Stability For Hydrogen Evolution Reaction Research Articles

A novel CoxNi1-xP/fs-Si self-supporting electrodes manufactured via femtosecond laser for highly efficient hydrogen evolution reaction

The direct growth of catalysts on three-dimensional self-supporting substrates is the trend of choice for the industrialization of water splitting. Although a large number of catalysts have been reported every year, there are only a handful of self-supporting substrates available for researchers to choose from. In this work, we introduce femtosecond laser micro-nano processing technology to fabricate a novel acid-resistant silicon substrate with super-hydrophilic and super-aerophobic properties (fs-Si). Rose-shaped Co0.67Ni0.33P micro-flowers grown on fs-Si (Co0.67Ni0.33P/fs-Si) can be used as an efficient and stable hydrogen evolution reaction (HER) electrocatalyst in acidic solution. XPS analysis and DFT calculation showed that the synergistic effect between CoNiP and fs-Si resulted in the required electronic states, enhanced the activity, endowed Pt-like HER performance. This work provides a new idea for expanding the variety of self-supported substrates and synthesizing highly efficient acidic HER electrodes.

A non-precious hydrogen catalyst coated metallic electrode in an electrochemical neutralization cell for simultaneous fuel and power generation

Non-precious metal (NPM) hydrogen catalysts are low-cost and highly efficient for the acidic hydrogen evolution reaction (HER). However, the overall activity of NPM catalysts at high current remains orders of magnitude lower than commercial platinum (Pt)-based catalysts. Herein, we report synthesis of NPM cobalt phosphide (CoP) catalyst-coated metallic electrode for HER with high current density of 100 mA/cm2 at −151 mV versus a reversible hydrogen electrode which outperforms commercial Pt-C coated electrode. We introduce an interfacial C layer to improve acidic H2 evolution reaction activity-stability trend at high current density which results comparable HER stability with atomic layer deposited Pt electrode. Finally, the electrode has been utilized as a cathode in electrochemical neutralization cells for full water splitting, Zn-H2O battery and H2/H+ fuel-cell, wherein electrochemical neutralization energy (ENE) converts to electrical energy toward enhancing device performance and simultaneous H2 generation. This study presents a potential approach for non-platinum group HER catalysts in ENE-harvested systems.

Ultrafast self-heating synthesis of robust heterogeneous nanocarbides for high current density hydrogen evolution reaction

Designing cost-effective and high-efficiency catalysts to electrolyze water is an effective way of producing hydrogen. Practical applications require highly active and stable hydrogen evolution reaction catalysts working at high current densities (≥1000 mA cm−2). However, it is challenging to simultaneously enhance the catalytic activity and interface stability of these catalysts. Herein, we report a rapid, energy-saving, and self-heating method to synthesize high-efficiency Mo2C/MoC/carbon nanotube hydrogen evolution reaction catalysts by ultrafast heating and cooling. The experiments and density functional theory calculations reveal that numerous Mo2C/MoC hetero-interfaces offer abundant active sites with a moderate hydrogen adsorption free energy ΔGH* (0.02 eV), and strong chemical bonding between the Mo2C/MoC catalysts and carbon nanotube heater/electrode significantly enhances the mechanical stability owing to instantaneous high temperature. As a result, the Mo2C/MoC/carbon nanotube catalyst achieves low overpotentials of 233 and 255 mV at 1000 and 1500 mA cm−2 in 1 M KOH, respectively, and the overpotential shows only a slight change after working at 1000 mA cm−2 for 14 days, suggesting the excellent activity and stability of the high-current-density hydrogen evolution reaction catalyst. The promising activity, excellent stability, and high productivity of our catalyst can fulfil the demands of hydrogen production in various applications.

