Efficient Electrocatalyst For Hydrogen Evolution Research Articles

Magnetic field assisted synthesis of dense braided rope NiCoP as a highly efficient hydrogen evolution electrocatalyst

The design of efficient stable and noble metal-free catalysts for the hydrogen evolution reaction is an important and challenging global task. In this work, high catalytic activity NiCoP braided rope was prepared by magneto-electrodeposition strategy for the first time. Notably, the magnetic field-induced magnetohydrodynamic effect serves multiple purposes. COMSOL numerical simulations reveal the formation mechanism of a braided rope structure. Density functional theory (DFT) calculations confirm that NiCoP has superior activity, attributed to Co active sites. In 1.0 M KOH and 0.5 M H2SO4, respectively, the overpotential of NiCoP prepared under 600 mT magnetic field (NiCoP-600) is only 48 and 34 mV at a current density of 10 mA cm−2. Additionally, the TOF of NiCoP-600 was 36 times as high as that of NiCoP at an overpotential of 100 mV. Furthermore, NiCoP-600 can be used as the cathode and anode for overall water splitting in an alkaline electrolyzer.

Mo-doped one-dimensional needle-like Ni3S2 as bifunctional electrocatalyst for efficient alkaline hydrogen evolution and overall-water-splitting

Hydrogen energy plays an important role in clean energy system and is considered the core energy source for future technological development owing to its lightweight nature, high calorific value, and clean combustion products. The electrocatalytic conversion of water into hydrogen is considered a highly promising method. An electrocatalyst is indispensable in the electrocatalytic process, and finding an efficient electrocatalyst is essential. However, the current commercial electrocatalysts (such as Pt/C and Ru) are expensive; therefore, there is a need to find an inexpensive and efficient electrocatalyst with high stability, corrosion resistance, and high electrocatalytic efficiency. In this study, we developed a cost-effective bifunctional electrocatalyst by incorporating molybdenum into nickel sulfide (Ni3S2) and subsequently tailoring its structure to achieve a one-dimensional (1D) needle-like configuration. The hydrogen production efficiency of nickel sulfide was improved by changing the ratio of Mo doping. By analyzing the electrochemical performance of different Mo-doped catalysts, we found that the Ni3S2-Mo-0.1 electrocatalyst exhibited the best electrocatalytic effect in 1 M KOH; at a current density of 10 mA cm−2, it exhibited overpotentials of 120 and 279 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively; at a higher current density of 100 mA cm−2, the HER and OER overpotentials were 396 and 495 mV, respectively. Furthermore, this electrocatalyst can be used in a two-electrode water-splitting system. Finally, we thoroughly investigated the mechanism of the overall water splitting of this electrocatalyst, providing valuable insights for future hydrogen production via overall-water-splitting.

Novel CoP/CoMoP2 heterojunction with nanoporous structure as an efficient electrocatalyst for hydrogen evolution

Novel CoP/CoMoP2 heterojunction with nanoporous structure as an efficient electrocatalyst for hydrogen evolution

Heterostructured FeP4/CoP@NF as trifunctional electrocatalysts for energy-efficient hydrogen production

The developing of efficient and cost-effective electrocatalysts for hydrogen evolution is of great significance to the development of hydrogen energy. It is believed that the efficient hydrogen generation of water cracking is restricted from the slow oxygen evolution reaction (OER) process. Consequently, it is highly recommended to find alternative anodizing to produce hydrogen to reduce electricity consumption. Urea oxidation reaction (UOR) is an alternative to the traditional anodic OER. In this paper, an electrocatalyst FeP4/CoP@NF-7.5 supported on nickel foam (NF) was designed by using a template-directed growth and low-temperature phosphating method. The FeP4/CoP@NF-7.5 with a rich interface gives it more active sites and enhances mass transfer and conductivity, possessing excellent catalytic performance against hydrogen evolution reaction (HER), OER and UOR in alkaline electrolyte. Thanks to the abundant interface and bimetallic synergy, the designed catalyst exhibits the overpotentials of 45 mV and 259 mV for HER and OER to transfer 10 mA cm−2. In addition, FeP4/CoP@NF-7.5 also possesses significant catalytic activity against UOR of 136 mV (j10) in 1 M KOH with 0.33 M urea, which provides another alternative to the low efficiency of OER through the reduction of hydrogen production costs. Finally, the overall water splitting test was undertaken in 1 M KOH containing/free of 0.33 M urea. Remarkably, only 1.43 V is required to drive on urea electrolyzer (j10 = 10 mA cm−2), while 1.52 V are gained on water electrolyzer. This paper lays the foundation for the developing of high-active transition bimetallic phosphide electrocatalysts for energy-saving hydrogen production.

