Aqueous substitution synthesis of platinum modified amorphous nickel hydroxide on nickel foam composite electrode for efficient and stable hydrogen evolution

Exploring highly active and stable electrocatalysts toward hydrogen evolution reaction (HER) is vital for the production of green energy and storage of intermittently renewable electrical energy. In this study, we fabricate Pt-modified Ni(OH)₂ on 3D nickel foam (Pt content: 1.5 wt %) via a one-step galvanic replacement reaction in aqueous solution to achieve a top performance of HER under alkaline conditions. It exhibits a negligible onset potential, a Tafel slope of 17 mV dec⁻¹, and overpotentials of 38, 114, and 203 mV to deliver 10, 50, and 100 mA cm⁻² current densities, respectively, which outperforms the commercial Pt/C and Pt sheet. Moreover, this catalyst shows enhanced durability towards HER, sustaining electrolysis at −20 mA cm⁻² for 4, 500 min in 1 M KOH with little degradation. Its good performances come from the synergism of flake-like Pt and amorphous Ni(OH)₂. This work provides not only a facile and easy scale-up approach to fabricate Pt−modified electrocatalysts with improved HER performance but also a new strategy to design self-supported high-performance hybrid materials of noble-metal and amorphous transitional metal hydroxides for sustainable energy conversion and storage.     

Enriched oxygen vacancy promoted heteroatoms (B,P, N,and S) doped CeO2: Challenging electrocatalysts for oxygen evolution reaction (OER) in alkaline medium

Increasing worldwide energy consumption has prompted considerable study into energy generation and energy storage systems in recent years. Chemical fuels may be produced efficiently via electrocatalytic water splitting, which uses electric and solar power. The development of efficient anodic electrocatalysts for efficient oxygen evolution reaction (OER) is a greater concern of present energy research. Cerium oxide (CeO₂) are promising electrocatalysts that exhibit outstanding OER but their reduced stability obstructs the practical application. A novel strategy was established to construct an effective catalyst of heteroatom (N, B, P and S) doped CeO₂ matrix were prepared. Moreover, the doping of heteroatoms into the CeO₂ matrix processes the improved electronic conductivity, reactive sites, increases the electrochemical catalytic activity, which enhances the water oxidation reaction. Consequently, well-suited alkaline electrolysers were brought together for water oxidation to ideal OER electrocatalytic activity. The OER activity of the electrocatalysts follows the order of S–CeO₂ (190 mV@10 mA cm⁻²), N– CeO₂ (220 mV @10 mA cm⁻²), P– CeO₂ (230 mV @10 mA cm⁻²), B–CeO₂ (250 mV @10 mA cm⁻²) and CeO₂ (260 mV @10 mA cm⁻²) in 1 M of KOH. From the kinetics analysis, Tafel slope value achieved for catalysts CeO₂, B–CeO_2, P–CeO₂, N–CeO₂ and S–CeO₂ are 142 mV dec⁻¹,121 mV dec⁻¹, 102 mV dec⁻¹, 98 mV dec⁻¹ and 83 mV dec⁻¹ respectively. These results validate that the S–CeO₂ electrode is prominent for OER performance with the requirement of cell voltage of 1.42 V at 10 mA cm⁻² current density. In addition, sulphur doped CeO₂ relatively have excellent stability through chrono-potentiometric analysis lasting for 20 h. Although the heteroatoms doped CeO₂ is acts as anode material, the preparation method is widespread, which will reduce the synthesis cost and streamline the preparation of electrode for OER. This research effort delivers a complete advantage for the development of robust, environmentally friendly and highly dynamic electrocatalysts for OER activity.     

