR applications. However, the practical production of these supported metal NPs necessitates a facile and scalable approach. Addressing this challenge, the present study introduces a novel method for solid-state synthesis of Ag/C using resonant acoustic mixing (RAM). The RAM technique successfully facilitated the deposition of Ag nanoparticles onto n-doped carbon support, forming Ag/N-C catalysts. The as-prepared Ag electrocatalysts exhibited excellent dispersion and uniformity in terms of particle size. A thiol-decorated Ag electrocatalyst (Ag-Th/N-C) was prepared using a simple soaking method to establish an Ag-thiol interface enhancing catalytic activity caused by promoted electron transfer from Ag to CO2. Significantly, the Ag-Th/N-C catalyst demonstrated an improved Faradaic efficiency of 87.26% for the reduction of CO2 to CO at − 1.1 V versus RHE compared to the pristine Ag/C catalyst (55.45%).

Superior silicon-free Cu catalyst for dimethyl oxalate hydrogenation: Exploring interaction between Cu and pyridinic-N-rich ultrathin carbon

The hydrogenation of dimethyl oxalate (DMO) is a key step in the economical and eco-friendly synthesis of high value-added alcohols from syngas. In this study, a pyridinic-N-rich ultrathin carbon was employed as a support to construct a silicon-free Cu catalyst for highly efficient DMO hydrogenation. N-doped ultrathin carbon support with a two-dimensional structure provided sufficient anchoring sites for Cu species. More critically, abundant pyridinic-N (72.3%) maintained Cu in an electron-deficient state via electronic interactions between Cu and the carbon support, thereby preserving the vital active sites Cu+ during the hydrogen-rich reaction. The new silicon-free Cu catalyst (Cu/0.1 N-UC) demonstrated an ethanol selectivity that was 1.8 times higher than that of the commonly used Cu/SiO2 catalyst. Additionally, the Cu/0.1 N-UC catalyst displayed superior stability and could convert the primary product to ethylene glycol by adjusting the reaction temperature. This study offers a novel approach for the development of promising silicon-free Cu catalysts for DMO hydrogenation.

Co-pyrolysis induced strong metal-support interaction in N-doped carbon supported Ni catalyst for the hydrogenolysis of lignin

Designing highly active and stable catalysts for the selective cleavage of the C-O bond of lignin is important to convert it into high-valued aromatic compounds. Herein, a facile synthetic strategy was developed using melamine as a soft template to prepare a highly active catalyst consisting of highly dispersed Ni nanoparticles on defective N-doped carbon support. The results indicated that the decomposition of melamine during the pyrolysis process induced the nitrogen atoms into aromatic carbon. The introduction of N-doped carbon support acted as anchor points for the Ni nanoparticles, strengthening the metal-support interaction. Approximately 100 conversion of the representative lignin model compounds, including 2-phenylethyl phenyl ether, were converted into their aromatic monomers under mild conditions. The as-prepared catalyst was stable and reusable after five cycles with no apparent signs of deactivation. Moreover, the theoretical calculation revealed that N-doped carbon supported Ni-based catalyst possessed a lower activation energy of C-O bond than only carbon supported Ni-based catalyst for the C-O bond cleavage in hydrogenolysis of lignin and its model compounds.

In-situ generation of ZnS nanoparticles in quasi-MOFs for efficient eNRR

Inspired by the nitrogenase, transition metal sulfides have made outstanding progress in the field of eNRR. ZnS has emerged in the eNRR due to the strong photoelectric properties. Specially, the physical and chemical properties of ZnS are closely related with the support. In our study, ZIF-8-L was selected as the template to prepared ZnS/quasi-MOFs (ZnS/ZIF-8-L-T (T represents reaction temperature)) catalysts by using partial pyrolysis method. In this reaction process, the metal nodes of ZIF-8-L reacted with BDS to create ZnS nanoparticles, the organic ligands were carbonized to form the N-doped carbon support and partial framework of ZIF-8-L were remained. The hierarchical pore structure and high specific surface area of ZnS/ZIF-8-L-T not only provided a wide space for molecular diffusion, but also improved the adsorption and activation of N2. Additionally, the hydrophobicity of N-doped carbon support inhibited HER and improved FE. When the calcination temperature reached 350 °C, the obtained ZnS/ZIF-8-L-350 catalyst achieved a high NH3 yield (53.44 μg·h−1·mg−1) and a good FE (15.75%) at -0.3 V vs. RHE in 0.05 M H2SO4 solution. This work highlights the importance of support in regulating the physicochemical structure of the catalytic active center and can guide the design of advanced eNRR catalysts.

