Superior Hydrogen Evolution Reaction Activity Research Articles

Sulfur-Phosphorus Doped Metal Composites As Superior Catalyst for Electrolytic Hydrogen Production in Real Seawater

In the face of the increasingly severe global energy crisis and challenges posed by climate change, promoting energy transition has become an international consensus. Among various renewable energy sources, hydrogen is considered an ideal energy carrier due to its clean and efficient characteristics. The electrolysis of seawater for hydrogen production has garnered widespread attention for its ability to fully utilize abundant seawater resources and the advantage of zero carbon dioxide emissions. However, achieving efficient, stable, and economically viable hydrogen production in seawater still faces many challenges, with catalyst design and optimization being recognized as key issues.Firstly, NiFe-LDH was synthesized using a simple one-pot solvothermal method. Subsequently, phosphorization, sulfurization, and sulfur-phosphorus co-doping were conducted to obtain samples namely NiFe-P, NiFe-S and NiFe-SP, respectively. Various electrochemical tests, including hydrogen evolution reaction (HER), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were firstly performed in simulated seawater to evaluate the electrochemical performance of the synthesized catalysts. The overall seawater splitting reaction was conducted with the same catalysts for both anode and cathode sides.After comparing the electrochemical activity of four different catalysts, it was found that NiFe-SP performs superior HER activity in alkaline simulated seawater. NiFe-SP required merely -0.143 V to deliver 100 mA cm-2 current density, which was 95 mV lower than NiFe-LDH to achieve the same current density. In EIS tests, NiFe-SP exhibited a smaller charge transfer resistance than NiFe-LDH, and NiFe-SP had the largest double-layer capacitance (Cdl) value in ECSA measurements, indicating that NiFe-SP possessed and lowest reaction resistance and the maximum electrochemically active surface area.X-ray Diffraction (XRD) and Raman spectroscopy analyses indicate that the catalyst, after sulfur-phosphorus doping, does not exhibit a pure-phase LDH structure but transforms into a heterogeneous structure of Ni3S2 and FeS2. Scanning Electron Microscopy (SEM) observations suggest that sulfur-phosphorus co-doping causes the original spherical structure of NiFe-LDH to aggregate, with the appearance of some lamellar structures on the surface. Energy Dispersive Spectroscopy (EDS) also confirms the successful doping of sulfur and phosphorus elements into NiFe-LDH, with uniform distribution on the material's surface.Finally, the catalyst underwent a 2000-hours continuous stability test at a constant current of 100 mA cm-² in real seawater. The results indicate that the potential of NiFe-SP increased by only 5%, demonstrating that the doping of sulfur and phosphorus not only reduces the catalytic overpotential but also significantly sustains potential retention. This suggests that the metal composite structure obtained after sulfur-phosphorus co-doping is well-formed and stable. The systematic electrochemical tests and stability evaluation in this study highlights the potential of sulfur-phosphorus co-doped metal composite NiFe-SP as an efficient and stable catalyst for real seawater electrolysis. This not only contributes to a deeper understanding of the fundamental principles governing catalyst behavior but also opens new possibilities for the practical application of hydrogen production technology. Figure 1

Ru-doping W4.6N4 nanoparticles anchored on N-doped graphene tubes as efficient hydrogen evolution electrocatalyst

Designing efficient electrocatalysts for hydrogen evolution reaction (HER) is essential to facilitate hydrogen energy applications. Herein, efficient strategies of doping with metal atoms (Ru) and incorporating with conductive carbon-based material (N-doping graphene tubes) have been developed to construct the hybrid electrocatalyst RuW4.6N4@N-GTs, in which, Ru-doped W4.6N4 nanoparticles integrated on the surface of N-doped graphene tubes. RuW4.6N4@N-GTs reveals superior HER activity and good stability, with a low overpotential of 29 mV to deliver the current density of 10 mA cm−2 and a low Tafel slope of 57 mV dec−1. The unique 3D nano-structure morphology of abundant homogeneous RuW4.6N4 nanoparticles supported on conductive N-GTs network carrier contributes to expose more electrochemical active sites, promoting electrolyte transport and gas emission. At the same time, the N-GTs skeleton could prevent the RuW4.6N4 particles from agglomerating and collapsing, thus leading to the superior stability during HER process. The in situ Ru heteroatom doping could cause the directional electron transfer and more nitrogen vacancies, thus modulating the electron structure of catalysts and optimizing the hydrogen adsorption free energy. The synergistic effect of the above merits endows RuW4.6N4@N-GTs with outstanding HER performance for potential applications in the hydrogen production field.