Integrating CoNiSe2 Nanorod-arrays onto N-doped Sea-sponge-C spheres for highly efficient electrocatalysis of hydrogen evolution reaction

A key issue for enhancing performance of hydrogen evolution reaction (HER) by utilizing seawater for sustainable clean energy is to develop a highly efficient, stable and economical electrocatalyst. Herein, a uniquely hierarchical nanostructure of CoNiSe2 nanorod-arrays (NRAs) integrated onto N-doped sea-sponge-carbon spheres (CoNiSe2/N-SSCSs) was designed and synthesized using successive ultrasonic spray pyrolysis (USP) and solvothermal - hydrothermal selenization (SHS) processes. Attributed to intrinsic HER activity of CoNiSe2 NRAs together with effective electron-transfer and ion-diffusion pathways of N-SSCSs, the CoNiSe2/N-SSCSs nanocomposites exhibited highly stable HER electrocatalytic performances in both alkaline electrolytes and alkaline simulated seawater. The required overpotential is as low as 88 mV with a Tafel slope of 83 mV dec−1 at 10 mA cm−2 in 1.0 M KOH, which are comparable to the electrode of commercial Pt/C (η10 = 35 mV &b = 58 mV dec−1).

Interface Engineering of NixSy@MnOxHy Nanorods to Efficiently Enhance Overall-Water-Splitting Activity and Stability

HighlightsThree-dimensional (3D) core‐shell heterostructured NixSy@MnOxHy nanorods grown on nickel foam (NixSy@MnOxHy/NF) were successfully fabricated via a simple hydrothermal reaction and a subsequent electrodeposition process.The fabricated NixSy@MnOxHy/NF shows outstanding bifunctional activity and stability for hydrogen evolution reaction and oxygen evolution reaction, as well as overall‐water‐splitting performance.The main origins are the interface engineering of NixSy@MnOxHy, the shell‐protection characteristic of MnOxHy, and the 3D open nanorod structure, which remarkably endow the electrocatalyst with high activity and stability.Exploring highly active and stable transition metal-based bifunctional electrocatalysts has recently attracted extensive research interests for achieving high inherent activity, abundant exposed active sites, rapid mass transfer, and strong structure stability for overall water splitting. Herein, an interface engineering coupled with shell-protection strategy was applied to construct three-dimensional (3D) core‐shell NixSy@MnOxHy heterostructure nanorods grown on nickel foam (NixSy@MnOxHy/NF) as a bifunctional electrocatalyst. NixSy@MnOxHy/NF was synthesized via a facile hydrothermal reaction followed by an electrodeposition process. The X-ray absorption fine structure spectra reveal that abundant Mn‐S bonds connect the heterostructure interfaces of NixSy@MnOxHy, leading to a strong electronic interaction, which improves the intrinsic activities of hydrogen evolution reaction and oxygen evolution reaction (OER). Besides, as an efficient protective shell, the MnOxHy dramatically inhibits the electrochemical corrosion of the electrocatalyst at high current densities, which remarkably enhances the stability at high potentials. Furthermore, the 3D nanorod structure not only exposes enriched active sites, but also accelerates the electrolyte diffusion and bubble desorption. Therefore, NixSy@MnOxHy/NF exhibits exceptional bifunctional activity and stability for overall water splitting, with low overpotentials of 326 and 356 mV for OER at 100 and 500 mA cm–2, respectively, along with high stability of 150 h at 100 mA cm–2. Furthermore, for overall water splitting, it presents a low cell voltage of 1.529 V at 10 mA cm–2, accompanied by excellent stability at 100 mA cm–2 for 100 h. This work sheds a light on exploring highly active and stable bifunctional electrocatalysts by the interface engineering coupled with shell-protection strategy.

A monolith electrode featuring FeS2 embedded in porous carbon nanofibers for efficient hydrogen evolution

Constructing electrode materials embracing with high effectivity and durable stability is of vital importance for hydrogen evolution reaction (HER) in electrochemical water splitting. Herein, a monolith electrode is designed with FeS2 nanoparticles embedded in porous carbon nanofibers (FeS2@CNFs) via an in-situ electrospinning strategy, which is directly used as an efficient electrode for HER without any extra-substrates. Such monolithic electrode eliminates interface problems between active catalysts and carriers and expends more intrinsic catalysis regions, which effectively shortens the pathway of electron/ mass transport. The FeS2@CNFs electrode displays good HER activity only with an overpotential of 168 mV at 10 mA cm−2. It is worth noting that this monolith electrode shows the excellent HER stability for nearly a week in 1 M KOH without any destruction of fibrous structure. Such considerable activities can be ascribed to the interwoven nanofiber-meshes that engineer the self-supportive architecture with stable strength and the carbon-encapsulation structure that prevents FeS2 from collapsing. The woven meshes and porous structure allow the sufficient penetration of electrolyte and fast gas diffusion. This work provides a valuable reference for rationally designing a monolith electrode effectively for gas-involved electrochemical application.

