Electrocatalytic Performance For Hydrogen Evolution Reaction Research Articles

Amorphous Ni(OH)2 encounter with crystalline CuS in hollow spheres: A mesoporous nano-shelled heterostructure for hydrogen evolution electrocatalysis

Highly active, durable and cost-effective eletrocatalysts are crucial for hydrogen evolution reaction (HER). Herein, we report novel hollow hybrid spheres comprising of amorphous Ni(OH)2 and crystalline CuS mesoporous nano-shelled heterostructures as efficient HER electrocatalysts. Spherical Cu2O particles are used as templates for fabrication of Ni(OH)2@CuS hollow spheres with nano-shelled heterostructures. The as-obtained catalysts exhibit much higher performance than the single Ni(OH)2, CuS, their physical mixture and crystalline Ni(OH)2@CuS toward water electrochemical reduction in alkaline medium. The superior HER electrocatalytic performance might be attributed to the unique hollow mesoporous nanoshelled architecture and the heterostructured synergetic effects between amorphous Ni(OH)2 and crystalline CuS, in which the short-range order of the inner amorphous Ni(OH)2 mesoporous shell creates abundant active sites on the surface, and the conductive CuS out layer promotes electron transportation. This work might open a door for designing and synthesizing of hollow nanomaterials with mesoporous nano-shelled heterostructures consist of amorphous and crystalline phase for applications in electrochemical catalysis and energy conversion.

Facile synthesis and excellent electrochemical performance of CoP nanowire on carbon cloth as bifunctional electrode for hydrogen evolution reaction and supercapacitor

In this paper, we report CoP nanowires supported on carbon cloth (CC) (CoP/CC) as a bifunctional electrode for hydrogen evolution reaction (HER) and supercapacitor. CoP/CC possess an excellent electrocatalytic performance for HER, with a Tafel slope of 56 mV/dec and a low overpotential of 68 mV to achieve a current density of 10 mA cm−2 . Remarkably, the bifunctional CoP/CC used as electrode for supercapacitor exhibit a higher specific capacitance of 674 F g−1 at a scan rate of 5 mV s−1 and maintains long-life cycling stability, retaining 86% of the initial capacitance after 10,000 cycles. CoP/CC will be a promising candidate as electrode for HER and supercapacitor.

Self-Supported Ferric Phosphide Spherical Clusters as Efficient Electrocatalysts for Hydrogen Evolution Reaction

The development of efficient and low-cost hydrogen evolution reaction (HER) electrocatalysts for renewable energy conversion techniques is highly desired. Self-Supported ferric phosphide spherical clusters on Ti foil (FeP/Ti) were developed via a low-temperature phosphorization of hydrothermal-synthesized FeOOH/Ti precursors. The FeP/Ti had large specific surface area, high porosity and high conductivity which could provide high catalytic activities. The FeP/Ti electrode showed a good electrocatalytic performance for HER in acidic media with a low onset overpotential of 27 mV, only needed overpotentials of 104 and 218 mV to reach current densities of 10 and 50 mA cm−2, respectively, and had a high exchange current density of 0.46 mA cm−2 as well as good long-term durability, close to the performance of commercial Pt/C catalysts. In addition, the binder-free preparation method for this self-supported HER electrode could be extended to many other fields.

A novel Ni-S-W-C electrode for hydrogen evolution reaction in alkaline electrolyte

Ni-S-W-C electrode, a novel efficient electrocatalyst for hydrogen evolution reaction (HER) in alkaline solution, has been prepared by pulse electrodeposition. The electrode shows excellent electrocatalytic activity with low overpotential of 262mV (at 10mA/cm2) and high exchange current density of 3.13×10-2mA/cm2, and exhibits much better HER activity than that of Ni-S, Ni-S-C, and Ni-S-W electrodes. The remarkable enhancement in electrocatalytic performance of Ni-S-W-C electrode is attributed to addition of tungsten and carbon. WS2 is formed in Ni-S-W-C electrode after the addition of tungsten, and is an efficient catalyst for hydrogen evolution with very low overpotential. The increased amorphization degree by carbon-doped is also benefit to improve HER electrocatalytic performance of Ni-S-W-C electrode.