Ring-shaped cavity anchor Pt to derive Pt/WO3-x heterointerfaces for efficient hydrogen evolution in acidic water and seawater

Developing novelplatinum (Pt)-based hydrogen evolution reaction (HER) catalysts with high activity and stability is significant for the ever-broader applications of hydrogen energy. However, achieving precise modulation of the ultrafine Pt nanoparticles coordination environment in conventional catalysts is challenging. In this work, we developed a unique “ring-shaped cavity induced” strategy to anchor the Ptx through the ring-shaped cavity of polyoxometalates (POMs) Na33H7P8W48O184 (denoted as P8W48). The NayPtx[P8W48O184] (PtxP8W48) was in-situ converted into abundant Pt/WO3-x heterostructure with Pt (∼2 nm) and highly depressed Pt-O-W heterointerfaces. Pt/WO3-x nanoparticles supported on highly conductive rGO exhibit superior HER activity. The overpotentials of the catalyst are only 2.8 mV and 4.7 mV at 10 mA·cm−2 in acidic water and seawater, far superior to commercial 20 % Pt/C catalyst. Additionally, the catalyst can be stabilized at a current density of 30 mA·cm−2 for 180 h. This study provides a feasible strategy for rational design of Pt-based catalysts for renewable energy applications.

Correlation between d Electrons and the Sweet Spot for the Hydrogen Evolution Reaction: Is Platinum Always the Best Electrocatalyst?

Herein, two Laves intermetallic series, ZrCo1.75M0.25 and NbCo1.75M0.25 (M = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt), were synthesized, and their hydrogen evolution reaction (HER) activities were examined to reveal the influence of d electrons to the corresponding HER activities. Owing to the different electronegativity between Zr and Nb (χZr = 1.33; χNb = 1.60), Co and/or M elements receive more electrons in ZrCo1.75M0.25 than that of the Nb one. This leads to the overall weak H adsorption energy (ΔGHad) of ZrCo1.75M0.25 series compared to that of NbCo1.75M0.25 and rationalizes well the superior HER activity of the Rh member compared to that of the Pt one in the ZrCo1.75M0.25 series. Under industrial conditions (333 K, 6.0 M KOH), ZrCo1.75Rh0.25 only requires an overpotential of 110 mV to reach the current density of 500 mA/cm2 and can be operated at high current density over 400 h. This work demonstrates that with a proper combination between elements in intermetallic phases, one can manipulate d electrons of the active metal to be closer to the sweet spot (ΔGHad = 0). The Pt member may no longer exhibit the best HER activity in series, and all elements exhibit the potential to outperform the Pt member in the HER with careful control of the d electron population.

Function‐Oriented Design of Amorphous MoS2 with Abundant Active Sites for High‐Efficiency Hydrogen Evolution Reaction

AbstractMolybdenum disulfide (MoS2) has received great interest as a highly active and cost‐effective electrocatalyst for hydrogen evolution reaction (HER). However, a main challenge for developing high‐efficiency electrocatalysts is to tailor the factors affecting the HER performance, such as composition, structure, and morphology. Herein, amorphous MoS2 electrodes with different Mo and S contents are successfully synthesized by the chemical bath deposition method using different molar ratios of Mo/S precursors (Mo/S: 4 : 1, 1 : 1 and 1 : 4) at various growth times. Experimental results indicate that the composition and the surface morphology of MoS2 are strongly sensitive to the Mo and S contents, which can create different surface roughness at the interface induced by growth times. The as‐prepared MoS2 electrode with a molar ratio of 1 : 4 exhibits superior HER activity in 1 M KOH, only requiring low overpotentials of 220 mV at 20 mA cm−2, which is much lower than those of MoS2 with a molar ratio of 1 : 1 (253 mV), and 4 : 1 (290 mV), respectively. This outstanding electrochemical performance of MoS2 (Mo/S, 1 : 4) with excellent long‐term stability can be attributed to its unique sulfur‐rich MoS2 nanosheet array structure with exposed abundant active sites, a high electrochemical active surface area (ECSA: 955.50 cm2) and superior roughness factor (RF: 3822).

