Pt-like Activity For Hydrogen Evolution Reaction Research Articles

Hydrogen Evolution in Neutral Media by Differential Intermediate Binding at Charge-Modulated Sites of a Bimetallic Alloy Electrocatalyst.

The energy barrier to dissociate neutral water has been lowered by the differential intermediate binding on the charge-modulated metal centers of Co85Mo15 sheets supported on Ni-foam (NF), where the overpotential for hydrogen evolution reaction (HER) in 1 M phosphate buffer solution (PBS) is only 50±9 mV at -10 mA cm-2. It has a turnover frequency (TOF) of 0.18 s-1, mass activity of 13.2 A g-1 at -200 mV vs. reversible hydrogen electrode (RHE), and produces 16 ml H2 h-1 at -300 mV vs. RHE, more than double that of 20 % Pt/C. The Moδ+ and Coδ- sites adsorb OH*, and H*, respectively, and the electron injection from Co to H-O-H cleaves the O-H bond to form the Mo-OH* intermediate. Operando spectral analyses indicate a weak H-bonded network for facilitating the H2O*/OH* transport, and a potential-induced reversal of the charge density from Co to the more electronegative Mo, because of the electron withdrawing Co-H* and Mo-OH* species. Co85Mo15/NF can also drive the complete electrolysis of neutral water at only 1.73 V (10 mA cm-2). In alkaline, and acidic media, it demonstrates a Pt-like HER activity, accomplishing -1000 mA cm-2 at overpotentials of 161±7, and 175±22 mV, respectively.

Nitrogen and Sulfur Co-Doped Carbon-Coated Ni3S2/MoO2 Nanowires as Bifunctional Catalysts for Alkaline Seawater Electrolysis.

Bifunctional catalysts have inherent advantages in simplifying electrolysis devices and reducing electrolysis costs. Developing efficient and stable bifunctional catalysts is of great significance for industrial hydrogen production. Herein, a bifunctional catalyst, composed of nitrogen and sulfur co-doped carbon-coated trinickel disulfide (Ni3S2)/molybdenum dioxide (MoO2) nanowires (NiMoS@NSC NWs), is developed for seawater electrolysis. The designed NiMoS@NSC exhibited high activity in alkaline electrolyte with only 52 and 191mV overpotential to attain 10mAcm-2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Significantly, the electrolyzer (NiMoS@NSC||NiMoS@NSC) based on this bifunctional catalyst drove 100mAcm-2 at only 1.71V along with a robust stability over 100h in alkaline seawater, which is superior to a platinum/nickel-iron layered double hydroxide couple (Pt||NiFe LDH). Theoretical calculations indicated that interfacial interactions between Ni3S2 and MoO2 rearranged the charge at interfaces and endowed Mo sites at the interfaces with Pt-like HER activity, while Ni sites on Ni3S2 surfaces at non-interfaces are the active centers for OER. Meanwhile, theoretical calculations and experimental results also demonstrated that interfacial interactions improved the electrical conductivity, boosting reaction kinetics for both HER and OER. This study presented a novel insight into the design of high-performance bifunctional electrocatalysts for seawater splitting.

Tetra-Coordinated W2 S3 for Efficient Dual-pH Hydrogen Production.

Two-dimensional (2D) transition-metal dichalcogenides (TMDs) have emerged as promising catalysts for the hydrogen evolution reaction (HER) that play a crucial role in renewable energy technologies. Breaking the inherent structural paradigm limitations of 2D TMDs is the key to exploring their fascinating physical and chemical properties, which is expected to develop a revolutionary HER catalyst. Herein, we unambiguously present metallic W2 S3 instead of energetically favorable WS2 via a unique stoichiometric growth strategy. Benefiting from the excellent conductivity and hydrophilicity of the tetra-coordinated structure, as well as an appropriate Gibbs free energy value and an enough low energy barrier for water dissociation, the W2 S3 as catalyst achieves Pt-like HER activity and high long-term stability in both acidic and alkaline electrolytes. For application in proton exchange membrane (PEM) and anion exchange membrane (AEM) electrolysers, W2 S3 as the cathode catalyst yields excellent bifunctionality index (ɳ =1.73 V, ɳ =1.77 V) and long-term stability (471 h@PEM with a decay rate of 85.7 μV h-1 , 360 h@AEM with a decay rate of 27.1 μV h-1 ). Our work provides significant insight into the tetra-coordinated W2 S3 and facilitates the development of advanced electrocatalysts for sustainable hydrogen production.

