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The evolution of cost-effective hydrogen evolution reaction (HER) electrocatalysts is of great significance for the development of clean energy. Exploring effective synthesis strategies to optimize the performance of non-noble metal electrocatalysts has always attracted our attention. Herein, ultrathin coordination polymers were used as precursors to controllably synthesize two-dimensional (2D) ultrathin dual-phase transition metal selenide (TMSs)/carbon–nitrogen (CN) composites (CoSe2–NiSe2/CN) by a two-step method (first a low temperature hydrothermal method for selenization, and then high temperature calcination selenization). Benefiting from its large specific surface area (49 m2 g−1), abundant catalytically active sites and synergistic effects, CoSe2–NiSe2/CN can significantly enhance the HER catalytic activity and exhibits good electrocatalytic activity with an overpotential of 150 mV at −10 mA cm−2, and a small Tafel slope of 42 mV dec−1 in an acidic electrolyte for the HER. This work provides a new strategy for optimizing the HER catalytic activity of TMSs by preparing 2D ultrathin dual-phase TMS composite materials.

The high performance of lithium–sulfur (Li–S) batteries generally suffers from the sluggish reaction kinetics and notorious shuttle effect, resulting from the multi-phase/interface evolution and multistep electron-transfer/non-transfer processes. In this article, the novel vanadium diboride (VB2) nanosheet shows the self-limiting lithiation property in the 1.5–2.8 V polysulfide reaction range, which can afford better electron/ion transport under the stable reaction interface of the catalytic mediator in the Li–S cell cycling. Moreover, electrochemical measurements and density-functional theory calculations reveal that the boron sites of VB2 have a strong surface interaction with Li2S4, which can further improve the conversion rate between Li2S4 and Li2S2/Li2S. Thereinto, these VB2-based Li–S cells possess high sulfur loading (4 mg cm−2), impressive current rate (2C), excellent cycling stability (1000 cycles), and great rate capability (1013 mA h g−1 at 5 mA cm−2). This work provides insight into the stable structure to support the advancement of electrocatalysis technology.

High-performance lithium-sulfur batteries are limited by the severe “shuttle effect” of polysulfide migration. To entrap and immobilize polysulfides, the development of catalytic material is an effective strategy for improving the lithium-sulfur batteries. Herein, we demonstrate that borophene-like boron subunits-inserted molybdenum frameworks of molybdenum diboride (MoB2) serves as a polysulfide-anchoring center to power redox reaction processing under the high-efficient electron transfer conditions. Specifically, MoB2 not only offers active sites to anchor polysulfide via covalent B-B and metallic Mo-Mo bonds-based low lithiation structure, but also provides a high conductivity to accelerate polysulfide conversion kinetics. With these advances, the liquid Li2S6-based MoB2 electrode (area: 2 cm2) offers a high initial capacity of 1116 mAh/g, and holds 558 mAh/g at 2 C after 500 cycles. Furthermore, the currently proposed MoB2 catalyst may significantly propel the advancement of electrocatalysis technology from lithium-sulfur batteries to metal-air batteries and carbon dioxide/nitrogen electrochemical reduction.

We investigate the electronic and transport properties of one-dimensional armchair phosphorene nanoribbons (APNRs) containing atomic vacancies with different distributions and concentrations using ab initio density functional calculations. It is found that the atomic vacancies are easier to form and detain at the edge region rather than a random distribution through analyzing formation energy and diffusion barrier. The highly local defect states are generated at the vicinity of the Fermi level, and emerge a deep-to-shallow transformation as the width increases after introducing vacancies in APNRs. Moreover, the electrical transport of APNRs with vacancies is enhanced compared to that of the perfect counterparts. Our results provide a theoretical guidance for the further research and applications of PNRs through defect engineering.