The effect of nitrogen doping on hydrogenation capability and stability of Cu-based catalyst in ester hydrogenation to methyl glycolate

Methyl glycolate (MG) was a significant chemical raw material of biodegradable and bioabsorbable polyglycolic acid (PGA). In this work, the N-doped layered carbon supported Cu catalysts were constructed for dimethyl oxalate (DMO) hydrogenation to MG. Nitrogen doping had significant effects on the particle size, valence state and electronic environment of Cu species. The electronic interaction between Cu species and N-doped carbon support improved the Cu0/(Cu0 + Cu+) ratio and electron density surrounding Cu species in N-doped catalysts. The synergistic effect of high Cu0/(Cu0 + Cu+) ratio and electron density made Cu species in Cu/C-E catalyst showed up to 74.84% MG yield. More importantly, the intimate interaction between Cu species and N-doped carbon support improved the thermal and valence stability of Cu catalyst, resulting in the Cu/C-E catalyst with a much higher stability of over 600 h than the currently reported Cu catalyst.

Self-driven electron enrichment of ultrafine PdAu nanoparticles for electrochemical CO2 reduction: High applicability of work function as an activity descriptor

Highly coupled metal/dopant-incorporated carbon dyads provide a possibility to modulate the electron density of metallic materials by forming a rectifying interface, thus showing an enhanced activity in electrochemical CO2 reduction reaction (ECRR). However, understanding the promotion effects of dopants for ECRR is limited to the prediction by theoretical interpretation and case-by-case studies. Herein, we report the direct experimental evidence that the work function, regulated by single structural factor-dopant contents, is significantly correlated to the ECRR reaction activity and kinetics. We prepared a series of PdAu/NxC electrocatalysts composed of ultrafine (∼5.7 nm) PdAu bimetallic nanoparticles and tailorable N-doped carbon supports. The wide range of the amount of N dopants allowed the modification of the band gap of the carbon easily. Using ultraviolet photoelectron spectroscopy (UPS) measurements, we demonstrate that the reactivity and kinetics trends of the PdAu/NxC in the ECRR can be intrinsically correlated with the work function of the catalysts. PdAu/N7.50C electrocatalyst with the highest N contents displays a 100% CO2-to-CO conversion and high conversion efficiency over a wide potential window, superior over other reported PdAu catalysts. This work provides a novel way to boost ECRR performance by deliberately lowering the work function of the metal/carbon electrocatalysts through the enhancement by dopants.

Sustainable chitosan hydrogen derived platinum/N-doped carbon aerogel for efficient oxygen reduction and hydrogen evolution reactions

Platinum (Pt)-based catalysts play a key role in electrocatalytic oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER), and reducing Pt content and maintaining high electrocatalytic activity and durability are essential to its promoted application. In this work, low content of Pt (10.5 wt%) loaded defective N-doped carbon aerogel (Pt/D-NCA) was synthesized using natural protonated chitosan complexed chloride platinate ion (chitosan-PtCl62-) as precursor. Pt/D-NCA exhibits better ORR (half-wave potential of 0.89 V vs RHE) and HER (57 mV vs RHE overpotential at 100 mA/cm2) performance than commercial 20 wt% Pt/C, and can be used as efficient cathode for Zn-air battery and water spitting. The defective N-doped carbon support can effectively reduce energy barrier of Pt sites through interface effect to inducing high intrinsic ORR and HER catalytic activity. This work provides a sustainable route to synthesize low Pt consumption electrocatalyst through a sustainable and environmentally friendly pathway.