Boron doping activate strong metal-support interaction for electrocatalytic hydrogen evolution reaction in full pH range

Developing rhodium-based electrocatalysts with strong metal-support interaction (SMSI) is crucial for hydrogen evolution reaction (HER) in full pH range, but it is still challenging. In this work, a boron doping strategy is proposed to activate the SMSI of ultra-small Rh nanoparticles encapsulated by N-doped carbon matrix (B-Rh@NC). Density functional theory (DFT) reveals that boron doping can regulate the electronic structure and the water adsorption energy, further boosting the HER activity. Consequently, the as-prepared B-Rh@NC nanospheres possess Pt-like activity for HER with low overpotentials in 1.0 M KOH (η10 = 26 mV), 0.5 M H2SO4 (η10 = 43 mV), and 1.0 M PBS (η10 = 70 mV), as well as outstanding stability. This work opens up a new way to construct remarkable pH-universal electrocatalysts.

Efficient Hydrogen Evolution on Nanoscale Graphdiyne.

Self-active metal-free graphdiyne (GDY) is used, which has a precise chemical structure, as a model carbon-based metal-free electrocatalyst to assess its activity in the hydrogen evolution reaction (HER) and to understand the origin of electrocatalytic performance at the atomic level. The studies reveal that the unusual electrocatalytic properties of GDY originate from its unique nanostructure, which can simultaneously provide highly active sites for hydrogen adsorption and facilitate the electron-transfer process for proton reduction. Accordingly, GDY can act as a metal-free efficient HER electrocatalyst with Pt-like HER activity, but with long-term durability superior to that of Pt/C under the wide pH range (from acidic to basic). To the best of knowledge, such HER performance is better than that of other reported metal-free electrocatalysts and most transition-metal electrocatalysts-even Pt-based ones.

Interface construction of P-Substituted MoS2 as efficient and robust electrocatalyst for alkaline hydrogen evolution reaction

Molybdenum disulfide is known as a promising candidate for Pt-based catalysts in the hydrogen evolution reaction (HER), while the lack of the active-edge-site in-plane dominantly limits their intrinsic activity. Herein, a new strategy is reported to synthesize interface construction between MoS 2 and MoP, derived from the partial phosphidation of MoS 2 by incorporating P source (MoS 2 –MoP/NC). As a novel interface engineering electrode, MoS 2 –MoP/NC exhibits not only Pt-like catalytic activity but robust durability in alkaline electrolyte. Experiments and density functional theory (DFT) calculations certify that the formation of S vacancies on MoS 2 basal plane are facilitated by interlayer-interface construction between MoS 2 and MoP. Due to the delocalized electron inside S vacancies, the exposed coordination-unsaturated Mo atoms of S-defected MoS 2 offer active sites for water adsorption and activation, which accelerates the water dissociation steps. On the other hand, MoP provides active sites for hydrogen formation and desorption, which could weaken the adsorption strength of atomic hydrogen through van der Waals force of interlayer-interface. Our results show that the origin of the enhanced alkaline HER catalytic performance of MoS 2 –MoP/NC comes from the introduction of new active sites by interface construction, which provides an insight into the development of interlayer-interface engineering on MoS 2 . It is expected that this interface construction strategy can be extended to other 2D metal sulfides for enhancing their electrocatalytic activity. • An interface construction between MoS 2 and MoP (MoS 2 –MoP/NC) was synthesized for HER. • MoS 2 –MoP/NC exhibits Pt-like HER activity and robust durability in alkaline solution due to the interface effect. • The interface can introduce new active sites by creating S vacancies and exposing coordination-unsaturated Mo atoms. • Coordination-unsaturated Mo atoms can strength H 2 O adsorption and decrease H 2 O dissociation barrier. • MoP provides sites for hydrogen formation and desorption, promoted by weakening atomic hydrogen adsorption.

