Efficient Electrochemical Hydrogen Evolution Research Articles

Rapid CO2 laser treatment of Pt–Fe MOF for efficient electrochemical hydrogen evolution reaction

The quest for efficient hydrogen production via electrochemical water splitting has led to extensive research on catalytic materials. This work focuses on enhancing the catalytic functionality of metal-organic frameworks (MOFs) by incorporating platinum (Pt) to improve the performance of the hydrogen evolution reaction (HER). Fe-based MOFs mixed with platinum precursors were altered through laser treatment, which caused considerable changes in their structure and catalytic activity in just 3 min. This was achieved without the need for vacuum or an inert atmosphere. Characterization techniques including X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and electrochemical measurements were used to characterize the synthesized materials. The laser-treated Pt–Fe MOF demonstrated outstanding HER performance with 3.5 wt% Pt content, outperforming commercial 20 wt% Pt/C catalysts, and exhibiting good stability even after prolonged cycling. These results highlight the potential of laser-treated MOFs for efficient and cost-effective electrochemical hydrogen generation.

NiS/Ni3S4 decorated double-layered hollow carbon spheres for efficient electrochemical hydrogen evolution reaction and supercapacitor

NiS/Ni3S4 anchored on the double-layer hollow carbon spheres (DLHCs@NixSy) were rationally conceived and synthesized via calcination and hydrothermal process. A series of characterization results confirmed nickel sulfide consisted of NiS and Ni2S3 phases formed. Double-layer hollow carbon spheres as substrates with good electrical conductivity, high specific surface area and hollow structure, not only serve as the active sites for nickel sulfide targeting and electron conduction, but also adapt to the volume change on cycling. Sample DLHCs@NixSy-1:2 prepared using optimized conditions exhibited enhanced electrochemical performance and energy storage in electrocatalytic hydrogen evolution and supercapacitor, respectively. The hybrid nanostructure just needed to afford the potential of 263 mV to reach the current density of 10 mA cm−2 without IR correction and delivered a high specific capacitance of 1160 F g−1 at a current density of 1 A g−1. Encouragingly, the asymmetric supercapacitor device created using DLHCs@NixSy-1:2 and active carbon exhibited a high energy density of 40 Wh/kg at 375 W/kg within the voltage window of 0–1.5 V. Furthermore, the device revealed preeminent cycling performance with a retention rate of 70 % after 2000 cycles at 4 A g−1. This result provided a reference for the synthesis of dual-functional materials with low cost and high efficiency.

Elucidating the performance of hexamethylene tetra-amine interlinked bimetallic NiCo-MOF for efficient electrochemical hydrogen and oxygen evolution.

Bimetallic metal-organic frameworks (MOFs) play a significant role in the electrocatalysis of water due to their large surface area and availability of increased numbers of pores. For the inaugural time, we examine the effectiveness of a hexamethylene tetra-amine (HMT)-induced 3D NiCo-MOF-based nanostructure as a potent bifunctional electrocatalyst with superior performance for overall water splitting in alkaline environments. The structural, morphological, and electrochemical properties of the as-synthesized bifunctional catalyst were examined thoroughly before analyzing its behavior towards electrochemical water splitting. The HMT-based NiCo-MOF demonstrated small overpotential values of 274 mV and 330 mV in reaching a maximum current density of 30 mA cm-2 for hydrogen and oxygen evolution mechanisms, respectively. The Tafel parameter also showed favorable HER/OER reaction kinetics, with slopes of 78 mV dec-1 and 86 mV dec-1 determined during the electrochemical evaluation. Remarkably, the NiCo-HMT electrode exhibited a double-layer capacitance of 4 mF cm-2 for hydrogen evolution and 23 mF cm-2 for oxygen evolution, while maintaining remarkable stability even after continuous operation for 20 hours. This research offers a valuable blueprint for implementing a cost-effective and durable MOF-based bifunctional catalytic system that has proven to be effective for complete water splitting. Decomposition of water under higher current densities is crucial for effective long-term generation and commercial consumption of hydrogen.