ZIF-8 derived Zn, Mn, S and P co-loaded on N doped carbon as efficient electrocatalyst for hydrogen evolution reaction (HER)

Developing low-cost electrocatalysts with excellent catalystic activity and superior stability for hydrogen evolution reaction (HER) is still a big challenge. In this paper, we adopted zeolitic imidazolate zinc framework (ZIF-8) as precursor to fabricate Zn, Mn, S and P co-loaded on N doped carbon (ZnMnSP/NDC) via pyrolysis, adsorption, sulphurization and phosphorization processes and investigated its catalytic activity for HER. After being carefully researched, the loading of Mn, S and P can obviously improve the catalytic activity of the catalyst for HER. Mn and P elements are loaded on porous carbon homogeneously. Zn can react with S to form ZnS. More interestingly, the loading of S element can highly improve the graphitic degree of porous carbon. Furthermore, ZnMnSP/NDC exhibits excellent long-term stability for HER in the alkaline solution. The excellent electrocatalytic performance of ZnMnSP/NDC may be attributed to the high loading of Mn, S, P element and the unique nanoparticle-embedded porous carbon structure. This work provides a valuable way to fabricate non-precious elements co-loaded N doped carbon with excellent catalytic performance for HER.

Boron-doped CoSe2 nanowires as high-efficient electrocatalyst for hydrogen evolution reaction

High activity and stable hydrogen evolution reaction (HER) catalysts have an indispensable influence on hydrogen production. Pyrite cobalt selenide (CoSe2) is considered an excellent non-noble metal compound HER catalyst due to its low price and excellent electrical conductivity. However, the HER catalytic activity of CoSe2 is still not ideal because of the weak adsorption of hydrogen on its active Co site. The anion introduction can improve the electronic structure of the catalyst and thereby enhance the performance of HER. Here, we report that B-doped CoSe2 nanomaterials on carbon cloth (B-CoSe2/CC) were successfully synthesized. Compared with CoSe2, B-CoSe2 exhibits better HER performance in 1 M KOH. The overpotential of B-CoSe2 catalyst is only 153 mV at 10 mA cm−2. Tafel slope of B-CoSe2/CC sample is only 85 mV dec−1. In addition, B-CoSe2/CC exhibits perfect long-term durability and cycle stability. Density functional theory (DFT) calculations illustrate that the doping of B improves the intrinsic conductivity of CoSe2 and optimizes the hydrogen adsorption free energy (ΔGH*) of Se and Co sites. This work not only proposes a new anion doping strategy to improve the electronic structure of cobalt-based selenides for improved HER performance, but also provides a reference for the screening and design of other transition metal compound HER electrocatalysts.

Encapsulation of Fe-CoP with P, N-co-doped porous carbon matrix as a multifunctional catalyst for wide electrochemical applications

Hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) serve as the most promising electrochemical processes for renewable energy. Developing multifunctional electrocatalysts with high performance for HER, OER and ORR still remains a challenge. Herein, we report a facile method to prepare P, N-co-doped porous carbon encapsulated Fe-CoP (A-Fe-CoP/CPN) electrocatalyst through freeze drying, carbonization, and KOH activation. The acquired A-Fe-CoP/CPN possesses abundant pores with large surface area, which provides sufficient defect-rich sites for HER, OER, and ORR, in alkaline or acidic electrolytes. The A-Fe-CoP/CPN shows low overpotential and good stability for HER and OER in alkaline electrolyte. Density functional theory (DFT) computations reveal that the addition of Fe greatly facilitates the rate-determining step and overall catalytic pathway for both HER and OER. A-Fe-CoP/CPN also exhibits low half-wave potential (E1/2) for ORR, which indicates an enhanced performance than that of the noble Pt/C catalyst. Zn-air battery equipped with the A-Fe-CoP/CPN catalyst exhibits a high energy density (849 mAh g−1) and a long-time stability at 5 mA cm−2. This finding not only offers a facile strategy to prepare porous carbon materials with defect-rich sites, but also provides guidance for developing multifunctional electrocatalysts for wide electrochemical reactions.

