Silicon has been intensively studied as an anode material for lithium-ion batteries (LIB) because of its exceptionally high specific capacity. However, silicon-based anode materials usually suffer from large volume change during the charge and discharge process, leading to subsequent pulverization of silicon, loss of electric contact, and continuous side reactions. These transformations cause poor cycle life and hinder the wide commercialization of silicon for LIBs. The lithiation and delithiation behaviors, and the interphase reaction mechanisms, are progressively studied and understood. Various nanostructured silicon anodes are reported to exhibit both superior specific capacity and cycle life compared to commercial carbon-based anodes. However, some practical issues with nanostructured silicon cannot be ignored, and must be addressed if it is to be widely used in commercial LIBs. This Review outlines major impactful work on silicon-based anodes, and the most recent research directions in this field, specifically, the engineering of silicon architectures, the construction of silicon-based composites, and other performance-enhancement studies including electrolytes and binders. The burgeoning research efforts in the development of practical silicon electrodes, and full-cell silicon-based LIBs are specially stressed, which are key to the successful commercialization of silicon anodes, and large-scale deployment of next-generation high energy density LIBs.

The development of nonprecious metal based electrocatalysts for hydrogen evolution reaction (HER) has received increasing attention over recent years. Previous studies have established MoC as a promising candidate. Nevertheless, its preparation requires high reaction temperature, which more than often causes particle sintering and results in low surface areas. In this study, we show supporting MoC nanoparticles on the three-dimensional scaffold as a possible solution to this challenge and develop a facile two-step preparation method for ∼3 nm MoC nanoparticles uniformly dispersed on carbon microflowers (MoC/NCF) via the self-polymerization of dopamine. The resulting hybrid material possesses large surface areas and a fully open and accessible structure with hierarchical order at different levels. MoO was found to play an important role in inducing the formation of this morphology presumably via its strong chelating interaction with the catechol groups of dopamine. Our electrochemical evaluation demonstrates that MoC/NCF exhibits excellent HER electrocatalytic performance with low onset overpotentials, small Tafel slopes, and excellent cycling stability in both acidic and alkaline solutions.

A very practical, 3D air electrode architecture based on a bifunctional cobalt oxide nanowire array that is active towards both the oxygen reduction and oxygen evolution reactions is introduced. This advanced carbon‐ and binder‐free electrode exhibits remarkable electrochemical durability, with 600 h of operation under ambient conditions in a rechargeable zinc‐air battery.

Ni3N nanoparticles are promising candidates for the electrocatalytic hydrogen oxidation reaction and hydrogen evolution reaction in alkaline solution.

Efficient water electrolysis for hydrogen production constitutes a key segment for the upcoming hydrogen economy, but has been impeded by the lack of high-performance and low-cost electrocatalysts for, ideally, simultaneously expediting the kinetics of both hydrogen and oxygen evolution reactions (HER and OER). In this study, the favored binding energetics of OER and HER reaction intermediates on iron-doped nickel phosphides are first predicted by density functional theory (DFT) simulations, and then experimentally verified through the fabrication of Fe-doped Ni2P nanoparticles embedded in carbon nanotubes using metal–organic framework (MOF) arrays on nickel foam as the structural template. Systematic investigations on the effect of phosphorization and Fe doping reveal that while the former endows a larger benefit on OER than on HER, the latter enables not only modulating the electronic structure, but also tuning the micromorphology of the catalyst, synergistically leading to both enhanced HER and OER. As a result, extraordinary performances of constant water electrolysis are demonstrated requiring only a cell voltage of 1.66 V to afford a current density of 500 mA cm–2, far outperforming the benchmark electrode couple composed of Pt/C and RuO2. Postelectrolysis characterizations combined with DFT inspection further reveal that while the Fe-doped Ni2P species are mostly retained after prolonged HER, they are in situ converted to Fe/P-doped γ-NiOOH during OER, serving as the actual OER active sites with high activity.