Low loading of P modified Rh nanoparticles encapsulated in N,P-doped carbon for boosted and pH-universal hydrogen evolution reaction

Searching for highly efficient and Pt-free electrocatalysts with comparable hydrogen evolution reaction (HER) activities to the benchmark Pt/C catalyst is highly demanded for developing renewable water electrolysis system but still remains challenging. In the current work, low loading of P modified ultrafine Rh nanoparticles encapsulated in N, P dual-doped carbon layers (Rh–P@NPC) have been prepared through a facile polymerization-impregnation followed by high-temperature pyrolysis process. Benefiting from the unique core-shell structural advantages and synergistic effect of Rh–P and NPC components, the resulting Rh–P@NPC catalyst not only exhibits remarkable electrocatalytic activity for HER in the whole pH range with a low overpotential of 31 mV, 65 mV, and 130 mV to drive a current density of 10 mA cm^?2 in 0.5 M H₂SO₄, 1.0 M KOH, and 1.0 M PBS, respectively, but also demonstrates high durability. It is worth to note that all these HER performances are on a par with commercial Pt/C catalysts for HER. This synthetic strategy provides possibility for the fabrication of carbon-based heterostructures with high catalytic activity and durability in harsh environments.     

Interface engineering of crystalline/amorphous Pt/TeOx nanocapsules for efficient alkaline hydrogen evolution

Hydrogen evolution reaction (HER) is an important process in electrochemical energy technology, and efficient electrocatalysts are of great significance for renewable and sustainable energy conversion. Here, we report a facile hydrothermal and heat treatment process to synthesize a series of Pt-based nanocapsules (NCs) as an effective hydrogen evolution catalyst. The Pt/TeO_x NCs exhibit excellent HER activity in an alkaline medium. The Pt/TeO_x NCs only need the overpotential of 33 mV to achieve the current density of 10 mA cm⁻², and the Tafel slope was as low as 29 mV dec⁻¹, which was even better than that of commercial Pt/C. Detailed experimental characterizations demonstrate that the interface between the crystalline Pt/amorphous TeO_x and the strong electron transfer contribute to alkaline HER activity. This work opens up a new direction for the preparation of efficient catalysts for electrocatalytic reactions or other conversion filed.     

Facile construction of 3D hyperbranched PtRh nanoassemblies: A bifunctional electrocatalyst for hydrogen evolution and polyhydric alcohol oxidation reactions

Development of highly effective and stable electrocatalysts is urgent for various energy conversion applications. Herein, a facile co-reduction approach was developed to fabricate three-dimensional (3D) hyperbranched PtRh nanoassemblies (NAs) under solvothermal conditions, where creatinine and cetyltrimethylammonium chloride (CTAC) were employed as the structure-directing agents. The as-synthesized nanocatalyst exhibited intriguing catalytic characters for hydrogen evolution reduction (HER) with a low overpotential (20 mV) at 10 mA cm⁻² and a small Tafel slope (49.01 mV dec⁻¹). Meanwhile, the catalyst showed remarkably enlarged mass activity (MA: 2.16/2.02 A mg⁻¹) and specific activity (SA: 4.16/3.88 mA cm⁻²) towards ethylene glycol and glycerol oxidation reactions (EGOR and GOR) alternative to commercial Pt black and homemade Pt₃Rh nanodendrites (NDs), PtRh₃ NDs and Pt nanoparticles (NPs). This method offers a feasible platform to fabricate bifunctional, efficient, durable and cost-effective nanocatalysts with finely engineered structures and morphologies for renewable energy devices.     

Aqueous substitution synthesis of platinum modified amorphous nickel hydroxide on nickel foam composite electrode for efficient and stable hydrogen evolution

Exploring highly active and stable electrocatalysts toward hydrogen evolution reaction (HER) is vital for the production of green energy and storage of intermittently renewable electrical energy. In this study, we fabricate Pt-modified Ni(OH)₂ on 3D nickel foam (Pt content: 1.5 wt %) via a one-step galvanic replacement reaction in aqueous solution to achieve a top performance of HER under alkaline conditions. It exhibits a negligible onset potential, a Tafel slope of 17 mV dec⁻¹, and overpotentials of 38, 114, and 203 mV to deliver 10, 50, and 100 mA cm⁻² current densities, respectively, which outperforms the commercial Pt/C and Pt sheet. Moreover, this catalyst shows enhanced durability towards HER, sustaining electrolysis at −20 mA cm⁻² for 4, 500 min in 1 M KOH with little degradation. Its good performances come from the synergism of flake-like Pt and amorphous Ni(OH)₂. This work provides not only a facile and easy scale-up approach to fabricate Pt−modified electrocatalysts with improved HER performance but also a new strategy to design self-supported high-performance hybrid materials of noble-metal and amorphous transitional metal hydroxides for sustainable energy conversion and storage.     