N-doped molybdenum carbides embedded in porous carbon for efficient hydrogen evolution

Transition metal carbides (TMCs) are regarded as cost-efficient and stable electrocatalysts for hydrogen evolution reaction (HER). Nitrogen doping into nanosized TMCs in a control manner (e.g. doping amount and site) is one of the most effective routes to intrinsically enhance the activity and durability owing to the ameliorated Mo–H strength and amplified active sites. Herein, an approach based on reticular chemistry is developed to synthesize nanosized N-doped Mo2C embedded in porous carbon (N–Mo2C/PC), via pyrolyzing a hybrid precursor consisting of highly-dispersed molybdates within melamine-benzenetricarboxylic acid supermolecule networks. With optimal N-doping, the N–Mo2C/PC electrocatalyst exhibits an excellent HER stability and activity with overpotential of 109 mV at 10 mA cm−2 in 0.5 M H2SO4, as well as 100 mV at 10 mA cm−2 in 1.0 M KOH. Density functional theory calculations confirm that the appropriate N doping on the surface of Mo2C nanoparticles would accelerate the HER process via weakening the Mo–H bond strength and lowering the H–H coupling barrier. Furthermore, Mo2C nanoparticles loaded on carbon cloth with high HER activity can also be successfully achieved by this strategy. This work paves a universal way to design active sites-enriched TMCs with high performance in energy conversion and storages.

A crown ether supramolecular host-guest complex with Keggin polyoxometalate: Synthesis, crystal structure and electrocatalytic performance for hydrogen evolution reaction

A new crown ether–polyoxometalate assembly [K(H24C12O6)]3[K(H24C12O6)(CH3CN)][SiMo12O40] (1) based on the Keggin-type polyanion [SiMo12O40]4− was successfully synthesized through one-pot strategy in acetonitrile solution. The polyanion is coordinated to two [K([18]-crown-6)]+ supramolecular cations via crown–K–O(POM) coordinate-covalent bonds, leading to the formation of a spindle-shaped discrete structure. Complex 1 exhibited good hydrogen evolution reaction (HER) activity in an acidic medium. Moreover, a small overpotential η10 of 120 mV and a Tafel slope of 112 mV dec−1 were obtained. This crown ether–polyoxometalate hybrid electrocatalyst also presented excellent HER stability even after 2000 cycles of operation.

Facile fabrication of carbon fiber skeleton structure of MoS2 supported on 2D MXene composite with highly efficient and stable hydrogen evolution reaction

Development of advanced electrocatalytic materials is the crucial technology in electrolytic water to produce clean hydrogen energy. Herein, we have developed a highly efficient and stable hydrogen evolution reaction (HER) electrocatalyst MoS2/Ti3C2@CNFs hybrid material, which obtained by sulfur vapor assisted graphitization of Mo/Ti3C2@PAN precursor. Conductive Ti3C2 MXene and carbon nanofiber (CNFs) were applied to construct the “plane-line” skeleton structure to effectively prevent the stacking of Ti3C2 flakes, increase the loading content of MoS2, enlarge the exposure active edge sites of MoS2 and accelerate charger transfer of MoS2. MoS2/Ti3C2@CNFs exhibits excellent electrocatalytic activity and high stability in HER compared to pure MoS2 and MoS2/Ti3C2 nanostructure. The excellent performance of MoS2/Ti3C2@CNFs in HER is attributed to the special characteristics of the skeleton structure and the strong interface coupling between MoS2 and Ti3C2 MXene. Our findings provide a viable approach for designing advanced nanostructures for catalysis, electronic devices, and other potential applications.

