Remarkable Hydrogen Evolution Reaction Performance Research Articles

One–step electrodeposition of Ni–Ce–Pr–Ho/NF as an efficient electrocatalyst for hydrogen evolution reaction in alkaline medium

Finding non-precious metal hydrogen evolution reaction (HER) electrocatalysts with high efficiency and low cost is a great challenge. A novel HER electrocatalyst of amorphous Nickel–Cerium–Praseodymium–Holmium coating supported on nickel foam (Ni–Ce–Pr–Ho/NF) was successfully synthesized through one-step galvanostatic electrodeposition. The Ni–Ce–Pr–Ho catalyst exhibited excellent electrocatalytic activity toward HER with a low overpotential of 78 mV at 10 mA cm−2 in 1 M KOH. The Tafel slope of Ni–Ce–Pr–Ho electrocatalyst (121.6 mV·dec−1) indicated that the hydrogen reaction mechanism for Ni–Ce–Pr–Ho electrocatalysts followed a typical Volmer–Heyrovsky step. The remarkable HER performance was attributed to Pr and Ho doping, which resulted in the development of an amorphous structure, satisfactory intrinsic activity, and high conductivity.

In-situ construction of ultrathin MoP-MoS2 heterostructure on N, P and S co-doped hollow carbon spheres as nanoreactor for efficient hydrogen evolution

Rational design hierarchical nano-heterojunction electrocatalysts with high activity and durability for hydrogen evolution reaction (HER) are attractive for sustainable energy conversion. Here, one-step and space-confine pyrolysis strategy is demonstrated to in-situ construct ultrathin MoP-MoS2 heterostructure on N, P and S co-doped hollow carbon spheres (MoP-MoS2/HCSs) that present remarkable HER performance. The intimate contact among MoP outer-layer, MoS2 intermediate layer and N, P and S co-doped HCSs inner-layer facilitates the formation of triple-shelled heterogeneous nanoreactor. Benefiting from abundant active sites, high specific surface area, heteroatomic doping, intimate catalyst-substrate contact and ultrathin active heterostructure, the resulting MoP-MoS2/HCSs not only displays significant electrocatalytic activity with low overpotentials (71 mV and 125 mV in 1.0 M KOH and 0.5 M H2SO4, respectively) at current density of 10 mA cm−2, but exhibits outstanding stability toward HER process. This study offers a promising approach to design hierarchical nano-heterojunction with remarkable electrochemical properties for green energy development.

Heterostructures induced between platinum nanoparticles and vanadium carbide boosting hydrogen evolution reaction

Electrolysis of water to produce clean and renewable hydrogen fuel is a very significant way for sustainable energy development. The most advanced catalysts for hydrogen evolution are Pt-based materials. However, due to the high cost and scarcity of Pt elements, it is indispensable to improve the stability and intrinsic catalytic activity of Pt. The design and synthesis of Pt/support materials provide an effective approach for efficient catalytic hydrogen evolution reaction (HER). Herein, an excellent heterostructure induced 4.78-Pt/V8C7 @C hybrid was synthesized as electrocatalyst for efficient electrocatalytic HER. The 4.78-Pt/V8C7 @C hybrid exhibits excellent HER activity due to the synergy interaction, which can modulate the electronic structure of Pt NPs and the hydrogen adsorption of Pt NPs surface. Notably, compared with commercial Pt/C, the 4.78-Pt/V8C7 @C hybrid exhibits more remarkable HER performance in acidic and alkaline media. The 4.78-Pt/V8C7 @C hybrid delivers an overpotential of 6 mV at 10 mA cm−2 in 0.5 M H2SO4. And the mass activity of 0.78 mA Ptg−1 is reached at − 0.02 V, which is 12.4 times that of Pt/C. This work provide that the vanadium carbide networks is an effective substrate material for the deposition of Pt NPs to improve HER activity and stability.

