HER Electrocatalysts Research Articles

Graphene oxide supported transition metal mixed oxide nanourchins onto bimetallic phosphide coatings as high performance hydrogen evolution electrodes in alkaline media

Recently, electrocatalyst with high reactivity and stability towards hydrogen evolution reactions are necessary for large scale high purity hydrogen production to resist upcoming energy crisis. The transition metal mixed oxide based HER electrocatalyst are promising candidates for hydrogen generation in renewable energy field due to their low-cost nature, ease of commercialization and green nature. Herein, graphene oxide supported MnO2-TiO2 nanourchins synthesized by thermal decomposition technique was incorporated to bimetallic phosphide ENCP coatings by electroless plating technique. During alkaline hydrogen evolution, the incorporation of composite onto bimetallic phosphide causes a drastic decreases in overpotential value to 190 mV dec−1 and respective Tafel slope value to 45 mV dec−1. The studies reveals that the modified electrode follows Volmer–Heyrovsky mechanism. The lower Rct of 140.8 Ω and a high Cdl value obtained from Nyquist plot of modified electrodes ensures the fastest electron transfer kinetics and confirms its more facile electrocatalytic nature towards hydrogen evolution. Also, a high value for exchange current density of modified electrode authenticate its superior HER performance. The modified electrodes was durable, long term stable, economically viable and performance was consistent over a wide span of time during alkaline hydrogen evolution reaction. The enhanced performance of modified electrode can be ascribed to the intermetallic synergetic effect arises within ENCP matrix and MnO2-TiO2 nanourchins. These conclusions lead to innovative insights on future perspective for the development and tuning of novel electrocatalysts with enhanced electrochemical performance for hydrogen evolution reaction.

Single‐Atom Co‐Decorated MoS2 Nanosheets Assembled on Metal Nitride Nanorod Arrays as an Efficient Bifunctional Electrocatalyst for pH‐Universal Water Splitting

AbstractThe commercialization of electrochemical water splitting technology requires electrocatalysts that are cost‐effective, highly efficient, and stable. Herein, an advanced bifunctional electrocatalyst based on single‐atom Co‐decorated MoS2 nanosheets grown on 3D titanium nitride (TiN) nanorod arrays (CoSAs‐MoS2/TiN NRs) has been developed for overall water splitting in pH‐universal electrolytes. When applied as a self‐standing cathodic electrode, the CoSAs‐MoS2/TiN NRs requires overpotentials of 187.5, 131.9, and 203.4 mV to reach a HER current density of 10 mA cm–2 in acidic, alkaline, and neutral conditions, respectively, which are superior to the most previously reported non‐noble metal HER electrocatalysts at the same current density. The CoSAs‐MoS2/TiN NRs anodic electrode also shows low OER overpotentials of 454.9, 340.6, and 508.0 mV, respectively, at a current density of 10 mA cm–2 in acidic, alkaline, and neutral mediums, markedly outperforming current OER catalysts reported elsewhere. More importantly, an electrolyzer delivered from the cathodic and anodic CoSAs‐MoS2/TiN NRs electrodes exhibits an extraordinary overall water splitting performance with good stability and durability in pH‐universal conditions.

Boosting electrocatalytic activity toward alkaline hydrogen evolution by strongly coupled ternary Ni3S4/Ni/Ni(OH)2 hybrid

Higher water dissociation barrier for Volmer step in alkaline hydrogen evolution greatly impedes its commercialization. In view of appropriate hydrogen binding strength on metallic Ni and promoted Volmer step on Ni(OH)2 as well as potential impact of Ni3S4 on Ni/Ni(OH)2, Ni3S4/Ni/Ni(OH)2 on Ti mesh (TM) is prepared rapidly by a simple one-pot electrodeposition. The sample prepared under 0.2 M Ni(NO3)2, 1.5 M thiourea and applied potential of -1.0 V (denoted as Ni3S4/Ni/Ni(OH)2/TM-0.2) exhibits excellent HER activity with overpotential (η) of 54 mV at -10 mA/cm2 and Tafel slope of 70 mV/dec, exceeding most of transitional metal-based electrocatalysts. The superior HER activity and long-term durability can be ascribed to strong synergistic effect and coupling effect between Ni3S4, Ni and Ni(OH)2. This work gives a simple and fast synthetic strategy for depositing highly active ternary Ni3S4/Ni/Ni(OH)2 hybrid HER electrocatalyst on conductive substrate surface, which is suitable for large-scale production.