Urchin-like Co0.8-Mn0.2-P/CC nanowires array: a high-performance and cost-effective hydrogen evolution electrocatalyst

Using cost-effective materials to replace precious Pt-based hydrogen evolution reaction (HER) catalysts holds great foreground for energy saving and environmental protection. In this work, we successfully prepared an urchin-like Co_0.8-Mn_0.2-P nanowires array supported on carbon cloth (CC) through a hydrothermal-phosphatization strategy and we also systematically studied its electrocatalytic HER performance. Electrochemical tests demonstrate that our urchin-like Co_0.8-Mn_0.2-P/CC possesses outstanding HER activity in acidic and alkaline media. In 0.5 M H₂SO₄, this urchin-like Co_0.8-Mn_0.2-P/CC only requires an overpotential of 55 mV to drive a current density of 10 mA cm⁻², with the Tafel slope of 55.9 mV dec⁻¹. Similarly, when reaching the same current density, just a particularly low overpotential of 61 mV is required with a corresponding Tafel slope of 41.7 mV dec⁻¹ in 1 M KOH. Furthermore, this electrocatalyst exhibits superior stability with 1000 cycles of cyclic voltammetry and 24 h in the I-T test. Such excellent HER catalytic performance can be attributed to the synergistic effect between Co and Mn atoms and high electrochemical active surface area (ECSA). Our work provides a valuable synthesis strategy of non-precious and high HER performance catalytic material.     

Electrocatalytic hydrogen evolution on metallic and bimetallic Pd–Co alloy nanoparticles

Increasing world energy demands and crises led to alternative energy production methods, such as fuel cells using hydrogen gas which is the half electrochemical reaction of water splitting process. Herein, we synthesize polyvinylpyrrolidone coated Pd, Co and Pd_xCo_1-x (x: 0.5, 0.12, 0.23, 0.49, 0.55, 0.62) metallic and bimetallic nanoparticles (NPs) via polyol process alternative to Pt-based catalysts for hydrogen evolution reaction (HER). Detailed structural analyses of Pd, Co and Pd_xCo_1-x NPs revealed that fcc-Pd, fcc/hcp-Co and fcc-PdCo NPs crystal structures, and the lattice parameters were calculated as 3.5358 Å for Co NPs and 3.9777 Å for Pd NPs. The average size confirmed below 9 nm via TEM imaging and XPS data confirmed the formation of a bimetallic PdCo structure. Although Pd catalyst is mostly responsible for HER process, Pd₆₂Co₃₈ catalysts reduced the onset potential to about 197 mV and provided greater current density. Although E_a values were slightly higher against the Pt/C (20 wt %) benchmark which is reported as 16 kJ mol⁻¹, PdCo NPs provided considerably reduced activation energy (E_a) values compared to Pd/C catalyst of 31 kJ mol⁻¹. The best onset potential was recorded for Pd₆₂Co₃₈ catalysts for HER activity which is 16 mV higher compared to commercially available Pt/C catalyst.     

Well-dispersed Pt nanodots interfaced with Ni(OH)2 on anodized nickel foam for efficient hydrogen evolution reaction

Hindered by price and scarcity, the exploitation of supported Pt-based electrocatalysts with Pt single atoms or Pt nanoclusters is an alternative way to decrease the dosage of Pt and improve the electrocatalytic performance for hydrogen evolution reaction (HER) of water splitting. The anodization technology is used to modify the surface of nickel foam (NF) to form the porous NiF₂ network structure. Then Pt nanodots interfaced with Ni(OH)₂ (Pt/Ni(OH)₂) hybrid on the anodized NF has been in-situ synthesized by a simple hydrothermal decomposition method. Results show that Pt nanodots on the substrate have good dispersion with the average size of 3 nm, and the Pt loading is only 0.229 mg cm⁻². The prepared electrode exhibits the low overpotentials of 25.9 mV and 211 mV at the current densities of 10 and 100 mA cm⁻², respectively, a small Tafel slope of 37.6 mV dec⁻¹, and the excellent durability for HER. The porous network nanostructure of Pt/Ni(OH)₂ hybrid, the large electrochemical surface area, the fast facilitated electron transport capability, and the firm adhesion of Pt nanodots with the anodized NF substrate contribute to the remarkable performance towards HER.     

