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Understanding the limitations of electrocatalytic activity and developing advanced catalysts with enhanced activity are of exceptional importance for future hydrogen energy applications. Due to the complexity of electrolytic hydrogen evolution in alkaline media, there are limited non-noble metal catalysts to afford large scale applications. Tungsten-based catalysts exhibit favorable stability but relatively low activity owing to their strong H* adsorption characteristics. In this work, cobalt hydroxides/cubic phase WN nanoparticles with strengthened interfaces and adjustable nitrogen vacancies anchored on multi-walled carbon nanotubes (Co(OH)2/c-WN1−x/CNTs) are exploited as highly efficient alkaline hydrogen evolution electrocatalysts, which exhibit remarkable activity with an overpotential of 78 mV at 10 mA cm−2 and a low Tafel slope of 43 mV dec−1 in 1 M KOH media. Density-functional theory calculations revealed that the interfacial combinations of Co(OH)2/c-WN1−x were tuned to facilitate the kinetics of hydrogen evolution, where Co(OH)2 promoted the adsorption of water molecules and the H–OH dissociation, and cubic phase WN with nitrogen vacancies (c-WN1−x) accelerated hydrogen generation by optimizing the hydrogen adsorption free energy.

Multimetal high-entropy alloys (HEAs) have been recognized as potential catalysts that can possibly replace the conventional metal oxides and noble metals for use in energy conversion and water splitting such as oxygen evolution reactions (OERs). However, their higher catalysis is restrained by the difficulty in the synthesis of HEAs with desirable morphologies and deformed crystal lattice structures. In this work, an advanced approach was developed to fabricate the smallest possible HEA (i.e., MnFeCoNiCu) with deformed nanoparticles supported on the carbon cloth (CC) surface. The nanoparticles were characterized to be single face-centered cubic (FCC) crystals with highly deformed lattices, giving rise to various defects (such as twins, dislocations and stacking faults). The high surface tension caused by these defects leads to a substantial reduction in the overpotential down to 263 mV for the production of 10 mA cm−2 with a very low Tafel slope of 43 mV dec−1 and a rather small charge transfer resistance of 0.644 Ω in 1.0 M KOH, which is exceptionally lower than that of RuO2 and the state-of-the-art HEAs and competitive in comparison to most metal oxides. This work proves that the lattice deformation manipulates the displacement of atoms over the nanoparticle surface that facilitates their catalytic activities that are higher than those of the state-of-the-art counterparts reported in the literature. It also provides an insight into the performance improvement of other nanostructures in energy applications.

Li3VO4 (LVO) anode materials with controllable morphologies ranging from spherical-assemblies, single-crystal nanorods, and flower shapes to bulk-shapes were fabricated via a solvothermal approach using different alcohols (i.e., ethanol, methanol, propanol, and butanol). XRD, SEM, BET, Raman and FTIR and galvanostatic charge/discharge measurements were carried out to correlate their structure/morphology with their electrochemical characteristics. The experimental results reveal that both structure and morphology play important roles in the Li+ ion storage of LVO, which degrades in the sequential order from nanorods, to spheres, to flowers and finally to bulk. The LVO nanorods are hierarchical and have a small particle size, high specific surface area, and high crystallinity; thus, they exhibit the largest Li+ ion diffusion coefficient and best electrochemical performance among the four electrodes. Moreover, coating carbon on the single-crystal LVO nanorods further enhances their Li+ ion storage ability. Consequently, the carbon-coated LVO nanorods deliver a high reversible capacity of 440 mA h g−1 at 0.1 A g−1 with good cycling stability and demonstrate great practical application. In addition, the results promote a better fundamental understanding of the Li+ ion storage behavior in LVO and provide insight into the optimal design of LVO and other vanadium-based electrode materials. MOE (Min. of Education, S’pore) Accepted version

Herein, we demonstrate a facile method to prepare hollow-structured oxygen-vacancy-rich Fe2O3/MnO2 nanorods. Our results show that oxygen vacancies are induced by nanoscale ion intermixing between Fe and Mn ions during the annealing process. Owing to their unique core–shell hollow nanostructure and the presence of oxygen vacancies, the Fe2O3/MnO2 nanorods show excellent electrochemical performances as an anode material for lithium ion batteries and a reversible capacity higher than 700 mA h g−1 after 2000 cycles.

In the present study, we report a synthetic strategy for the direct fabrication of hybrid vertical graphene/lithium titanate–CNTs arrays via atomic layer deposition in combination with chemical vapor deposition. A novel array architecture was formed where active lithium titanate (Li4Ti5O12, LTO) was uniformly sandwiched by a vertical graphene backbone and an interconnected CNTs shell. The hybrid omnibearing conductive network was identified to be an extremely stable porous structure and demonstrated superior ultra-high rate capability (146 mA h g−1 at 50C and 131 mA h g−1 at 100C) with a capacity of 136 mA h g−1 at 20C after 10 000 cycles when used as an electrode in lithium ion batteries. This special electrode construction strategy is expected to provide a new route for the manufacture of electrochemical energy storage with ultra-high rate capability and ultra-stability.

Herein we converted Fe–Ni hydroxide nanosheets into an Fe–Ni phosphide nanoparticle-stack array on Ni foam by low-temperature phosphorization treatment for promoting the specific surface area of Fe–Ni phosphide and further improving its oxygen evolution reaction (OER) activities. The alkaline electro-activated Fe–Ni–P nanoparticle-stack array exhibits exceptional OER activities in both alkaline and neutral media.

In the present paper, hollow-porous α-Fe2O3 microspheres are prepared via cation etching of zinc citrate microspheres and subsequent thermal treatment. The superior performance of the as-obtained α-Fe2O3 microspheres as an anode material for lithium ion batteries is evaluated. After 1000 cycles, the capacity still remains more than 1100 mA h g−1 at a current rate of 1 A g−1. Meanwhile, the crystal size induced phase transition of Fe2O3 microspheres (α → γ → β) is observed during cycling by the measurements of ex situ XRD and TEM, which is responsible for their abnormal performance fluctuation.

Carbon nanotubes (CNTs) are synthesized through a novel low cost self-vaporized chemical vapor deposition (SCVD) technique from an indecomposable solid carbon source for the first time. This method was manipulated to avoid the injection of flammable gasses, by producing gaseous carbon (e.g. CO) through an in situ catalyzed gasification of the intermediate product induced by KOH. Simultaneously, the as-produced gaseous carbons will deposit onto the pre-imbedded Ni nanocatalyst surface and form CNTs. The growth mechanism is discussed in detail by adjusting the KOH amount. The as-prepared CNTs are rich in oxygen and deficiencies, which endow them with abundant active sites for electrochemical applications. Superior supercapacitor performance is achieved with a specific capacitance 6 times higher than that of commercial CNTs. This technique represents a novel, convenient approach toward large scale production of CNTs directly from a solid carbon precursor, and would show promising applications in various industrial fields.