Fabric-like rhodium-nickel-tungsten oxide nanosheets for highly-efficient electrocatalytic H2 generation in an alkaline electrolyte

Transition-metal based oxides with custom-designed phases are effective oxygen evolution reaction (OER) electrocatalysts. However, their applications in water splitting are limited because of insufficient catalytic performance in hydrogen evolution reaction (HER) in alkaline media. In this work, we engineer fabric-like rhodium-nickel-tungsten oxide nanosheets (Rh2O3-NiWO4) on plasma-treated nickel foam (PNF) with a one-step hydrothermal approach for potential applications as industry-grade HER electrocatalysts. Benefiting from rich active sites exposed on the heterostructure, low hydrogen binding energy on Rh, and enhanced charge delivery rates, Rh2O3-NiWO4/PNF catalyst exhibits superior HER activity than that achieved by a commercially available Pt/C catalyst. This is evidenced by the fact that the overpotentials of Rh2O3-NiWO4/PNF for delivering current densities of 10 (j10) and 1000 (j1000) mA cm−2 in 1.0 M KOH are merely 19 and 293 mV, respectively. Meanwhile, the small Tafel slope (18 mV dec−1) of the optimized catalyst manifests the fast HER kinetics. In addition, Rh2O3-NiWO4/PNF exhibits ultra-stable HER performance, and the current density (j100) only decrease 7.69 % after 100 h chronoamperometric curves (I-t) test. The present work provides a new approach for designing high-performance, low-cost 2D electrocatalysts for H2 production and other clean energy-related applications.

Multi‐Interface Engineering of Self‐Supported Nickel/Yttrium Oxide Electrode Enables Kinetically Accelerated and Ultra‐Stable Alkaline Hydrogen Evolution at Industrial‐Level Current Density

AbstractThe development of highly active and robust non‐noble‐metal electrocatalysts for alkaline hydrogen evolution reaction (HER) at industrial‐level current density is the key for industrialization of alkaline water electrolysis. Herein, a superhydrophilic self‐supported Ni/Y2O3 heterostructural electrocatalyst is constructed by a high‐temperature selective reduction method, which demonstrates excellent catalytic performance for alkaline HER at high current density. Concretely, this catalyst can drive 10 mA cm−2 at a low overpotential of 61.1 ± 3.7 mV, with a low Tafel slope of 52.8 mV dec−1. Moreover, it also shows outstanding long‐term durability at high current density of 1000 mA cm−2 for 500 h in 1 m KOH, evidently exceeding the metallic Ni and Pt/C(20%) catalysts. The superior HER activity can be attributed to the multi‐interface engineering of the Ni/Y2O3 electrode. Construction of Ni/Y2O3 heterogeneous interface with dual active sites lowers the energy barrier of water dissociation and optimizes the hydrogen adsorption energy, thus synergistically accelerating the overall HER kinetics. Also, its superhydrophilic self‐supported electrode structure with the firm electrocatalyst‐substrate interface and weakened electrocatalyst‐bubble interfacial force ensures rapid charge transfer, prevents catalyst shedding, and expedites the H2 gas bubble release timely, further enhancing the catalytic activity and stability at high current density.

