HER Catalytic Activity Research Articles

MOFs derived carbon nanotubes coated CoNi alloy nanocomposites with N-doped rich-defect and abundant cavity structure as efficient trifunctional electrocatalyst

This paper introduces a facile strategy to fabricate trifunctional electocatalysts through one pool treatment on MOFs to obtain carbon nanotube coated ultrafine CoNi alloy (CoNi@NCNTs) nanocomposites with N-doped rich-defect and abundant cavity structure. During the pyrolysis process, volatile CNx species from dicyandiamide were trapped by ZIF-67@Ni-ZIF nanosheets, simultaneously introducing nitrogen atom into carbon matrix to achieve the rich-defect porous nanotubes and abundant cavity structure. The as-prepared nanomaterials can simultaneously boost the ORR, OER and HER catalytic activity with strong durability. Significantly, the CoNi@NCNTs-700 exhibits excellent electrocatalytic activity including half-wave potential (EORR, 1/2) of 0.80 V, lower operating voltage (EOER, 10) of 1.60 V at 10 mA cm−2 and potential difference (ΔE) of 0.80 V between EOER, 10 to EORR, 1/2 in 0.1 M KOH, and low overpotential (EHER, 10) of −0.130 V reaching 10 mA cm−2 in acidic medium. The remarkable activity is ascribed to defect-rich porous carbon nanotubes structure and the synergistic effect between CoNi alloy nanoparticles, N-dope carbon and CoNi-Nx. And hollow structure facilitates to improve conductivity and stability. This work offers a useful archetypical template to design and construct efficient and stable trifunctional electrocatalysts, illustrating its viability for practical applications of energy conversion and storage devices.

Molybdenum Carbide-Embedded Multichannel Hollow Carbon Nanofibers as Bifunctional Catalysts for Water Splitting.

With the environmental pollution and non-renewable fossil fuels, it is imperative to develop eco-friendly, renewable, and highly efficient electrocatalysts for sustainable energy. Herein, a simple electrospinning process used to synthesis Mo2 C-embedded multichannel hollow carbon nanofibers (Mo2 C-MCNFs) and followed by the pyrolysis process. As prepared lotus root-like nanoarchitecture could offer rich porosity and facilitate the electrolyte infiltration, the Mo2 C-MCNFs delivered favourable catalytic activity for HER and OER. The resultant catalysts exhibit low overpotentials of 114 mV and 320 mV at a current density of 10 mA cm-2 for HER and OER, respectively. Furthermore, using the Mo2 C-MCNFs catalysts as a bifunctional electrode toward overall water splitting, which only needs a small cell voltage of 1.68 V to afford a current density of 10 mA cm-2 in the home-made alkaline electrolyzer. This interesting work presents a simple and effective strategy to further fabricating tunable nanostructures for energy-related applications.

Large-scale Two-dimensional MoSx Catalyst Prepared under Mild Conditions for Enhancing Electrocatalytic Hydrogen Evolution Reaction.

As an electrocatalyst with abundant resources and great potential, molybdenum disulfide is regarded as one of the most likely alternatives to expensive noble-metals catalysts. However, it is still a challenge to achieve large scale production of few-layer MoS2 with enhancing activity of electrocatalytic hydrogen reaction at ambient conditions. Herein, we developed a simple environmentally friendly two-step method, which included intercalation reaction and a subsequent electrochemical reduction reaction for mass preparation of defect-rich desulfurized MoSx (D-MoSx ) nanosheets with plentiful sulfur vacancies. The ratio of sulfur-molybdenum atoms can be adjusted from 2 : 1 to 1.4 : 1 by regulating the desulfurization voltage. It was found that the HER catalytic activity of the D-MoSx was enhanced compared with that of pristine MoS2 (P-MoS2 ), the current density of D-MoSx (desulfurization at -1.0 V) at -0.3 V versus RHE was about 169% of the P-MoS2 , and the Tafel slope decreased to 136 mV dec-1 . This method can be widely applied to large-scale preparation of other two-dimensional materials.

Morphological and Electronic Dual Regulation of Cobalt-Nickel Bimetal Phosphide Heterostructures Inducing High Water-Splitting Performance.

