Noble Metal-free Electrocatalysts Research Articles

TM LDH Meets Birnessite: A 2D-2D Hybrid Catalyst with Long-Term Stability for Water Oxidation at Industrial Operating Conditions.

Efficient noble-metal free electrocatalyst for oxygen evolution reaction (OER) is critical for large-scale hydrogen production via water splitting. Inspired by Nature's oxygen evolution cluster in photosystem II and the highly efficient artificial OER catalyst of NiFe layered double hydroxide (LDH), we designed an electrostatic 2D-2D assembly route and successfully synthesized a 2D LDH(+)-Birnessite(-) hybrid. The as-constructed LDH(+)-Birnessite(-) hybrid catalyst showed advanced catalytic activity and excellent stability towards OER under a close to industrial hydrogen production condition (85 °C and 6 M KOH) for more than 20 h at the current densities larger than 100 mA cm-2 . Experimentally, we found that besides the enlarged interlayer distance, the flexible interlayer NiFe LDH(+) also modulates the electronic structure of layered MnO2 , and creates an electric field between NiFe LDH(+) and Birnessite(-), wherein OER occurs with a greatly decreased overpotential. DFT calculations confirmed the interlayer LDH modulations of the OER process, attributable to the distinct electronic distributions and environments. Upshifting the Fe-3d orbitals in LDH promotes electron transfer from the layered MnO2 to LDH, significantly boosting up the OER performance. This work opens a new way to fabricate highly efficient OER catalyst for industrial water oxidation.

Fabrication of electrospun nickel sulphide nanoparticles onto carbon nanofibers for efficient urea electro-oxidation in alkaline medium

To design and synthesize a noble-metal free electrocatalyst with increased efficiency and stability during urea electro-oxidation in alkaline solution is still an important challenge in the electrocatalytic field. In this work, carbon nanofibers were decorated with nickel sulphide nanoparticles [NiS@CNFs] through the electrospinning technique with subsequent heating into an argon atmosphere at 900 °C for 2 h. This formed nanomaterial was extensively characterized through X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), Raman spectroscopy and N2 adsorption-desorption measurements. A conductive network of intertwined CNFs was clearly detected by FE-SEM analysis technique with varied diameters in the range of 0.6–1 μm. A highly porous nature could be suggested after incorporating NiS nanospecies resulting in increased specific surface area and valuable electrocatalytic activity for urea molecules electro-oxidation. The pore size distribution curves showed a decreased average pore diameter for NiS@CNFs nanocomposite by 2.53 folds when compared to that at CNFs. The electroactivity of NiS@CNFs nanomaterial for catalyzing urea electro-oxidation was investigated using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy measurements. Increased activity of this nanocatalyst was registered when urea molecules were added in increased concentrations into KOH solution. Lowered resistance values were also obtained describing the charge transfer process to confirm the feasibility of the studied reaction at NiS@CNFs surface. Moreover, its drawn chronoamperogram showed a stable performance during operation for long periods revealing a lowered catalytic decay. Accordingly, the aforementioned results of our fabricated nanomaterial could provide a good guide for fabricating suitable electrocatalysts for various electrocatalytic purposes.

FeNi-functionalized 3D N, P doped graphene foam as a noble metal-free bifunctional electrocatalyst for direct methanol fuel cells

Designing high-performance bifunctional electrocatalysts for oxygen reduction (ORR) and methanol oxidation (MOR) reaction is essential for the wide application of direct methanol fuel cells. Here, we have prepared a novel three-dimensional (3D) FeNi-functionalized N, P doped graphene foam (FeNi@NP-GF) by a simple and cost-effective one-step pyrolysis method, as excellent bifunctional electrocatalyst for direct methanol fuel cells. Compared with metal-free and transition metal single-doped graphene foam catalysts (NP-GF, Fe@NP-GF and Ni@NP-GF), the resulting FeNi@NP-GF catalyst showed more positive half-wave potential and higher limiting current density in ORR reaction. Furthermore, it manifests a four-electron transfer process and strong methanol crossover resistance in the alkaline medium. The above results ascribed to the synergistic effect of Fe/Ni-Nx species formed with Fe/Ni and N species and multiple active sites in the 3D porous graphene material. Moreover, FeNi@NP-GF acted as good support for Pt nanoparticles (NPs). Pt/FeNi@NP-GF catalyst displayed remarkable catalytic performance and high stability for methanol electrooxidation reaction in acid medium.