Achieving highly exposed active sites of molybdenum carbide with the assistance of NH4Cl for efficient hydrogen evolution

Molybdenum carbide (Mo2C) shows tremendous potentials in electrocatalytic hydrogen evolution reaction (HER). Nonetheless, the rational design of Mo2C and establishment of structure-performance correlation are still challenging. Herein, a facile NH4Cl-assisted approach has been realized to fabricate Mo2C by employing ammonium heptamolybdate and melamine as molybdenum and carbon sources, respectively. By virtue of the intercalation into the interlayers of intermediate graphitic carbon nitride, HCl molecules released from NH4Cl play a pivotal role in purifying the superfluous carbon matrix, which is a common byproduct during the preparation process of carbide. Furthermore, the participation of NH4Cl can sharply decrease in carbon content and significantly enhance the exposure of active carbide sites, which is proved to be the most essential factor affecting the catalytic activity of materials. As a result, the as-prepared catalyst presents remarkable HER performance in alkaline media, with a low overpotential of 126 mV at 10 mA cm−2 as well as small Tafel slope of 60.97 mV dec−1. Impressively, it even surpasses commercial Pt/C in the pragmatically meaningful high-current region (>80 mA cm−2), demonstrating its great potential to substitute the noble metal catalysts in practical alkaline HER process.

Regulation of hydrogen evolution performance of titanium oxide–carbon composites at high current density with a Ti–O hybrid orbital

AbstractRational design and controllable synthesis of practical electrodes with high stability and activity at high current density for a hydrogen evolution reaction (HER) are critical for renewable and sustainable energy conversion. However, high‐performance TiO2‐based electrocatalysts for HER are quite limited, and the catalytic active centers still remain elusive. Herein, a simple strategy is demonstrated for the synthesis of TiO2–carbon composite (TiO2/C) with high HER performance and stability. The remarkable HER performance of TiO2/C can be ascribed to the doping of carbon atoms, which leads to stronger hybridization of Ti 3d and O 2p orbitals, thus substantially improving the electrocatalytic efficiency. This study elucidates that the hydrogen evolution activity of oxide electrocatalysts can be largely improved by regulating their electronic structures by doping carbon atoms and also provides an effective strategy for designing heterostructured electrocatalysts with high catalytic activity and stability at high current density for HER.

Vanadium-Regulated Ultrafine Molybdenum Carbide Nanoparticles by Anchorage on Graphene for Highly Active Hydrogen Evolution Reaction

Platinum-like molybdenum carbide (Mo2C) coupled with carbon-based supports is an effective strategy to promote the performance of catalysis and energy storage. However, inevitable aggregation of Mo2C impede the achievement of high catalytic performance for hydrogen evolution reaction (HER). Herein, a vanadium-doped Mo2C nanoparticles anchorage on graphene (V-Mo2C) was developed. The V atoms can effectively regulate the electronic structure of Mo2C, improving the intrinsic activity and kinetics of electrocatalyst for HER. The ultrafine Mo2C nanoparticles with the size of about 2 nm are firmly anchorage on conductivity graphene substrate, which increases the number of active sites and contributes the high HER activity. As results, the V-Mo2C nanocomposite exhibits a remarkable HER performance with overpotentials of 284 mV at -10 mAand#183;cm-2 and corresponding Tafel slopes of 65.0 dec-1 in 1M KOH. Notable, the V-Mo2C hybrid is observed long term stability for andgt; 24 h, demonstrating that the structure of Mo2C nanoparticles anchored on graphene can significantly improve the performance for HER as well as stability. This work provides a reference for the synthesis of high-performance ultrafine transition metal carbide for HER or other catalytic system.

Reduced TiO2 nanotube array as an excellent cathode for hydrogen evolution reaction in alkaline solution

Anodic TiO2 nanotube (TNT) arrays have been intensively investigated as anodes in water splitting (WS) cells because of their excellent chemical stability. However, anodic TNT is seldom considered as a cathode for the hydrogen evolution reaction (HER) in an electrochemical WS cell. This study shows that a reduced TNT (R-TNT) sample prepared with a cathodic reduction technique without loading any co-catalyst can achieve remarkable HER performance. At − 1.0 V vs reversible hydrogen electrode in 1 M NaOH in dark, R-TNT achieved a current of − 221 mA, which is 17000-times of that achieved when using TNT and 5-times of that with Ti-foil as cathode. Chronopotentiometry tests were carried out sequentially at @ −100, − 50 and − 10 mA for 24 h and decay rates of 1.3%, 5.2% and 18.4% were measured, which indicate a good stability of the R-TNT sample.

