Enhanced Hydrogen Evolution Reaction Research Articles

Low Zn-doped Co3O4 nanorods for enhanced hydrogen evolution reaction

Transition metal oxides have been identified as the best potential candidates to replace Pt-based HER catalysts. But they are still limited by the high HER overpotential, due to the undesirable adsorption/desorption of surface hydrogen. In this work, Zn with low concentrations were incorporated into the tetrahedral Co2+ sites of Co3O4 by hydrothermal and subsequent annealing treatment. They exhibit excellent HER performance. Particularly, when the Zn content in Co3O4 is 6.3 at%, an overpotential of 79.2 mV at the current density of 10 mA cm−2 was obtained in alkaline medium, which significantly better than pure Co3O4 catalyst (196.3 mV). Moreover, the current density of the Zn-doped Co3O4 catalyst can maintained 93 % after 10 h and 80 % after 20 h. DFT calculations reveal that the ΔGH* of Zn-doped Co3O4 (0.827 eV) is smaller and closer to zero than pure Co3O4 (1.023 eV). This work provides a deep insight into the rational design of low-level metal-doped cobalt oxide-based electrocatalysts.

Rapid Joule heating fabrication of Ru cluster-loaded WO3 on carbon nanotubes to enhance alkaline electrocatalytic hydrogen production activity

The design of efficient electrocatalysts for hydrogen evolution reaction (HER) suitable for industrial applications remains a challenging task. In this work, Ru clusters were loaded onto WO3 which were grown on carbon nanotubes (WRu/C-JH) using a rapid Joule heating method. The crystal phases of WO3 was transformed, and abundant active sites were exposed during the rapid heating and cooling process. All these modifications contributed to the greatly improved electrocatalytic activity in HER. As tested, in 1 M KOH, it only required an overpotential of 22 mV to reach 10 mA cm−2 and 401 mV to reach a high current density of 1 A cm−2 on WRu/C-JH. Moreover, WRu/C-JH demonstrated excellent stability at 500 mA cm−2 for 100 h. Furthermore, a two-electrode system was constructed to assess overall water splitting performance of WRu/C-JH. This system was capable of reaching 100 mA cm−2 at a low voltage of 1.94 V. The mechanism of the enhancement in HER for as-prepared sample was also deeply discussed.

Atomic Layer Engineering of Pd Nanosheets for an Enhanced Hydrogen Evolution Reaction.

Thickness control of two-dimensional (2D) metal nanosheets (metallenes) has scientific significance for energy and catalyst applications, yet is unexplored owing to the lack of an efficient approach for the tailored synthesis of metallenes with controlled atomic layers. Here we report a 2D template-directed synthesis of ultrathin Pd nanosheets with well-controlled thicknesses. Molecularly thin single-crystalline Pd nanosheets with well-defined hexagonal morphologies were synthesized via a one-pot method with 2,4,6-trichlorophenyl formate. Such Pd nanosheets were used as hard templates for the tailored synthesis of the Pd nanosheets with controlled thicknesses (9, 11, 13, and 15 atomic layers). Hard X-ray photoelectron spectroscopy and density functional theory calculations revealed unique electronic states in thickness-controlled Pd nanosheets; these states included reduced surface charges to bulk, increased work functions, and decreased d-band centers. Thus, atomic layer engineering of Pd nanosheets enabled the fine-tuning of the surface electronic states to improve the hydrogen evolution reaction.

Electrodeposition of FeNiCoCrMn high-entropy alloys on copper foam for enhanced hydrogen evolution reaction——influence of additives and deposition potential

High-entropy alloys (HEAs) have been paid attention for their exceptional material properties. FeNiCoCrMn HEAs electrocatalysts were synthesized on copper foam by electrodeposition. The effects of deposition potential and additives on the surface morphology and crystal structure of the catalysts were investigated, and their hydrogen evolution reaction (HER) performance in 1.0 M KOH solution was studied. The high deposition potential enhanced nucleation, leading to intricate structural formations, while CTAB and citrate additives notably altered the surface texture of the catalysts, affecting HER activity. Notably, Fe0.19Ni0.24Co0.29Cr0.18Mn0.1 electrocatalyst with a low Tafel slope of 84.7 mV dec−1 showed good HER activity, only required the overpotential of 191 mV to achieve a current density of 10 mA cm−2.