Electrocatalytic water splitting (EWS) is a key technology for generating clean and sustainable hydrogen, which can store abundant energy but is impeded by the insufficient efficiency of the anode and cathode catalyst. Designing and constructing non-noble metal composite bifunctional electrocatalysts for promoting both the cathodic hydrogen evolution (HER) and anodic oxygen evolution reactions (OER) is clearly of great importance for EWS. Thus, the chemical composition and morphology of cobalt-nickel bimetal phosphide (Ni, Co)2P nanoparticles (NPs) encapsulated in nitrogen-doped carbon nanotube hollow microspheres (NCNHMs) can regulate the redox-active sites and enhance the electron transfer, resulting in superior splitting efficiency. Contributing to the synergistic effects between highly active Co-Ni bimetal phosphide NPs and NCNHMs, the obtained Co-Ni bimetal phosphide/NCNHMs display remarkable electrochemical performance for water splitting compared with Ni2P/NCNHMs. Therefore, the Ni1.4Co0.6P/NCNHMs catalysts achieved through a nitriding-phosphidation strategy derived from a hollow Ni1.4-Co0.6-based metal organic framework (MOF) exhibit superior HER catalytic activity (87.9 mV at 10 mA cm-2 tested in 0.5 M H2SO4 and 64.4 mV at 10 mA cm-2 tested in 1 M KOH) and OER catalytic activity (320.0 mV at 10 mA cm-2 tested in 1 M KOH). The Ni1.4Co0.6P/NCNHMs deliver excellent water-splitting catalytic activity (1.55 V at 10 mA cm-2 tested in 1 M KOH), which is competitive with that of current non-noble metal electrocatalysts. Density functional theory (DFT) simulations and related experimental results suggest that the electron transfer from Co doping and coating with NCNHMs improves the electronic states, which would enhance the binding strength with H-bonds and then promote the electrocatalytic activity.

Understanding the role of boron and stoichiometric ratio in the catalytic performance of amorphous Co-B catalyst

The structural, electronic and hydrogen adsorption properties of amorphous CoB, Co2B and Co3B structures were investigated using first principle calculations to evaluate their catalytic activity for HER. A total of eight different sites were considered for hydrogen adsorption, of which the threefold site with two Co and single B atom (TF-2Co-B) was found to be most active site for all the three amorphous Co-B structures. The B atom donates electronic charge to the Co-B bond, while, the presence of Co atom is responsible for achieving the optimal charge density necessary for favorable hydrogen adsorption. This interaction between the Co and B atoms makes bonding region between the Co and B atoms most favorable for hydrogen adsorption and not lone Co atom nor the B atom, thus, determining the active sites of Co-B catalyst. The best catalytic behavior of Co2B stoichiometry was credited to the perfect balance of magnetic properties, optimum hydrogen adsorption energies and considerable number of active sites it displayed.

One-step synthesis of Co9S8@Ni3S2 heterostructure for enhanced electrochemical performance as sodium ion battery anode material and hydrogen evolution electrocatalyst

In this work, sheet-like Co9S8 was directly grown on Ni3S2 spheres (donate as Co9S8@Ni3S2) via a one-step hydrothermal synthetic approach. The structural characterization of Co9S8@Ni3S2 revealed that the Co9S8 nanosheets were perpendicularly arrayed on Ni3S2 spheres. This heterostructure thus fixes the two-dimensional Co9S8 in position on Ni3S2 spheres to obtain a stable heterostructural material. Due to the strengthened morphological structure, high surface area, metallic feature of Co9S8 and Ni3S2, and the synergetic effect, the Co9S8@Ni3S2 showed excellent performance in sodium ion battery (SIB) anode and HER cathode. The electrochemical tests showed that Co9S8@Ni3S2 can demonstrate excellent HER catalytic activity with only −0.16 ​V and −0.23 ​V overpotential needed to achieve 10 ​mA ​cm−2 and 100 ​mA ​cm−2 current density in acidic condition. Besides, Co9S8@Ni3S2 heterostructure as an anode in SIB also delivered high discharge capacity of 699 ​mAh g−1 at 0.5 ​A ​g−1 current density in the first cycle, with 92% Columbic efficiency.