Rational design of ultrahigh porosity Co foam supported flower-like FeNiP-LDH electrocatalysts towards hydrogen evolution reaction

The development of high-efficiency, stable and low-cost electrocatalysts is a matter of cardinal significance for large-scale electrolytic hydrogen production from water. In this study, we report a hierarchical electrocatalyst of flower-like FeNiP-LDH (FeNiP on layered double hydroxide) loaded on ultrahigh porosity Co foam (CF). The structure/component superiorities and hydrogen evolution reaction (HER) performance of this electrode were examined in detail. In alkaline solution, the resulting FeNiP-LDH/CF yields a current density of 10 mA/cm2 at an overpotential of − 39 mV, which is superior than most documented transition metal phosphides electrocatalysts and even Pt catalyst (~ −53 mV). In particular, this electrode with an undamaged microstructure can maintain its HER activity over 16 h at high current density of 500–600 mA/cm2. Such remarkable HER performance originates from the satisfactory porous nature of Co foam as well as the special surface structure and electronic properties of phosphide/hydroxide. This work not only offers a viable modular approach for the synthesis of high-performance HER electrocatalysts, but also allows an in-depth understanding of structure-activity relationships of multistage 3D materials for energy and catalysis application.

System Theoretical Study on the Effect of Variable Nonmetallic Doping on Improving Catalytic Activity of 2D-Ti3C2O2 for Hydrogen Evolution Reaction.

2D MXenes have been found to be one of the most promising catalysts for hydrogen evolution reaction (HER) due to their excellent electronic conductivity, hydrophilic nature, porosity and stability. Nonmetallic (NM) element doping is an effective approach to enhance the HER catalytic performance. By using the density functional theory (DFT) method, we researched the effect of nonmetallic doping (different element types, variable doping concentrations) and optimal hydrogen absorption concentration on the surface of NM-Ti3C2O2 for HER catalytic activity and stability. The calculation results show that doping nonmetallic elements can improve their HER catalytic properties; the P element dopants catalyst especially exhibits remarkable HER performance (∆GH = 0.008 eV when the P element doping concentration is 100% and the hydrogen absorption is 75%). The origin mechanism of the regulation of doping on stability and catalytic activity was analyzed by electronic structures. The results of this work proved that by controlling the doping elements and their concentrations we can tune the catalytic activity, which will accelerate the further research of HER catalysts.

Activation of interfacial P sites of CoP in RuP3/CoP nanosheets boosts hydrogen evolution reaction at all pH values

Developing cost-effective electrocatalysts with efficient activity and superior stability for hydrogen evolution reaction (HER) over a wide pH range is highly desirable and remains a significant challenge. Herein, we report CoP supported RuP3 nanosheet (RuP3–CoP NS) HER electrocatalysts through an ice-templating method. Constructing heterojunctions of RuP3 and CoP can reduce the loading of scarce Ru species in the catalyst, and meanwhile, maintain efficient HER activity over a wide pH range. The RuP3–CoP NS catalyst with only about 15 wt.% loading of Ru species exhibits remarkable HER performance with excellent catalytic stability and low overpotentials of 25, 60, and 81 mV at 10 mA/cm2 in alkaline, acidic, and neutral media, respectively. The density functional theory calculations indicated that the RuP3 could induce boosting the catalytic activity of P sites in CoP. The enhancement of the HER performance can be attributed to the electron transfer from RuP3 to the P sites in CoP, which changes its electronic structure, and thus, optimizing the adsorption strength of H∗.

Atomic Sulfur Filling Oxygen Vacancies Optimizes H Absorption and Boosts the Hydrogen Evolution Reaction in Alkaline Media.