Crystallinity and interfacial Mo–N–C bond engineered MoS2 embedded graphitic nitrogen doped carbon hollow sphere for enhanced HER activity

To restrain fossil fuel depletion, the need of the hour is the development of efficient, durable, and non-precious electrocatalysts for the hydrogen evolution reaction (HER). The hierarchical nanostructure consisting of transition metal dichalcogenides and graphitic heteroatom-doped carbon with an abundant interfacial M–N–C catalytic site is highly demanding for electrolytic applications. Herein, we report crystallinity-engineered ultrathin MoS2 nanosheets hierarchy over nitrogen-doped graphitic carbon (NC) hollow spheres as a promising material for HER. The well optimized NC@MoS2 demonstrates superior HER activity with a low onset overpotential of 9 mV and an overpotential of 145 mV at a current density of −10 mA cm−2. It exhibits low Tafel slope of 39 mV dec−1 and excellent chronoamperometric stability. Superior HER activity originates from interfacial Mo–N–C bonds. Density functional theory (DFT) calculations unveil that Mo–N–C bonds between MoS2 and NC matrix ease electronic transportation and further diminish Gibbs free energy for HER.

Insight into Controllable Metal-Support Interactions in Metal/Metal Electrocatalysts for Efficient Energy-Saving Hydrogen Production.

Controllable metal-support interaction (MSI) modulations have long been studied for improving the performance of catalysts supported on metal oxides. However, the corresponding in-depth study for metal1-metal2 (M1-M2) composited configurations is rarely achieved due to the lack of reliable models and manipulation mechanisms of MSI modifications. We modeled ruthenium on copper support (Ru-Cu) metal catalysts with negligible interfacial contact potential (e0.06 V) and investigated MSI-dependent hydrogen evolution reaction (HER) catalysis kinetics induced by an electronic hydroxyl (HO-) modifier. Comprehensive simulations and characterizations confirmed that adjusting the HO- coverage can readily realize the tailorable improvement of MSI, facilitating charge migration at the Ru-Cu interface and optimizing the overall HER pathway on active Ru. As a result, a 5/10 monolayer (ML) HO-modified catalyst (5/10 ML) exhibits superior HER activity and durability owing to the relatively stronger MSI. This catalyst also ensured sustainable and efficient hydrogen generation in a urea electrolyzer with significant energy savings. Our work provides a valuable reference for optimizing the MSI-activity relationship in M1-M2 catalysts that target more than just HER.

MoS2−x/GCD-MoS2−x nanostructures for tuning the overpotential of Volmer-Heyrovsky reaction of electrocatalytic hydrogen evolution

MoS2 nanostructures are famous electrocatalysts in hydrogen evolution reaction (HER). The presence of graphene was already reported to boost the electrocatalytic activity of MoS2. This work reports the influence of Sulphur deficiency and economically synthesizable green carbon dot (GCD) incorporation into hydrothermally synthesized MoS2 nanostructures on the electrocatalytic activity of HER. All as-synthesized nanocatalysts are Sulphur deficient (MoS2−x and GCD-MoS2−x) and exhibited superior HER activity as compared to commercial MoS2. MoS2−x 220 exhibited a Tafel slope of 43 mV/Dec indicates the reaction mechanism as Volmer-Heyrovsky with Heyrovsky as rate determining step. Best electrocatalytic parameters are observed for the same catalyst with overpotential: 247 mV at 10 mA/cm2, Turnover frequency: 0.42 s−1, double layer capacitance: 23.8 mF/cm2 and electrochemically active surface area: 595/cm2. The obtained preferable HER parameters suggest that Sulphur deficiency and incorporation of GCD in MoS2 are playing a vital role in HER electrocatalysis.

Interface regulation of Zr-MOF/Ni2P@nickel foam as high-efficient electrocatalyst for pH-universal hydrogen evolution reaction