Nitrogen-Doped Mixed-Phase Cobalt Nanocatalyst Derived from a Trinuclear Mixed-Valence Cobalt(III)/Cobalt(II) Complex for High-Performance Oxygen Evolution Reaction.

Because of a continuous increase in energy demands and environmental concerns, a focus has been on the design and construction of a highly efficient, low-cost, environmentally friendly, and noble-metal free electrocatalyst for energy technology. Herein we report facile synthesis of the mixed-valence trinuclear cobalt complex 1 by the reaction of 2-amino-1-phenylethanol and CoCl2·6H2O in methanol as the solvent at room temperature. Further, 1 was reduced by using aqueous N2H4 as a simple reducing agent, followed by calcination at 300 °C for 3 h, yielding a nitrogen-doped mixed phase cobalt [β-Co(OH)2 and CoO] nanocatalyst (N@MPCoNC). Both 1 and N@MPCoNC were characterized by various physicochemical techniques. Moreover, 1 was authenticated by single-crystal X-ray diffraction studies. The hybrid N@MPCoNC reveals a unique electronic and morphological structure, offering a low overpotential of 390 mV for a stable current density of 10 mA cm-2 with high durability. This N@MPCoNC showed excellent electrocatalytic as well as photocatalytic activity for oxygen evolution reaction compared to 1.

Theoretical and experimental investigations of Co-Cu bimetallic alloys-incorporated carbon nanowires as an efficient bi-functional electrocatalyst for water splitting

Application of noble metal-free electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) during electrocatalytic water splitting is crucial for clean energy conversion and has drawn extensive attention. However, the development of highly active and low cost electrocatalysts is a considerable challenge. Herein, Co-Cu alloy nanoparticles-incorporated carbon nanowires electrocatalyst was synthesized and evaluated for both OER and HER. The nanomaterials were fabricated by facile electrospinning of sol-gel composed of cobalt acetate, copper acetate, and poly(vinyl alcohol) followed by calcination in an inert environment. Adjusting the composition of the metallic counterpart was found to significantly enhance electrochemical properties of the catalyst. Furthermore, the unique nanowire morphology and structural properties of incorporated Co-Cu alloy, the (Co0.95Cu0.05@CNWs) composition exhibits good electrocatalytic performance for both OER and HER in the alkaline medium. Physicochemical characterizations using X-ray diffraction, X-ray photoelectron spectroscope, scanning electron microscopy, and transmission electron microscopy have confirmed the formation of alloy structure and nanowire morphology. The optimum composition (Co0.95Cu0.05@CNWs) requires small overpotential, ɳ10 of ∼285 mV for oxygen evolution reaction (OER) and ∼160 mV for hydrogen evolution reaction (HER) with the corresponding Tafel slope of 92 mV dec−1 and 172 mV dec−1 versus the reversible hydrogen electrode, respectively. In addition, only negligible loss in activity was observed after 1000 cycles and prodeces cell voltage of 1.58 V at current of 10 mA/cm2 and 1.72 V at current density of 50 mA/cm2 in two electrode system. Density Functional Theory (DFT) calculations were employed to verify experimental results. Electronic density of states (DOS) results reveal an increase in electronic states near the Fermi level upon Co-Cu heterojunctioning with CNWs. This is indicative of improved catalytic activity and more favorable binding energies of HER and OER intermediates. Reaction coordinate diagrams for HER and OER were developed, which aided in identifying thermodynamically limiting steps. This work may provide a feasible approach for incorporating other transition metals to design low-cost and high-performance bifunctional electrocatalysts for overall water splitting.