Facile galvanic replacement method for porous Pd@Pt nanoparticles as an efficient HER electrocatalyst

In realm of renewable energy, development of an efficient and durable electrocatalyst for H₂ production through electrochemical hydrogen evolution reaction (HER) is indispensable. Herein, we demonstrate a simple preparation of carbon-supported nanoporous Pd with surface coated Pt (CS–PdPt) by a simple galvanic replacement reaction (GRR). The phase purity and porosity have been confirmed by XRD, HRTEM, and N₂ sorption techniques. As HER electrocatalyst, CS-PdPt showed a low overpotential of 26 mV in 0.5 M H₂SO₄ at current density of 10 mA cm⁻², which is lower than the commercial Pt/C electrode. The CS-PdPt catalyst exhibits an overpotential of 46 mV in 1 M KOH, and 50 mV in neutral buffer (1 M PBS) at 10 mA cm⁻². The CS-PdPt furnished with small Tafel values of 33, 88, and 107 mV dec⁻¹ in acidic, alkaline, and neutral medium, respectively. Accelerated durability test at 100 mV s⁻¹ for 1000 cycles demonstrated a negligible change in HER activity.     

Construction of P,N-codoped carbon shell coated CoP nanoneedle array with enhanced OER performance for overall water splitting

Water electrolysis to generate hydrogen (H₂) and oxygen (O₂) was a sustainable alternative for clean energy in the future but remained challenging. Herein, we fabricated a nanoneedle-like CoP core coated by a P,N-codoped carbon shell (CoP@PNC@NF). The hierarchical structure, unique nanoneedle-like morphology, CoP core, and P,N-codoped carbon shell were responsible for the high electrocatalytic activity. Electrocatalytic tests demonstrated that CoP@PNC@NF displayed low overpotentials of 137.6 and 148.4 mV, as well as Tafel slopes of 59.89 and 56.40 mV dec⁻¹ for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, at 10 mA cm⁻² in 1.0 M KOH. The bifunctional electrocatalyst CoP@PNC@NF also exhibited a low cell voltage of 1.458 V to yield 10 mA cm⁻² in the two-electrode system and could maintain the activity for 50 h. The Faradaic efficiencies of CoP@PNC@NF for both HER and OER were nearly 100%. The result outperformed the precious-metal-based electrocatalyst apparatus (RuO₂||Pt/C) and other carbon-coated transition-metal phosphides (TMPs). This work paved the way for the rational design of carbon shell-coated TMPs with low energy barriers for converting and storing electrochemical energy.     

Synthesis and electrochemical study of coinage metal nanodendrites for hydrogen evolution reaction

Herein, we report a facile one-step synthesis route to fabricate the coinage metal nanodendrites (NDs) via a tailored galvanic replacement reaction (GRR). Cu, Ag and Au NDs are directly grown on glassy carbon plate (GCP) from the mixture of their precursor solutions and Zn dust. The formed NDs are uniformly distributed to the substrate and obtained the unique structures with sharp tips and tertiary branches. The electrocatalytic activity of the synthesized NDs towards the hydrogen evolution reaction (HER) is further investigated in 0.5 M H₂SO₄ using linear sweep voltammetry (LSV) and the Tafel slope. The results demonstrate that the nanodendrites formed through the GRR process exhibit greater catalytical activity towards HER in comparison to the polycrystalline Cu, Ag and Au. The prepared Au NDs exhibits the highest catalytic performance with a current density of ?10.68 mA cm^?2 at overpotential of 67 mV and a low Tafel slope of 65 mV dec^?1. The simple and easy synthesis approach, the unique morphology and high electrocatalytic activity and excellent stability make the developed Cu, Ag and Au NDs highly efficient catalysts for green energy and electrochemical applications.     