Defect-rich 1T-MoS2 nanosheets towards efficient electrochemical hydrogen evolution by simultaneous phase and defect engineering

Molybdenum sulfide (MoS2) has been considered as a promising candidate to replace Pt for the electrochemical hydrogen evolution reaction (HER). However, the disadvantages of inert basal planes and low conductivity limit its application in HER. Herein, we report a facile strategy to achieve simultaneous phase transition and defect engineering in MoS2 by adjusting the ratio of sulfur precursor to molybdenum precursor in the synthesis process. The excess thiourea are adsorbed on the surface of as-formed MoS2 nanocrystallites, which hinders the further crystallization process and creates a large amount of defects on the basal planes. Besides, ammonia ions could in situ insert into the interlayers of MoS2 and induce a phase transition from 2H–MoS2 to 1T-MoS2. The optimized defect-rich 1T-MoS2 catalyst shows a small overpotential of 232 mV at 10 mA cm−2 and Tafel slope of 61 mV dec−1 in acidic media. The superior HER activity is attributed to the defect-rich and 1T-phase structure, which contributes significantly enhanced electronic conductivity and greatly exposed active sites.

Highly Efficient Electrochemical Hydrogen Evolution with Ultra-Low Loading of Strongly Adhered Pt Nanoparticles on Carbon.

The development of robust electrocatalysts with low platinum content for acidic hydrogen evolution reaction (HER) is paramount for large scale commercialization of proton exchange membrane electrolyzers. Herein, a simple strategy is reported to synthesize a well anchored, low Pt containing Vulcan carbon catalyst using ZnO as a sacrificial template. Pt containing ZnO (PZ) is prepared by a simultaneous borohydride reduction. PZ is then loaded onto Vulcan carbon to produce a very low Pt content electrocatalyst, PZ@VC. PZ@VC with 2wt.% Pt shows excellent performance for acidic HER in comparison to the commercial Pt/C (20wt.%) catalyst. PZ@VC with a very low Pt loading shows significantly low η10 and η100 values (15 and 46mV, respectively). PZ@VC on coating with Nafion (PZ@VC-N) shows further improvement in its performance (η10 of 7mV, η100 of 28mV) with ≈300h of stability (≈10mA cm-2 ) with only 4 µgPt cm-2 . PZ@VC-N shows a record high mass activity of 71 A mgPt -1 (32 times larger than Pt/C (20 wt.%) at 50mV of overpotential. Post reaction characterizations reveal Pt nanoparticles are embedded onto VC with no traces of zinc, suggestive of a strong metal-support interaction leading to this high stability at low Pt loading.

Synthesis of NiMoO4/NiMo@NiS Nanorods for Efficient Hydrogen Evolution Reactions in Electrocatalysts.

As traditional energy structures transition to new sources, hydrogen is receiving significant research attention owing to its potential as a clean energy source. The most significant problem with electrochemical hydrogen evolution is the need for highly efficient catalysts to drive the overpotential required to generate hydrogen gas by electrolyzing water. Experiments have shown that the addition of appropriate materials can reduce the energy required for hydrogen production by electrolysis of water and enable it to play a greater catalytic role in these evolution reactions. Therefore, more complex material compositions are required to obtain these high-performance materials. This study investigates the preparation of hydrogen production catalysts for cathodes. First, rod-like NiMoO4/NiMo is grown on NF (Nickel Foam) using a hydrothermal method. This is used as a core framework, and it provides a higher specific surface area and electron transfer channels. Next, spherical NiS is generated on the NF/NiMo4/NiMo, thus ultimately achieving efficient electrochemical hydrogen evolution. The NF/NiMo4/NiMo@NiS material exhibits a remarkably low overpotential of only 36 mV for the hydrogen evolution reaction (HER) at a current density of 10 mA·cm-2 in a potassium hydroxide solution, indicating its potential use in energy-related applications for HER processes.

