Flexible lithium-ion batteries (LIBs) have recently attracted increasing attention with the fast development of bendable electronic systems. Herein, a facile and template-free solvothermal method is presented for the fabrication of hybrid yolk-shell CoS2 and nitrogen-doped graphene (NG) sheets. The yolk-shell architecture of CoS2 encapsulated with NG coating is designed for the dual protection of CoS2 to address the structural and interfacial stability concerns facing the CoS2 anode. The as-prepared composite can be assembled into a film, which can be used as a binder-free and flexible electrode for LIBs that does not require any carbon black conducting additives or current collectors. When evaluating lithium-storage properties, such a flexible electrode exhibits a high specific capacity of 992 mAh g(-1) in the first reversible discharge capacity at a current rate of 100 mA g(-1) and high reversible capacity of 882 mAh g(-1) after 150 cycles with excellent capacity retention of 89.91%. Furthermore, a reversible capacity as high as 655 mAh g(-1) is still achieved after 50 cycles even at a high rate of 5 C due to the yolk-shell structure and NG coating, which not only provide short Li-ion and electron pathways, but also accommodate large volume variation.
The electrocatalytic reduction of CO 2 to liquid fuels is a promising strategy to store the intermittent renewable energies into high-value chemicals. Here, two-dimensional SnO 2 nanosheet (∼3 nm in thickness) materials were synthesized using the hydrothermal method and characterized as efficient electrocatalysts for CO 2 reduction to formate. Compared to the monometallic Snbased catalysts, the SnO 2 nanosheet electrodes exhibit a much improved performance. A large current density of 471 mA cm −2 for formate production and a high Faradaic efficiency of 94.2% are simultaneously achieved using a three-compartment microfluidic flow cell electrolyzer. These results set a new record for formate production among monometallic Sn-based catalysts for the CO 2 electroreduction reaction. Density functional theory calculations reveal the intrinsic improvement in the performance by the SnO 2 surface site over the metallic Sn site.
Recent advances in polymer acceptors that focus on structure–property relationships, which may provide guidance for photovoltaic materials, were systematically summarized.
Interface engineering is promising but still challenging for developing highly efficient and stable non‐noble‐metal‐based electrocatalysts for water splitting. Herein, partially phosphidated core@shell Co@Co–P nanoparticles encapsulated in bamboo‐like N, P co‐doped carbon nanotubes (denoted as Part‐Ph Co@Co–P@NPCNTs) are prepared through a pyrolysis–oxidation–phosphidation strategy. In this structure, each Co nanoparticle is covered with a thin Co–P layer to form a special core@shell heterojunction interface, and the core@shell structure is further encapsulated by N, P co‐doped CNTs that not only protect the Co from corrosion but also guarantee an effective and fast electron transfer on cobalt phosphide. As a bifunctional catalyst for both the hydrogen evolution reaction and oxygen evolution reaction, it exhibits an excellent activity for overall water splitting, and enables long‐term operation without significant degradation. Density functional theory calculations demonstrate that the interface of the Co/Co2P heterojunction could lower the values of ΔGH* (hydrogen adsorption) and ΔGB (water dissociation), which are negatively correlated to the j10, because of the electronic structures of up‐shifted d‐band center. This study not only presents an efficient and stable electrocatalyst for overall water splitting but also provides a special route for the interface engineering of heterostructures.
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