Currently, the development of economical and effective non-noble metal electrocatalysts is vital for advancing hydrogen evolution reaction (HER) and enabling its widespread applications. The customizable pore structure and enormous surface area of metal–organic frameworks (MOFs) have made them to become promising non-noble metal electrocatalysts for HER. However, MOFs have some challenges, including low conductivity and instability, which can result in them having high overpotentials and slow reaction kinetics in electrocatalytic processes. In this work, we present an innovative approach for synthesizing cost-effective and high-efficient Zr-MOF-derived pH-universal electrocatalysts for HER. It entails creating the interfaces of the electrocatalysts with suitable proportions of phosphide nanostructures. Zr-MOF/Ni2P@nickel foam (NF) electrodes with interface regulated by Ni2P nanostructures were successfully developed for high-efficient pH-universal HER electrocatalysts. The presence of Ni2P nanostructures with abundant active sites at the Zr-MOFs@NF interfaces boosted the electronic conductivity and local charge density of the hybrid electrocatalysts. This helped to improve their reaction kinetics and electrocatalytic activity. By optimizing the Ni2P amount, Zr-MOF/Ni2P@NF demonstrated impressive stability and superior HER activities, with a low overpotential of 149 mV (acidic electrolytes) and 143 mV (alkaline electrolytes) at 10 mA cm−2. The proven strategy in this work can be expanded to many types of MOF-based materials for wider practical applications.

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.

Octahedral Pd3Cu7 Catalysts on Diverse Support Materials for Efficient Hydrogen Evolution: Theoretical Investigation and Mechanistic Perspective.

This work showcases a novel strategy for the synthesis of shape-dependent alloy nanostructures with the incorporation of solid substrates, leading to remarkable enhancements in the electrocatalytic performance. Herein, an aqueous medium approach has been used to synthesize an octahedral PdXCuY alloy of different Pd:Cu ratios to better comprehend their electrocatalytic potential. With the aim to outperform high activity and efficient stability, zirconium oxide (ZrO2), graphene oxide nanosheets (GONs), and hexagonal boron nitride nanosheets (hBNNs) solid substrates are occupied to decorate the optimized Pd3Cu7 catalyst with a minimum 5 wt % metal loading. When compared to the counterparts and different ratios, the Pd3Cu7@hBNNs catalyst exhibited an optimal activity for hydrogen evolution reaction (HER). The lower overpotential and Tafel values observed are 64 and 51 mV/dec for Pd3Cu7@hBNNs followed by Pd3Cu7@ZrO2, which showed a 171 mV overpotential and a 98 mV/dec Tafel value, respectively. Meanwhile, the Pd3Cu7@GONs were found to have a 202 mV overpotential and a 110 mV/dec Tafel value. The density functional theory, which achieves a lower free energy (ΔGH*) value for Pd3Cu7@hBNNs than the other catalysts for HER, further supports its excellent performance in achieving the Volmer-Heyrovsky mechanism path. Moreover, the superior HER activity and sturdier resilience after 8 h of stability may be due to the synergy between the metal atoms, monodisperse decoration, and the coordination effect of the support material.

Machine Learning for the Expedited Screening of Hydrogen Evolution Catalysts for Transition Metal-Doped Transition Metal Dichalcogenides

Two-dimensional transition metal dichalcogenides (TMDs) have gained attention as potent catalysts for the hydrogen evolution reaction (HER). The traditional trial-and-error methodology for catalyst development has proven inefficient due to its costly and time-intensive nature. To accelerate the catalyst development process, the Gibbs free energy of hydrogen adsorption ( Δ G H ∗ ), computed using the density functional theory (DFT), is widely used as the paramount descriptor for evaluating and predicting HER catalyst performance. However, DFT calculations for Δ G H ∗ are time-consuming and thus pose a challenge for high-throughput screening. Herein, we devise a predictive model for Δ G H ∗ within transition metal-doped TMD systems using a machine learning (ML) framework. We calculate DFT Δ G H ∗ values for 150 TM-doped MX2 (CrS2, MoS2, WS2, MoSe2, and MoTe2) and apply various ML algorithms. We validate the universality of our model by constructing 15 new external test sets. The prediction results show a high correlation coefficient of R 2 = 0.92 . Based on feature analysis, the three most important parameters are the number of valence electrons of the doped transition metal, the distance of the valence electrons of the doped transition metal, and the electronegativity of the doped transition metal. Our DFT-based ML model provides a useful guideline for the material development process through Δ G H ∗ prediction and facilitates the efficient design of transition metal dichalcogenide catalysts that exhibit superior HER activity.