Engineering of the N-doped carbon support for improved performance of supported Pd catalysts in hydrogen production from gas-phase formic acid

Development of N-doped Pd/C catalysts for hydrogen production from gas-phase formic acid is a challenge. To elucidate the efficient routes of nitrogen insertion on the surface of a mesoporous carbon support, the latter was treated with melamine (Mel), dicyandiamide or NH3 at 673 and 823 K. Pyrolysis of the melamine/carbon mixture taken in a 1:2 ratio provides an increase in the reaction rate by a factor of 5. The inserted N-sites strongly interact with Pd leading to the formation of highly dispersed Pd nanoparticles (∼1.6 nm) and active atomically dispersed Pd2+ species. With a further increase of the Mel/C ratio, the number of surface N-sites decreases due to occupation of carbon support pores with a g–C3N4–type residue. This provides a decrease in the Pd dispersion leading to lower reaction rates. Therefore, melamine is an efficient N precursor. The considered synthesis of N-doped catalysts could be scaled.

Highly Dispersed Ni on Nitrogen-Doped Carbon for Stable and Selective Hydrogen Generation from Gaseous Formic Acid.

Ni supported on N-doped carbon is rarely studied in traditional catalytic reactions. To fill this gap, we compared the structure of 1 and 6 wt% Ni species on porous N-free and N-doped carbon and their efficiency in hydrogen generation from gaseous formic acid. On the N-free carbon support, Ni formed nanoparticles with a mean size of 3.2 nm. N-doped carbon support contained Ni single-atoms stabilized by four pyridinic N atoms (N4-site) and sub-nanosized Ni clusters. Density functional theory calculations confirmed the clustering of Ni when the N4-sites were fully occupied. Kinetic studies revealed the same specific Ni mass-based reaction rate for single-atoms and clusters. The N-doped catalyst with 6 wt% of Ni showed higher selectivity in hydrogen production and did not lose activity as compared to the N-free 6 wt% Ni catalyst. The presented results can be used to develop stable Ni catalysts supported on N-doped carbon for various reactions.

Atomically dispersed Ni-N-C catalyst derived from NiZn layered double hydroxides for efficient electrochemical CO2 reduction

Atomically dispersed catalytic metal sites anchored on N-doped carbon support catalysts (M-N-C) show great prospects for CO2 electroreduction. Here, single-layer NiZn layered double hydroxides (NiZn-LDHs) was used as a sacrificial assistant to fabricate single-Ni atom anchored on ultrathin porous carbon catalyst. NiZn-LDHs were exfoliated to single-layer by polyhydroxy compounds which took as the carbon resource in Ni-N-C, and single layer NiZn LDHs taking as the Ni resource could avoid the agglomeration of Ni atoms during calcining. The CO Faradaic efficiency (FECO) of the synthesized Ni-N-C catalyst exceeded 90% at −0.6 to −1.0 V and a FECO of 95.2% with a current density of 24 mA cm−2 at −0.9 V. This work not only provides a new method for preparing M-N-C catalysts, but also offers an effective and controllable strategy for large-scale production of high-performance single-atom catalysts.

Metal–Organic Framework-Derived Co-Doped ZnO Nanostructures Anchored on N-Doped Carbon as a Room-Temperature Chemiresistive Hydrogen Sensor

The impending need to utilize H2 for multiple applications has surged the need to develop H2 sensors. Development of selective and rapid room-temperature H2 sensors is an uphill task without the doping of precious metals (Pd, Pt, and Au) in semiconductor metal oxide (SMO) sensors. Nanostructure of the SMOs could play a decisive role in gas sensing properties of the material. In this study, metal–organic framework (MOF)-derived Co–ZnO anchored on nitrogen-doped carbon (Co–ZnO–N/C) nanomaterial has been demonstrated as an effective rapid room-temperature H2 sensor. The pyrolysis of monometallic ZIF-8 (Zn) gave rise to amorphous ZnO stabilized on nitrogen-doped carbon (ZnO–N/C) and was found to be innocent for H2 sensing, whereas the pyrolysis of bimetallic ZIF(Co–Zn) resulted in the formation of Co–ZnO–N/C nanostructure with a high dispersion of Co on amorphous ZnO. Co–ZnO–N/C inherited the nanostructure of the parent precursor with rhombododecahedron particles of 200–300 nm and possessed subnanometer pores. Co inclusion into ZnO has converted the innocent amorphous ZnO–N/C into a rapid room-temperature H2 sensor (by measuring the dynamic change in the resistance with respect to time). Co–ZnO–N/C displayed a 3.7% response % with 17–26 s of recovery–response times for 1% concentration of H2 under room-temperature conditions. The unique nanostructure of Co–ZnO–N/C enhanced the signal transduction (via N-doped carbon support) and promoted H2 diffusion (through subnanometer pores). Higher-temperature H2 sensing studies were also conducted at 200 °C, wherein Co–ZnO–N/C displayed an increase in response to 5.7% with 8–16 s of response–recovery times. Co–ZnO–N/C chemiresistor is a rare example that does not contain precious metals yet exhibits room-temperature hydrogen sensing.