In Situ Fabrication of Ni–Mo Bimetal Sulfide Hybrid as an Efficient Electrocatalyst for Hydrogen Evolution over a Wide pH Range

Electrochemical water splitting to produce hydrogen bears a great commitment for future renewable energy conversion and storage. By employing an in situ chemical vapor deposition (CVD) process, we prepared a bimetal (Ni and Mo) sulfide-based hybrid nanowire (NiS2/MoS2 HNW), which was composed of NiS2 nanoparticles and MoS2 nanoplates, and revealed that it is an efficient electrocatalyst for the hydrogen evolution reaction (HER) over a wide pH range due to the collective effects of rational morphological design and synergistic heterointerfaces. On a simple glassy carbon (GC) electrode, NiS2/MoS2 HNW displays overpotentials at −10 mA cm–2 catalytic current density (η10) of 204, 235, and 284 mV with small Tafel slopes of 65, 58, and 83 mV dec–1 in alkaline, acidic, and neutral electrolyte, respectively, exhibiting pH-universal-efficient electrocatalytic HER performance, which is comparable to the recently reported state-of-the-art sulfide-based HER electrocatalysts. Theoretical calculations further confirm t...

Macroporous Inverse Opal-like MoxC with Incorporated Mo Vacancies for Significantly Enhanced Hydrogen Evolution.

The hydrogen evolution reaction (HER) is one of the most important pathways for producing pure and clean hydrogen. Although platinum (Pt) is the most efficient HER electrocatalyst, its practical application is significantly hindered by high-cost and scarcity. In this work, an MoxC with incorporated Mo vacancies and macroporous inverse opal-like (IOL) structure (MoxC-IOL) was synthesized and studied as a low-cost efficient HER electrocatalyst. The macroporous IOL structure was controllably fabricated using a facile-hard template strategy. As a result of the combined benefits of the Mo vacancies and structural advantages, including appropriate hydrogen binding energy, large exposed surface, robust IOL structure and fast mass/charge transport, the synthesized MoxC-IOL exhibited significantly enhanced HER electrocatalytic performance with good stability, with performance comparable or superior to Pt wire in both acidic and alkaline solutions.

FeS2 Nanoparticles Embedded in Reduced Graphene Oxide toward Robust, High‐Performance Electrocatalysts

AbstractDeveloping low‐cost, highly efficient, and robust earth‐abundant electrocatalysts for hydrogen evolution reaction (HER) is critical for the scalable production of clean and sustainable hydrogen fuel through electrochemical water splitting. This study presents a facile approach for the synthesis of nanostructured pyrite‐phase transition metal dichalcogenides as highly active, earth‐abundant catalysts in electrochemical hydrogen production. Iron disulfide (FeS2) nanoparticles are in situ loaded and stabilized on reduced graphene oxide (RGO) through a current‐induced high‐temperature rapid thermal shock (≈12 ms) of crushed iron pyrite powder. FeS2 nanoparticles embedded in between RGO exhibit remarkably improved electrocatalytic performance for HER, achieving 10 mA cm−2 current at an overpotential as low as 139 mV versus a reversible hydrogen electrode with outstanding long‐term stability under acidic conditions. The presented strategy for the design and synthesis of highly active earth‐abundant nanomaterial catalysts paves the way for low‐cost and large‐scale electrochemical energy applications.

Nickel phosphide nanoparticles decorated nitrogen and phosphorus co-doped porous carbon as efficient hybrid catalyst for hydrogen evolution

The design of efficient and robust Ni2P-based hybrid catalysts for hydrogen evolution reaction (HER) is still in challenge. In this work, a hybrid catalyst composed of monodispersed Ni2P nanoparticles (NPs) and N, P co-doped porous carbon (NPPC) was synthesized through a facile thermal decomposition and used as an efficient electrocatalyst for the HER in 0.5M H2SO4 solution. Series technologies including X-ray diffraction, Raman, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and N2 sorption are used to characterize the as-synthesized catalysts. The electrochemisty experiments suggested that the as-synthesized Ni2P/NPPC displayed efficient electrocatalytic performance with a low onset overpotential (51mV), small Tafel slope (74mVdec−1), high exchange current density (0.12mAcm−2), large electrochemical double-layer capacitance (21.97mFcm−2) and high conductivity for the HER. The needed overpotentials are 159 and 184mV to reach to the current density of 10 and 20mAcm−2, respectively. Simultaneously, Ni2P/NPPC also displayed good stability in acid solution. The more defects and active sites on the porous carbon which are offered by the co-doped N and P atoms as well as the synergistic effect between NPPC and Ni2P NPs are contributed to the excellent catalytic performance for HER. The current study suggests that introducing the N, P heteroatoms co-doped carbon materials to the Ni2P-based catalysts could enhance HER electrocatalytic performance efficiently.