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

Heterostructured CNT-RuSx nanomaterials for efficient electrochemical hydrogen evolution reaction

Heterostructured CNT-RuSx nanomaterials have been prepared by a facile and straightforward in-situ construction strategy. The obtained CNT-RuSx with abundant C- S-Ru interfaces demonstrates excellent catalytic hydrogen evolution activity comparable to commercial Pt/C. To afford a current density of 10 mA/cm2, the required overpotential was only 17 mV with a smaller Tafel slope of 35 mV/dec in 1 M KOH. Meanwhile, the outstanding catalytic stability is also achieved on CNT-RuSx, no obviously degradation in performance during long-term electrolysis under basic conditions. Theoretical calculations show that the C-S-Ru interfaces will facilitate the dissociation of water and reduce the free energy of H adsorption, thereby leading to dramatically enhanced hydrogen evolution performance. This work provides a technical guidance for the rational design and synthesis of novel C-based commercial catalysts for renewable energy conversion systems.

Hydride-containing 2-Electron Pd/Cu Superatoms as Catalysts for Efficient Electrochemical Hydrogen Evolution.

The first hydride-containing 2-electron palladium/copper alloys, [PdHCu11 {S2 P(Oi Pr)2 }6 (C≡CPh)4 ] (PdHCu11 ) and [PdHCu12 {S2 P(Oi Pr)2 }5 {S2 PO(Oi Pr)} (C≡CPh)4 ] (PdHCu12 ), are synthesized from the reaction of [PdH2 Cu14 {S2 P(Oi Pr)2 }6 (C≡CPh)6 ] (PdH2 Cu14 ) with trifluoroacetic acid (TFA). X-ray diffraction reveals that the PdHCu11 and PdHCu12 kernels consist of a central PdH unit encapsulated within a vertex-missing Cu11 cuboctahedron and complete Cu12 cuboctahedron, respectively. DFT calculations indicate that both PdHCu11 and PdHCu12 can be considered as axially-distorted 2-electron superatoms. PdHCu11 shows excellent HER activity, unprecedented within metal nanoclusters, with an onset potential of -0.05 V (at 10 mA cm-2 ), a Tafel slope of 40 mV dec-1 , and consistent HER activity during 1000 cycles in 0.5 M H2 SO4 . Our study suggests that the accessible central Pd site is the key to HER activity and may provide guidelines for correlating catalyst structures and HER activity.

Hydride‐containing 2‐Electron Pd/Cu Superatoms as Catalysts for Efficient Electrochemical Hydrogen Evolution

AbstractThe first hydride‐containing 2‐electron palladium/copper alloys, [PdHCu11{S2P(OiPr)2}6(C≡CPh)4] (PdHCu11) and [PdHCu12{S2P(OiPr)2}5{S2PO(OiPr)} (C≡CPh)4] (PdHCu12), are synthesized from the reaction of [PdH2Cu14{S2P(OiPr)2}6(C≡CPh)6] (PdH2Cu14) with trifluoroacetic acid (TFA). X‐ray diffraction reveals that the PdHCu11 and PdHCu12 kernels consist of a central PdH unit encapsulated within a vertex‐missing Cu11 cuboctahedron and complete Cu12 cuboctahedron, respectively. DFT calculations indicate that both PdHCu11 and PdHCu12 can be considered as axially‐distorted 2‐electron superatoms. PdHCu11 shows excellent HER activity, unprecedented within metal nanoclusters, with an onset potential of −0.05 V (at 10 mA cm−2), a Tafel slope of 40 mV dec−1, and consistent HER activity during 1000 cycles in 0.5 M H2SO4. Our study suggests that the accessible central Pd site is the key to HER activity and may provide guidelines for correlating catalyst structures and HER activity.

Bimetallic sulfides arrays with three-dimensional nanostructure for efficient electrochemical hydrogen evolution

The efficient and low-cost electrocatalyst for hydrogen evolution reaction (HER) is highly desired to meet the practical needs in scalable production of hydrogen fuel. In this paper, we report a two-step strategy for fabrication of metallic sulfides supported on nanoporous NiFe alloy (S-np-Ni4.5Fe4.5(Al)). When served as an integrated hydrogen evolution cathode, the S-np-Ni4.5Fe4.5(Al) shows remarkable catalytic activity and superior stability in acidic medium, and it needs overpotentials of 81 and 202 mV to achieve current densities of 10 and 100 mA cm−2, respectively. This work offers an attractive way to construct low-cost and high-performance catalyst for large-scale water electrolysis.