Rational design of free-standing 3D Cu-doped NiS@Ni2P/NF nanosheet arrays for hydrogen evolution reaction

Using low cost and high efficiency non-precious bimetallic phosphosulphide as electrocatalyst for hydrogen evolution reaction (HER) is not only convenient but also environment-friendly for industrial production. Therefore, we propose a simple and efficient method to prepare a series of Cu-doped bimetallic phosphosulphide nanosheet arrays on nickel foam (CuNiS@Ni₂P/NF). The CuNiS@Ni₂P/NF exhibits the superior HER performance with appropriate doping amount of Cu. It just needs a potential of 144 mV to obtain the current density of 10 mA cm⁻² in 1.0 M KOH, which is smaller than that of CuNiS@Ni₂P/NF-0.25 (206 mV) and CuNiS@Ni₂P/NF-0.125 (219 mV). The excellent HER performance of CuNiS@Ni₂P/NF nanosheet arrays can be ascribed to: (i) the moderate Cu-doped effectively optimized the electronic structure and morphology of the electrocatalyst; (ii) typical nanosheet arrays structures exposing more active sites; (iii) the high immanent activity excited by the multi-component synergy.     

Crystalline nickel sulfide integrated with amorphous cobalt sulfide as an efficient bifunctional electrocatalyst for water splitting

The development of highly efficient and low-cost electrocatalysts is critical to the mass production of hydrogen from water splitting. Herein, a facile yet effective method was developed to synthesize bimetallic sulfides Ni₃S₂/CoS_x, which were aimed for use as the electrocatalysts in both HER and OER. Encouragingly, the Ni₃S₂/CoS_x demonstrated a low overpotential of 110 mV for HER at a current density of 10 mA·cm^?2. It was discovered that the surface of Ni₃S₂/CoS_x during OER process would undergo an in-situ oxidation to form MOOH (M = Co, Ni), that is, MOOH/Ni₃S₂/CoS_x were the real functioning species in catalysis, which had an excellent OER activity and a low overpotential of 226 mV. Additionally, the assembled electrolyzer required only a low cell voltage of 1.53 V to achieve a current density of 10 mA·cm^?2 in a 1 M KOH solution, and its performance was stable. Overall, this work provided a promising strategy for the facile fabrication of low-cost amorphous electrocatalysts, which is expected to promote the progress of overall water splitting.     

Pt-based catalyst decorated by bimetallic FeNi2P with outstanding CO tolerance and catalytic activity for methanol electrooxidation

Subjected to CO poisoning and weak catalytic performance, there are still large barriers to the effective use of direct methanol fuel cells. Therefore, bimetallic FeNi₂P/C hybrid is synthesized by a facile hydrothermal method and low temperature phosphorization process. Subsequently, the as-synthesized FeNi₂P/C is employed as catalytic support to load Pt nanoparticles. Due to the existence of phosphorus and the difunctional effects of Fe and Ni, electrochemical results demonstrate that the prepared Pt–FeNi₂P/C compound exhibits an outstanding catalytic activity of 1125 mA·mg-1 Pt during methanol oxidation in acid solution, tower over that of Pt–FeP₄/C (721 mA·mg^-1_Pt), Pt–Ni₂P/C (588 mA·mg^-1_Pt) and Pt/C-JM (284 mA·mg^-1_Pt), separately. Significantly, bimetallic Pt–FeNi₂P/C hybrid shows the optimal anti poisoning tolerance, which onset potential is negatively shifted 0.2 eV in comparison of Pt/C-JM. Hence, Pt-based catalyst decorated by bimetallic phosphides with excellent anti poisoning tolerance would be a superb material to flourish the catalytic field.     