Electrocatalytic Ethanol Oxidation on Cobalt–Bismuth Nanoparticle-Decorated Reduced Graphene Oxide (Co–Bi@rGO): Reaction Pathway Investigation toward Direct Ethanol Fuel Cells

Direct ethanol fuel cells (DEFCs) are one of the resourceful and sustainable technologies for energy applications. Ethanol oxidation has been used to construct cost-effective and proficient electrocatalysts to substitute noble-based electrocatalysts like Rh, Pd, Ir, and Ag. Here in, we have presented a surface modification approach of doping a crucial oxophilic character metal onto a transition metal with carbon support. Noble metal-free cobalt–bismuth bimetallic nanoparticle-decorated reduced graphene oxide (Co–Bi@rGO) electrocatalysts were fabricated for enhanced ethanol oxidation reaction from their synergetic effect of rGO, Co, and Bi. A highly active, cost-effective, and efficient approach has been developed for the preparation of Co–Bi@rGO (Co NPs; ∼2 nm), initially Bi@rGO (Bi NPs@rGO; ∼50 nm), by a simple reduction method followed by Co, by Galvanic exchange of Bi atoms with Co. The as-synthesized nanocomposites were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and BET surface area measurement studies. Cyclic voltammetric studies show an ultralow onset potential of 0.28 V with a high current density of 10.25 mA/cm2, having a higher enhancement factor for Co–Bi@rGO compared to other individuals, including Bi NPs, Bi@rGO, and rGO under similar electrolyte conditions, which could be due to their synergetic cooperative interactions at electrified interfaces. Combined results from chronoamperometry (i–t) and electrochemical impedance spectroscopy show that Co–Bi@rGO is highly durable and sensitive toward the ethanol oxidation reaction compared to individual counterparts. This work also provides the noble metal-free bimetallic electrocatalysts for ethanol oxidation and assists in hydrogen production from an agricultural base.

Electrocatalytic ethylbenzene valorization using a polyoxometalate@covalent triazine framework with water as the oxygen source.

Ethylbenzene (EB) oxidation is an important transformation in the chemical industry. Herein, PMo10V2@CTF, a noble metal free electrocatalyst, was used to promote the oxidative upgrading of EB. Under ambient conditions, 65% of EB was converted to three value-added products using water as the oxygen source yielding a total Faraday efficiency of 90.4%. This excellent performance is ascribed to the homogeneous dispersion of PMo10V2 and its dual role in the electrocatalytic process.

Current trends and perspectives on emerging Fe-derived noble-metal-free oxygen electrocatalysts

This article discusses recent progress in the development of Fe-derived noble metal-free electrocatalysts, including the strategies used for design, synthesis, and assessment of their performance in alkaline conditions.

Design principles of noble metal-free electrocatalysts for hydrogen production in alkaline media: combining theory and experiment

Water electrolysis is a promising solution to convert renewable energy sources to hydrogen as a high-energy-density energy carrier. Although alkaline conditions extend the scope of electrocatalysts beyond precious metal-based materials to earth-abundant materials, the sluggish kinetics of cathodic and anodic reactions (hydrogen and oxygen evolution reactions, respectively) impede the development of practical electrocatalysts that do not use precious metals. This review discusses the rational design of efficient electrocatalysts by exploiting the understanding of alkaline hydrogen evolution reaction and oxygen evolution reaction mechanisms and of the electron structure–activity relationship, as achieved by combining experimental and computational approaches. The enhancement of water splitting not only deals with intrinsic catalytic activity but also includes the aspect of electrical conductivity and stability. Future perspectives to increase the synergy between theory and experiment are also proposed.

Wide pH range electrocatalytic hydrogen evolution using molybdenum phosphide nanoparticles uniformly anchored on porous carbon cloth

The development of efficient and inexpensive electrocatalysts is regarded as an urgent concern in electrochemical water-splitting system. Herein, we propose a novel strategy for the fabrication of molybdenum phosphide nanoparticles (MoP NPs) anchored on porous carbon cloth (MoP@PCC) as a noble metal–free electrocatalyst for hydrogen evolution reaction (HER). Benefiting from the thin and uniform coating of ultrafine molybdenum dioxide (MoO2) NPs on PCC, less-aggregated MoP NPs can be formed on PCC after thermal phosphidation, resulting in an efficient performance for HER over a wide pH range. Particularly, MoP@PCC exhibited good electrocatalytic activities in alkaline and neutral solutions with low overpotentials of 122 and 160 mV at a current density of −10 mA cm−2, respectively. Additionally, MoP@PCC exhibited long-term stability and durability with continuous 10,000 cyclic voltammetry (CV) cycles and chronopotentiometric operation over 50 h, both in alkaline and neutral solutions.