High-valence metal doped Co2FeAl alloy as efficient noble-metal-free electrocatalyst for alkaline hydrogen evolution reaction

Most efficient electrochemical hydrogen evolution reaction (HER) catalysts in alkaline solutions are based on precious metals, whose rarity and high cost are severely limiting their large-scale applications. In this work, we synthesized Mo-doped and W-doped Co2FeAl alloys by a simple coprecipitation method. The HER in alkaline solution is promoted through the synergistic effect of thermal annealing and doping of high-valence metal atoms. Thermal annealing could optimize the surface morphology and improve the crystallinity. In the meantime, the doping of high-valence metal atoms could further regulate the crystal structure and electronic structure of alloys. Therefore, annealing temperatures and doping concentrations have a marked impact on the catalytic performance. In particular, when the Mo doping concentration is 27 at% and the annealing temperature is 750 ℃, the synthesized Co2FeAlMo1.5 (750 ℃) alloy electrocatalyst exhibits the superior HER performance in alkaline media. It displays a low overpotential of only 71 mV at 10 mA cm−2 and a Tafel slope of 110 mV dec−1. An excellent stability is also demonstrated that the electrocatalyst can work stably for 20 h and the overpotential is only shifted by 2 mV after 1000 cycles. A series of characterization tests indicate that the crystal structure and electronic structure of Co2FeAlMo1.5 (750 ℃) are optimized, which can improve the catalytic activity and promote alkaline HER. This work provides a new strategy for improving the catalytic performance of non-noble metal electrocatalysts for alkaline HER.

NiMoO4-CuO nanorod array as electrocatalysts for efficient electrochemical hydrogen evolution reactions

• The synthesis of NiMoO 4 -CuO /CF nanorods arrays is simple. • NiMoO 4 -CuO/CF has good HER activity and good stability. • The surface of NiMoO 4 -CuO/CF electrode has superhydrophilic and superaerophobic. • The formation process of bubbles on the electrode surface can be observed by CCD. Hydrogen is considered to be an energy source with a high potential to replace traditional fuels. Herein, NiMoO 4 -CuO nanorod arrays are constructed on copper foam (CF) substrate. Synergistic effect between NiMoO 4 and CuO can improve the electron transfer rate. Meanwhile, the superhydrophilic and superaerophobic structure of NiMoO 4 -CuO/CF promotes the diffusion of electrolyte and ensures the rapid release of bubbles. Therefore, only an overpotential of 59 mV is required to achieve the current density of 50 mA·cm −2 . At the current density of 50 mA·cm −2 for 24 h, the catalytic performance of the electrode has no obvious change, demonstrating that NiMoO 4 -CuO/CF electrocatalyst has outstanding stability, which provides a new pathway to synthesizing highly efficient HER electrocatalysts.

Optimizing the electronic structure of CoNx via coupling with N-doped carbon for efficient electrochemical hydrogen evolution

Transition metal nitrides (TMNs) have been regarded as an excellent class of electrocatalysts for hydrogen evolution reaction (HER), but there is still huge room for improvement. In this work, cobalt nitride (CoNx) coupled with N-doped carbon (NC) and supported by nickel foam (NF) is designed as an efficient HER electrocatalyst (NF/CoNx@NC). The introduction of NC can not only optimize the electronic structure of CoNx to boost the intrinsic activity, but also enhance the electronic conductivity and stability of the catalyst. As a result, NF/CoNx@NC exhibits excellent HER performance. On the one hand, it only needs an overpotential of 69 mV to deliver a current density of 20 mA cm−2 in 1.0 mol/L KOH, far better than that of CoNx (182 mV). On the other hand, the electronic conductivity and stability of the catalyst can be significantly enhanced after the introduction of NC. This work has done successful material design with the goal of enhancing the intrinsic activity, electronic conductivity, and stability, which has certain reference and guiding significance for the design of novel transition metal-based electrocatalysts.