Hydrogen spillover in MoOxRh hierarchical nanosheets boosts alkaline HER catalytic activity

The low intrinsic catalytic performance and stability are the two dominant obstacles for alkaline hydrogen evolution reaction (HER) electrocatalyst. Herein, amorphous molybdenum oxide (MoOx) has been introduced to rhodium hierarchical nanosheets (MoOxRh-HNS) at atomic level efficiently reducing the barrier for hydrogen spillover from Rh to MoOx; thereby, MoOxRh-HNS exhibit superior HER activity with mass activity of 23.9 A mgnoble metal−1 at overpotential of 200 mV, which is boosted by 10.8- and 14.9-fold with relative to Rh-HNS and Pt/C in alkaline media, respectively. Meanwhile, Tafel slope is as low as 22.5 mV dec−1 for MoOxRh-HNS revealing a hydrogen-spillover-involving HER mechanism proved by the electrochemical test as well as operando electrochemical impedance spectroscopy. Density functional theory calculation indicates the adsorbed hydrogen on MoOxRh promotes the water dissociation and balances the hydrogen binding strength to a moderate level. Simultaneously, the hierarchical nanosheet structure contributes a robust HER stability at 500 mA cm−2. This work offers a new methodology to construct a high-performance alkaline HER electrocatalyst with industrial-level current density.

Dual in-plane/out-of-plane Ni2P-BP/MoS2 Mott-Schottky heterostructure for highly efficient hydrogen production

A catalyst innovation with the aim of developing noble-metal-free substitutes is one key aspect for future sustainable hydrogen energy deployment. Herein, we fabricated a dual in-plane/out-of-plane Ni2P-black phosphorus (BP)/MoS2 heterostructure through an all-solution process for the hydrogen evolution reaction (HER). The covalently cross-connected MoS2 and metallic Ni2P-BP interfaces benefit the charge transfer in the electrochemical performances via the Mott-Schottky effect. For the HER, the Ni2P-BP/MoS2 heterostructure shows excellent catalytic activity with a low overpotential of 99 mV at 10 mA cm−2 and a small Tafel slope of 97 mV dec−1 in alkaline electrolyte. The first-principle calculations verify that the work function difference at the Mott-Schottky interface favors electron transfer from Ni2P-BP to outer-surface MoS2 to boost the HER process. Therefore, the Ni2P-BP/MoS2 heterostructure presents near-neutral hydrogen adsorption free energy (ΔGH*, −0.0287 eV), indicating superior HER activity beyond the counterparts (MoS2, BP, and Ni2P-BP). This work inspires possibilities for optimizing BP-based composites through multidimensional interface engineering with the goal of achieving highly efficient hydrogen production electrocatalysis.

Wet chemical synthesis of rhodium nanoparticles anchored on cobalt/nitrogen-doped carbon nanofibers for high-performance alkaline and acidic hydrogen evolution

Constructing high-activity electrocatalysts towards hydrogen evolution reaction (HER) is an essential way to achieve efficient, green and sustainable energy from water electrolysis. In this work, rhodium (Rh) nanoparticles anchored on cobalt (Co)/nitrogen (N)-doped carbon nanofibers (NCNFs) catalyst is prepared by the electrospinning-pyrolysis-reduction method. The synergy effect between Co-NCNFs and Rh nanoparticles contributes to the superior HER activity and favorable durability. The optimized 0.15Co-NCNFs-5Rh sample exhibits ultralow overpotentials of 13 and 18 mV to reach 10 mA cm−2 in an alkaline and acidic electrolyte, surpassing many Rh-based or Co-based electrocatalysts reported in the literature. Additionally, the Co-NCNFs-Rh sample shows a better HER activity than benchmark Pt/C catalyst in an alkaline medium at all current densities and in an acidic condition at higher current densities, offering its promising practical applications. Thus, this work provides an efficient methodology to construct high-performance HER electrocatalysts.

