The development of electrocatalysts to generate hydrogen, with good activity and stability, is a great challenge in the fields of chemistry and energy. Here we demonstrate a "hitting three birds with one stone" method to synthesize less toxic metallic WO2-carbon mesoporous nanowires with high concentration of oxygen vacancies (OVs) via calcination of inorganic/organic WO3-ethylenediamine hybrid precursors. The products exhibit excellent performance for H2 generation: the onset overpotential is only 35 mV, the required overpotentials for 10 and 20 mA/cm(2) are 58 and 78 mV, the Tafel slope is 46 mV/decade, the exchange current density is 0.64 mA/cm(2), and the stability is over 10 h. Further studies, in combination with density functional theory, demonstrate that the unusual electronic structure and the large amount of active sites, generated by the high concentration of OVs, as well as the closely attached carbon materials, were key factors for excellent performance. Our results experimentally and theoretically establish metallic transition metal oxides (TMOs) as intriguing novel electrocatalysts for H2 generation. Such TMOs with OVs might be promising candidates for other energy storage and conversion applications.
The
design of highly efficient non-noble-metal electrocatalysts
for large-scale hydrogen production remains an ongoing challenge.
We report here a Ni2P nanoarray catalyst grown on a commercial
Ni foam substrate, which demonstrates an outstanding electrocatalytic
activity and stability in basic electrolyte. The high catalytic activity
can be attributed to the favorable electron transfer, superior intrinsic
activity, and the intimate connection between the nanoarrays and their
substrate. Moreover, the unique “superaerophobic” surface
feature of the Ni2P nanoarrays enables a remarkable capability
to withstand internal and external forces and release the in situ
generated H2 bubbles in a timely manner at large current
densities (such as >1000 mA cm–2) where the hydrogen
evolution becomes vigorous. Our results highlight that an aerophobic
structure is essential to catalyze gas evolution for large-scale practical
applications.
Nanoporous FeP nanosheets are successfully synthesized via the anion-exchange reaction of inorganic-organic hybrid Fe18S25-TETAH (TETAH = protonated triethylenetetramine) nanosheets with P ions. The as-prepared nanoporous FeP nanosheets exhibit high electrochemical hydrogen evolution reaction activity in acidic medium.
Transition metal dichalcogenide materials have been explored extensively as catalysts to negotiate the hydrogen evolution reaction, but they often run at a large excess thermodynamic cost. Although activating strategies, such as defects and composition engineering, have led to remarkable activity gains, there remains the requirement for better performance that aims for real device applications. We report here a phosphorus-doping-induced phase transition from cubic to orthorhombic phases in CoSe2. It has been found that the achieved orthorhombic CoSe2 with appropriate phosphorus dopant (8 wt%) needs the lowest overpotential of 104 mV at 10 mA cm−2 in 1 M KOH, with onset potential as small as −31 mV. This catalyst demonstrates negligible activity decay after 20 h of operation. The striking catalysis performance can be attributed to the favorable electronic structure and local coordination environment created by this doping-induced structural phase transition strategy.
Highly mesoporous carbon foam (MCF) with a high specific surface area has been successfully synthesized via a facile, cost-effective and template-free Pechini method. The as-prepared MCF exhibits a high specific surface area of 1478.55 m 2 g À1 and a commendable pore size distribution for impregnating sulfur. After sulfur loaded in MCF, the relationship between pore size distribution of mesoporous carbon foam/ sulfur nanocomposite (MCF/S) and the content of loaded sulfur is investigated in detail, which impacts on subtle variation of lithium storage performance. MCF/S (57.22 wt%) delivers an initial discharge of 1285 mA h g À1 and retains 878 mA h g À1 after 50 cycles. Compared with pristine sulfur, MCF/S cathodes display enhanced electrochemical performances, which can be attributed to the cross-linked hierarchical structure of MCF conductive matrix. Based on the advantages of the template-free Pechini method such as low cost, relative simplicity and atomic-scaled mixing, the MCF with hierarchical porous structure can be generalized to other practical applications including electrochemical double-layer capacitors, adsorption, separation, catalyst supports, etc. In addition, we believe that this modified Pechini method is general and can be extended to the fabrication of other types of mesoporous carbon by changing metal salts and organic reagents.
A facile in situ partial surface‐oxidation strategy to integrate CoO domains with CoSe2 nanobelts on Ti mesh (denoted as CoO/CoSe2) via direct calcination of CoSe2‐diethylenetriamine precursors is reported. The resulted self‐supported CoO/CoSe2 exhibits an outstanding activity and stability in neutral media toward both hydrogen evolution reaction and oxygen evolution reaction.
Transition‐metal phosphides have stimulated great interest as catalysts to drive the hydrogen evolution reaction (HER), but their use as bifunctional catalytic electrodes that enable efficient neutral‐pH water splitting has rarely been achieved. Herein, we report the synthesis of ternary Ni0.1Co0.9P porous nanosheets onto conductive carbon fiber paper that can efficiently and robustly catalyze both the HER and water oxidation in 1 m phosphate buffer (PBS; pH 7) electrolyte under ambient conditions. A water electrolysis cell comprising the Ni0.1Co0.9P electrodes demonstrates remarkable activity and stability for the electrochemical splitting of neutral‐pH water. We attribute this performance to the new ternary Ni0.1Co0.9P structure with porous surfaces and favorable electronic states resulting from the synergistic interplay between nickel and cobalt. Ternary metal phosphides hold promise as efficient and low‐cost catalysts for neutral‐pH water splitting devices.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.