High HER Activity Research Articles

Facile and fast synthesis of Ni composite coating on Ti mesh by electrodeposition method for high-performance hydrogen production

Herein, the Ni composite coating comprised of metallic Ni (Ni0) and Ni(OH)2 was rapidly deposited on Ti mesh by facile, low cost and environmental-friendly electrodeposition method with only NiSO4 as electrolyte. HER experiments revealed that Ni composite coating on Ti mesh with electrodeposition time of 360 s (Ni/TM-360 s) exhibited the highest HER activity with overpotential of 205 mV at −10 mA/cm2, surpassing some previously reported Ni-based electrocatalysts. This catalyst also presented long-term durability. This method may provide an effective and green strategy for synthesizing Ni composite coating HER electrocatalyst with decent activity and stability.

In situ synthesis of a Fe3S4/MIL-53(Fe) hybrid catalyst for an efficient electrocatalytic hydrogen evolution reaction.

The development of efficient MOF-based electrocatalysts with good stability to produce hydrogen is a great challenge in the field of sustainable energy conversion. Herein, we introduced a controlled in-situ sulfurization strategy to generate a highly active and stable hybrid catalyst containing good conductive Fe3S4 ultrasmall nanosheets attached on the surface of 3D MIL-53(Fe) for the hydrogen evolution reaction in acidic solutions.

Ultra-small Mo2C nanodots encapsulated in nitrogen-doped porous carbon for pH-universal hydrogen evolution: insights into the synergistic enhancement of HER activity by nitrogen doping and structural defects

A facile one-pot synthesis method was used. The synergistic effect of nitrogen doping and structure defects on the carbon layer leaded to the high HER activity.

Novel nickel–cobalt phosphite with face-sharing octahedra derived electrocatalyst for efficient water splitting

Nickel–cobalt phosphite (CoNiPO) including local structural motifs with face-sharing octahedra shows excellent OER activity. The derivatized electrocatalyst (NiP2@CoNiPO) exhibits high HER activity. DFT calculations indicated the super-exchange effect in CoNiPO can adjust local electronic structure and improve their catalytic activity.

Abundant Vanadium Diboride with Graphene-like Boron layers for Hydrogen Evolution

We report on the design of abundant and highly active VB2 for hydrogen production. Density functional theory (DFT) calculations have predicted very high HER activity of the graphene-like B-layer, the V-terminated {100} layer, and the mixed V/B-terminated {101} layer of VB2. Bulk samples and nanoparticles of VB2 were synthesized and tested for their HER performance. The results indicate that both bulk and nano-VB2 are active for HER, consistent with theoretical predictions. In addition, the HER activity of VB2 is significantly increased at the nanoscale if compared to the bulk, reaching an overpotential of 192 mV at 10 mA/cm2 current density. Increased surface area and higher density of active sites are responsible for the higher nanoscale activity, making nano-VB2 the best HER boride to date in terms of abundance, stability, and activity in acidic solution.

Facile synthesis of silk-cocoon S-rich cobalt polysulfide as an efficient catalyst for the hydrogen evolution reaction

A silk-cocoon structured S-rich cobalt polysulfide (CoSx, x ≈ 3.9) catalyst with high HER activity has been developed for the first time.

Carbon-encapsulated nickel-cobalt alloys nanoparticles fabricated via new post-treatment strategy for hydrogen evolution in alkaline media

This paper addresses a new post-treatment strategy for the formation of carbon-encapsulated nickel-cobalt alloys nanoparticles, which is easily controlled the performance of target products via changing precursor composition, calcination conditions (e.g., temperature and atmosphere) and post-treatment condition. Glassy carbon electrode (GCE) modified by the as-obtained carbon-encapsulated mono- and bi-transition metal nanoparticles exhibit excellent electro-catalytic activity for hydrogen production in alkaline water electrolysis. Especially, Ni0.4Co0.6@N-Cs800-b catalyst prepared at 800 °C under an argon flow exhibited the best electrocatalytic performance towards HER. The high HER activity of the Ni0.4Co0.6@N-Cs800-b modified electrode is related to the appropriate nickel-cobalt metal ratio with high crystallinity, complete and homogeneous carbon layers outside of the nickel-cobalt with high conductivity and the synergistic effect of nickel-cobalt alloys that also accelerate electron transfer process.

Hexagonal-Phase Cobalt Monophosphosulfide for Highly Efficient Overall Water Splitting.