Regulating the electronic structure of Pt SAs-Ni2P for enhanced hydrogen evolution reaction

The single atom catalysts (SACs) show immense promise as catalytic materials. By doping the single atoms (SAs) of precious metals onto substrates, the atomic utilization of these metals can be maximized, thereby reducing catalyst costs. The electronic structure of precious metal SAs is significantly influenced by compositions of doped substrates. Therefore, optimizing the electronic structure through appropriate doping of substrates can further enhance catalytic activity. Here, Pt single atoms (Pt SAs) are doped onto transition metal sulfide substrate NiS2 (Pt SAs-NiS2) and phosphide substrate Ni2P (Pt SAs-Ni2P) to design and prepare catalysts. Compared to the Pt SAs-NiS2 catalyst, the Pt SAs-Ni2P catalyst exhibits better hydrogen evolution catalytic performance and stability. Under 1 M KOH conditions, the hydrogen evolution mass activity current density of the Pt SAs-Ni2P catalyst reaches 0.225 A mgPt–1 at 50 mV, which is 33 times higher than that of commercial Pt/C catalysts. It requires only 44.9 mV to achieve a current density of 10 mA cm−2. In contrast, for the Pt SAs-NiS2 catalyst, the hydrogen evolution mass activity current density is 0.178 A mgPt–1, requiring 77.8 mV to achieve a current density of 10 mA cm−2. Theoretical calculations indicate that in Pt SAs-Ni2P, the interaction between Pt SAs and the Ni2P substrate causes the Pt d-band center to shift downward, enhancing the H2O desorption and providing optimal H binding sites. Additionally, the hollow octahedral morphology of Ni2P provides a larger surface area, exposing more reactive sites and improving reaction kinetics. This study presents an effective pathway for preparing high-performance hydrogen evolution electrocatalysts by selecting appropriate doped substrates to control the electronic structure of Pt SAs.

Antimony-assisted controlled growth of PtSe2 ribbon arrays for enhanced hydrogen evolution reaction

In this study, we report the successful synthesis of few-layer parallel PtSe2 ribbons on an Au foil employing a surface melting strategy via the chemical vapor deposition growth method at 650 °C. The controlled formation of parallel ribbons was directed by the Au steps generated through antimony treatment. These ribbons exhibit an average length of exceeding 100 μm and a width of approximately 100 nm across a substantial area. Electrocatalysis measurements showcase the catalytic performance of PtSe2 ribbons grown on Au foil, which can be further augmented through subsequent oxidation treatment. This investigation introduces an effective growth method for few-layer ribbons at low temperatures and broadens the scope of employing the substrate-guided strategies for the synthesis of one-dimensional materials. Additionally, it underscores the potential of PtSe2 ribbons as an electrocatalyst for hydrogen evolution.

Enhanced hydrogen evolution reaction activity through samarium-doped nickel phosphide (Ni2P) electrocatalyst

Hydrogen evolution reaction (HER) stands out among conventional hydrogen production processes by featuring excellent advantages. However, the uncompetitive production cost due to the low energy efficiency has hindered its development, necessitating the introduction of cost-effective electrocatalysts. In this study, we introduced samarium doping as a high-potential approach to improve the electrocatalytic properties of nickel phosphide (Ni2P) for efficient HER. Samarium-doped Ni2P was synthesized via a facile two-step vapor–solid reaction technique. Different physical and electrochemical analyses showed that samarium doping significantly improved pure Ni2P characteristics, such as particle size, specific surface area, electrochemical hydrogen adsorption, intrinsic activity, electrochemical active surface area, and charge transfer ability in favor of HER. Namely, Ni2P doped with 3%mol of samarium (Sm0.03Ni2P) with a Tafel slope of 67.8 mV/dec. and overpotential of 130.6 mV at a current density of 10 mA/cm2 in 1.0 M KOH solution exhibited a notable performance, suggesting Sm0.03Ni2P and samarium doping as a remarkable electrocatalyst and promising promoter for efficient HER process, respectively.