Hierarchical CoO@MoN heterostructure nanowire array as a highly efficient electrocatalyst for hydrogen evolution

The high energy barrier and sluggish electron transfer are regarded as the most important reasons that restricting the performance of electrocatalysts for hydrogen evolution. The hierarchical CoO@MoN heterostructure nanowire array is fabricated, with adjusted electronic structure for tuning the binding strength of intermediates. As a result, CoO@MoN exhibits an excellent activity that is close to the benchmark Pt/C toward hydrogen evolution in alkaline medium. The theoretical computations indicate that the coupling of CoO and MoN can lead to the facilitated electron transfer for the tuned band structure. Besides, the energy barrier in the reaction is greatly reduced for the ameliorated binding strength of intermediates on CoO@MoN. This work demonstrates the significance of accelerating the electron transfer and reducing the energy barrier by rationally constructing the heterostructure, which paves the road to the exploitation of highly active and cost-efficient electrocatalysts for hydrogen evolution.

Hierarchical-heterostructured porous intermetallics in nickel-cobalt-aluminum alloys as efficient electrocatalysts for hydrogen evolution

Extensive researches have unequivocally revealed the remarkable potential of hierarchical porous intermetallic materials within the realms of electrocatalysis and energy materials. Nevertheless, the efficient and cost-effective synthesis of such electrocatalysts remains a challenging task, and the atomic-level mechanisms underlying hydrogen evolutions at active catalytic sites are still insufficiently comprehended. Herein, we report a novel synthesis technique for the hierarchical-heterostructured non-noble Ni-Co-Al intermetallics using spark plasma sintering followed by a selective dealloying process. This approach maximizes the electrochemical active surface area, thereby facilitating highly efficient hydrogen evolution reactions with an impressively low overpotential of only 75 mV at a current density of 10 mA cm−2 and a Tafel slope of 54 mV dec−1. Through operando X-ray absorption fine structure and theoretical calculations, the dynamic evolution process during the hydrogen evolution reaction procedure is investigated and the atomic Ni and Co sites are identified as synergistic catalytic sites. These characteristics render this hierarchical-heterostructured porous intermetallics appealing contenders for electrocatalysts utilized in high-performance large-scale hydrogen generation applications.

Ni3S2 nanocrystals in-situ grown on Ni foam as highly efficient electrocatalysts for alkaline hydrogen evolution

Ni3S2 nanocrystals in-situ grown on Ni foam as highly efficient electrocatalysts for alkaline hydrogen evolution

MOF Template-Derived Carbon Shell-Embedded CoP Hierarchical Nanosheet as Bifunctional Catalyst for Overall Water Splitting.