Rapid and facile laser-assistant preparation of Ru-ZIF-67-derived CoRu nanoalloy@N-doped graphene for electrocatalytic hydrogen evolution reaction at all pH values

High temperature pyrolysis needs complicated and harsh preparative condition, such as inert gas protection, long reaction time and high pyrolysis temperature. This work reported that a cobalt-ruthenium nanoalloy coated with nitrogen- doped graphene (CoRu@NG-x) was rapidly prepared from Ru-ZIF-67 as precursors by laser engraving in air environment and at room temperature for the first time. The addition of a small amount of ruthenium in cobalt can further improve the hydrogen catalytic performance. CoRu@NG-3 (Ru, 0.18wt%) is an efficient HER electrocatalyst in a wide pH range. Compared with the reported ruthenium alloys, the content of ruthenium in CoRu@NG-3 is the lowest. It's worth noting that the optimal CoRu@NG-3 shows overpotentials of 62, 52 and 88 mV at the current density of 10 mA cm−2 in 1.0 M KOH, 0.5 M H2SO4 and 1.0 M PBS solution for HER catalysis. CoRu@NG-3 also has a good stability under all pH conditions. This study may offer a novel strategy to rapidly prepare electrode materials at room temperature and in the air.

Multi-Phase Heterostructure of CoNiP/Cox P for Enhanced Hydrogen Evolution Under Alkaline and Seawater Conditions by Promoting H2 O Dissociation.

Hydrogen evolution reaction (HER) is a key step for electrochemical energy conversion and storage. Developing well defined nanostructures as noble-metal-free electrocatalysts for HER is promising for the application of hydrogen technology. Herein, it is reported that 3D porous hierarchical CoNiP/Cox P multi-phase heterostructure on Ni foam via an electrodeposition method followed by phosphorization exhibits ultra-highly catalytic activity for HER. The optimized CoNiP/Cox P multi-phase heterostructure achieves an excellent HER performance with an ultralow overpotential of 36mV at 10mA cm-2 , superior to commercial Pt/C. Importantly, the multi-phase heterostructure shows exceptional stability as confirmed by the long-term potential cycles (30,000 cycles) and extended electrocatalysis (up to 500 h) in alkaline solution and natural seawater. Experimental characterizations and DFT calculations demonstrate that the strong electronic interaction at the heterointerface of CoNiP/CoP is achieved via the electron transfer from CoNiP to the heterointerface, which directly promotes the dissociation of water at heterointerface and desorption of hydrogen on CoNiP. These findings may provide deep understanding on the HER mechanism of heterostructure electrocatalysts and guidance on the design of earth-abundant, cost-effective electrocatalysts with superior HER activity for practical applications.

Metal–organic framework-derived Ni doped Co3S4 hierarchical nanosheets as a monolithic electrocatalyst for highly efficient hydrogen evolution reaction in alkaline solution

High density of active sites and promoted mass transfer offered by hierarchical nanosheet structure as well as the good electrical conductivity and modified electronic structure caused by Ni doping collectively enhanced the alkaline HER performance of Ni doped Co 3 S 4 HNS grown in Ti mesh. Hierarchical nanostructure construction and electronic structure engineering are commonly employed to increase the electrocatalytic activity of HER electrocatalysts. Herein, Ni doped Co 3 S 4 hierarchical nanosheets on Ti mesh (Ni doped Co 3 S 4 HNS/TM) were successfully prepared by using metal organic framework (MOF) as precursor which was synthesized under ambient condition. Characterization results confirmed this structure and Ni incorporation into Co 3 S 4 lattice as well as the modified electronic structure of Co 3 S 4 by Ni doping. Alkaline HER performance showed that Ni doped Co 3 S 4 HNS/TM presented outstanding HER activity with 173 mV overpotential at −10 mA·cm −2 , surpassing most of metal sulfide-based electrocatalysts. The hierarchical structure, superior electrical conductivity and electronic structure modulation contributed to the accelerated water dissociation and enhanced intrinsic activity. This work provides a new avenue for synthesizing hierarchical nanostructure and simultaneously tuning the electronic structure to promote HER performance, which has potential application in designing highly efficient and cost-effective HER nanostructured electrocatalyst.