CoSe2@NiSe2 nanoarray as better and efficient electrocatalyst for overall water splitting

Electrocatalytic water splitting is identified as one of the most promising solutions to energy crisis. The CoSe₂@NiSe₂ materials were first prepared and in situ grown on nickel foam by typical hydrothermal and selenification process at 120 °C. The results show that the CoSe₂@NiSe₂ material used as the 3D substrates electrode can maximize the synergy between the CoSe₂ and NiSe₂, and also exhibits high efficiency of water splitting reaction. The lower overpotential of only 235 mV is presented to attain 20 mA cm⁻² compared to the benchmark of RuO₂ electrodes (270 mV @ 20 mA cm⁻²). Besides, the CoSe₂@NiSe₂ material also shows a remarkable improved hydrogen evolution reaction activity compared to NiSe₂ (192 mV@10 mA cm⁻²) and Co precursor catalysts (208 mV@10 mA cm⁻²) individually, which a low overpotential of only 162 mV is achieved at 10 mA cm⁻². The CoSe₂@NiSe₂ catalysts exhibit excellent water splitting performance (cell voltage of 1.50 V@ 10 mA cm⁻²) under alkaline conditions. It was proved that the high water splitting performance of the catalyst is attributed to high electrochemical activity area and synergistic effect. The work offers new ideas for the exploitation of synergistic catalysis of composite catalysts and adds new examples for the exploitation of efficient, better and relatively non-toxic electrocatalysts.     

Interface engineering of crystalline/amorphous Pt/TeOx nanocapsules for efficient alkaline hydrogen evolution

Hydrogen evolution reaction (HER) is an important process in electrochemical energy technology, and efficient electrocatalysts are of great significance for renewable and sustainable energy conversion. Here, we report a facile hydrothermal and heat treatment process to synthesize a series of Pt-based nanocapsules (NCs) as an effective hydrogen evolution catalyst. The Pt/TeO_x NCs exhibit excellent HER activity in an alkaline medium. The Pt/TeO_x NCs only need the overpotential of 33 mV to achieve the current density of 10 mA cm⁻², and the Tafel slope was as low as 29 mV dec⁻¹, which was even better than that of commercial Pt/C. Detailed experimental characterizations demonstrate that the interface between the crystalline Pt/amorphous TeO_x and the strong electron transfer contribute to alkaline HER activity. This work opens up a new direction for the preparation of efficient catalysts for electrocatalytic reactions or other conversion filed.     

MoS2/NiFeS2 heterostructure as a highly efficient electrocatalyst for overall water splitting at high current densities

Searching for efficient, stable and low-cost nonprecious catalysts for oxygen and hydrogen evolution reactions (OER and HER) is highly desired in overall water splitting (OWS). Herein, presented is a nickel foam (NF)-supported MoS₂/NiFeS₂ heterostructure, as an efficient electrocatalyst for OER, HER and OWS. The MoS₂/NiFeS₂/NF catalyst achieves a 500 mA cm⁻² current density at a small overpotential of 303 mV for OER, and 228 mV for HER. Assembled as an electrolyzer for OWS, such a MoS₂/NiFeS₂/NF heterostructure catalyst shows a quite low cell voltage (≈1.79 V) at 500 mA cm⁻², which is among the best values of current non-noble metal electrocatalysts. Even at the extremely large current density of 1000 mA cm⁻², the MoS₂/NiFeS₂/NF catalyst presents low overpotentials of 314 and 253 mV for OER and HER, respectively. Furthermore, MoS₂/NiFeS₂/NF shows a ceaseless durability over 25 h with almost no change in the cell voltage. The superior catalytic activity and stability at large current densities (>500 mA cm⁻²) far exceed the benchmark RuO₂ and Pt/C catalysts. This work sheds a new light on the development of highly active and stable nonprecious electrocatalysts for industrial water electrolysis.     