SnO2/CeO2 nanoparticle-decorated mesoporous ZSM-5 as bifunctional electrocatalyst for HOR and ORR

Developing highly efficient noble metal-free electrocatalysts for hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) in alkaline exchange membrane fuel cells (AEMFCs) is of great importance for the large-scale applications, which, however, still remains a great challenge. Here we present the synthesis of SnO2 and CeO2 nanoparticle-decorated mesoporous ZSM-5 (denoted as SnCe-ZSM) via electrostatic interaction, which, surprisingly, not only exhibits excellent catalytic activity towards HOR, but also largely enhance ORR performance. The strong electronic interaction between SnO2 and CeO2 nanoparticles synergistically leads to the electron-enrichment on SnO2 and oxygen vacancy accumulation on CeO2, which respectively enable the hydrogen and oxygen adsorption/activation concurrently, finally resulting in the significant enhancements of the electrocatalytic activity towards both HOR and ORR. Additionally, the SnCe-ZSM based zinc-air battery exhibits a remarkably high power density of 98 mW/cm2 and excellent stability during discharging/charging cyclic tests for 60 h. The SnCe-ZSM electrocatalyst provides a significant paradigm for designing bifunctional composite catalysts for applications in clean energy devices.

Electrocatalytic Hydrogen Evolution Reaction with Multilayer Graphene-Covered Ni Particles Synthesized by Microwave-Assisted Catalytic Methane Decomposition

It is known that the type of electrocatalysts used in the hydrogen evolution reaction (HER) are critical for energy technologies such as water splitting and hydrogen fuel cells. Thus, in recent years, increasing attention has been paid to the development of noble metal-free electrocatalysts. It has recently been reported that Ni–C-based catalysts exhibit HER activity comparable to that of Pt in an acidic medium. Moreover, we have recently developed a new metal–carbon powder, which contained multilayer graphene-covered Ni particles as the main component, synthesized by multimode microwave-assisted catalytic CH4 decomposition using a multimode microwave reactor. Thus, in this study, we investigated the electrocatalytic HER over the Ni–C powder using a digital potentiostat equipped with a potential sweep unit. Figure 1 shows the current–potential curve in the presence or absence of dissolved oxygen in an aqueous H2SO4 solution; the curve was obtained using a carbon paste electrode filled with the Ni–C powder. A reduction current based on HER was observed from approximately 0.0 V (referred vs. SHE), while the onset potential was shown to be slightly affected by the presence or absence of dissolved oxygen. Therefore, the Ni–C powder can be used as a noble metal-free electrocatalyst to implement the HER with excellent electrochemical performance in acidic medium. *Figure 1. Linear sweep voltammograms with the carbon paste electrode (Φ = 3 mm) filled with the Ni–C powder, synthesized by a multimode microwave-assisted process in an acidic solution under different atmospheres. SR = 10 mV/s. Figure 1

Cobalt/Dihydroxybenzimidazole-Derived Amorphous MOF TAL-2 As a Single Precursor for Trifunctional ORR/Oer/HER Electrocatalyst Material

Preparation of cost-efficient noble metal-free multifunctional electrocatalyst materials with high performance and stability for oxygen evolution reaction (OER), oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) – referred to as trifunctional catalysts – remains an outstanding challenge. The catalyst material was prepared from amorphous metal–organic framework TAL-2, which was obtained from cobalt salt and dihydroxybenzimidazole and outperformed the benchmark catalysts in ORR and OER reactions (0.1 M KOH: ∆E = 0.73 V, AMFCs: j = 1100 mA cm–2, P = 400 mW cm–2). Use of dopants or modifying conditions was unnecessary for this material to be used as a trifunctional electrocatalyst.