The hydrogen evolution reaction (HER) usually has sluggish kinetics in alkaline solution due to the difficulty in forming binding protons. Herein we report an electrocatalyst in which sulfur atoms are doping in the oxygen vacancies (VO ) of inverse spinel NiFe2 O4 (S-NiFe2 O4 ) to create active sites with enhanced electron transfer capability. This electrocatalyst has an ultralow overpotential of 61 mV at the current density of 10 mA cm-2 and long-term stability of 60 h at 1.0 Acm-2 in 1.0 M KOH media. In situ Raman spectroscopy revealed that S sites adsorb hydrogen adatom (H*) and in situ form S-H*, which favor the production of hydrogen and boosts HER in alkaline solution. DFT calculations further verified that S introduction lowered the energy barrier of H2 O dissociation. Both experimental and theoretical investigations confirmed S atoms are active sites of the S-NiFe2 O4 .

Vanadium doped 1T MoS2 nanosheets for highly efficient electrocatalytic hydrogen evolution in both acidic and alkaline solutions

Electrocatalysis plays a major role in the development of clean and sustainable energies. For efficient hydrogen evolution reaction (HER) in water splitting, active, robust, and cost-effective catalysts are highly desired. Here, we present a facile approach to fabricate 1T-phase dominant V-doped MoS2 nanosheets which can be easily grown on carbon paper at a large scale. The 5 at.% V-doped MoS2 nanosheets achieve excellent catalytic performance, showing more than 10-fold increase of current density compared with 2H MoS2 and a surprisingly low onset potential of 102 mV vs reversible hydrogen electrode (RHE). Moreover, it exhibits good catalytical stability in both acidic and alkaline solutions. The remarkable HER performance mainly attributes to the synergistic effects of the modified structure of MoS2 with enhanced active sites, increased electrical conductivity, optimised energy level and near-zero Gibbs free energy of hydrogen binding. This work may shed light on achieving highly efficient electrocatalysts toward practical applications.

Tailoring the 3d-orbital electron filling degree of metal center to boost alkaline hydrogen evolution electrocatalysis

Understanding the origins of the sluggish kinetics and finding a descriptor to predict the alkaline hydrogen evolution reaction (HER) activity are crucial for the rational design of advanced transition metal-based electrocatalysts. Here, taking CoP as a model, we develop a strategy at the atomic level to boost the alkaline HER performance through tailoring the 3d-orbital electron filling degree of Co center by anions engineering. We find the water dissociation step rather than hydrogen adsorption-desorption is the root of sluggish alkaline HER kinetics. As expected, the obtained Se-doped CoP (Se-CoP) delivers remarkable HER performance with the overpotential of 41 mV at 10 mA cm−2 and TOF value of 0.158 s−1 at 200 mV in alkaline electrolyte. Moreover, we have also proved that this design principle can be applied to other anions (O and S) doped CoP, providing a new avenue for rational design of transition metal-based electrocatalysts towards alkaline HER.

A Janus cobalt nanoparticles and molybdenum carbide decorated N-doped carbon for high-performance overall water splitting

The fabrication of high-performance and stable electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of importance for sustainable water-splitting technologies. Herein, the cobalt (Co) nanoparticles and molybdenum carbide (Mo2C) heterostructures anchored N-doped carbon (Co/Mo2C@NC-800) was designed as bifunctional electrocatalyst for overall water splitting via a simple pyrolysis approach for metal organic frameworks (MOFs) precursor. This composite shows a remarkable performance for HER and OER with a small overpotential of 121 mV and 311 mV at 10 mA cm−2, respectively. When the optimized electrocatalyst was employed as both anode and cathode for overall water splitting in a two-electrode system, the electrolyzer achieves a low cell voltage of 1.67 V at 10 mA cm−2 in 1 M KOH, as well as a superior and stable long-time operation of 30 h. The promising hybrid material demonstrates excellent electrocatalysis performance due to effective combination of the best of both worlds: Mo2C with remarkable HER performance and Co nanoparticles with excellent OER activity. The Mo2C possesses strong hydrogen binding energy and Co exhibits prominent electrical conductivity, thus the construction of heterostructures achieves more active sites with different functions and significantly boosts HER and OER process. The novel and effective synthesis strategy provides new insights into the design of outstanding non-noble metal bifunctional electrocatalysts for overall water splitting.