Facile Synthesis of Mo2C Nanocrystals Embedded in Nanoporous Carbon Network for Efficient Hydrogen Evolution

AbstractExploring facile and easily‐scalable methods for synthesizing earth‐abundant, cost‐effective and efficient hydrogen evolution reaction (HER) electrocatalysts is essential for the mass production of hydrogen as a clean and sustainable energy carrier. We report here a simple strategy to produce Mo2C nanocrystals embedded in carbon network (Mo2C@C) by the direct pyrolysis of ammonium molybdate and polyvinylpyrrolidone (PVP). It is found that PVP can be effectively used as a single source to form carbides and carbon network. The long polymer chain and coordinating capability with transition metal of PVP make it possible to form connected porous carbon network and well‐dispersed Mo2C nanocrystals in several nanometers. The carbonization of PVP not only effectively in‐situ prevents the aggregation of Mo2C nanocrystals during their formation, but also provides conductive porous matrix. As a result, the Mo2C@C composite exhibits the superior electrocatalytic performance for HER, which can be ascribed to the large number of active sites from plenty of small Mo2C nanocrystals and the efficient mass and electron transport network from carbon matrix. This strategy may inspire the exploration of cost‐effective functional polymer as single source for both carbon precursor and nanostructure‐directed reagent to mass‐produce well‐defined metal carbides nanostructures embedded in porous carbon network for energy applications.

New insights into high-valence state Mo in molybdenum carbide nanobelts for hydrogen evolution reaction

Hydrogen evolution reaction (HER) is considered to be one of the most promising strategies to create hydrogen. Recently, searching high-efficient, stable, and earth-abundant electrocatalysts to replace precious metals for practical utilizations of HER is attracting more and more attentions. Herein, novel molybdenum carbide nanobelts containing Mo of high-valence state derived from MoO3-ethylenediamine inorganic/organic hybrid precursors are successfully synthesized via a facile one-pot pyrolysis method. The molybdenum carbide nanobelts are characterized using XRD, SEM, TEM and XPS. Moreover, the high-valence state Mo and their relative content in the molybdenum carbide nanobelts can be identified by XPS. The high-resolution XPS spectra of Mo 3d indicates in the molybdenum carbide nanobelts the proportion of high-valence state Mo in active Mo components is 51.3%. More importantly, the as-synthesized products exhibit excellent electrocatalytic activity for HER with a low onset overpotential of 50 mV and a small Tafel slope of 49.6 mV dec−1 in acidic medium (0.5 M H2SO4). Besides, the catalysts require only overpotentials of 143 and 234 mV to achieve current densities of 10 and 220 mA cm−2, respectively. Furthermore, they also exhibit good durability after 2000 cycles and constant current density test. Such excellent electrocatalytic HER performance can be ascribed to the high intrinsic activity of high-valence state Mo in Molybdenum Carbide. Synthesizing molybdenum carbide with high-valence state Mo electrocatalysts for HER will open up an exciting alternative avenue to acquire outstanding HER electrocatalytic activity.