The rational design and synthesis of nonprecious, efficient, and stable electrocatalysts to replace precious noble metals are crucial to the future of hydrogen economy. Herein, a partial sulfurization/phosphorization strategy is proposed to synthesize a nonstoichiometric pyrrhotite-type cobalt monophosphosulfide material (Co0.9S0.58P0.42) with a hexagonal close-packed phase for electrocatalytic water splitting. By regulating the degree of sulfurization, the P/S atomic ratio in the cobalt monophosphosulfide can be tuned to activate the Co3+/Co2+ couples. The synergy between the nonstoichiometric nature and the tunable P/S ratio results in the strengthened Co3+/Co2+ couples and tunable electronic structure and thus efficiently promotes the oxygen/hydrogen evolution reaction (OER/HER) processes toward overall water splitting. Especially for OER, the Co0.9S0.58P0.42 material, featured with a uniform yolk-shell spherical morphology, shows a low overpotential of 266 mV at 10 mA cm-2 (η10) with a low Tafel slope of 48 mV dec-1 as well as high stability, which is comparable to that of the reported promising OER electrocatalysts. Coupled with the high HER activity of Co0.9S0.58P0.42, the overall water splitting is demonstrated with a low η10 at 1.59 V and good stability. This study shows that phase engineering and composition control can be the elegant strategy to realize the Co3+/Co2+ couple activation and electronic structure tuning to promote the electrocatalytic process. The proposed strategy and approaches allow the rational design and synthesis of transition metal monophosphosulfides toward advanced electrochemical applications.

The Enhanced CO Tolerance of Platinum Supported on FeP Nanosheet for Superior Catalytic Activity Toward Methanol Oxidation

The inferior CO-like intermediates tolerance of Pt nanoparticle greatly hampered the MOR activity and durability. To alleviate this issue, tremendous efforts have been made to create oxygen-containing groups on neighbouring Pt site for oxidizing the poisonous carbonaceous species. Given this, two-dimensional FeP nanosheet with excellent HER activity was utilized as support and cocatalyst. FeP nanosheet with special Feδ+ and Pδ− active sites was conductive to mass transfer, fast charge transfer and facilitating water dissociation for generating OH species to removal CO-like intermediates on Pt sites. The XRD, XPS, SEM and TEM analysis demonstrated that the Pt nanoparticle with an average size of 3.68nm was successfully deposited on the FeP nanosheet surface. The methanol oxidation experiments in acidic medium revealed that the as-prepared binary Pt/FeP nanosheet hybrid exhibited superior MOR activity with enhanced anodic peak current density of 0.994mA/cm2, which was 2.74-fold greater than that of commercial Pt/C, and the intensive CO oxidation peak potential was negatively shifted about 100mV with respect to that of Pt/C. The better CO tolerance of Pt/FeP nanosheet hybrid might be attributed to cooperative effect from down-shifted d-band center of Pt, abundant hydroxyls on the Pt/FeP and special activity of Feδ+ and Pδ−. In addition, this hybrid electrocatalyst also showed relatively higher HER activity compared with that of Pt/C. This study provides a promising application of metal phosphide in methanol oxidation for enhancing CO resistance capability of Pt-based catalyst.

A high active hydrogen evolution reaction electrocatalyst from ionic liquids-originated cobalt phosphide/carbon nanotubes

Ionic liquid/carbon nanotubes (IL/CNTs) composite was applied as the precursor to prepare CNTs-supported cobalt phosphide via low-temperature phosphidation. CoP(MBMG)/CNTs, generated from N,N-bis(4-(methoxycarbonyl)benzyl)-N-methyl-d-glucaminium dibromodichlorocobaltate(II) (MBMG)2-CoCl2Br2), exhibits the best catalytic activity toward hydrogen evolution reaction with an onset overpotential of 55 mV, a Tafel slope of 58 mV dec−1, 95% Faradaic efficiency (FE), current densities of 10 and 20 mA cm−2 at overpotentials of 135 and 160 mV, and it can maintain the catalytic activity for at least 27 h. FT-IR, Raman spectroscopy, XPS and XRD were utilized to investigate the phosphidation process. All experimental results confirmed that anion from (MBMG)2-CoCl2Br2 can form CoP and glucaminium-based cation can become amorphous carbon after phosphidation to obtain the high HER activity of CoP(MBMG)/CNTs.

Vanadium sulfides interwoven nanoflowers based on in-situ sulfurization of vanadium oxides octahedron on nickel foam for efficient hydrogen evolution

Novel vanadium sulfides interwoven nanoflowers supported on nickel foam (VO-S/NF) has been synthesized through a facile two-step access. Firstly, octahedron-structured vanadium oxides as precursor were anchored on the surface of NF (VO/NF) by a hydrothermal process. Secondly, in-situ sulfurization in H2S gas has been applied to prepare VO-S/NF. XRD shows that VO-S/NF sample is composed of mixture phases including VS and Ni3S2, implying the interface effect between VS and Ni3S2. SEM images demonstrate that octahedron-structured VO from VO/NF changed to VO-S interwoven nanoflowers on VO-S/NF, which are composed of vertical interwoven nanosheets. It can enlarge surface area to expose abundant active sites and facilitate mass and charge transportation. The electrochemical measurements display the enhanced HER activity of VO-S/NF requiring an overpotential of 165mV to deliver 10mAcm−2, which may be ascribed to the novel structure of VS interwoven nanosheets and the synergistic effect between VS and Ni3S2. Furthermore, VO-S/NF remains high HER activity for at least 10h with excellent structural stability confirmed by post-HER characterization such as XRD, SEM and XPS. Therefore, it may provide a new way to design multiple transition metal sulfides-based electrocatalysts with unique nanostructure as well as interface effect for HER in alkaline.