3D Nickel–Manganese bimetallic electrocatalysts for an enhanced hydrogen evolution reaction performance in simulated seawater/alkaline natural seawater

In this paper, we report an inexpensive one-step synthesis of self-supported 3D nickel-manganese (NiMn) bimetallic coatings and their application for the hydrogen evolution reaction in simulated seawater (1 M KOH + 0.5 M NaCl) and alkaline natural seawater (1 M KOH + natural seawater). These binary coatings were electrodeposited on a titanium substrate using a facile electrochemical deposition method by a dynamic hydrogen bubble template technique. The as-deposited NiMn coatings with variable Mn amounts produce typical globular and unique porous architecture with abundant pores of different sizes. The activity of these fabricated catalysts towards the hydrogen evolution reaction was investigated by linear sweep voltammetry towards simulated seawater and alkaline natural seawater at different temperatures. The surface morphology and composition of the catalysts were also characterized by scanning electron microscopy and inductively coupled plasma optical emission spectroscopy. The as-prepared NiMn/Ti electrocatalyst, which was electrodeposited using a chemical bath containing Ni2+ and Mn2+ ions with a molar ratio of Ni2+:Mn2+ = 1:5, exhibits excellent hydrogen evolution activity in simulated seawater with an ultra-low overpotential of 64.2 mV to reach a current density of 10 mA cm−2. It is noteworthy that this NiMn/Ti electrocatalyst also achieves a current density of 10 mA cm−2 in alkaline natural seawater with a comparably low overpotential of 79.3 mV. The current densities increase by ca. 1.75–2.35 times with an increase in temperature from 25 °C to 75 °C for hydrogen evolution in both electrolytes. This bimetallic catalyst has shown excellent long-term stability at a constant potential of −0.23 V (vs. RHE) and a constant current density of 10 mA cm−2 for 10 h, which ensures higher durability and robustness for practical application of seawater splitting technology.

The impact of sodium lauryl sulfate on hydrogen evolution reaction in water electrolysis

This study confirms the sodium lauryl sulfate (SLS) surfactant is effective to enhance water electrolysis performance especially when combined with NaCl. The water electrolysis experiment on different concentrations of SLS and SLS-NaCl mixture electrolyte were performed. The results indicate the presence of NaCl is more effective to enhance the SLS containing electrolyte performance instead of adding more SLS concentration. More SLS concentration is effective to enhance hydrogen evolution reaction (HER) when NaCl is added. The effectiveness of NaCl is shown by the order of final HER SLS 0.5 M + NaCl 3.9212 × 10−7 Mol. L−1, SLS 0.3 M + NaCl 3.8789 × 10−7 Mol. L−1, and, SLS 0.5 M 3.6758 × 10−7 Mol. L−1. The SLS creates positively charged micelles which increases ion mobility and HER. The NaCl accelerates the HER due to the formation of smaller ion clusters that react more quickly with the cathode. Therefore, this study reveals the mechanism of electrolysis enhancement by surfactant mixed electrolyte.

A highly efficient and self-supporting nanoporous FeMoC catalyst for enhanced hydrogen evolution reaction

Optimizing structure and surface morphologies in electrocatalyst design are important to enhance the intrinsic activity of the hydrogen evolution reaction (HER). Mo-based phosphides and carbides have been confirmed as the widely-reported catalysts for HER. However, the origin of their enhanced catalytic activity is not fully clarified. Herein, the np-FeMoC and np-FeMoP with a self-supporting nanoporous structure were prepared using the melt-spinning and dealloying methods. Benefiting from the self-supporting electrode, nanoporous structure, abundant active species, low charge-transfer resistance and electron synergy, the np-FeMoC exhibits good catalytic performance. The np-FeMoC performs a low overpotential of 50.8 mV at 10 mA cm−2 current density for HER in 1 M KOH. This value is 2.7 times lower than that of the np-FeMoP sample, indicating a synergistic effect between Mo2C and Fe. From XPS and in-situ Raman results, it was observed that the dissolution of Mo2C occurs accompanied by dynamic evolution during the HER process on the np-FeMoC surface. This work unveils the intrinsic activity of Mo-based carbide and phosphide, providing valuable guidance for reasonable exploit of high-performance HER catalysts.