Facile one-step in-situ encapsulation of non-noble metal Co2P nanoparticles embedded into B, N, P tri-doped carbon nanotubes for efficient hydrogen evolution reaction

Developing high performance, good stability and noble-metal-free electrocatalysts for renewable hydrogen evolution reaction (HER) remain a substantial challenge. Herein, we introduce a novel facile one-step in-situ strategy through pyrolysis for the synthesis of Co2P nanoparticles encapsulated Boron, Nitrogen, and Phosphorous tri-doped carbon nanotubes (Co2P/BNP-CNTs). The synergetic effect between Co2P nanoparticles and heteroatom doped CNTs contributes to the remarkable HER performance. The Co2P/BNP-CNT-900 electrocatalyst shows a low overpotential of 133 mV at a current density of 10 mA cm−2 and a small Tafel slope of 90 mV dec−1 in 0.1 M KOH media. More importantly, the Co2P/BNP-CNT-900 electrocatalyst exhibits superior long-term stability in alkaline solution at −0.25 V versus Reversible Hydrogen Electrode (RHE) for 15 h and up to 1000 cycles with negligible performance loss. Overall, our works suggest a one-pot facile synthesis strategy for rational designing high-performance electrocatalysts with enhanced HER performance.

Unveiling active sites by structural tailoring of two‐dimensional niobium disulfide for improved electrocatalytic hydrogen evolution reaction

Here we report, unveiling the active sites for improved electrocatalytic hydrogen evolution reaction (HER) by structural tailoring of Niobium Disulfide (NbS2). NbS2 synthesized by chemical vapor deposition method, structural deformation is carried out by post-argon plasma and annealing treatment. Plasma-treated (P.T) NbS2 exhibits layer-by-layer stacked (≈250 nm) long and (≈200 nm) wide flakes, which show more edge sites and demonstrates low hydrogen evolution activity. Annealed NbS2 flakes are enlarged in size (≈1 μm) having more surface area which shows additional active basal plane sites and demonstrate remarkable HER performance at 10 mA cm−2. As the thickness of NbS2 is reduced, more basal planes are exposed hence improved HER activity was achieved. This enhanced electrocatalytic change demonstrates that the basal planes are the main active sites for HER in NbS.

Active and stable graphene supporting trimetallic alloy-based electrocatalyst for hydrogen evolution by seawater splitting

The hydrogen evolution reaction (HER), adopting seawater as an electrolyte solution, is a promising and more sustainable alternative for the production of hydrogen, yet requiring more economic, highly efficient and stable electrocatalysts than the current ones. Herein, the synthesis of a Ni, Ru, Ir-based and graphene-supported nano-structured catalyst through an easily scalable, cost-effective, surfactant-free approach has been proposed. XRD, SEM, TEM images and EDX maps showed the formation of trimetallic NiRuIr alloy nanoparticles (average diameter: 8 nm) supported on a few-layer graphene. After characterization, the HER stability and activity of the sample were tested in a 0.5 M H2SO4, in a KCl neutral solution as well as in real seawater. In the acidic electrolyte environment a 0.06 V overpotential was maintained even after 11,000 cycles and the Tafel slope recorded was very low (28 mV/dec). In the neutral solution a very low overpotential (0.10 V) and a low Tafel slope (72 mV/dec) were also obtained. Furthermore, in real seawater the sample exhibits a Tafel slope of 48 mV/dec, maintains a low overpotential of 0.08 V for 250 cycles and a constant current density for 200 h of test without significant losses and with almost a 100% hydrogen production efficiency. The results obtained proved the remarkable HER performance of the synthesized electrocatalyst, especially in real seawater in virtue of synergistic alloying effects and the presence of the graphene support.