Spatially confined growth of ultrathin NiFe layered double hydroxide nanosheets within carbon nanofibers network for highly efficient water oxidation

The rational design of catalysts with low cost, high efficient and robust stability toward oxygen evolution reaction (OER) is greatly desired but remains a formidable challenge. In this work, a one-pot, spatially confined strategy was reported to fabricate ultrathin NiFe layered double hydroxide (NiFe-LDH) nanosheets interconnected by ultrafine, strong carbon nanofibers (CNFs) network. The as-fabricated NiFe-LDH/CNFs catalyst exhibits enhanced OER catalytic activity in terms of low overpotential of 230 mV to obtain an OER current density of 10 mA cm^?2 and very small Tafel slope of 34 mV dec^?1, outperforming pure NiFe-LDH nanosheets assembly, commercial RuO₂, and most non-noble metal catalysts ever reported. It also delivers an excellent structural and electrocatalytic stability upon the long-term OER operation at a large current of 30 mA cm^?2 for 40 h. Furthermore, the cell assembled by using NiFe-LDH/CNFs and commercial Pt/C as anode (+) and cathode (?) ((+)NiFe-LDH/CNFs||Pt/C(?)) only requires a potential of 1.50 V to deliver the water splitting current of 10 mA cm^?2, 130 mV lower than that of (+)RuO₂||Pt/C(?) couple, demonstrating great potential for applications in cost-efficient water splitting devices.     

Silicon monoxide assisted synthesis of Ru modified carbon nanocomposites as high mass activity electrocatalysts for hydrogen evolution

Extremely low content of Ruthenium (Ru) nanoparticles were loaded on the carbon black (Ru/C) via reducing Ru ions with silicon monoxide. The obtained Ru/C nanocomposites exhibit an exciting electrochemical catalytic activity for hydrogen evolution reaction (HER) in the oxygen-free 0.5 M H₂SO₄ medium. The optical one (Ru/C-2) with a low Ru amount of 2.34% shows higher activity than previously reported Ru-based catalysts. The overpotential at 10 mA cm⁻² is 114 mV and the Tafel slope is 67 mV·dec⁻¹. Ru/C-2 catalyst also has good stability. The overpotential that afford the current density of 10 mA cm⁻² of 20 wt% Pt/C increased 92 mV while that of Ru/C-2 only increased 50 mV after a 30,000 s chronopotentiometry test. Furthermore, the mass activity of Ru/C-2 catalyst is even better than that of the commercial 20 wt% Pt/C when the overpotential is larger than 0.18 V. This silicon monoxide-mediated strategy may open a new way for the fabrication of high performance electrocatalysts.     

Well-dispersed Pt nanodots interfaced with Ni(OH)2 on anodized nickel foam for efficient hydrogen evolution reaction

Hindered by price and scarcity, the exploitation of supported Pt-based electrocatalysts with Pt single atoms or Pt nanoclusters is an alternative way to decrease the dosage of Pt and improve the electrocatalytic performance for hydrogen evolution reaction (HER) of water splitting. The anodization technology is used to modify the surface of nickel foam (NF) to form the porous NiF₂ network structure. Then Pt nanodots interfaced with Ni(OH)₂ (Pt/Ni(OH)₂) hybrid on the anodized NF has been in-situ synthesized by a simple hydrothermal decomposition method. Results show that Pt nanodots on the substrate have good dispersion with the average size of 3 nm, and the Pt loading is only 0.229 mg cm⁻². The prepared electrode exhibits the low overpotentials of 25.9 mV and 211 mV at the current densities of 10 and 100 mA cm⁻², respectively, a small Tafel slope of 37.6 mV dec⁻¹, and the excellent durability for HER. The porous network nanostructure of Pt/Ni(OH)₂ hybrid, the large electrochemical surface area, the fast facilitated electron transport capability, and the firm adhesion of Pt nanodots with the anodized NF substrate contribute to the remarkable performance towards HER.     