Synthesis of Fe2O3 Nanorod and NiFe2O4 Nanoparticle Composites on Expired Cotton Fiber Cloth for Enhanced Hydrogen Evolution Reaction.

The design of cheap, noble-metal-free, and efficient electrocatalysts for an enhanced hydrogen evolution reaction (HER) to produce hydrogen gas as an energy source from water splitting is an ideal approach. Herein, we report the synthesis of Fe2O3 nanorods-NiFe2O4 nanoparticles on cotton fiber cloth (Fe2O3-NiFe2O4/CF) at a low temperature as an efficient electrocatalyst for HERs. Among the as-prepared samples, the optimal Fe2O3-NiFe2O4/CF-3 electrocatalyst exhibits good HER performance with an overpotential of 127 mV at a current density of 10 mA cm-2, small Tafel slope of 44.9 mV dec-1, and good stability in 1 M KOH alkaline solution. The synergistic effect between Fe2O3 nanorods and NiFe2O4 nanoparticles of the heterojunction composite at the heterointerface is mainly responsible for improved HER performance. The CF is an effective substrate for the growth of the Fe2O3-NiFe2O4 nanocomposite and provides conductive channels for the active materials' HER process.

NiCo2S4 nanotubes in situ anchored double-layered hollow carbon nanospheres towards enhanced overall water splitting

An efficient approach is developed to fabricate hybrid nanomaterials by anchoring in situ NiCo2S4 components on hollow double-layered carbon nanospheres (DCs). NiCo(CO3)(OH)2 is deposited on DCs and then reacted with S ions to create NiCo2S4 phase. Because of the homogeneous distribution of nanoparticles and well-developed interface, samples reveal excellent electrochemical activity. The compositions of NiCo2S4/hollow DCs (denoted as DCs-x-y, x and y are the molar ratios of Ni and Co in precursors) are adjusted to test the growth kinetics and morphology evolution. Under optimized conditions, the capabilities of composite sample DCs-0.20–0.30 outperform DCs and NiCo2S4 alone, which is ascribed to the high specific surface area and the existence of monodispersed hollow carbon spheres improving the distribution of NiCo2S4 and the overall conductivity to increase active sites. Especially, the optimized sample DCs-0.20–0.30 exhibits high performances and stability for enhanced hydrogen evolution reaction (HER) in both acidic and alkaline conditions and oxidation evolution reaction (OER) in alkaline electrolyte. Furthermore, using DCs-0.20–0.30 sample as both the cathode and anode in the alkaline electrolyzer, the current density of 10 and 100 mA cm−2 at 1.736 and 2.171 V are obtained. The sample also displays excellent durability for 20 h at 10 mA cm−2.

Facile synthesis of MoSe2 embedded in La2O3 crystal for enhancing hydrogen evolution reaction

ABSTRACT Molybdenum diselenide (MoSe2) is a potential catalyst for the electrocatalytic hydrogen evolution reaction (HER). However, MoSe2 exhibits a high overpotential in HER due to its low density of active sites, which may limit its practical applicability. Tuning the assisted metal interaction is an effective method for altering the atomic structure and catalytic efficiency of transition metal catalysts. Herein, we report a simple hydrothermal process for synthesising hybrid MoSe2-La2O3 heterostructures for HER. The electrocatalytic HER of nanoflower MoSe2 was improved in the presence of a supported lanthanide-oxide interaction (La2O3), proving that La2O3 materials produce additional activity sites in the MoSe2 materials. The nanocomposite was drop-cast onto screen-printed carbon electrodes (SPCE) and showed reduced overpotential values compared to pristine MoSe2 and La2O3 materials. Across all ratios tested, the MoSe2-La2O3 (M-L2) nanocomposites with a molar ratio of 1:2 exhibit rapid charge transfer during HER performance, with a Tafel slope value of 66 mV/dec and an onsetpotential of 270 mV.