Porphyrin-Modified Cobalt Sulfide as a Developed Noble Metal-free Photoelectrocatalyst toward Methanol Oxidation under Visible Light

Designing noble metal-free electrocatalysts with highly efficient performance toward methanol oxidation reaction (MOR) still remains a significant challenge. Herein, 5,10,15,20-tetrakis(4-carboxylp...

Melamine-assisted synthesis of ultrafine Mo2C/Mo2N@N-doped carbon nanofibers for enhanced alkaline hydrogen evolution reaction activity

Noble metal-free electrocatalysts with high activity are highly desirable for the large-scale application of hydrogen evolution reaction (HER). Mo2C-based nanomaterials have been proved as a promising alternative to noble metal-based electrocatalysts owing to the Pt-resembled d-band density and optimal intermediates-adsorption properties. However, the aggregation and excessive growth of crystals often occur during their high-temperature synthesis procedure, leading to low catalytic utilization. In this study, the ultrafine Mo2C/Mo2N heterostructure with large surface and interface confined in the N-doped carbon nanofibers (N-CNFs) was obtained by a melamine-assisted method. The synergistic effect of Mo2C/Mo2N heterostructure and plenty active sites exposed on the surface of ultrafine nanocrystals improves the electrocatalytic activity. Meanwhile, the N-CNFs ensure fast charge transfer and high structural stability during reactions. Moreover, the in-situ synthesis method strengthens the interfacial coupling interactions between Mo2C/Mo2N heterostructure and N-CNFs, further enhancing the electronic conductivity and electrocatalytic activity. Owing to these advantages, Mo2C/Mo2N@N-CNFs exhibit excellent HER performance with a low overpotential of 75 mV at a current density of 10 mV cm−2 in alkaline solution, superior to the single phased Mo2C counterpart and recently reported Mo2C/Mo2N based catalysts. This study highlights a new effective strategy to design efficient electrocatalysts via integrating heterostructure, nanostructure and carbon modification.

Polyoxometalate Derived Mo Based Hybrid HER Electrocatalysts with Carbon as Matrix and Their Application in Zn-H+ Battery

H2 has been considered as a promising successor for traditional fossil fuels due to its sustainable and clean. In H2 production, electrocatalytic hydrogen evolution reaction (HER) is the core step. Many noble metal free electrocatalysts for electrochemical H2 generation have been explored in the past few years. Mo based materials, such as MoxC (x = 1 or 2), MoP, MoS2 and MoxN (x = 1 or 2) have been confirmed as effective electrocatalysts in both acidic and basic conditions with small overpotential, excellent stability and nearly 100% Faradic efficiency in H2 generation. Because of excellent solubility, controllable dimension and various components, Mo based polyoxometallates (POMs), such as [PMo12O40]3−, [Mo7O24]6−, [P2Mo5O23]6−, [Mo6O19]2− and [XMo6O24]4− (X = Co2+, Cu2+, Ni2+), are ideal precursors to synthesize Mo based electrocatalyst. Here, we summarized Mo based hybrid electrocatalysts in form of MoxC, MoP, MoS2 and MoxN with carbon as matrix, which derived from POM since 2013. In this review, we focus on the synthetic strategy and HER activity of these electrocatalyst. We anticipate this review can provide more insight into the structural and composition regulation of POM precursor to design and synthesis Mo based HER electrocatalyst with more excellent activity.

3D Hydrangea Macrophylla-like Nickel-Vanadium Metal-Organic Frameworks Formed by Self-Assembly of Ultrathin 2D Nanosheets for Overall Water Splitting.

The development of highly efficient and low-cost bifunctional noble metal-free electrocatalysts for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is an effective strategy for improving efficiency. Herein, novel three-dimensional (3D) bimetallic metal-organic frameworks containing Ni and V with adjustable stoichiometry were synthesized on nickel foam successfully. Notably, Ni2V-MOFs@NF only require rather low overpotentials of 244 and 89 mV for the OER and HER, respectively, and expedites overall water splitting with 1.55 V at 10 mA cm-2 with robust durability during the 80 h test. The high efficiency of the novel obtained electrocatalysts should be attributed to the particular morphological design of the two-dimensional (2D) ultrathin nanosheets self-assembling into a 3D nanoflower and the electronic structure regulation resulting from the synergetic interaction between nickel and vanadium. Subsequent theoretical calculations reveal the following conclusions: (I) the exceptional electronic conductivity of Ni2V-MOFs shows enhanced optimization as a result of electronic structure reconstruction, (II) the energy barrier reduction of the rate-limiting step is responsible for the enhanced dynamics of Ni2V-MOFs for the OER, and (III) the facilitation of the adsorption of H+ and H2O plays a key role in progressing the HER catalytic activity of Ni2V-MOFs.