Directly growth of highly uniform MnS–MoS2 on carbon cloth for advanced H2 evolution electrocatalyst in different pH electrolytes

The activation energy barrier of the H–O bond of water molecules is high, and thus the rate of H₂ evolution reaction (HER) via water splitting is very slow. Hence, chemists are committed to finding high-performance, cheap and stable catalysts for realizing efficient H₂ production. The molybdenum disulfide (MoS₂)-based bimetallic sulfide electrocatalysts are favored by researchers because of their particular structures and properties. Herein, the Waugh type polyoxometalate (POM) is used as raw materials. A series of MnS–MoS₂ electrocatalysts are in-situ coupled on carbon cloth (CC) substrate by a hydrothermal sulfidation method. The catalyst MnS-MoS₂-CC possesses high catalytic activity for HER in a alkaline electrolyte, showing a low overpotential of 54 mV at a current density of 10 mA cm^?2, which is very close to 35 mV of the 20% Pt/C electrode. Meanwhile, under a current density of over 50 mA cm^?2, the overpotential of MnS-MoS₂-CC is less than that of the 20% Pt/C electrode. Moreover, the electrocatalysts show overpotentials of 141 mV and 201 mV at a current density of 10 mA cm^?2 in 0.5 M H₂SO₄ and 1.0 M phosphate buffer solution (PBS), respectively. Besides the high catalytic activity, the MnS-MoS₂-CC electrode shows long-term durability in a wide pH range, which is confirmed by several methods including the tests of linear sweep voltammetry (LSV) curve, current density vs. time (I-t) curve, and scanning electron microscopy (SEM). This work provides a feasible route for the preparation of HER electrocatalysts applied in broad pH conditions, especially for alkaline solutions.     

Facile galvanic replacement method for porous Pd@Pt nanoparticles as an efficient HER electrocatalyst

In realm of renewable energy, development of an efficient and durable electrocatalyst for H₂ production through electrochemical hydrogen evolution reaction (HER) is indispensable. Herein, we demonstrate a simple preparation of carbon-supported nanoporous Pd with surface coated Pt (CS–PdPt) by a simple galvanic replacement reaction (GRR). The phase purity and porosity have been confirmed by XRD, HRTEM, and N₂ sorption techniques. As HER electrocatalyst, CS-PdPt showed a low overpotential of 26 mV in 0.5 M H₂SO₄ at current density of 10 mA cm⁻², which is lower than the commercial Pt/C electrode. The CS-PdPt catalyst exhibits an overpotential of 46 mV in 1 M KOH, and 50 mV in neutral buffer (1 M PBS) at 10 mA cm⁻². The CS-PdPt furnished with small Tafel values of 33, 88, and 107 mV dec⁻¹ in acidic, alkaline, and neutral medium, respectively. Accelerated durability test at 100 mV s⁻¹ for 1000 cycles demonstrated a negligible change in HER activity.     

One-pot solvothermal synthesis of Co2P nanoparticles: An efficient HER and OER electrocatalysts

Development of an inexpensive electrocatalyst for hydrogen evolution (HER) and oxygen evolution reactions (OER) receives much traction recently. Herein, we report a facile one-pot ethyleneglycol (EG) mediated solvothermal synthesis of orthorhombic Co₂P with particle size ~20–30 nm as an efficient HER and OER catalysts. Synthesis parameters like various solvents, temperatures, precursors ratios, and reaction time influences the formation of phase pure Co₂P. Investigation of Co₂P as an electrocatalyst for HER in acidic (0.5 M H₂SO₄) and alkaline medium (1.0 M KOH), furnishes low overpotential of 178 mV and 190 mV, respectively to achieve a 10 mA cm^?2 current density with a long term stability and durability. As an OER catalyst in 1.0 M KOH, Co₂P shows an overpotential of 364 mV at 10 mA cm^?2 current density. Investigation of Co₂P NP by XPS analysis after OER stability test under alkaline medium confirms the formation of amorphous cobalt oxyhydroxide (CoOOH) as an intermediate during OER process.     