Double loading of nickel phosphide surface for efficient hydrogen evolution reaction

Metal phosphide, as a highly conductive, chemically stable catalyst material, modulating its hydrogen adsorption is crucial to enhance hydrogen evolution reaction (HER) activity. In this study, we propose a double loading strategy to build Ag and AgP2 heterogeneous structures on Ni2P nanosheets (Ag-AgP2/Ni2P). This is the first application of AgP2 materials in HER. This innovative synthesis was achieved by liquid-phase adsorption of precursors and heat-treatment phosphorization, surface adsorbed AgNO3 is converted to Ag-AgP2 double loading at the same time as Ni2P formation. Density functional theory (DFT) calculations reveal that the double loading structure optimizes charge distribution and d-band center. Its hydrogen adsorption free energy is closer to electroneutrality than that of single loading and simple heterostructures. Benefiting from the special structure, Ag-AgP2/Ni2P exhibits excellent HER performance in alkaline media, requiring only 78 mV overpotential to reach 10 mA cm−2 and stability up to 200 h. This dual loading strategy broadens the perspective of heterogeneous electrocatalyst development.

Engineering bimetallic single-atom catalysts utilizing the reducibility of HxMoO3 for high efficiency hydrogen evolution

Bimetallic single-atom catalysts have garnered substantial interest due to their extraordinary catalytic prowess, which arises from atomic-level synergistic effects that can significantly enhance hydrogen evolution reaction (HER) kinetics beyond the capabilities of monometallic single-atom catalysts. However, the fabrication of bimetallic single-atom catalysts remains a tremendous challenge. Herein, we introduce an in-situ reduction method to fabricate bimetallic single-atom catalysts anchored on hydrogenated molybdenum trioxide (HxMoO3, 0 < x ≤ 2). Intriguingly, HxMoO3 exhibits inherent reducing capabilities that facilitate the in-situ reduction of some metal ions to metallic single atoms in steps on its surface, thereby enabling the constructing of bimetallic single-atom structures. As a testament to this strategy, the prepared PtM/HxMoO3 catalysts (M = Ag, Au, Pd, Rh) with ultra-low noble metal loadings (wt% < 1%) on the nano-HxMoO3 support exhibit remarkable efficiency in HER. Outperforming both monometallic single-atom catalysts (M/HxMoO3) and commercial Pt/C, these catalysts demonstrate enhanced HER performance, and the PtPd/HxMoO3 exhibits outstanding performance with an overpotentials of 10 mV at 10 mA/cm2, Tafel slope of 36 mV/dec, and long-term durability in acidic media. The presence of Pt single-atom significantly enhances the electrochemical surface area (ECSA) and accelerates the kinetics of the HER for other metal single atoms.

Formation of ferromagnetic Fe5Se8 via phase transition and enhanced hydrogen evolution reaction with alternating magnetic fields

Leveraging alternating magnetic fields (AMFs) to induce localized heating in catalysts has emerged as a powerful approach to boost electrocatalytic reactions. However, the rational design and synthesis of ferromagnetic catalysts that can be stably coupled with an AMF to improve the hydrogen evolution reaction (HER) performance are still urgent and challenging. Herein, the ferromagnetic triclinic Fe5Se8 has been realized through the phase transition from nonmagnetic orthorhombic FeSe2 synergistically triggered by the selenium vacancies and the strain engineering, making it a good candidate for AMFs-assisted HER. Experimental results and theoretical calculation demonstrate that the phase transition-prepared ferromagnetic Fe5Se8 exhibits much better HER performance than nonmagnetic FeSe2. More importantly, under high-frequency AMF stimulation, the HER performance of ferromagnetic Fe5Se8 is greatly enhanced (the overpotential decreased by 63 mV), which is mainly attributed to the localized magnetic heating effect. This study realizes the controlled phase transition synthesis of ferromagnetic catalysts, indicating that AMF is an effective approach to manipulate the performance of ferromagnetic catalysts.