CoP nanorods decorated biomass derived N, P co-doped carbon flakes as an efficient hybrid catalyst for electrochemical hydrogen evolution

How to enhance the catalytic performance of electrocatalyst for the hydrogen evolution reaction (HER) is the main focus among many researches. In this work, an efficient hybrid composed of CoP nanorods (NRs) and N, P co-doped carbon flakes (NPCFs) which were synthesized by direct pyrolysis of the mixture of biomass macromolecule sodium alginate and ammonium hypophosphite was constructed. The as-synthesized CoP/NPCFs hybrid catalyst exhibits efficient electrocatalytic activity with a low onset overpotential (45mV), small Tafel slope (67mVdec−1), high exchange current density (1.37×10−3mAcm−2), large electrochemical double-layer capacitance (9.25mFcm−2) and good stability for HER in 0.5M H2SO4 solution. The good HER electrocatalytic performance derived from the more defects and active sites in the catalyst as well as the strong synergetic effect between NPCFs and CoP NRs. This study opens a door for designing low-cost transition metal phosphide catalysts decorated heteroatom doped carbon materials for water splitting.

Ordered mesoporous Ni[sbnd]Co alloys for highly efficient electrocatalytic hydrogen evolution reaction

Mesoporous Ni100−xCox alloys (0 ≤ x ≤ 100) have been fabricated by electroless deposition method using lyotropic liquid crystals (LLC) as meso-structural template and then evaluated as low-cost electrocatalysts for the hydrogen evolution reaction (HER) in alkaline medium. The mesoporous NiCo catalyst of 58:42 atomic ratio (Ni58Co42) manifests the highest electrocatalytic activity toward the HER, exhibiting a low onset overpotential (η) of 52 mV and a small Tafel slope of 60 mV dec−1. In addition, this ordered mesostructured Ni58Co42 catalyst shows a long-term durability under harsh hydrogen evolution cycling test and 25 h chronoamperometry measurement. The outstanding HER electrocatalytic performance of the Ni58Co42 is mainly related to the synergetic combination of Ni and Co, as well as the enlarged exposure of catalytically active sites and improved transport of electrons and reacting agents arising from the unique ordered bicontinuous mesopores.

In-situ grown of Ni2P nanoparticles on 2D black phosphorus as a novel hybrid catalyst for hydrogen evolution

Nickel phosphide-based nanomaterials have been acted as efficient catalysts for the hydrogen evolution reaction (HER), however, the design of novel and high performance HER catalyst is still a challenge. Herein, we report a novel 2D material black phosphorus (BP) as support for constructing Ni2P-based hybrid catalyst by a one-pot thermal decomposition approach. TEM results indicated that the monodispersed Ni2P nanoparticles with small size and good dispersion supported on the surface of layered BP, which implied that more catalytic active sites may be exposed for HER. The as-synthesized Ni2P/BP hybrid exhibits high HER electrocatalytic performance with low onset overpotential (70 mV), small Tafel slope (81 mV dec−1), large double-layer capacitance (1.24 mF cm−2), high conductivity and good stability, which can be assigned to the strong synergistic effect between Ni2P and BP. Therefore, BP may be a suitable support for constructing excellent catalysts in electrocatalysis.

Self-supported ternary Co0.5Mn0.5P/carbon cloth (CC) as a high-performance hydrogen evolution electrocatalyst

Scalable production of earth-abundant, easy-to-prepare, and cost-effective electrocatalysts for the hydrogen evolution reaction (HER) is essential for sustainable energy-based systems. Herein, we systematically studied the electrocatalytic HER performance of a self-supported ternary Co0.5Mn0.5P/carbon cloth (CC) nanomaterial prepared using a hydrothermal reaction and phosphorization process. Electrochemical tests demonstrated that the ternary Co0.5Mn0.5P/CC nanomaterial could be a highly active electrocatalyst in acidic media, with overpotentials of only 41 and 89 mV, affording current densities of 10 and 100 mA·cm–2, respectively, and a Tafel slope of 41.7 mV·dec–1. Furthermore, the electrocatalyst exhibited superior stability, with 3,000 cycles of cyclic voltammetry from–0.2 to 0.2 V at a scan rate of 100 mV·s–1 and 40 h of static polarization at a fixed overpotential of 83 mV, indicating its potential for large-scale hydrogen production.

Gas-solid phase growth of hierarchical nanoporous nanoplates for water splitting in acidic conditions

Electrochemical production of H2 is hindered by the high cost of noble metal catalysts. Herein, a novel hierarchical nanoporous β-Mo2C nanoplate was fabricated by a chemical vapor deposition (CVD)-based gas-solid growth strategy for the first time. The parallelogram (or hexagon)-like structure grows directly on conductive substrates and shows uniform nanoporous ligament-pore texture with a pore size of ∼20–40 nm. When evaluated as a binder-free electrode for hydrogen evolution reaction (HER), the hierarchical β-Mo2C nanoplates exhibit an excellent electrocatalytic performance for HER with a small overpotential of ∼80 mV, a small Tafel slope of 68 mV decade−1 and remarkable stability.