A 3D binder-free AgNWs@NiMo/PU electrode for efficient hydrogen evolution reaction

Developing stable and efficient electrocatalysts for hydrogen evolution reaction is of great significance for the production of clean hydrogen energy from water splitting. In this work, 3D [email protected]/PU electrode was obtained by electrodepositing NiMo alloy onto three-dimensional silver nanowires conductive substrate (3D AgNWs/PU) which was uniformly assembled on the surface of the skeleton of a polyurethane sponge (PU). 3D AgNWs/PU provides good electrolyte permeability, rich active site attachment points, good electronic conductivity and electrocatalytic synergy, which greatly improves the catalytic activity. In addition, 3D [email protected]/PU electrode does not need to use adhesive in the process of hydrogen evolution, which can improve the hydrogen evolution performance and stability of the electrode. Specifically, the optimized electrode ([email protected]/PU-1200 s) exhibits excellent hydrogen evolution performance by achieving a low overpotential of 32 mV (vs. RHE) at a current density of 10 mA cm−2, with a Tafel slope of 72 mV dec-1 (in 1 M KOH). More interestingly, it also has good stability after 10 h of stability test. Therefore, this study provides a feasible way to develop stable and efficient 3D HER electrocatalysts.

One Step Hydrothermal Synthesis of Ni-MoS2-RGO Bifunctional Electrocatalysts for HER and OER

One Step Hydrothermal Synthesis of Ni-MoS2-RGO Bifunctional Electrocatalysts for HER and OER

Green electroless plating of cuprous oxide nanoparticles onto carbon nanotubes as efficient electrocatalysts for hydrogen evolution reaction

Cuprous oxide (Cu2O) nanoparticles supported on pristine carbon nanotubes (Cu2O/CNTs) were synthesized by a facile and green electroless plating method, in which glucose replaced formaldehyde as the reducing agent. The as-prepared Cu2O/CNTs nanocomposite materials as electrocatalysts exhibited remarkable electrocatalytic activity towards hydrogen evolution reaction in alkaline solution, with an overpotential of 101 mV at −10 mA cm−2 and a Tafel slope of 88 mV dec−1. In addition, Cu2O/CNTs electrocatalysts maintained high electrocatalytic activity after the accelerated durability tests in 0.1 M KOH. All these results indicated Cu2O/CNTs can be utilized as efficient HER electrocatalysts for water splitting.

Hierarchical Co and Nb dual-doped MoS2 nanosheets shelled micro-TiO2 hollow spheres as effective multifunctional electrocatalysts for HER, OER, and ORR

Abstract Heteroatom doping engineering has emerged as an intriguing strategy to enhance electrocatalytic efficiency. Herein, a multiple transition metal doping approach is developed through the incorporation of both Co and Nb into hierarchical MoS2 ultrathin nanosheets directly grown on micro-TiO2 hollow spheres (Co,Nb-MoS2/TiO2 HSs) to boost the hydrogen evolution (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). The Co and Nb dual-doping effects modify the electronic structure of the host MoS2 towards maximizing the HER, OER, and ORR performance. Additionally, the unique hollow spherical structure and heterostructured synergistic effects between the TiO2 core and MoS2 shell provide effective channels for electron transfer and large surface area with abundant exposed void spaces for ion diffusion/penetration. Therefore, the Co,Nb-MoS2/TiO2 HSs catalyst demonstrates extraordinary activity and stability with small overpotentials of 58.8 and 260.0 mV at 10 mA cm−2 for the HER and OER, respectively. When employed as both cathodic and anodic electrode in an electrolyzer, the catalyst requires an operating voltage of 1.57 V to achieve 10 mA cm−2. The catalyst also exhibits great potential for the ORR with high onset potential of + 0.96 V and half-wave potential of +0.87 V, as well as direct four-electron transfer process.

One-step construction of Co2P nanoparticles encapsulated in N, P co-doped biomass-based porous carbon as bifunctional efficient electrocatalysts for overall water splitting

The graphic shows a core-shell Co2P nanoparticles as bifunctional electrocatalyst for HER and OER. The collaborative effect between NPPC and Co2P can improve the charge transfer rate and further enhanced catalytic activity.

Crystalline porphyrin-based graphdiyne for electrochemical hydrogen and oxygen evolution reactions

Co-Loaded porphyrin-graphdiyne (CoPor-GDY) as a bifunctional electrocatalyst for HER and OER.

Copper catalysts for photo- and electro-catalytic hydrogen production

Square planar1, square pyramidal2and trigonal bipyramidal3copper complexes are poor catalysts for hydrogen evolution (HER) under photocatalytic conditions, whereas1is, or forms, a good and enduring electrocatalyst for HER, but2and3do not.

Shape-selective rhodium nano-huddles on DNA for high efficiency hydrogen evolution reaction in acidic medium

Cost-effective Rh NPs have been synthesized over a DNA scaffold which acts as an effective electrocatalyst for HER in acidic medium. DNA stabilized Rh NPs during synthesis and also acts as a stable binder with minimum loading for electrocatalysis.