Hydrogen Evolution and Wastewater Treatment of Hydrangeal‐like Catalyst Decroatedby the NiS Nanosheet and PdNanoparticle

AbstractMultifunctional catalysts with photodegradation of organic contaminants and electrocatalytic hydrogen evolution are extremely urgent. In this work, a unique MoS2 hollow microsphere with a diameter of 1.5 μm was fabricated without adding any spherical template by an improved hydrothermal process. Interestingly, the MoS2 hollow microspheres with introduction of the NiS and Pd nanoparticles greatly restrain recombination rates of electron‐hole pairs, resulting in the outstanding photocatalytic activity. The RhB removal rates of the MoS2 hollow microsphere and the NPMS composites were 7 and 10 times higher than that of pure MoS2, respectively, for the high concentration of macrocyclic contaminants under visible‐light illumination. Furthermore, the optimal robust NPMS hybrids exhibite a lower overpotential of 100 mV (at 10 mV cm−2) and a smaller Tafel slope of 50 mV dec−1. The unique structure composite catalysts possess more exposed active sites and defects to enhance the catalytic activity for HER and removal of organic pollution.

Promoting the hydrogen evolution performance of 1T-MoSe2-Se: Optimizing the two-dimensional structure of MoSe2 by layered double hydroxide limited growth

Designing of catalysts with high activity and earth abundance which can further enhance the electrocatalytic hydrogen evolution performance so as to improve the hydrogen production efficiency. In this paper, we synthesized 1T-MoSe2-Se/MgAl-LDH composites by in-situ hydrothermal reduction method. The high proportion 1T phase (73.73%) of ultra-thin layer 1T-MoSe2-Se was obtained by acid dissolution operation, which can be ascribed to the limiting growth effect of MgAl-LDH. Compared to Pure MoSe2, it dramatically improved HER catalytic activity. the optimal 1T-MoSe2-Se (24 h) exhibits superior HER performance with a small overpotential (122 mV at the current density of 10 mA cm−2) and Tafel slope (54 mV dec−1) as well as excellent electrochemical stability. The introduction of Se can promote the conductivity of 1T-MoSe2-Se catalyst. Moreover, the best electrocatalytic hydrogen evolution performance can be exhibited synergistically only when the optimal match between MoSe2 and Se is achieved, which are confirmed by XPS analysis and HER test results.

Pt nanoparticles/Fe-doped α-Ni(OH)2 nanosheets array with low Pt loading as a high-performance electrocatalyst for alkaline hydrogen evolution reaction

To decrease energy loss in water-alkali electrolysis, it is crucial to construct highly active HER electrocatalyst in alkaline media. In this work, Pt nanoparticles uniformly immobilized on Fe-doped α-Ni(OH)2 nanosheets array with low Pt loading was designed through one-step liquid-phase route. Impressively, the optimized Pt2.3%-Fe0.05Ni0.95(OH)2 with ∼3.5 nm size of Pt nanoparticles displays superior HER electrocatalytic performance in alkaline electrolyte. It can drive 10 mA cm−2 at very low overpotential of 18 mV, and 500 mA cm−2 of high current density at fairly low overpotential of 159 mV with a small Tafel slope of 25.6 mV dec−1. Its mass activity is 15.23 mA μgPt−1 at − 0.070 V vs. RHE, almost 28.7 times relative to Pt/C. Moreover, it presents distinguished stability in both low and high current densities. Fe3+ ions doped in α-Ni(OH)2 lattice by partial substitution of Ni2+ ions provides a good platform for anchoring ultrafine Pt nanoparticles. A synergy between the Fe-doped α-Ni(OH)2 nanosheets interface for water dissociation and the Pt nanoparticles surface for adsorbed H atoms recombination enhances the catalytic activity for HER. The strong contact between Pt nanoparticles and site-specific Fe3+-O(H)–Pt bonds of Fe-doped α-Ni(OH)2 nanosheets is contributed to its outstanding activity and stability.

Plasma-assisted nitrogen doping in Ni-Co-P hollow nanocubes for efficient hydrogen evolution electrocatalysis.

To surmount the issues of a limited specific surface area and slow electrolyte diffusion in composite electrocatalysts, three-dimensional (3D) porous hollow nanocubes are fabricated, in which bimetal Ni-Co phosphide composites are covered with nanoparticles. The abundant hollow space provides more active sites for the catalyst, and simultaneously ensures efficient mass transfer and electron transport during the hydrogen evolution reaction (HER). A plasma-assisted approach is employed for smart N-doping in the Ni-Co phosphide hollow nanocubes (N-Ni-Co-P HNCs). The N-Ni-Co-P HNC catalyst exhibits a remarkable HER performance in 1 M KOH, evidenced by the low overpotentials of 47.9 mV and 150.5 mV at the current density of 10 mA cm-2 and 50 mA cm-2, respectively, as well as the excellent long-time stability. Essentially, the N doping tailors the electronic states and optimizes the free energy of hydrogen adsorption (ΔGH*) greatly, and the 3D porous hollow structure with porous nanoparticles stacked enlarges the specific active area substantially. Their synergistic effects result in the remarkably enhanced catalytic activity for the HER.