Unveiling Hydrogen Passivation Effects in TiC-Based Single-Atom Catalysts for Enhanced Hydrogen Evolution Reaction

Unveiling Hydrogen Passivation Effects in TiC-Based Single-Atom Catalysts for Enhanced Hydrogen Evolution Reaction

Metal-support interface engineering for stable and enhanced hydrogen evolution reaction

Hydrogen has emerged as a green and sustainable pathway towards achieving global decarbonization and net-zero emissions, intensely driving the need for efficient hydrogen production protocols. Electrocatalytic hydrogen evolution reaction (HER) holds great potential as a scalable, eco-friendly and safe avenue for efficient hydrogen production. However, the large-scale implementation of electrocatalytic HER is substantially challenged by the high-cost and unstable materials that are mainly fabricated from noble metals, e.g., Pt and Pd. Given this challenge, we adopted an interface engineering strategy to immobilize nanoscale Pt particles within the framework of nitrogen-doped CNTs, namely Pt@N-CNTs, where electronic metal-support interaction (EMSI) plays an important role in enabling orbital rehybridization and regulating the charge transfer through the metal-support interface, thereby considerably improving the electrocatalytic activity. With limited content of noble metals, our developed Pt@N-CNTs delivered superior HER performance with an ultralow overpotential of 5.8 mV at 10 mA cm−2 and demonstrated a high mass activity of 12.72 A mgPt−1 at an overpotential of 50 mV as well as excellent stability under harsh acidic conditions. At 500 mA cm−2, Pt@N-CNTs surprisingly exhibited an overpotential of 55.2 mV, outperforming that of commercial 20 wt% Pt/C catalysts (131.5 mV). Importantly, we established a straightforward, scalable, and time-saving microwave reduction strategy, alluding to its promising commercial viability. This work therefore sheds light on the development of high-performance electrocatalysts for hydrogen evolution and water electrolysis.

Revealing Hydrogen Spillover on 1T/2H MoS2 Heterostructures for an Enhanced Hydrogen Evolution Reaction by Scanning Electrochemical Microscopy.

The in situ characterization of the heterostructure active sites during the hydrogen evolution reaction (HER) process and the direct elucidation of the corresponding catalytic structure-activity relationships are essential for understanding the catalytic mechanism and designing catalysts with optimized activity. Hence, exploring the underlying reasons behind the exceptional catalytic performance necessitates a detailed analysis. Herein, we employed scanning electrochemical microscopy (SECM) to in situ image the topography and local electrocatalytic activity of 1T/2H MoS2 heterostructures on mixed-phase molybdenum disulfide (MoS2) with 20 nm spatial resolution. Our measurements provide direct data about HER activity, enabling us to differentiate the superior catalytic performance of 1T/2H MoS2 heterostructures compared to other active sites on the MoS2 surface. Combining this spatially resolved electrochemical information with density functional theory calculations and numerical simulations enables us to reveal the existence of hydrogen spillover from the 1T MoS2 surface to 1T/2H MoS2 heterostructures. Furthermore, it has been verified that hydrogen spillover can significantly enhance the electrocatalytic activity of the heterostructures, in addition to its strong electronic interaction. This study not only contributes to the future investigation of electrochemical processes at nanoscale active sites on structurally complex electrocatalysts but also provides new design strategies for improving the catalytic activity of 2D electrocatalysts.

Strain regulation of bond length in single Ru sites via curving support surface for enhanced hydrogen evolution reaction

The intrinsic activity of single-atom catalysts is influenced by the local electronic structures of metal centers, with existing modulation strategies limited to adjacent atomic coordination. However, the impacts of support surface geometry on local bonding environment, and thus electronic structures of single-atom centers have rarely been known. Here, we prepared highly curved B,N co-doped carbon-supported ruthenium catalyst with an ultra-low Ru loading of 0.4 wt%, which exhibited an ultrahigh turnover frequency (TOF) of 10 H2 s−1 (38 times that of Pt/C) and superior stability in alkaline hydrogen evolution reaction (HER). We found that curving support surface induced the strain, resulting in 1.5% compressed Ru-N and 4% stretched Ru-B bonds, leading to the accumulation of positive charge and quenching of spin polarization at Ru sites, thereby achieving the optimal binding of H* and enhanced performance for HER. This work highlights the significant support effects upon the structural design of active sites.