Hydrogen evolution reaction activity and stability of sintered porous Ni-Cu-Ti-La2O3 cathodes in a wide pH range

Finding a low-cost, efficient, stable, and workable electrode for the production of hydrogen based on the hydrogen evolution reaction (HER) is particularly critical. At present, the use of Pt/C electrodes is under development, but the expensive cost hinders its wide application in the HER field. Herein, a novel porous Ni-Cu-Ti-La 2 O 3 cathode with a porosity of 29.07% was proved to be an excellent substitute for the HER, which was fabricated by vacuum sintering based on powder metallurgy. The hydrogen evolution efficiency is superior to that of commercial 20% Pt/C under pH = 14.1 condition (2.67 mol/L KOH). The HER activity is also close to commercial 20% Pt/C under pH = 0.1 (1 mol/L HCl) and pH = 8.1 (3.34% simulated seawater) conditions and exceeds it after reaching a high potential. Meanwhile, it can achieve good HER stability within 48 h and maintain its HER activity after 1000 continuous cycle electrolysis. • The porous Ni–Cu-Ti-La 2 O 3 cathodes were sintered through powder metallurgy. • The cathodes exhibited excellent HER activity and stability in a wide pH range. • The HER activity of the cathodes is superior to that of 20% Pt/C in 2.67 mol/L KOH. • The La 2 O 3 and La phases greatly increased the real surface area of the cathodes.

Molybdenum nitride as a metallic photoelectrocatalyst for hydrogen evolution reaction via introduction of electron traps to improve the separation efficiency of photogenerated carriers

Metallic photoelectrocatalysts possess a wide light absorption range and the fast hydrogen evolution reaction (HER) kinetics, which can be used as the next generation of catalysts towards photoelectrocataytic HER. In this work, molybdenum nitride has been fabricated via an in-suit growth method on metal molybdenum substance (Mo 3 N 2 /Mo foil). The metallic and optical property of Mo 3 N 2 was confirmed by the DFT calculations and experimental results from UV–visible absorption spectrum and valence X-ray photoelectron spectroscopy spectrum. Photocatalytic HER rate of Mo 3 N 2 reached to 158.78 μmol h −1 g −1 . Furthermore, Mo 3 N 2 –MoS 2 /Mo foil was prepared to improve photoelectrocatalytic performance. Herein, a suitable energy band alignment for Mo 3 N 2 –MoS 2 /Mo foil was proposed based on experiments and DFT calculations, and the formation of a heterojunction (Mo 3 N 2 –MoS 2 ) effectively suppressed the recombination of photo-generated carriers. The results of photoelectrocatalytic experiments suggested that the photocurrent density of Mo 3 N 2 –MoS 2 /foil was effectively enhanced about 1.5 times than that of simplex Mo 3 N 2 /Mo foil. The electrochemical experiments (LSV and EIS) indicated that the metallic nature of Mo 3 N 2 was also beneficial to electrocatalytic HER, and the overpotential of Mo 3 N 2 –MoS 2 /Mo foil at 10 mA cm −2 was −173 mV. This work provides a potential candidate for photoelectrocatalytic electrodes. • Metallic Mo 3 N 2 plays a dominant role in photoelectrocatalytic HER activity. • The metallic and optical nature were verified by experiments and DFT calculation. • Mo 3 N 2 –MoS 2 heterojunction was used to improve the photoelectrocatalytic property. • Schottky barrier effectively suppress the recombination of photoinduced carriers. • Mo 3 N 2 –MoS 2 /Mo foil electrode exhibits superior stability for HER.

Modulating surface segregation of Ni2P-Ru2P/CCG nanoparticles for boosting hydrogen evolution reaction in pH-universal