Highly dispersed platinum deposited on nitrogen-doped vertical graphene array for efficient electrochemical hydrogen evolution

The electrochemical hydrogen evolution is a key technology for future renewable energy conversion and storage. Platinum is the most efficient catalyst for hydrogen evolution reaction (HER), but its mass activity should be boosted further. Herein, we deposited platinum on nitrogen-doped vertical graphene through an atomic layer deposition method. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy confirmed that the platinum was highly dispersed on the array substrate. On account of the array structure and high dispersion of platinum, the synthesized catalyst exhibited high HER performance with a low overpotential of 42 mV at 10 mA cm−2 and a low Tafel slope of 52.2 mV dec−1. Significantly, the synthesized catalyst exhibited a high mass activity of 4.45 A mg−1 Pt, which was ∼13 times higher than that of commercial Pt/C.

Rational design of NiFe alloys for efficient electrochemical hydrogen evolution reaction: effects of Ni/Fe molar ratios.

Developing and designing high-performance and stable NiFe electrodes for efficient hydrogen production are the greatest challenges in electrochemical water splitting. In this work, NiFe alloys with different Ni and Fe contents are prepared by a simple electrodeposition method using different molar ratios of Ni/Fe precursors (Ni/Fe; 1 : 3, 1 : 1 and 3 : 1). The obtained NiFe electrode with a molar ratio of 3 : 1 exhibited better electrocatalytic activity for the HER than the other NiFe electrodes with 1 : 3 and 1 : 1 molar ratios. The NiFe (Ni/Fe, 3 : 1) electrode required an overpotential of 133 mV to reach a current density of 10 mA cm-2, which was much lower than those of NiFe with molar ratio of 1 : 3 (220 mV), and 1 : 1 (365 mV), respectively. Tafel slope analyses demonstrated that the HER mechanism of NiFe alloy coatings followed the Volmer reaction type. The superior electrocatalytic performance of the NiFe alloy for HER depending on precursor molar ratio of Ni/Fe was attributed to their composition in terms of Ni and Fe content, structure and surface morphology. Specifically, the electrodeposition of the NiFe alloy was obtained in a molar ratio Ni/Fe, 3 : 1, and induced the formation of NiFe layered double hydroxide (LDH) with a nanosheet-array structure. The high electrocatalytic activity of NiFe LDH (Ni/Fe, 3 : 1) confirmed the critical influence of Ni and Fe contents in the alloy resulting in an increase the active surface on the surfaces, which is most likely explained by the higher surface roughness and the low crystallinity structure of NiFe nanosheet-array, supported by ECSA measurement, XRD, SEM and AFM analyses. The present strategy may open an avenue for developing cost-effective, stable and high-performance electrocatalysts as advanced electrodes for large-scale water splitting.

Recent advances in cobalt-based catalysts for efficient electrochemical hydrogen evolution: a review.

Hydrogen (H2) is a new type of renewable energy that can meet people's growing energy needs and is environmentally friendly. In order to improve the industrial application prospects and electrochemical performance of hydrogen evolution catalysts, extensive research on transition metal materials has been carried out. Among the many catalytic materials, cobalt is an element with potential for the hydrogen evolution reaction (HER) due to its abundant reserves, low cost, and small energy barrier for H adsorption. This review classifies the latest research on cobalt-based catalysts according to the types of compound, including cobalt-based sulfides, phosphides, carbides, borides, oxides, etc., and summarizes the latest research progress of cobalt-based compound catalysts in acidic and alkaline media. Strategies to tune the properties of cobalt-based compound catalysts for high catalytic activity for HER are focused on, including structural engineering, defect engineering, and doping, etc. The advantages and limitations of each modified approach are reviewed. Not only that, but also the catalytic activity and advantages of the catalyst are evaluated by using density functional theory (DFT) calculation-related descriptors, activity evaluation parameters, etc. Finally, limitations and challenges of cobalt-based materials for HER are presented, as well as prospects for future research. This paper aims to understand the chemical and physical factors that affect cobalt-based catalysts, and to find directions for future research on cobalt-based catalysts.