Maize-like CoP nanorod arrays as an efficient and robust electrocatalyst for superior hydrogen generation

High-performance, low-cost and robust electrocatalysts for the hydrogen evolution reaction (HER) play a critical role in large-scale hydrogen production via water splitting. Herein, we proposed a synthesis strategy for the self-assembly of maize-like CoP nanorod arrays with abundant active sites via a combination of conventional hydrothermal reaction and low-temperature phosphorization. This unique architecture exhibited remarkable catalytic performance for the HER, with a low overpotential of 130 mV at a current density of 10 mA cm^?2 and a small Tafel slope of 59 mV dec^?1 in 1.0 M KOH electrolyte, as well as good stability as verified by chronoamperometry measurement for 10 h. Density functional theory calculations further revealed that these maize-like CoP nanorod arrays with dense active sites and a high phosphorization degree could boost the HER performance in terms of low adsorption energy and free energy. This work provided a facile strategy towards manipulating morphology engineering to enhance the HER activity of CoP-based catalysts.     

PdCu bimetallic nanoparticles decorated on ordered mesoporous silica (SBA-15) /MWCNTs as superior electrocatalyst for hydrogen evolution reaction

In the present study, a novel electrocatalyst with excellent catalytic performance based on PdCu bimetallic nanoparticles (NPs) supported on ordered mesoporous silica and multi-walled carbon nanotubes (PdCu NPs/SBA-15-MWCNT) was prepared for electrochemical hydrogen evolution reaction (HER). For this purpose, low-cost mesoporous SBA-15 was synthesized using silica extracted from Stem Sweep Ash (SSA) as an economically attractive silica source. Mesoporous SBA-15 with unparalleled porous structure is a stable support for PdCu bimetallic NPs which prevents the accumulation of PdCu bimetallic NPs and improves its efficiency in the catalytic process. The main advantage of this strategy is low loading of bimetallic catalyst with high catalytic activity. The presence of both mesoporous SBA-15 and MWCNTs materials in PdCu/SBA15-MWCNTs/carbon paste electrode (CPE) increases the metallic active sites and the electrical conductivity of electrode which provides great performance for HER. PdCu/SBA15-MWCNTs-CPE provided small Tafel slope (45 mV dec^?1), low onset potential (~-150 mV), high current density (?165.24 mA cm^?2at -360 mV) and exchange current density (2.51 mA cm^?2) with great durability for HER in H₂SO₄ solution. Analysis of kinetic data suggests that the electrocatalyst controls HER by the Volmer-Heyrovsky mechanism. In addition, studies showed that the presence of sodium dodecyl sulfate (SDS) in electrolyte can decrease the potential of HER and increase the current density.     

Hollow hexagonal NiSe–Ni3Se2 anchored onto reduced graphene oxide as efficient electrocatalysts for hydrogen evolution in wide-pH range

Integrating transition metal complexes with carbon-based materials, especially graphene, is a useful strategy for synthesizing effective hydrogen evolution catalysts. Herein, we report a design of hollow hexagonal NiSe–Ni₃Se₂ nanosheets grown on reduced graphene oxide (NiSe–Ni₃Se₂/rGO) by a simple hydrothermal method as an effective catalyst for hydrogen evolution reaction (HER) in the full pH range. In 0.5 M H₂SO₄, the NiSe–Ni₃Se₂/rGO possesses 112 mV to achieve 10 mA cm^?2 and a small Tafel slope (61 mV dec^?1). In 1.0 M PBS and 1.0 M KOH, the overpotentials are 261 and 188 mV at 10 mA cm^?2, and Tafel slopes are 103 and 92 mV dec^?1, respectively. Meanwhile, it owns good cycle stability and durability over 20 h in the whole pH range (0-14). In all solutions, the HER performance of NiSe–Ni₃Se₂/rGO is better than that of NiSe–Ni₃Se₂. This is because the rGO substrate accelerates the electron transfer and improves the electrical conductivity, increasing HER activity of catalyst.     

Boosting activity and stability by coupling Pt–Ni nanoparticles with La-modified flexible carbon nanofibers for hydrogen evolution reaction

Platinum (Pt) is considered as the most efficient catalyst for hydrogen evolution reaction (HER) with a nearly zero overpotential, but it is limited by the high cost and poor stability. Herein, we report an efficient electrocatalyst of Pt–Ni alloy nanoparticles (NPs) supported on the La-modified flexible carbon nanocomposite fibers (PtNi@La-CNFs) for HER. The rare earth metal oxide in the catalyst has a structure-effect relationship with the carbon fibers to form a flexible fiber membrane. Experimental results show that the macroscopic and microscopic properties of carbon nanocomposite fibers can be optimized by doping La₂O₃, and the Pt–Ni NPs can be anchored effectively. The Pt₁Ni₁@La-CNFs electrocatalyst exhibits a small overpotential of 32 mV to achieve current density of 10 mA cm^?2 with a low Tafel slope of 51 mV dec^?1 in alkaline medium, outperforming that of Pt@La-CNFs and the commercial Pt/C catalyst. This study reveals that the multiple coupling effect of rare earth compound, precious metal, and transition metal in composite catalyst can tailor its the electronic configuration, and results in an enhanced HER performance. This work opens up a novel approach to design high active and low cost Pt-based HER catalysts.     