Mo2C Nanoparticles Dispersed on Hierarchical Carbon Microflowers for Efficient Electrocatalytic Hydrogen Evolution.

The development of nonprecious metal based electrocatalysts for hydrogen evolution reaction (HER) has received increasing attention over recent years. Previous studies have established Mo2C as a promising candidate. Nevertheless, its preparation requires high reaction temperature, which more than often causes particle sintering and results in low surface areas. In this study, we show supporting Mo2C nanoparticles on the three-dimensional scaffold as a possible solution to this challenge and develop a facile two-step preparation method for ∼3 nm Mo2C nanoparticles uniformly dispersed on carbon microflowers (Mo2C/NCF) via the self-polymerization of dopamine. The resulting hybrid material possesses large surface areas and a fully open and accessible structure with hierarchical order at different levels. MoO42- was found to play an important role in inducing the formation of this morphology presumably via its strong chelating interaction with the catechol groups of dopamine. Our electrochemical evaluation demonstrates that Mo2C/NCF exhibits excellent HER electrocatalytic performance with low onset overpotentials, small Tafel slopes, and excellent cycling stability in both acidic and alkaline solutions.

Mo2C nanoparticles embedded within bacterial cellulose-derived 3D N-doped carbon nanofiber networks for efficient hydrogen evolution

Molybdenum carbide (Mo2C) has been considered as a promising non-noble-metal hydrogen evolution reaction (HER) electrocatalyst for future clean energy devices. In this work, we report a facile, green, low-cost and scalable method for the synthesis of a Mo2C-based HER electrocatalyst consisting of ultrafine Mo2C nanoparticles embedded within bacterial cellulose-derived 3D N-doped carbon nanofiber networks (Mo2C@N-CNFs) using 3D nanostructured biomass as a precursor. The electrocatalyst exhibits remarkable HER activity (an overpotential of 167 mV achieves 10 mA cm−2 and a high exchange current density of 4.73 × 10−2 mA cm−2) and excellent stability in acidic media as well as high HER activity in neutral and basic media. Further theoretical calculations indicate a strong synergistic effect between Mo2C nanoparticles and N-CNFs in the Mo2C@N-CNF catalyst, which leads to an impressive HER performance. Embedding metal-based nanoparticles in bacteria-generated aerogels is a promising way to produce hydrogen fuel using water and electricity. Most water electrolysis methods use platinum catalysts to make hydrogen–oxygen bond splitting easier. But platinum's scarcity has prompted investigations into alternatives such as molybdenum carbide (Mo2C), a catalyst that shows increased activity when coupled with carbon nanofibers. Shu-Hong Yu and colleagues from Hefei, University of Science and Technology of China, now report that bacterial cellulose — a low-cost biomass synthesized by microbes — can act as a favorable support for Mo2C nanocatalysts. Straightforward immersion of bacterial cellulose in an ammonium molybdate precursor solution, followed by freeze drying and pyrolysis, yielded a three-dimensional porous network dotted with spatially separated Mo2C nanoparticles and nitrogen dopants. Tests showed the catalyst had excellent water splitting capabilities over the pH range 0 to 14. A new type of non-noble-metal hydrogen evolution reaction (HER) electrocatalyst based on ultrafine Mo2C nanoparticles embedded within 3D N-doped carbon nanofiber networks was fabricated by using a cheap, green, 3D nanostructured biomass (bacterial cellulose) as precursor. It exhibits remarkable electrocatalytic HER performance from pH 0 to pH 14.