High-performance bifunctional Fe-doped molybdenum oxide-based electrocatalysts with in situ grown epitaxial heterojunctions for overall water splitting

The design and development of low-cost, abundant reserves, high catalytic activity and durability bifunctional electrocatalysts for water splitting are of great significance. Here, simple hydrothermal and hydrogen reduction methods were used to fabricate a uniform distribution of Fe-doped MoO₂/MoO₃ sheets with abundant oxygen vacancies and heterojunctions on etched nickel foam (ENF). The Fe– MoO₂/MoO₃/ENF exhibited a small overpotential of 36 mV at 10 mA cm⁻² for hydrogen evolution reaction (HER), an excellent oxygen evolution reaction (OER) overpotential of 310 mV at 100 mA cm⁻² and outstanding stabilities of 95 h and 120 h for the HER and OER, respectively. As both cathode and anode catalysts, the heterogeneously structured Fe– MoO₂/MoO₃/ENF required a low cell voltage of 1.57 V at 10 mA cm⁻². Density functional theory (DFT) calculations show that Fe doping and MoO₂/MoO₃ heterojunctions can significantly reduce the band gap of the electrode, accelerate electron transport and reduce the potential barrier for water splitting. This work provides a new approach for designing metal ion doping and heterostructure formation that may be adapted to transition metal oxides for water splitting.     

Lattice-strained Pt nanoparticles anchored on petroleum vacuum residue derived N-doped porous carbon as highly active and durable cathode catalysts for PEMFCs

High cost and poor durability of Pt-based cathode catalysts for oxygen reduction reaction (ORR) severely hamper the popularization of proton exchange membrane fuel cells (PEMFCs). Tailoring carbon support is one of effective strategies for improving the performance of Pt-based catalysts. Herein, petroleum vacuum residue was used as carbon source, and nitrogen-doped porous carbon (N-PPC) was synthesized using a simple template-assisted and secondary calcination method. Small Pt nanoparticles (Pt NPs) with an average particles size of 1.8 nm were in-situ prepared and spread evenly on the N-PPC. Interestingly, the lattice compression (1.08%) of Pt NPs on the N-PPC (Pt/N-PPC) was clearly observed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), which was also verified by the shift of (111) crystal plane of Pt on N-PPC to higher angles. The X-ray photoelectron spectroscopy (XPS) results suggest that the N-PPC support had a strong effect on anchoring Pt NPs and endowing surface Pt NPs with lowered d band center. Thus, the Pt/N-PPC as a catalyst simultaneously boosted the ORR activity and durability. The specific activity (SA) and mass activity (MA) of the Pt/N-PPC at 0.9 V reached 0.83 mA cm⁻² and 0.37 A mg_Pt⁻¹, respectively, much higher than those of the commercial Pt/C (0.21 mA cm⁻² and 0.11 A mg_Pt⁻¹) in 0.1 M HClO₄. The half-wave potential (E_1/2) of Pt/N-PPC exhibited only a minimal negative shift of 7 mV after 30,000 accelerated durability tests (ADT) cycles. More importantly, an H₂–O₂ fuel cell with a Pt/N-PPC cathode achieved a power density of 866 mW cm⁻², demonstrating that the prepared catalyst has a promising application potential in working environment of PEMFCs.     

Constructing microstructures in nickel-iron layered double hydroxide electrocatalysts by cobalt doping for efficient overall water splitting

The development of Ni–Fe layered double hydroxide (NiFe LDH) catalysts for overall water splitting (OWS) is urgently required. NiFe LDHs are promising catalysts for the oxygen evolution reaction (OER). However, their hydrogen evolution reaction (HER) performance is restricted by slow kinetics. The construction of multiple types of active sites to simultaneously optimise the OER and HER performance is significant for OWS using NiFe LDHs. Hence, a Co-doped NiFe LDH electrocatalyst with dislocations and stacking faults was designed to modulate the electronic structure and generate multiple types of activity sites. The Co_0.03-NiFe_0.97 LDH catalyst only required overpotentials of 280 (50 mA cm⁻², OER) and 170 mV (10 mA cm⁻², HER). However, it reached a current density of 50 mA cm⁻² at 1.53 V during OWS. Co_0.03-NiFe_0.97 LDHs could be stabilised for 140 h at 1.52 V. Furthermore, Co_0.03-NiFe_0.97 LDHs exhibited a higher electrocatalytic activity than commercial Raney nickel and Pt/C||IrO₂ under industrial conditions. The significant specific surface area, high conductivity, and unique microstructures are the major factors contributing to the excellent OWS performance. This study suggests an efficient strategy for introducing microstructures to fabricate catalysts with high activity for application in OWS.     