The design of earth-abundant and highly efficient bifunctional electrocatalysts for hydrogen evolution and oxygen evolution reactions (HER/OER) is crucial for hydrogen production through overall water splitting. Herein, we report a novel nanostructure consisting of vertically oriented CoP hierarchical nanosheet arrays with in situ-assembled carbon skeletons on a Ti foil electrode. The novel Zeolitic Imidazolate Framework-67 (ZIF-67) template-derived hierarchical nanosheet architecture effectively improved electrical conductivity, facilitated electrolyte transport, and increased the exposure of the active sites. The obtained bifunctional hybrid exhibited a low overpotential of 72 mV at 10 mA cm-2 and a small Tafel slope of 65 mV dec-1 for HER, and an improved overpotential of 329 mV and a Tafel slope of 107 mV dec-1 for OER. Furthermore, the assembled C@CoP||C@CoP electrolyzer showed excellent overall water splitting performance (1.63 V) at a current density of 10 mA cm-2 and superior durability. This work provides a structure engineering strategy for metal-organic framework (MOF) template-derived hybrids with outstanding electrocatalytic performance.

Highly efficient and stable electrocatalyst for hydrogen evolution by molybdenum doped Ni-Co phosphide nanoneedles at high current density

Highly efficient and stable electrocatalyst for hydrogen evolution by molybdenum doped Ni-Co phosphide nanoneedles at high current density

Defined organic-octamolybdate crystalline superstructures derived Mo2C@C as efficient hydrogen evolution electrocatalysts

Hydrogen evolution electrocatalysts derived from metal-organic crystalline frameworks can inherit the merits of ordered and adjustable structures with high surface area. In this paper, organic-octamolybdate crystalline superstructures (OOCS) with a fixed stoichiometric ratio of Mo8(L)2 and high Mo content (>40 wt%) were synthesized using flexible ligands with controllable lengths (named as OOCS-1–3). Then, molybdenum carbides coated with carbon layers as electrocatalysts (Mo2C@C-1–3) can be obtained directly from a one-step high-temperature carbonization process using OOCS-1–3 as precursors. As a typical example, Mo2C@C-3 exhibits satisfactory hydrogen evolution activity with a low overpotential of 151 mV (1.0 mol/L KOH) at 10 mA/cm2 and stability for 24 h. The electrocatalytic activity is mainly from the synergistic interactions between the carbon layers and molybdenum carbide species. Furthermore, compared with the initial content of C, N, Mo in OOCS and Mo2C@C, the catalytic activity increases with the N amount. This work makes organic-octamolybdate crystalline superstructures used as general precursors to product high Mo content electrocatalysts applied in energy storage and conversion fields.

Mesoporous PtPb Nanosheets as Efficient Electrocatalysts for Hydrogen Evolution and Ethanol Oxidation

AbstractUsing a one‐pot hydrothermal method with ethylenediamine, we have synthesized mesoporous PtPb nanosheets that exhibit exceptional activity in both hydrogen evolution and ethanol oxidation. The resulting PtPb nanosheets have a Pt‐enriched structure with up to 80 % atomic content of Pt. The synthetic method generated a significant mesoporous structure, formed through the dissolution of Pb species. These advanced structures enable the mesoporous PtPb nanosheets to achieve a current density of 10 mA cm−2 with an extreme low overpotential of 21 mV for hydrogen evolution under alkaline conditions. Furthermore, the mesoporous PtPb nanosheets exhibit superior catalytic activity and stability for ethanol oxidation. The highest catalytic current density of PtPb nanosheets is 5.66 times higher than that of commercial Pt/C. This research opens up new possibilities in designing mesoporous, two‐dimensional noble‐metal‐based materials for electrochemical energy conversion with excellent performance.

Mesoporous PtPb Nanosheets as Efficient Electrocatalysts for Hydrogen Evolution and Ethanol Oxidation.

Using a one-pot hydrothermal method with ethylenediamine, we have synthesized mesoporous PtPb nanosheets that exhibit exceptional activity in both hydrogen evolution and ethanol oxidation. The resulting PtPb nanosheets have a Pt-enriched structure with up to 80% atomic content of Pt. The synthetic method generated a significant mesoporous structure, formed through the dissolution of Pb species. These advanced structures enable the mesoporous PtPb nanosheets to achieve a current density of 10 mA/cm2 with an extreme low overpotential of 21 mV for hydrogen evolution under alkaline conditions. Furthermore, the mesoporous PtPb nanosheets exhibit superior catalytic activity and stability for ethanol oxidation. The highest catalytic current density of PtPb nanosheets is 5.66 times higher than that of commercial Pt/C. This research opens up new possibilities in designing mesoporous, two-dimensional noble-metal-based materials for electrochemical energy conversion with excellent performance.