ZIF-8 derived N-doped porous carbon confined ultrafine PdNi bimetallic nanoparticles for semi-hydrogenation of alkynes

Catalytic semi-hydrogenation of alkynes to alkenes plays an important role in the polymer, fragrance, medicine, and other chemical industrial fields. However, increasing the selectivity of alkenes during the semi-hydrogenation process is a huge challenge. Herein, N-doped porous carbon support (NC) was fabricated from zinc-based zeolite imidazole frameworks (ZIF-8). Ultrafine PdNi bimetallic nanoparticles (NPs) were uniformly dispersed, stably anchored on the NC support, and used as an efficient alkynes semi-hydrogenation catalyst. The synthesized Pd2Ni2/NC catalyst had a selectivity of 95.1% toward styrene and high catalytic activity (TOF=977.7 h−1) for the semi-hydrogenation of phenylacetylene under mild reaction conditions. The catalyst was mainly through metal-support interaction and electron transfer between Pd and Ni metal, modulating the electronic structure of the active sites, thus improving the selectivity of styrene. Selective hydrogenation of various substituted alkynes on Pd2Ni2/NC catalyst has also proved excellent applicability, and the obtained catalyst can be reused with favorable stability. This study adjusted the catalytic performance by adding a secondary metal, which provided a useful strategy for designing highly efficient catalysts for the semi-hydrogenation of alkynes.

2-Dimensional metal-organic framework derived N-doped carbon immobilized Pd nanoparticles for hydrogen release from formic acid

Hydrogen release from formic acid is a significant energy supply route. However, the current catalysts suffer from low catalytic efficiency and stability. Herein, a porous N-doped carbon material with high N content (16.87%) and a large surface area (1544 m2·g−1) were designed using a 2-dimensional metal-organic framework and etching agent potassium chloride. Due to its high N content and large surface area, ultrafine Pd particles are uniformly distributed on the porous N-doped carbon support, which effectively enhances excellent reactivity and enables a TOF value of 2365 h−1 under additive-free conditions. The research also revealed that the strong interaction between Pd particles and pyridinic-N species can significantly slow metal agglomeration. Hence, the Pd/NCZIF-L (KCl) displayed good activity even after 10 cycling experiments, and it is a particularly competitive catalyst for hydrogen release from formic acid.

Synergistic Effect of Fe Single-Atom Catalyst for Highly Efficient Microwave-Stimulated Remediation of Chloramphenicol-Contaminated Soil.

Chloramphenicol (CAP) has long been used extensively in agriculture and is severely toxic to the biological environment. Microwave catalysis appears a promising method for soil remediation due to its fast and effective heat transfer, but it is challenging to prepare catalysts with good electromagnetic wave absorption and robust catalytic activity. In this study, atomically dispersed Fe on three-dimensional N-doped carbon supports (3D Fe-NC) is firstly used for microwave remediation of soil. Thanks to the synergistic effect of microwave "hot spots" and reactive oxygen species (•OH, •O2 - ), 3D Fe-NC can completely remove 99.9% of CAP in 5min. The removal rate constant is nearly twice that of commercial activated carbon. Significantly, the germination rate of lettuce seeds in microwave-repaired soil contaminated by CAP reaches 70%. This work demonstrates the application of Fe single-atom catalyst in microwave remediation of contaminated soil, providing a novel insight for agricultural soil remediation.

Pt3Co/Co Composite Catalysts on Porous N-Doped Carbon Support Derived from ZIF-67 with Enhanced HER and ORR Activities.