Super-hydrophilic/super-aerophobic Ni2P/Co(PO3)2 heterostructure for high-efficiency and durable hydrogen evolution electrocatalysis at large current density in alkaline fresh water,alkaline seawater and industrial wastewater

Seawater electrolysis has become an efficient method which makes full use of natural resources to produce hydrogen. However, it suffers high energy cost and chloride corrosion. Herein, we first present a Ni₂P/Co(PO₃)₂/NF heterostructure in which Co(PO₃)₂ with the nano-rose morphology in-situ grown on the rough Ni₂P/NF. The unique 3D nano-rose structure and the optimized electronic structure of the heterostructure enable Ni₂P/Co(PO₃)₂/NF super-hydrophilic and super-aerophobic characteristics, and highly facilitate hydrogen evolution reaction (HER) kinetics in alkaline fresh water, alkaline seawater and even industrial wastewater at large current density, which is rarely reported. Significantly, at large current densities, Ni₂P/Co(PO₃)₂/NF only requires overpotentials of 217 and 307 mV for HER to achieve 1000 mA cm⁻² in alkaline fresh water and alkaline seawater, respectively, and requires an overpotential of 469 mV for HER to deliver 500 mA cm⁻² in industrial wastewater. Furthermore, the overall seawater splitting system in the two-electrode electrolyzer only requires voltage of 1.98 V to drive 1000 mA cm⁻², which also demonstrates significant durability to keep 600 mA cm⁻² for at least 60 h. This study opens a new avenue of designing high efficiency electrocatalysts for hydrogen production at large current densities in alkaline seawater and industrial wastewater.     

Towards continuous ammonia electro-oxidation reaction on Pt catalysts with weakened adsorption of atomic nitrogen

One of the key challenges for ammonia-fed anion exchange membrane fuel cells is to the ammonia electro-oxidation reaction (AEOR) at anode, which has sluggish kinetics and generates atomic nitrogen (N_ads) poisoning the Pt catalyst. In this study, a comparative study on Pt/Ta₃N₅, Pt/Ta₂O₅, Pt/carbon black, and Pt plate are conducted in order to clarify the promoting effect of the support materials for Pt catalysts. X-ray photoelectron spectroscopy analysis and density functional theory calculations reveal that the support materials significantly affect the electron condition of the Pt, resulting in the tuned adsorption energy of N_ads on Pt surface. The electrochemical analysis demonstrates that the weakened adsorption of N_ads lowers the coverage of N_ads on Pt surface, resulting in the enhanced performance and stability of Pt catalysts for AEOR. In particular, Pt/Ta₃N₅ catalyst exhibits a current density of 5.92 mA cm⁻² of AEOR at −0.34 V vs. SCE, which is higher than that of Pt/Ta₂O₅ (2.56 mA cm⁻², −0.35 V vs. SCE) and Pt/C (4.45 mA cm⁻², −0.26 V vs. SCE). The achievements in this study demonstrate the importance of controlling the type of supports for the development of an active electrocatalyst for continuous AEOR.     

Ni3S2-MoSx nanorods grown on Ni foam as high-efficient electrocatalysts for overall water splitting

In order to solve the problem of large overpotential in water electrolysis for hydrogen production, transition metal sulfides are promising bifunctional electrocatalysts for hydrogen evolution reaction/oxygen evolution reaction that can significantly reduce overpotential. In this work, Ni₃S₂ and amorphous MoS_x nanorods directly grown on Ni foam (Ni₃S₂-MoS_x/NF) were prepared via one-step solvothermal process, which were used as a high-efficient electrocatalyst for overall water splitting. The Ni₃S₂-MoS_x/NF composite exhibits very low overpotentials of 65 and 312 mV to reach 10 mA cm⁻² and 50 mA cm⁻² in 1.0 M KOH for HER and OER, respectively. Besides, it exhibits a low Tafel slope (81 mV dec⁻¹ for HER, 103 mV dec⁻¹ for OER), high exchange current density (1.51 mA cm⁻² for HER, 0.26 mA cm⁻² for OER), and remarkable long-term cycle stability. This work provides new perspective for further the development of highly effective non-noble-metal materials in the energy field.     