• The activity exhibits a volcanic relationship along with Ni/Ru molar ratio. • The average size of Ni 2 P-Ru 2 P on graphene is from 2.98 to 6.40 nm. • The Ni 2 P-Ru 2 P exhibits excellent activity and stability for HER in pH-universal. • The hydrogen adsorption and H 2 O dissociation depend on the Ni/Ru ratio. Transition metal phosphides with high catalytic activity and durability for the hydrogen evolution reaction (HER) are promising candidates. Herein, we synthesized various Ni 2 P-Ru 2 P nano catalysts with different Ni/Ru ratio supported on chemically converted graphene (CCG) under 10 vol% H 2 /Ar 2 atmosphere. The average size of Ni 2 P-Ru 2 P nanoparticles monotonously increases from 2.98 nm to 6.40 nm with the increase of reduction temperature from 500℃ to 800℃. Meanwhile, the ratio of Ru/Ni is also monotonically increase from 0.67 to 0.85 according to the X-ray photoelectron spectroscopy, suggesting the segregation of Ni to the surface. The Ni 2 P-Ru 2 P/CCG-800 shows the best performance for HER with low overpotentials of 21.83 mV (1 M KOH), 113.38 mV (1 M PBS) and 49.42 mV (0.5 M H 2 SO 4 ), when the current density reaches 10 mA cm −2 . Besides, its Tafel slope of Ni 2 P-Ru 2 P/CCG-800 is 56.92 mV dec −1 in 1 M KOH (67.85 mV dec −1 in 1 M PBS, 45.98 mV dec −1 in 0.5 M H 2 SO 4 ). The superior HER activity of Ni 2 P-Ru 2 P/CCG-800 can be ascribed to the synergistic effect of Ni and Ru near surface. Density functional theory calculations reveal that the introduction of Ni atom into Ru 2 P accelerates H 2 O dissociation at Ru sites and H 2 formation at Ni sites.

Ni3S2 nanosheets decorated on NiCo2O4 flakes-arrays directional growth of Ni foam for enhanced electrochemical hydrogen generation

• NiCo 2 O 4 /Ni 3 S 2 /NF core–shell arrays on Ni foam were constructed by Ni 3 S 2 loaded on NiCo 2 O 4 arrays. • The hierarchical nanostructures of NiCo 2 O 4 /Ni 3 S 2 /NF contribute excellent activity and stability for HER. • NiCo 2 O 4 /Ni 3 S 2 /NF provides large active sites and faster charge transfer. Electrochemically production of hydrogen is an appealing approach to provide clean energy at an affordable price. Much research has been assigned to the development of functional catalysts that are efficient electrocatalysts for the hydrogen evolution reaction (HER). In this study, the nanocomposite catalyst composition of Ni 3 S 2 /NiCo 2 O 4 on nickel foam as a non-noble-metal has been prepared via a convenient chemical conversion route. The synthesized catalyst demonstrates excellent stability and durability in aqueous environments, which makes it a very active, stable, low-cost and promising catalytic system in the field of energy analysis, conversion and storage. Here, the prepared electrode to achieve a current density of 10 mA cm −2 requires an overpotential of 184 mV with a Tafel slope of 97 mV dec -1 in alkaline solution (1 M KOH) and an overpotential of 140 mV with a Tafel slope of 53.6 mV dec -1 in acidic condition (0.5 M H 2 SO 4 ). The catalytic system's activity can be maintained for at least 14 h in KOH 1 M and H 2 SO 4 0.5 M. Also, the present work investigates the electrochemical characterization of the samples in which the current density is normalized by geometric area, electrochemical active surface area (ECSA) and BET specific surface area.

MoP-Mo2C quantum dot heterostructures uniformly hosted on a heteroatom-doped 3D porous carbon sheet network as an efficient bifunctional electrocatalyst for overall water splitting

• MoP-Mo 2 C quantum dot heterostructures uniformly distribute on carbon sheet network. • MoP-Mo 2 C/NPC possesses abundant heterogeneous interfaces and pore structure. • MoP-Mo 2 C/NPC exhibits low overpotentials and ultrahigh stability for HER and OER. In this work, we constructed MoP-Mo 2 C quantum dot heterostructures uniformly hosted on a three-dimensional (3D) hierarchically porous thin N,P-doped carbon sheet network (MoP-Mo 2 C/NPC) by a novel one-pot simultaneous phosphating-carbonization-activation of molybdenum-chelated resin and KOH. Chelate confinement not only prevents the aggregation of MoP/Mo 2 C quantum dots, but also synchronously produces a carbon sheet network doped with N and P without the requirement for post-atom doping. The prepared MoP-Mo 2 C/NPC exhibited a large specific surface area, a high electron conductivity, and abundant active sites for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). As a result, MoP-Mo 2 C/NPC with a low calculated Gibbs free energy for H adsorption exhibited an excellent electrocatalytic activity and an ultrahigh stability for both the HER and OER processes in an alkaline medium. In addition, the assembled MoP-Mo 2 C/NPC || MoP-Mo 2 C/NPC alkaline electrolyzer delivered a current density of 10 mA cm −2 at an overpotential of only 1.55 V, and maintained > 95% of the initial current density after 168 h (1 week) of activity, which is superior to that of the state-of-the-art Pt/C || RuO 2 /C system in the overall water splitting process.