In situ electro-oxidation modulation of Ru(OH)x/Ag supported on nickel foam for efficient hydrogen evolution reaction in alkaline media

Transition metal hydroxides for hydrogen evolution reaction (HER) usually have been limited by poor intrinsic activity and weak conductivity. In our work, in situ electro-oxidation as an effective way has been used to modulate the electronic states of active sites for ruthenium hydroxides, which provides obviously enhanced activity for HER in alkaline media. Ag-modified nickel foam (NF) as substrate can provide the excellent conductivity to improve the charge transfer rate of Ru(OH)x/Ag/NF. In situ electro-oxidation process has been conducted for Ru(OH)x/Ag/NF through OER measurements in alkaline media, which results in the formation of more Ru (IV) as higher actives sites for HER. Compared to Ru(OH)x/NF, X-ray photoelectron spectroscopy (XPS) and polarization curves prove that Ag doping in Ru(OH)x/Ag/NF may contribute to the oxidization of ruthenium from Ru (III) to Ru (IV) during in situ electro-oxidation. The obtained Ru(OH)x/Ag/NF exhibits Pt-like HER activity with a very low overpotential of 103.2 mV to drive 100 mA cm−2 in 1.0 M KOH. The excellent stability of Ru(OH)x/Ag/NF has also been demonstrated. Therefore, our work provides a new strategy by modulating valence state of active sites for transition metal hydroxides for efficient HER.

Scalable Synthesis of Bimetallic Phosphide Decorated in Carbon Nanotube Network as Multifunctional Electrocatalyst for Water Splitting

It is challengeable to obtain a scalable method to synthesize nonprecious electrocatalysts with high efficiency and stability for overall water splitting, to replace the costly and scarce noble metal based electrocatalysts (e.g., Pt- and Ru-based materials). Herein, bimetallic (Fe, Co)P nanoparticles decorated in carbon nanotube network (FCP-CN) are synthesized through a facile and scalable spray drying and subsequent phosphorization process. The FCP-CN hybrid delivers excellent performance in hydrogen evolution reaction both in acidic and alkaline media, oxygen evolution reaction, and overall water splitting: it possesses an Pt-like hydrogen evolution reaction activity with an ultralow onset overpotential of 18 mV in acid; remarkably, it shows an ultrasmall Tafel slope of 38 mV dec–1 in oxygen evolution reaction; being employed as both cathode and anode, this catalyst demonstrates promising performance of overall water splitting with high long-term stability. The performance is superior among recently reported transition-metal-based catalysts for overall water splitting. This work provides a scalable and low-cost synthesis strategy to synthesize nonprecious and multifunctional transition-metal-based catalysts with unique nanoarchitecture and outstanding catalytic performance for water splitting.

Worm-like S-doped RhNi alloys as highly efficient electrocatalysts for hydrogen evolution reaction

Precious metals are considered as the most efficient electrocatalysts for boosting the dynamic process of cathode in water electrolysis devices. Due to the large surface areas and the low coordination numbers of surface atoms, their one-dimensional ultrafine nanowires and two-dimensional ultrathin nanosheets are continually being investigated, while stacking problems inevitably affect their activities and stabilities.We describe herein a three-dimensional metal network electrocatalyst consisting of a worm-like S-doped RhNi alloy (S-RhNi), which improves the performance for hydrogen evolution reaction (HER). Experimental results reveal that S-RhNi exhibits Pt-like HER activity with an onset potential close to 0 mV and a Tafel slope of 24.61 mV dec−1 in 0.5 M H2SO4 aqueous solution, having also good stability. The polarization curve shifts only 3.9 mV at a current density of −60 mA cm−2 after 1,000 cycles and the potential displays a slight change after holding the current density at −20 mA cm−2 for 10 h. This improved performance is supposed to be originated from the combination between the worm-like RhNi alloy, doped S atoms, and the three-dimensional structure. Overall, the results obtained and the facile synthesis methods offer a promising electrocatalyst for scaling-up hydrogen evolution.