Bifunctional electrocatalysts of CoFeP/rGO heterostructure for water splitting

Bifunctional non-precious electrocatalysts with high performance are highly desired for renewable energy but remain challenging. Herein, a CoFeP/rGO heterostructure was rational developed based on the synergistic effect, including superior conductivity, increased catalytic active sites of rGO support and the regulated electron distribution of bimetallic phosphide. At a current of 10 mA cm^?2, the CoFeP/rGO-2 composite exhibits excellent HER activity with low overpotentials of 101 mV and 76 mV in 1.0 M KOH and 0.5 M H₂SO₄ electrolyte, respectively. And highly active alkaline OER performance was provided with an overpotential of only 275 mV to reach a current density of 10 mA cm^?2. By the way, the CoFeP/rGO-2 electrode showed a pleasured working voltage of 1.58 V for overall water splitting in alkaline environment. More importantly, the long term durability and higher stability of the catalysts demonstrated their feasibility of bimetallic phosphide/rGO system as bifunctional electrocatalysts.     

Ultra-fine Ru nanoparticles decorated V2O3 as a pH-universal electrocatalyst for efficient hydrogen evolution reaction

Developing high-efficiency electrocatalysts viable for pH-universal hydrogen evolution reaction (HER) has attracted great interest because hydrogen is a promising renewable energy carrier for replacing fossil fuels. Herein, we present a facile strategy for fabricating ultra-fine Ru nanoparticles (NPs) decorated V₂O₃ on the carbon cloth substrates as efficient and stable pH-universal catalysts for HER. Benefiting from the metallic property and electronic conductivity of V₂O₃ matrix, the optimized hybrid (Ru/V₂O₃-CC) exhibits excellent HER activities in a wide pH range, achieving lower overpotentials of 184, 219, and 221 mV at 100 mA cm⁻² in 0.5 M H₂SO₄, 1.0 M KOH and 1.0 M phosphate-buffered saline, respectively. Moreover, the electrode remains superior stability with negligible degradation after 5000 cyclic voltammetry scanning whether in acidic, alkaline or neutral media. Experimental results, combined with theoretical calculations, demonstrate that the interaction between Ru NPs and the support V₂O₃ induces the local electronic density diversity, allowing optimization of the adsorption energy of Ru towards hydrogen intermediate H1, thus favoring the HER process.     

Carbon nanorod supported metal alloy nanocubes using polydopamine as location reagent for water splitting

Transition metal catalysts were supposed to be the most likely substitute for commercial noble metal catalysts, and the development of highly active and long-term catalyst for water splitting are the future trend. Herein, Ni rectangular nitrogen doped carbon nanorods@Fe–Co nanocubes (Ni-CNRs@Fe–Co cubes) were fabricated via a facile template-free method. This simple strategy not only realizes the structure tailoring, but also achieves high-quality nitrogen-doping. Specifically, nickel dimethylglyoxime [Ni(dmg)₂] with rectangular rodlike structure was firstly synthesized by solution method, then metal-organic frameworks Fe–Co nanocube with different contents were loaded on rectangular carbon nanorods with polydopamine as the locating and the connecting agent, and finally Ni-CNRs@xFe-Co cubes were obtained by a one-step calcination. A series of electrochemical tests were researched on materials with different metal contents in the 1 M KOH solution. The Ni-CNRs@Fe–Co cubes show excellent electrocatalytic activity in the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). For HER and OER, the Tafel slopes were 83.3 mV dec⁻¹ and 71 mV dec⁻¹, the onset potential were −167 mV and 1.62 V, and reached the current densities of 10 mA cm⁻², the overpotential just needed 196 mV and 433 mV, respectively. This novel synthetic strategy will provide a template-free way for cheap electrocatalysts of non-precious metal for OER and HER.