Applying surface strain and coupling with pure or N/B-doped graphene to successfully achieve high HER catalytic activity in 2D layered SnP3-based nanomaterials: a first-principles investigation

Applying external strain and coupling with pure or N/B-doped graphene can be viewed as effective strategies to further improve the HER activity of 2D layered SnP3 nanomaterials by optimizing the adsorption state of H* and electronic properties.

Investigation of the Support Effect in Atomically Dispersed Pt on WO3-x for Utilization of Pt in the Hydrogen Evolution Reaction.

Single-atom catalysts (SACs) have attracted growing attention because they maximize the number of active sites, with unpredictable catalytic activity. Despite numerous studies on SACs, there is little research on the support, which is essential to understanding SAC. Herein, we systematically investigated the influence of the support on the performance of the SAC by comparing with single-atom Pt supported on carbon (Pt SA/C) and Pt nanoparticles supported on WO3-x (Pt NP/WO3-x ). The results revealed that the support effect was maximized for atomically dispersed Pt supported on WO3-x (Pt SA/WO3-x ). The Pt SA/WO3-x exhibited a higher degree of hydrogen spillover from Pt atoms to WO3-x at the interface, compared with Pt NP/WO3-x , which drastically enhanced Pt mass activity for hydrogen evolution (up to 10 times). This strategy provides a new framework for enhancing catalytic activity for HER, by reducing noble metal usage in the field of SACs.

Investigation of the Support Effect in Atomically Dispersed Pt on WO3−x for Utilization of Pt in the Hydrogen Evolution Reaction

AbstractSingle‐atom catalysts (SACs) have attracted growing attention because they maximize the number of active sites, with unpredictable catalytic activity. Despite numerous studies on SACs, there is little research on the support, which is essential to understanding SAC. Herein, we systematically investigated the influence of the support on the performance of the SAC by comparing with single‐atom Pt supported on carbon (Pt SA/C) and Pt nanoparticles supported on WO3−x (Pt NP/WO3−x). The results revealed that the support effect was maximized for atomically dispersed Pt supported on WO3−x (Pt SA/WO3−x). The Pt SA/WO3−x exhibited a higher degree of hydrogen spillover from Pt atoms to WO3−x at the interface, compared with Pt NP/WO3−x, which drastically enhanced Pt mass activity for hydrogen evolution (up to 10 times). This strategy provides a new framework for enhancing catalytic activity for HER, by reducing noble metal usage in the field of SACs.

Phosphate Doped Ultrathin FeP Nanosheets as Efficient Electrocatalysts for the Hydrogen Evolution Reaction in Acid Media

AbstractUltrathin nanosheets of non‐layered materials have attracted intensive interests due to their abundantly accessible active sites. Herein, we demonstrate that the ultrathin FeP nanosheets (FeP‐I NS) with abundant mesoporosity and phosphate dopants can be facilely synthesized using ultrathin γ‐Fe2O3 NS as precursors. The as‐prepared catalyst displays good HER catalytic activity with an low overpotential (η) of 95/160 mV at the current densities of 10/100 mA cm−2 and small Tafel slope of 41 mV dec−1 as well as good stability during a period of 24 h in acid media. Additional experimental results reveal that the unique structural features of FeP‐I NS (i. e., ultrathin morphology, abundant mesoporosity, local structural distortion and amorphous domains) are key factors for achieving good HER activity. The computational studies demonstrate that the phosphate dopants (i. e., Fe2P2O7) contribute to the superior catalytic performance of FeP by reducing the Gibbs free energy of intermediate H* adsorption (ΔGH*) to the catalyst surface as well as by tailoring the electronic properties of the catalyst.

Simple vapor-solid-reaction route for porous Cu2O nanorods with good HER catalytic activity.