In situ photodeposition of MoSx on CdS nanorods as a highly efficient cocatalyst for photocatalytic hydrogen production

In situ photodeposition of MoSx on CdS-nanorods for photocatalytic HER was achieved with (NH4)2MoS4 as a precursor. The optimal MoSx loading amount is 0.2 wt% and its performance is comparable to the well-known Pt cocatalyst. A junction in form of Cd–S–Mo bond was proposed to account for the higher HER activity.

High-efficiency electrochemical hydrogen evolution based on the intermetallic Pt2Si compound prepared by magnetron-sputtering

An intermetallic Pt2Si compound was prepared by magnetron sputtering, which exhibited higher HER activity than that of Pt in acidic solution.

Growth of MoSe2 nanosheets with small size and expanded spaces of (002) plane on the surfaces of porous N-doped carbon nanotubes for hydrogen production.

MoSe2 nanosheets with small size and expanded spaces between the (002) planes were grown on the surfaces of porous N-doped carbon nanotubes (NCNTs) with much higher HER activity than carbon nanotubes without N dopants. Owing to the synergistic effects between the MoSe2 nanosheets and the porous NCNT substrate, MoSe2/NCNTs exhibit superior HER activity to layered metal chalcogenides reported previously.

Ni–Cu nano-crystalline alloys for efficient electrochemical hydrogen production in acid water

The Ni–49%Cu nano-crystallins alloy showed higher HER activity than electrodeposited Ni because their nano-sized roughness results in a high surface area.

Exploration of the electrochemical mechanism of ultrasmall multiple phases molybdenum carbides nanocrystals for hydrogen evolution reaction

Ultrasmall multiple phases molybdenum carbides nanocrystals (down to 2.5 nm) on graphene support were synthesized by a simplein situmethod. These hybrids show extraordinary high HER activity in acid media.

Tunable and Specific Formation of C@NiCoP Peapods with Enhanced HER Activity and Lithium Storage Performance.

The superior properties of nanomaterials with a special structure can provide prospects for highly efficient water splitting and lithium storage. Herein, we fabricated a series of peapodlike C@Ni2-x Cox P (x≤1) nanocomposites by an anion-exchange pathway. The experimental results indicated that the HER activity of C@Ni2-x Cox P catalyst is strongly related to the Co/Ni ratio, and the C@NiCoP got the highest HER activity with low onset potential of ∼45 mV, small Tafel slope of ∼43 mV dec(-1) , large exchange current density of 0.21 mA cm(-2) , and high long-term durability (60 h) in 0.5 m H2 SO4 solutions. Equally importantly, as an anode electrode for lithium batteries, this peapodlike C@NiCoP nanocomposite gives excellent charge-discharge properties (e.g., specific capacity of 670 mAh g(-1) at 0.2 A g(-1) after 350 cycles, and a reversible capacity of 405 mAh g(-1) at a high current rate of 10 A g(-1) ). The outstanding performance of C@NiCoP in HER and LIBs could be attributed to the synergistic effect of the rational design of peapodlike nanostructures and the introduction of Co element.

Defect‐Rich CoP/Nitrogen‐Doped Carbon Composites Derived from a Metal–Organic Framework: High‐Performance Electrocatalysts for the Hydrogen Evolution Reaction

AbstractA defect‐rich CoP/nitrogen‐doped carbon composite is reported for the first time derived from ZIF‐67 by means of low‐temperature phosphidation process. As a hydrogen evolution reaction electrocatalyst, the obtained CoP‐N‐C has high HER activity and good stability with a low onset overpotential of 31 mV, a small Tafel slope of 42 mV dec−1, a large exchange current density of 1.6×10−1 mA cm−2, and a 10 mA cm−2 current density at overpotential 91 mV.

Enhanced hydrogen evolution reaction on few–layer MoS2 nanosheets–coated functionalized carbon nanotubes

The oxygen– or nitrogen–functionalized multiwalled carbon nanotubes (O– or N–MWCNT) coated with few–layer MoS2 nanosheets (MoS2/MWCNTs) were successfully synthesized by a facile hydrothermal method. The results suggest that the N–MWCNT is favorable for the dispersion of few–layer MoS2 nanosheets due to the strong interaction between the N-containing groups and Mo precursor. The N–MWCNT coated with few–layer MoS2 (MoS2/N–MWCNT) exhibits the highest HER activity: onset potential of 90 mV vs. reversible hydrogen electrode, Tafel slope of 40 mV dec−1, high current density of 80.3 mA cm−2 at overpotential 0.2 V, together with excellent stability during 10,000 cycles. Such high HER activity is superior to most of MoS2–based catalysts reported so far, and attributed to the intimate contacts between highly conductive network of N–MWCNT and thin MoS2 nanosheets, the high quantity of unsaturated sulfur atoms or the bridging S22−, and high pyridinic and graphitic N concentrations. This work shows that the few–layer MoS2 nanosheets coated on conductive N–doped MWCNT has a great potential for electrocatalytic hydrogen evolution.

Origin of hydrogen evolution activity on MS2 (M = Mo or Nb) monolayers

The Volmer reaction is thermodynamically governed by adiabatic electron and proton affinities, and the high HER activity of 2D MS2 monolayers comes from their large adiabatic electron affinities.