Cobalt-based Metalloporphyrins As Efficient Electro-catalysts for Hydrogen Evolution From Acetic Acid and Water

Cobalt-based Metalloporphyrins As Efficient Electro-catalysts for Hydrogen Evolution From Acetic Acid and Water

V6O13 Micro-Flower Arrays Grown In Situ on Ni Foam as Efficient Electrocatalysts for Hydrogen Evolution at Large Current Densities

Developing a high-activity, robust and economic electrocatalyst for large-scale green hydrogen production is still of great significance. Herein, a novel V6O13 nanosheets self-assembled micro-flower array self-supporting electrode is synthesized using a facile one-pot hydrothermal route. Owing to the large electrochemically active surface area of a unique hierarchical micro-flower and the stable all-in-one structure, the as-prepared V6O13/NF electrode delivers impressive HER activity with extremely low overpotentials of 125 and 298 mV at large current densities of 100 and 1000 mA cm−2, respectively, and a long-term durability for at least 90 h in an alkaline condition. This work extends the application of vanadium oxides to the realm of electrocatalytic hydrogen fuel production.

From atomic bonding to heterointerfaces: Co2P/WC constructed by lacunary polyoxometalates induced strategy as efficient hydrogen evolution electrocatalysts at all pH values

Herein, a novel in-situ “atomic binding to heterointerface” strategy is proposed to obtain Co2P/WC@NC/CNTs catalyst with abundant heterointerface between cobalt phosphide and tungsten carbide (Co2P/WC) by the polyoxometalates (POMs)-based metal–organic frameworks (MOFs) precursor. The natural quasi interfaces in K10[Co4(H2O)2(PW9O34)2] molecule crucially guide the abundant Co2P/WC heterointerfaces down to atomic level. Meanwhile, MOFs cages can effectively encapsulate nanosized POMs at molecular level to control the size and dispersion of Co2P/WC nanoparticle, while carbon nanotubes (CNTs) enhance conductivity at nanoscale level. The interfacial electronic modulation between Co2P and WC lowering the energy barrier of the rate determining step, thus Co2P/WC@NC/CNTs showed reasonable hydrogen evolution reaction (HER) activity and stability in all-pH media including sea water. This work provides a “bottom-up” synthetic strategy for confined heterostructures, thus offering the prospect for more efficient interfacial charge modulation.

Mo, V and M (M=Mn, Fe, Co, Cu) Co-modulated Ni oxides in-situ derived from nickel foam as efficient electrocatalysts for alkaline hydrogen evolution and oxygen evolution

The highly efficient catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are of great significance for electrochemical water splitting. Direct transforming nickel foam (NF) into nickel-based catalysts attracts extensive attention because of its excellent stability and high conductivity. However, the catalytic performances of this kind of catalyst are still far from expected. Herein, we report a series of Ni oxides co-modulated by Mo, V and M (M=Mn, Fe, Co, Cu) as efficient catalysts for water splitting, which are directly prepared through a simple NF-transformation method. Especially, a MoVNi catalyst displays a low Tafel slope of 68 mV/dec and a small overpotential of 76 mV at 10 mA/cm2 for HER in 1.0 M KOH solution. The OER performances of MoVNi can be greatly enhanced by M introduction. For example, Fe-MoVNi only requires 374 mV to achieve 100 mA/cm2 and shows no declination in a-20 h stability test at 100 mA/cm2 in 1.0 M KOH media. Such performances outperform the recently reported best-performing Ni oxides catalysts in an alkaline environment. The excellent catalytic performances suggest great promise in practical applications.