In this work, a simple vapor-solid reaction route was designed for the preparation of porous Cu2O nanorods with good HER catalytic performance, employing Cu(OH)2 nanorods as the precursor and ethylene glycol as the reductant. The reaction was carried out under an Ar atmosphere in the temperature range of 200-280 °C for 2 h. The final product was characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), (high-resolution) transmission electron microscopy (TEM/HRTEM), X-ray photoelectron spectroscopy (XPS), HAADF-STEM-EDS mapping and nitrogen adsorption-desorption isotherms. It was found that pure Cu2O was always obtained in the temperature range of 200-280 °C and well retained the outline of the precursor. Nevertheless, electrochemical experiments showed that porous Cu2O nanorods prepared at 200 °C (labeled as Cu2O-200) exhibited much stronger HER catalytic activity than those obtained at higher temperatures, which were labeled as Cu2O-220, Cu2O-240, Cu2O-260 and Cu2O-280, respectively. In an alkaline solution of 1.0 M KOH, Cu2O-200 presented a low overpotential of ∼184 mV, a small Tafel slope of 106 mV dec-1, and a high durability over 20 h at a current density of 10 mA cm-2. The above good performances were attributed to the high surface area and high-speed electronic transmission networks of Cu2O-200, which provided fast transportation and short diffusion path for the electrolyte and evolved H2 bubbles.

MOF-derived uniform Ni nanoparticles encapsulated in carbon nanotubes grafted on rGO nanosheets as bifunctional materials for lithium-ion batteries and hydrogen evolution reaction.

The rational-design and synthesis of transition-metal compounds with outstanding electrochemical activity and durability for renewable energy systems have attracted tremendous research interest in recent years. Herein, we report a facile and unique strategy to synthesize N-doped carbon nanotube-encapsulated Ni nanoparticles on reduced graphene oxide (Ni@NC-rGO). The optimized nanostructure determines the synergetic effects among the Ni nanoparticles, N-doped CNTs and graphene nanosheets, thus resulting in extraordinary electrochemical performances. When applied as an anode for lithium-ion batteries (LIBs), the Ni@NC-rGO electrode displayed high reversible capacity, stable cycling performance and superior rate capability. Moreover, the resulting Ni@NC-rGO nanocomposites exhibited low overpotential and considerable durability for the hydrogen evolution reaction (HER). Our study may provide a feasible methodology for the preparation of high-performance nanostructured materials for practical energy storage and conversion applications.

Surface intercalated spherical MoS2xSe2(1-x) nanocatalysts for highly efficient and durable hydrogen evolution reactions.

An efficient hydrogen evolution reaction (HER) depends essentially on high-performing electrocatalysts. The aggregation of catalysts normally deteriorates their activity and stability. In this study, a two-step route was used to synthesize surface intercalated well-dispersed spherical MoS2xSe2(1-x) nanocatalysts. The resulting catalysts present a highly active and stable performance towards the HER with an overpotential of -143 mV at 10 mA cm-2, and a Tafel slope of 53.8 mV dec-1. The mechanism for the enhanced HER was analyzed and was attributed to three factors: (i) large numbers of defects and edge active sites arising from the coexistence of S and Se elements; (ii) enhanced electric conductivity arising from the phase transition from the semiconducting 2H-phase to metallic 1T-phase during the intercalation process; and (iii) enlarged contact areas between active sites and electrolyte caused by the increased surface roughness due to the surface intercalation. This work not only deepens our understanding of the improved HER performance of surface intercalated catalysts, but also provides novel strategies for preparing durable electrocatalysts through surface engineering.

Electronic structure modulation of NiS2 by transition metal doping for accelerating the hydrogen evolution reaction

We give a systematic study of the HER catalytic activity of transition metal doped NiS2 by first principles calculations and experiments.

Hydrogen adsorption trends on various metal-doped Ni2P surfaces for optimal catalyst design.

In this study, we looked at the hydrogen evolution reaction on Mg-, Mo-, Fe-, Co-, V-, and Cu-doped Ni3P2 and Ni3P2 + P terminated Ni2P surfaces. The DFT calculated hydrogen adsorption free energy was employed as a predictor of the materials' catalytic HER activity. Our results indicate that doping can substantially improve the catalytic activity of the Ni3P2 terminated surface. In contrast, the Ni3P2 + P terminated one seems to be catalytically active irrespective of the type of doping, including in the absence of doping. Based on our doping energy and adsorption free energy calculations, the most promising dopants are iron and cobalt, whereas copper is less likely to function well as a doping element.

Modulating the surface segregation of PdCuRu nanocrystals for enhanced all-pH hydrogen evolution electrocatalysis

Core–shell PdCuRu trimetallic nanocrystals with a Pd-rich shell can be obtained by leveraging controlled surface segregation, and high-performance HER catalytic activity finally was achieved at all pH values.