In situ coupled MoO3 with CoP/rGO to construct three-dimensional self-supported catalyst for highly efficient alkaline hydrogen evolution reaction

In order to solve the crisis of energy depletion and protect the beautiful natural environment, the development of efficient, cost-effective and stable hydrogen evolution reaction (HER) electrocatalyst has attracted great attention, but it is still an urgent challenge to fabricate an abundant and low cost electrocatalyst. In this article, a novel HER catalyst with heterogeneous structure interfaces was in situ synthesized by multi-step electrodeposition method, and the mechanism of the enhancement of its electrocatalytic activity was elucidated by the combination of density functional theory (DFT) calculation and multi-characterizations. The initial overpotential is only 83 mV and the Tafel slope is only 58.5 mV/dec, which is better than most of other reported CoP-based electrocatalyst. At the meantime, DFT calculations show that the incorporation of MoO3 and rGO leads to electron redistribution among different components, which ensures efficient adsorption and activation of H2O molecules and hydrogen atoms. Therefore, this work will contribute to the understanding of the mechanisms associated with heterojunctions and provide guidance for the rational design of a hybrid catalyst.

NiMo@C3N5 heterostructures with multiple electronic transmission channels for highly efficient hydrogen evolution from alkaline electrolytes and seawater

Designing highly efficient and stable electrocatalysts for hydrogen evolution reaction (HER), particularly in seawater, still remains a challenging task. Herein, the unique heterostructures composed of 1D NiMo cores and 2D C3N5 shells (NiMo@C3N5) are rationally designed and demonstrated as the robust HER catalysts in both alkaline electrolytes and natural seawater, where the carbon-based shell can effectively protect the catalyst core from seawater poisoning. Based on the experimental investigation and density functional theory calculation, multiple electronic transmission channels were found to establish at the interface between NiMo cores and C3N5 shells, thus providing efficiently optimized HER pathways to achieve minimized overpotential with a reduced energy barrier of the rate-determining step. More importantly, the NiMo@C3N5 hybrids exhibit stable HER performance with a high Faradaic efficiency of 94.8% in seawater, which is superior to that of commercial Pt/C. All these results can evidently highlight a feasible strategy to develop high-performance HER electrocatalysts via interface engineering.

Prussian blue analogue derived cobalt–nickel phosphide/carbon nanotube composite as electrocatalyst for efficient and stable hydrogen evolution reaction in wide-pH environment

Transition metal phosphides, especially bimetallic phosphides, are promising noble-metal-free electrocatalysts for hydrogen evolution reaction (HER). However, their inferior charge transfer ability constrains further performance improvement. In this work, a facile strategy is reported to fabricate Co2P/Ni2P/carbon nanotube (CNT) composite from a precursor Co-Ni Prussian blue analogue. The combination of Co2P/Ni2P and CNT endows Co2P/Ni2P/CNT with improved electrical conductivity and a richer electrochemically active surface area. As a result, the Co2P/Ni2P/CNT composite exhibits desirable HER activities across a wide pH range, delivering a benchmark current density of 10 mA cm−2 at overpotentials as low as 151 and 202 mV in 0.5 M H2SO4 and 1 M KOH electrolytes, respectively, as well as remarkable electrocatalytic stabilities over 48 h in both electrolytes. This strategy enables the design of high-performance electrocatalysts for efficient and stable hydrogen generation.