NiSe/Ni3Se2 on nickel foam as an ultra-high-rate HER electrocatalyst: common anion heterostructure with built-in electric field and efficient interfacial charge transfer.

One grand challenge in green hydrogen production is to design efficient HER electrocatalysts for high-rate alkaline water electrolysis. Nickel chalcogenide coatings on nickel foam (NF) are promising HER electrocatalysts, but their high-rate performances are yet to be improved. The current work reports a NiSe/Ni3Se2@NF for alkaline HER, which requires an overpotential of only 336 mV to achieve an ultra-high current density of 1250 mA cm−2, outperforming commercial Pt/C. The low onset potential of NiSe/Ni3Se2@NF is attributed to its morphology, and high surface area, as well as multiple active sites and electronic structure modulation because of the heterostructure. While these features are well-known within the current knowledge framework, new understandings are proposed on its superior high-rate performance. The common-anion feature offers abundant interfacial Ni–Se bonding and low resistance for efficient interfacial charge transfer, whereas the heterovalent-Ni-cation in the heterostructure results in a built-in electric field that further enhances the high-rate performance. This work provides new insights on both the mechanistic and methodological aspects of designing high-performance electrocatalysts operating at high current densities.

"Superaerophobic" NiCo bimetallic phosphides for highly efficient hydrogen evolution reaction electrocatalysts.

A "superaerophobic" NiCo bimetallic phosphide electrocatalyst has been fabricated by employing bimetal-organic frameworks as self-sacrificing templates. An overpotential of only 205 mV can drive the HER current density to 800 mA cm-2, which is even superior to that for Pt/C. This study provides a promising approach for the development of industrialized HER electrocatalysts.

Ru@N/S/TiO2/rGO: a high performance HER electrocatalyst prepared by dye-sensitization.

Hydrogen production from water-splitting is one of the most promising hydrogen production methods, and the preparation of the hydrogen evolution reaction (HER) catalyst is very important. Although Pt-based materials have the best catalytic activity for HER, their high price and scarcity greatly limit their large-scale industrial application prospects. Herein, a new method to prepare HER catalyst is described, where dyes used in dye-sensitized solar cells (DSSCs) were used as precursors. A high performance HER catalyst (Ru@N/S/TiO2/rGO, Ru nanoparticles (NPs) supported on N/S-doped TiO2/rGO hybrids) was prepared, and the stereoscopic molecular structure of the porphyrin dye, JR1, not only provides a prerequisite for the preparation of the hyperdispersed Ru NPs, but also successfully realizes N/S co-doping. The Ru@N/S/TiO2/rGO shows an excellent catalytic performance for the HER, which is almost the same as that with Pt/C. In 0.5 M H2SO4, the overpotential is 60 mV at 10 mA cm-2, and the Tafel slope is only 51 mV dec-1. In 1 M KOH, the overpotential is only 5 mV at 10 mA cm-2, and the Tafel slope is only 45 mV dec-1, and this performance is much better than most of the HER catalysts that have been reported. When Ru@N/S/TiO2/rGO is utilized as a catalyst in an alkaline water electrolyzer, a bias of only 1.52 V is able to complement overall water-splitting at 10 mA cm-2 (1.78 V, 100 mA cm-2). The molecular structure and coordination metal species of the dyes are easy to adjust, and the the stereoscopic structure is very helpful for inhibiting the aggregation of the metal NPs, and the strong anchoring effect with TiO2 or other carbon materials is also very helpful to achieve heteroatom doping. In addition, the process of dye-sensitization is simple and repeatable, and is a novel and efficient method to prepare the electrocatalyst.

Synergistically enhanced alkaline hydrogen evolution reaction by coupling CoFe layered double hydroxide with NiMoO4 prepared by two-step electrodeposition

The optimized CoFe LDH/NiMoO4/Cu NW/Cu foam as HER electrocatalyst presents promising application prospect in water splitting with ultralow overpotential of 45 mV at -10 mA/cm2 and long-term durability.

Ruthenium nanoparticles supported on S-doped graphene as an efficient HER electrocatalyst

An efficient HER catalyst was prepared by doping graphene and wrapping ruthenium nanoparticles, and its performance is comparable to that of commercial Pt/C.

Advanced hydrogen evolution electrocatalysts promising sustainable hydrogen and chlor-alkali co-production

The joint development of electrocatalytic hydrogen evolution and the chlor-alkali industry are proposed clearly for the first time, and the recent progress of HER electrocatalysts and engineering issues in this field have been reviewed.