Bamboo-like N-doped carbon tubes encapsulated Co2P–Fe2P derived from zeolitic imidazolate framework as an efficient trifunctional electrocatalyst for water splitting and Zn-air batteries

The development of high-performance and stable trifunctional electrocatalysts is a pressing challenge for the practical application of water splitting and regenerative Zn-air batteries. Herein, bamboo-like N-doped carbon tubes encapsulated Co₂P–Fe₂P nanoparticles (CoFe-PN/C) was fabricated via a facile template-sacrificial approach by using CoZn-ZIF trapping Fe³⁺ (CoFeZn/C) as the precursor. The incorporation of Fe³⁺ was achieved by the one-pot synthesis approach during crystallization of ZIF, which led to the generation of the unique bamboo-like tube structure under the condition of simultaneous phosphating and carbonization. Benefiting from the large surface area, the optimized electronic structure of active sites and the unique bamboo-like nanotube, the resultant CoFe-PN/C can be used as the trifunctional electrocatalyst possessing a small overpotential at 10 mA cm⁻² for the HER (178 mV) and OER (300 mV), as well as a high half-wave potential of 0.884 V for ORR (40 mV more positive than that of commercial 20 wt% Pt/C). Moreover, the self-designed CoFe-PN/C||CoFe-PN/C alkaline electrolyzer driving 50 mA cm⁻² only need operating potential of 1.84 V and the maximum discharge power density of the CoFe-PN/C-assembled ZABs could achieve 152.0 mW cm⁻², superior to those of Pt/RuO₂ couple. This work will facilitate the development and application of trifunctional electrocatalysts based on bi-transition metallic phosphides for energy conversion and storage technology.     

Multilevel N-doped carbon nanotube/graphene supported cobalt phosphide nanoparticles for electrocatalytic hydrogen evolution reaction

Electrochemical water splitting plays an important role in alternative energy studies, since it is highly efficient and environment-friendly. Accordingly, it is an ideal way of providing alternative to meet the urgent need of finding sustainable and clean energy. This study presents the fabrication of CoP attached on multilevel N-doped CNT/graphene (CoP–CNT/NG) hybrids. The multilevel carbon structure can enhance electrical conductivity efficiently and increase the reaction active area immensely. The obtained electrocatalyst exhibits great electronic conductivity (17.8 s cm⁻¹) and HER activity with low overpotential (155 mV at 10 mA cm⁻²), low Tafel slope (69.1 mV dec⁻¹) in 0.5 M H₂SO₄. In addition, the CoP–CNT/NG displays prominent electrochemical durability after 18 h.     

Interfacial coupling effect of CoO/CoMoO4 promotes alkaline hydrogen electrode for hydrogen energy storage system

Herein, CoO and CoMoO₄ heterostructure supported on nickel foam (CoO/CoMoO₄@NF) are proposed as an effective bifunctional hydrogen evolution reaction (HER) and hydroxide reaction (HOR) electrocatalyst. The electron density distribution at the interface can be optimized by coupling CoO and CoMoO₄, thereby improving conductivity and regulating the hydrogen binding energy (HBE) and hydroxyl binding energy (OHBE). CoO/CoMoO₄@NF exhibits high stability and activity with an exchange current density of ∼3.67 mA cm⁻². Co/CoMoO₄@NF reaches the current density of −10 mA cm⁻² at only −29 mV and the corresponding Tafel slope of 40.2 mV dec⁻¹. This work provides a promising solution for non-precious metal catalyst for hydrogen reaction in energy storage.