A high-density nickel-cobalt alloy embedded in nitrogen-doped carbon nanosheets for the hydrogen evolution reaction.

The development of novel non-noble electrocatalysts is critical for an efficient electrochemical hydrogen evolution reaction (HER). In this study, high-density nickel-cobalt alloy nanoparticles embedded in the bent nitrogen-doped carbon nanosheets are prepared as a high-performance catalyst. The optimized Ni7Co3/NC-500 catalyst displays quite a low overpotential of 90 mV at a current density of 10 mA cm-2, and a small Tafel slope of 64 mV dec-1 in alkaline medium, and even performs better than commercial 20% Pt/C at a high current density (η150 = 233 mV for Ni7Co3/NC-500 and η150 = 267 mV for 20% Pt/C). Specifically, the high-density nickel-cobalt alloy (with an average size of 6.2 nm and a distance of <3.0 nm) embedded in the bent carbon nanosheets provides plentiful active sites. Furthermore, in situ visualization of the produced hydrogen bubbles shows that the small size of hydrogen bubbles (d = 0.2 mm for Ni7Co3/NC-500 vs. d = 0.8 mm for 20% Pt/C) resulting from the small water contact angle and the bent nanosheet structure would inhibit the aggregation of H2 bubbles on the surface to facilitate efficient mass diffusion. Density functional theory calculations reveal that the formation of the nickel-cobalt alloy can effectively lower water dissociation energy barriers and optimize hydrogen adsorption Gibbs free energy, manifesting a high HER activity.

Synergistic effect in ultrafine PtNiP nanowires for highly efficient electrochemical hydrogen evolution in alkaline electrolyte

Platinum-based catalysts play an important role in electrochemical hydrogen evolution reaction, which is a renewable and clean way to produce H2. Herein, we have successfully synthesized the ultrafine PtNiP NWs with diameter less than 5 nm via a simple two-step hydrothermal reaction method. Impressively, the PtNiP NWs exhibit one of the best electrocatalytic activity toward HER under alkaline conditions, which can reach current density of 500 mA cm−2 only at the −0.153 V vs RHE with Tafel slop of only 30 mV dec−1. The DFT calculation results show synergistic effect of Pt, Ni and P atoms, where Ni atoms are conducive to the adsorption of H2O and P atoms are helpful for the dissociation of H2O, significantly improving kinetic processes of hydrogen evolution reaction. This work could be instructive and meaningful to design highly efficient and stable HER catalyst in alkaline condition for practical applications.

1 T-Phase Enriched P doped WS2 nanosphere for highly efficient electrochemical hydrogen evolution reaction

In recent years, great attention has been devoted to transition metal-based dichalcogenides (TMDs), in particular to the 1 T-phase enriched TMDs, which possess much higher hydrogen evolution reaction (HER) activity than the 2H-phase. Currently, how to prepare the stable metallic phase TMDs nanomaterials to achieve an endurable HER is one of the main challenges for practical applications. In this study, we present a reliable and tunable 1 T-phase TMDs-based synthetic strategy to atomically engineer non-metal doping sites onto metallic 1 T-WS2. Benefiting from engineering phosphorus atoms, the optimized electrocatalyst shows great enhancement in the HER. We reveal that P doped WS2 will produce 1 T-phase enriched WS2|P catalyst, which is beneficial to expose more active sites and improve the conductivity of the material. More interestingly, the HER activities of 1 T-WS2|P-5 electrocatalyst outperforms 2H-WS2, demonstrating a low overpotential (ηHER = 125 mV @ 10 mA cm−2), a small Tafel slope (HER = 73.73 mV dec−1), and significant durability under acidic conditions. Simultaneously, the 1 T-WS2|P-5 catalyst also presents an overpotential of 190 mV at 10 mA cm−2 and a low Tafel slope of 92.11 mV dec−1 under alkaline conditions. Moreover, the catalyst has excellent catalytic stability under acidic and alkaline conditions. We introduce the first example of 1 T phase enrichment P doped WS2 as a HER electrochemical catalyst, and this work is expected to open a new door for the discovery of other 1 T-phase TMDs as effective catalysts for renewable energy.