Engineering Mott–Schottky Heterojunction Auδ+/1T-MoS1.76 Electrocatalyst for Boosting Hydrogen Evolution Reaction

The hydrogen evolution reaction (HER) with MoS2 as the electrocatalyst typically suffers from its inert kinetics due to the unsuitable adsorption capability of MoS2 toward hydrogen. To address this issue, we herein successfully design and synthesize a Mott–Schottky (M–S) heterojunction Auδ+/MoS1.76 electrocatalyst by integrating interfacial chemistry, phase engineering, and S-vacancy implantation and demonstrate that Auδ+/MoS1.76 has superior HER activity and good stability with a low overpotential (∼90 mV) and a low Tafel slope (∼47 mV dec–1). Density functional theory calculation indicates that engineering of the Auδ+/MoS1.76 M–S interface can naturally endow MoS1.76 with more negative charges, effectively regulating the MoS2 electronic structure, stabilizing the 1T metallic phase, and optimizing Gibbs free energy of H adsorption. This work provides an alternative strategy to modify the electronic structure of transition-metal dichalcogenides and deepens our understanding of catalytic behavior of MoS2 toward HER.

Carbon nanotubes encapsulated transition metals for efficient hydrogen evolution reaction: coupling effect of 3d orbital and π-bond

Carbon materials are widely used in various industrial applications due to their outstanding stability and robustness in diverse structures, yet it remains a revolutionary and challenging task in activating low-cost carbon materials for efficient catalysis. Herein, inspired by the successful experimental synthesis, we for the first-time exploited carbon nanotubes (CNTs) encapsulated transition metal (TM) atoms (TM@CNTs) for hydrogen evolution reaction (HER) using density functional theory (DFT) calculations. The Gibbs free energy of the H–C bond on the pristine CNTs is too positive, which prevents the adsorption of H atoms. However, TM@CNTs (TM = Fe, Co, Ni) have superior HER activity than those widely recognized Pt and MoS2 catalysts, benefiting from disrupting the π conjugations and activating the stable sp2 hybridizations among carbon atoms in CNTs. A new set of metal-free catalytic surfaces with strong HER activity have been developed. Meanwhile, the HER activity of graphene nanosheets loaded on the most ubiquitous facet (111) of TMs (TM@G, TM = Fe, Co, Ni) was also calculated. However, TM@G shows inferior HER activity than that of TM@CNTs, which is attributed to the large curvature of CNTs. These new findings manifest a universal strategy for carbon materials activation that will inspire the rational design of carbon-based electrocatalysts for efficient water splitting reaction.

Nano-modulated synthesis of NiCoP nanosheets coated by NiCoP nanoparticles for efficient water splitting

BackgroundNiCo-based phosphides are given more concerns as superior hydrogen evolution reaction (HER) catalysts in electrolysis industrialization. Nevertheless, the single NiCo-based phosphides have finite active sites and electronic structures to limit their HER behaviors. MethodsNiCoP nanosheets anchored on Ni foam (NF) are first synthesized by hydrothermal reaction and phosphorization technique. Then, the NiCoP nanosheets are coated by the small size of NiCoP nanoparticles using the same methods to obtain NiCoP nanoparticles@NiCoP nanosheets (NiCoP NPs@NiCoP NSs/NF), which possess abundant active sites and strong electron structures. Significant findingsAs expected, the NiCoP NPs@NiCoP NSs/NF display superior HER activity (a small overpotential of 87 mV@50 mA·cm−2 and Tafel slope of 155 mV·dec−1) and durability in 1 M KOH solution at 313 K. In addition, an electrolytic cell is also assembled by applying NiCoP NPs@NiCoP NSs/NF as a cathode, and NiCo2Al-LDHs@ZnFeAl-LDHs/NF as an anode, which also exhibits admirable electrocatalytic behaviors. Hence, these results imply that NiCoP NPs decorated on the surface of NiCoP NSs play a significant role in regulating the electronic structure and boosting electrocatalytic active sites of NiCoP NPs@NiCoP NSs, which provides a possibility to achieve great application potential in the electrolytic water industry.