Interfacial engineering of Co5.47N/Mo5N6 nanosheets with rich active sites synergistically accelerates water dissociation kinetics for Pt-like hydrogen evolution

The development of highly efficient hydrogen evolution electrocatalysts with platinum-like activity requires precise control of active sites through interface engineering strategies. In this study, a heterostructured Co5.47N/Mo5N6 catalyst (CoMoNx) on carbon cloth (CC) was synthesized using a combination of dip-etching and vapor nitridation methods. The rough nanosheet surface of the catalyst with uniformly distributed elements exposes a large active surface area and provides abundant interface sites that serve as additional active sites. The CoMoNx was found to exhibit exceptional hydrogen evolution reaction (HER) activity with a low overpotential of 44 mV at 10 mA cm−2 and exceptional stability of 100 h in 1.0 M KOH. The CoMoNx(−)||RuO2(+) system requires only 1.81 V cell voltage to reach a current density of 200 mA cm−2, surpassing the majority of previously reported electrolyzers. Density functional theory (DFT) calculations reveal that the strong synergy between Co5.47N and Mo5N6 at the interface can significantly reduce the water dissociation energy barrier, thereby improving the kinetics of hydrogen evolution. Furthermore, the rough nanosheet architecture of the CoMoNx catalyst with abundant interstitial spaces and multi-channels enhances charge transport and reaction intermediate transportation, synergistically improving the performance of the HER for water splitting.

Consecutive Synthesis of MoO2, Mo2C and MoS2 Nanodots as Efficient Electrochemical Hydrogen Evolution Electrocatalysts

Consecutive Synthesis of MoO2, Mo2C and MoS2 Nanodots as Efficient Electrochemical Hydrogen Evolution Electrocatalysts

NiCu alloys anchored Co3O4 nanowire arrays as efficient hydrogen evolution electrocatalysts in alkaline and neutral media

Robust and long-lasting non-precious metal electrocatalysts are essential to achieve sustainable hydrogen production. In this work, we synthesized Co3O4@NiCu by electrodepositing NiCu nanoclusters onto Co3O4 nanowire arrays that were formed in situ on nickel foam. The introduction of NiCu nanoclusters altered the inherent electronic structure of Co3O4, significantly increasing the exposure of active sites and enhancing endogenous electrocatalytic activity. Co3O4@NiCu exhibited overpotentials of only 20 and 73 mV, respectively, at 10 mA cm−2 current densities in alkaline and neutral media. These values were equivalent to those of commercial Pt catalysts. Finally, the electron accumulation effect at the Co3O4@NiCu, along with a negative shift in the d-band center, is finally revealed by theoretical calculations. Hydrogen adsorption on consequent electron-rich Cu sites was effectively weakened, leading to a robust catalytic activity for the hydrogen evolution reaction (HER). Overall, this study proposes a practical strategy for creating efficient HER electrocatalysts in both alkaline and neutral media.

N-, Se-, and S-Doped Bimetallic NiCoP Nanosheet Arrays as Efficient Hydrogen Evolution Electrocatalysts

N-, Se-, and S-doped NiCoP nanosheet arrays with the same doping content were prepared on nickel foam (NF) as efficient electrocatalysts for the hydrogen evolution reaction (HER). Experimental results and theoretical calculations mutually verified that N, Se, and S doping modulated the electronic structure of NiCoP and thus accelerated the intrinsic charge transport, which eventually enhanced the HER activity. N-NiCoP/NF, Se-NiCoP/NF, and S-NiCoP/NF catalysts show overpotential of 149, 153, and 137 mV at a current density of 100 mA cm–2, respectively, lower than 154 mV of 20% Pt-C@NF. Additionally, S-NiCoP/NF exhibits long-term robustness for the HER in 120 h of continuous electrolysis with negligible current attenuation. It is expected that S-NiCoP/NF may be applicable in water electrolysis with improved efficiency.