Modification of polyaniline-WO3 as a noble metal-free photo electrocatalyst with (6, 6) - Phenyl-C61- butyric acid methyl ester for solar photoelectrochemical water splitting

Development of semiconductors with appropriate bandgap energies, strong light absorption, effectual charge carrier separation, and rapid transport of photogenerated electrons and holes as photoanode for photoelectrochemical (PEC) water oxidation has gained a lot of attention in the recent years. In our previous studies, the PEC performance of polyaniline-WO3 (PANI-W) nanocomposite was confirmed as a high-performance organic-inorganic photoelectrocatalyst. In this research, we modified polyaniline-WO3 photoelectrocatalyst with (6, 6)-phenyl-C61-butyric acid methyl ester (PC61BM) as an efficient fullerene derivative with high electron-accepting capability and excellent electron mobility for solar-induced water oxidation. The as-synthesized compounds were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The electrochemical measurements showed that the activity of PC61BM modified polyaniline-WO3 toward water electro-oxidation enhanced. A photocurrent density of 1.63 mAcm−2 at 1.23 V vs. RHE achieved for PANI-W-PCBM indicating ~2.5-fold improvement compared to that of PANI-W. Furthermore, the charge transfer resistance (Rct) of PANI-W-PCBM at electrode/electrolyte interface under light irradiation is 433 Ωcm2 which is 5.64 times lower than that of PANI-W (2441 Ωcm2). The modification of PANI-W nanocomposite with PC61BM suppressed the recombination of photogenerated electrons and holes and provided more active sites for oxygen evolution reaction due to the outstanding electrical conductivity, carrier mobility, and large surface area of PC61BM. Therefore, modification of organic-inorganic nanocomposite with conjugated carbon-based materials increased the PEC water splitting activity.

CoP-embedded nitrogen and phosphorus co-doped mesoporous carbon nanotube for efficient hydrogen evolution

Hydrogen evolution reaction (HER) through the electrochemical process at low overpotentials is vital for sustainable energy production. However, the fabrication of non-precious materials with high efficiency for the HER remains a challenge. Here, a new catalyst that consists of cobalt (Co) species embedded nitrogen (N) and phosphorus (P) co-doped carbon nanotubes (CNT) is fabricated by the polymerization of dopamine on the cobalt-nitrilotriacetic coordination polymer nanowire surface, followed by the phosphidation and carbonization under high temperature. After the pretreatment by potassium hydroxide (KOH) and the removal of metallic Co nanoparticles by sulfuric acid (H2SO4), the activated catalyst (A-Co/N,P-CNT-700) exhibits an overpotential of 44 mV to obtain 10 mA cm−2 current density , approaching the value of commercial Pt/C catalyst (27 mV). The catalyst could easily maintain ~ 95% of its original HER activity after 15–hour stability test. The superior performance arises from the unique N-Co-P surface bonding states at the interface between CoP nanoparticles (1–4 nm) and N,P co-doped CNT. To the best of our knowledge, such HER performance is the best among noble metal free electrocatalysts in acidic electrolytes.

Electrocatalytic Hydrogen Evolution Reaction with Multilayer Graphene-Covered Ni Particles Synthesized by Microwave-Assisted Catalytic Methane Decomposition

We developed a new method for the production of large amounts of carbon–nickel (C–Ni) powder, which contained multilayer graphene-covered Ni particles as the main component, using multimode microwave-assisted catalytic CH4 decomposition. Electrocatalytic hydrogen evolution reaction of the C–Ni powder in acidic solution was investigated using electrochemical method. The C–Ni powder can be used as a noble metal-free electrocatalyst to implement the hydrogen evolution reaction with good electrochemical performance in the acidic solution.