The primary challenge for efficient H2 evolution and hydrogen energy conversion is to develop highly active and stable catalysts with simple and reliable preparation processes. In this regard, we have designed and synthesized a porous carbon-supported low-Pt alloy catalyst (Pt3Co/Co@C composite) using ZIF-67 as a template. It showed uniformly dispersed Pt3Co/Co on the porous carbon layer due to the confinement effect of the porous carbon layer. Pt3Co/Co@C demonstrated excellent activity for the hydrogen evolution reaction in the full pH range, with an overpotential of 187 mV in 0.5 M H2SO4 to attain 100 mA/cm2 as well as long-term stability. It also displayed superior mass activity for the oxygen reduction reaction (ORR) at 0.85 V (vs RHE) compared to the commercial Pt/C. Furthermore, the Pt3Co/Co@C catalyst exclusively enabled a four-electron reaction process under ORR conditions without the competitive pathway to H2O2. The current work provides guidance for the design and facile synthesis of Pt-based catalysts with enhanced performance.

Effects of Graphitic and Pyridinic Nitrogen Defects on Transition Metal Nucleation and Nanoparticle Formation on N-Doped Carbon Supports: Implications for Catalysis

Functionalization of carbon supports with heteroatom dopants is now widely regarded as a promising route for stabilizing and strengthening the interactions between the support and metal catalysts. Tuning the type and density of heteroatom dopants allows for the tailoring of nanoscale catalyst–support interactions; however, an understanding of these phenomena has not yet been fully realized because of the complexity of the system. In this work, computational modeling, materials synthesis, and advanced nanomaterial characterization are used to systematically investigate the intriguing effect of the two most common nitrogen functionalities in the carbon-based supports on the interactions with selected transition metals toward realizing catalytic applications. Specifically, this study utilized density functional theory to evaluate adsorption energies and modes of adsorption for 12 metals located in groups 8–11 and periods 4–6 with pyridinic and graphitic N defects. Based on these results, further electronic structure investigation of the period 4 metals was conducted to elucidate periodic group trends. Experimental work included synthesis and nanomaterial characterization of a subset of materials featuring three metals each supported on two types of N-doped carbon supports and undoped graphene. Characterization of nanomaterials with scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy confirmed that N functionalities enhanced the interactions with the selected transition metals when compared to the undoped support and demonstrated that the nature of the defect influences these interactions. Both computations and experiments agreed that Fe and Co are biased toward the graphitic sites over pyridinic sites, while Ni has an affinity to both defects without a statistically significant preference. This work established a correlation between computational and experimental work and a framework that can be expanded to other metals and alternative dopants beyond nitrogen in tailoring nanoscale catalyst–support interactions for a breadth of catalytic applications.

Nickel-induced charge redistribution in Ni-Fe/Fe3C@nitrogen-doped carbon nanocage as a robust Mott-Schottky bi-functional oxygen catalyst for rechargeable Zn-air battery

Designing earth-abundant and advanced bi-functional oxygen electrodes for efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are extremely urgent but still ambiguous. Thus, metal-semiconductor nanohybrids were developed with functionally integrating ORR-active Ni species, OER-active Fe/Fe3C components, and multifunctional N-doped carbon (NDC) support. Expectantly, the resulted NDC nanocage embedded with Ni-Fe alloy and Fe3C particles, as assembled Mott-Schottky-typed catalyst, delivered a promoted half-wave potential of 0.904 V for ORR and a low overpotential of 315 mV at 10 mA/cm2 for OER both in alkaline media, outperforming those of commercial Pt/C and RuO2 counterparts. Most importantly, the optimized Ni-Fe/Fe3C@NDC sample also afforded a peak power density of 267.5 mW/cm2 with a specific capacity of 773.8 mAh/gZn and excellent durability over 80 h when used as the air electrode in rechargeable Zn-air batteries, superior to the state-of-the-art bi-functional catalysts. Ultraviolet photoelectron spectroscopy revealed that the introduction of Ni into the Fe/Fe3C@NDC component could well manipulate the electronic structure of the designed electrocatalyst, leading to an effective built-in electric field established by the Mott-Schottky heterojunction to expedite the continuous interfacial charge-transfer and thus significantly promote the utilization of electrocatalytic active sites. Therefore, this work provides an avenue for the designing and developing robust and durable Mott-Schottky-typed bi-functional catalysts for promising energy conversion.