Tunable Ag Micromorphologies Show High Activities for Electrochemical H2 Evolution and CO2 Electrochemical Reduction

Contaminate-free nanostructured Ag is prepared from electrochemical redox-treated Ag by two different potential pulses (DP and r-DP) in an NaBr aqueous solution. Agr-DP and AgDP from r-DP and DP, respectively, are easily tuned for their activities in the hydrogen evolution reaction (HER) favoring or selective CO2 reduction reaction (CO2RR). Agr-DP shows Pt-like HER activity in H2SO4 aqueous solution, and AgDP is capable of electrochemically reducing CO2 to CO with approximately 97.8% catalytic selectivity at a low overpotential of ∼0.25 V in NaHCO3 aqueous solution. The electrochemical signals for the first observed CO2•– intermediate adsorption (CO2ads•–) and HCO3– adsorption (HCO3–ads) in the selected NaClO4 aqueous solution were used to understand the possible role of HCO3– in CO2RR.

When NiO@Ni Meets WS2 Nanosheet Array: A Highly Efficient and Ultrastable Electrocatalyst for Overall Water Splitting.

The development of low-cost, high-efficiency, and stable bifunctional electrocatalysts toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of paramount importance for large-scale water splitting. Here, we develop a new strategy for the first design and synthesis of a NiO@Ni decorated WS2 nanosheet array on carbon cloth (NiO@Ni/WS2/CC) composite. This composite serves as a unique three-dimensional (3D) synergistic electrocatalyst that not only combines the intrinsic properties of individual NiO@Ni and WS2, but also exhibits significantly improved HER and OER activities when compared to that of pure NiO@Ni and WS2. This electrocatalyst possesses Pt-like activity for HER and exhibits better OER performance than that for commercial RuO2, as well as demonstrating superior long-term durability in alkaline media. Furthermore, it enables an alkaline electrolyzer with a current density of 10 mA cm–2 at a cell voltage as 1.42 V, which is the lowest one among all reported values to date. The excellent performance is mainly attributed to the unique 3D configuration and multicomponent synergies among NiO, Ni, and WS2. Our findings provide a new idea to design advanced bifunctional catalysts for water splitting.

RuP2 -Based Catalysts with Platinum-like Activity and Higher Durability for the Hydrogen Evolution Reaction at All pH Values.

Highly active, stable, and cheap Pt-free catalysts for the hydrogen evolution reaction (HER) are under increasing demand for future energy conversion systems. However, developing HER electrocatalysts with Pt-like activity that can function at all pH values still remains as a great challenge. Herein, based on our theoretical predictions, we design and synthesize a novel N,P dual-doped carbon-encapsulated ruthenium diphosphide (RuP2 @NPC) nanoparticle electrocatalyst for HER. Electrochemical tests reveal that, compared with the Pt/C catalyst, RuP2 @NPC not only has Pt-like HER activity with small overpotentials at 10 mA cm-2 (38 mV in 0.5 m H2 SO4 , 57 mV in 1.0 m PBS and 52 mV in 1.0 m KOH), but demonstrates superior stability at all pH values, as well as 100 % Faradaic yields. Therefore, this work adds to the growing family of transition-metal phosphides/heteroatom-doped carbon heterostructures with advanced performance in HER.

Pt-modified molybdenum carbide for the hydrogen evolution reaction: From model surfaces to powder electrocatalysts

This work explores the opportunity to substantially reduce the cost of hydrogen evolution reaction (HER) electrocatalysts by supporting one monolayer (ML) of platinum (Pt) on low-cost molybdenum carbide (Mo2C) substrate. These efforts were primarily directed towards scaling a thin-film catalyst to high surface area particles. Electrochemical experiments investigated single-phase Mo2C thin films modified by different coverages of Pt for the HER. The ML Pt–Mo2C thin film showed Pt-like HER activity while displaying excellent stability under HER conditions. The promising results on thin films were then extended to more practical powder catalysts. Samples of various Pt loadings on Mo2C powders were synthesized using the co-impregnation method and were evaluated for HER activity. The ability to successfully link electrochemical activity on thin films and powder catalysts was thus demonstrated.