Synthesis of functional Ni2P/CC catalyst and the robust performances in hydrogen evolution reaction and nitrate reduction

The non-precious transition metal phosphides (TMPs) as robust and effective hydrogen evolution reaction (HER) catalysts have attracted enormous attention, due to the merits of earth-abundance, low price, desirable stability and high efficiency. However, the conventional preparation process of this kind of catalyst is inconvenient. Herein, we report a facile approach toward the fabrication of nickel phosphide (Ni2P) assembled on carbon cloth (CC) via the coupling method of electroless plating and low temperature phosphorization. Then, the crystallinity, morphology and chemical component of fabricated self-supporting Ni2P/CC catalyst employed for the HER process were characterized, and the HER property was successively evaluated in three types of electrolytes (i.e., acidic, neutral and alkaline solutions). The as-prepared Ni2P/CC catalyst displays a remarkable HER performance, which can be corroborated by the small Tafel slope (b = 50 mV dec−1), high exchange current density (j0 = 6.6 × 10−2 mA cm−2), acceptable overpotential (119 mV) to attain the current density of 10 mA cm−2, as well as the superb stability (<5% decay after 24 h potentiostatic test) in 0.5 M H2SO4. In addition, it should be noted that the HER process of Ni2P/CC catalyst can be competent for the reduction of nitrate from the solution, and an efficiency of 63.2% for this nutrient pollutant is achieved.

3D hierarchical MOF-derived CoP@N-doped carbon composite foam for efficient hydrogen evolution reaction

Developing efficient Pt-free electrochemical catalysts for hydrogen evolution reaction (HER) is crucial for an energy source with low pollutant emissions. Herein, zeolitic imidazolate framework-67 (ZIF-67) polyhedrons are first in situ grown on the fibrils of commercial melamine foam at room temperature, and then phosphided and carbonized to obtain the free-standing 3D hierarchical CoP@N-doped carbon composite foam (CoP@NC/CF) with interconnected architecture. The 3D interconnected carbon networks provide efficient and fast channels for the rapid transfer of ions and electrons, and inhibit the agglomeration of CoP nanoparticles. The unique structure of CoP@NC/CF thus allows for delivering the remarkable HER performance with a low overpotential of 151.3 mV at 10 mA cm−2, small Tafel slope of 64.8 mV dec−1, and excellent long-term stability. This research provides a new strategy for the rational design and facile synthesis of the free-standing 3D CoP-based catalysts for high-performance HER.

Ultrathin nickel phosphide nanosheet aerogel electrocatalysts derived from Ni-alginate for hydrogen evolution reaction

Transition metal phosphides (TMPs) have been regarded as an alternative to Pt-based catalysts for hydrogen evolution reaction (HER) on account of their high performance and low cost. The ultrathin two-dimensional (2D) nanosheets of TMPs can expose abundant active sites and facilitate the transfer of mass/charge to enhance HER performance. However, the synthesis of ultrathin 2D nanosheets of TMPs is still a great challenge. Herein, we reported a novel and scalable strategy to prepare 2D ultrathin nickel phosphide nanosheets (∼2.5 nm) by using alginate as precursor through ice-templating process. The role of ice-templating is that the growth of the ice crystals would squeeze Ni-alginate into 2D nanosheets, and then forming Ni-alginate aerogels. The three-dimensional (3D) interconnected porous network of aerogels was advantageous to reduce the lattice strains of subsequent oxidation and phosphorization process. It is the key step to prepare 2D ultrathin nickel phosphides (Ni2P and Ni5P4) nanosheets. As expected, all the prepared Ni5P4 nanosheet aerogels displayed remarkable HER performance in 1 M KOH electrolyte. Especially, due to their ultrathin 2D nanosheets and high P percentage, the Ni5P4-500-350 sample with excellent long-term stability exhibits a low overpotential of 147 mV at current density of 10 mA cm−2 and a low Tafel slope of 57 mV dec−1.