Layered Transition Metal Dichalcogenides As Electrocatalysts for Hydrogen Evolution and Their Trends Emerging from Electrochemical Treatment

Layered transition metal dichalcogenides (TMDs) are thrust into the limelight within the scientific community thanks to their properties that can be exploited for a myriad of applications in electrochemistry and electrocatalysis of hydrogen evolution reaction (HER). Of interest, we investigate the correlation between electrochemical treatment of exfoliated MoS2, WS2, MoSe2 and WSe2 nanosheets in the hopes of electrochemically activating their electrochemical and electrocatalytic properties. In the electrochemical aspect, we show that electrochemical activation is achieved, for all TMDs except WS2, via electro-reduction at selected reductive potentials based on their innate electrochemistry while all TMDs become electrochemically deactivated upon electro-oxidation. Across all TMDs, MoSe2 exhibits most prominent charge transfer activation. Scrutinizing further, we conclude that molybdenum metal and selenium chalcogen type are more prone to electrochemical activation than tungsten metal and sulfur chalcogen type. Contemporary research into TMDs as prospective electrocatalysts for hydrogen evolution has been overwhelming; driven by the ardent pursuit of cheaper alternatives to the rare precious metal platinum, which is the best electrocatalyst to date. TMDs are abundant in nature and also exhibit promising electrocatalytic performance for HER. It provides an interesting perspective to explore the influence of electrochemical potential on the efficiency of the TMDs as a HER electrocatalyst. We found that MoS2 demonstrated better HER performance upon electro-reduction whereas the electro-oxidation of WS2 deteriorated the HER performance significantly. Conversely, the HER efficiency of MoSe2 and WSe2 remained largely unperturbed by electrochemical pretreatment. Therefore, in terms of HER electrocatalysis, we conclude that sulfur-containing TMDs are more receptive to electrochemical redox treatment compared to selenium-containing TMDs. These findings are advantageous towards the electrochemistry of TMDs and provide insights into the effectiveness and feasibility of electrochemical activation for charge transfer and HER electrocatalysis applications. The administration of such knowledge to electrochemical and energy applications in future will be indefinitely beneficial.

Hollow Structured Micro/Nano MoS2 Spheres for High Electrocatalytic Activity Hydrogen Evolution Reaction

Molybdenum disulfide (MoS2) has attracted extensive attention as a non-noble metal electrocatalyst for hydrogen evolution reaction (HER). Controlling the skeleton structure at the nanoscale is paramount to increase the number of active sites at the surface. However, hydrothermal synthesis favors the presence of the basal plane, limiting the efficiency of catalytic reaction. In this work, perfect hollow MoS2 microspheres capped by hollow MoS2 nanospheres (hH-MoS2) were obtained for the first time, which creates an opportunity for improving the HER electrocatalytic performance. Benefiting from the controllable hollow skeleton structure and large exposed edge sites, high-efficiency HER activity was obtained for stacked MoS2 thin shells with a mild degree of disorder, proving the presence of rich active sites and the validity of the combined structure. In general, the obtained hollow micro/nano MoS2 nanomaterial exhibits optimized electrocatalytic activity for HER with onset overpotential as low as 112 mV, low Tafel slope of 74 mV decade(-1), high current density of 10 mA cm(-2) at η = 214 mV, and high TOF of 0.11 H2 s(-1) per active site at η = 200 mV.

MoS2/NbSe2 Hybrid Nanobelts for Enhanced Hydrogen Evolution

Recently, MoS2 nanosheets have attracted extensive interest for the application in electrocatalytic hydrogen evolution reaction (HER) because of its highly active edge sites and chemical stability. However, the aggregation in nanosized MoS2 reduces the density of exposed surface edge sites, degrading its electrochemical catalytic activity. In this paper, we report a hybrid structure of MoS2/NbSe2 nanobelts with enhanced electrochemical catalytic performance. The hybrid structure feature and chemical composition were investigated by transmission electron microscopy and X-ray photoelectron spectroscopy. With the introduction of one dimensional metallic NbSe2, the MoS2 surface edge sites were highly exposed in MoS2/NbSe2 nanobelts, resulting in an enhanced electrocatalytic performance in HER. A Tafel slope of 79.5 eV/dec was obtained in MoS2/NbSe2, much lower than that of MoS2 (137.6 eV/dec). At the over potential of −0.65 V vs. RHE, the catalytic current density of MoS2/NbSe2 nanobelts is 205 mA/cm2, five times larger than that of MoS2 nanosheets (43 mA/cm2).