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CdS quantum dots (CdS QDs) are regarded as a promising photocatalyst due to their remarkable response to visible light and suitable placement of conduction bands and valence bands. However, the problem of photocorrosion severely restricts their application. Herein, the CdS QDs-Co9S8 hollow nanotube composite photocatalyst has been successfully prepared by loading Co9S8 nanotubes onto CdS QDs through an electrostatic self-assembly method. The experimental results show that the introduction of Co9S8 cocatalyst can form a stable structure with CdS QDs, and can effectively avoid the photocorrosion of CdS QDs. Compared with blank CdS QDs, the CdS QDs-Co9S8 composite exhibits obviously better photocatalytic hydrogen evolution performance. In particular, CdS QDs loaded with 30% Co9S8 (CdS QDs-30%Co9S8) demonstrate the best photocatalytic performance, and the H2 production rate reaches 9642.7 μmol·g−1·h−1, which is 60.3 times that of the blank CdS QDs. A series of characterizations confirm that the growth of CdS QDs on Co9S8 nanotubes effectively facilitates the separation and migration of photogenerated carriers, thereby improving the photocatalytic hydrogen production properties of the composite. We expect that this work will facilitate the rational design of CdS-based photocatalysts, thereby enabling the development of more low-cost, high-efficiency and high-stability composites for photocatalysis.

Co9S8 is considered to be one of the most promising anode materials because of its high theoretical capacity. In this work, hierarchical cage-like Co9S8 microspheres composed of well-crystallized nanosheets are successfully synthesized at 180 °C by a hydrothermal method using KOH and disodium ethylenediamine tetraacetate (Na2EDTA) as a mineralizer and a complexing agent, respectively. X-ray diffraction and scanning electron microscopy measurements show that KOH is beneficial in promoting the crystallization and development of Co9S8, avoiding the formation of impurities, while Na2EDTA is conducive to the generation of cage-like microspheres with the micro/nano architecture and better crystallization. The unique hierarchical cage-like micro/nano architecture can effectively relieve the volume change in the cycling process, and the well-crystallized Co9S8 nanosheets in the cage-like microspheres can offer much more active sites for Li+ accommodation, and thus the hierarchical cage-like Co9S8 microspheres composed of well-crystallized nanosheets show superior cycling stability and rate capability, e.g., a high capacity of 303.5 mAh g−1 after 1000 cycles at a high rate of 1.0 A g−1. This work provides a new approach for improving the electrochemical performance of LIBs by constructing a hierarchical anode material.

The electrocatalytic hydrogen evolution activity of transition metal sulfide heterojunctions are significantly increased when compared with that of a single component, but the mechanism behind the performance enhancement and the preparation of catalysts with specific morphologies still need to be explored. Here, we prepared a Co9S8/MoS2 heterojunction with microsphere morphology consisting of thin nanosheets using a facile two-step method. There is electron transfer between the Co9S8 and MoS2 of the heterojunction, thus realizing the redistribution of charge. After the formation of the heterojunction, the density of states near the Fermi surface increases, the d-band center of the transition metal moves downward, and the adsorption of both water molecules and hydrogen by the catalyst are optimized. As a result, the overpotential of Co9S8/MoS2 is superior to that of most relevant electrocatalysts reported in the literature. This work provides insight into the synergistic mechanisms of heterojunctions and their morphological regulation.

Co9S8 is a potential anode material for its high sodium storage performance, easy accessibility, and thermostability. However, the volume expansion is a great hindrance to its development. Herein, a composite containing Co9S8 nanofibers and hollow Co9S8 nanospheres with N, S co-doped carbon layer (Co9S8@NSC) is successfully synthesized through a facile solvothermal process and a high-temperature carbonization. Ascribed to the carbon coating and the large specific surface area, severe volume stress can be effectively alleviated. In particular, with N and S heteroatoms introduced into the carbon layer, which is conducive to the Na+ adsorption and diffusion on the carbon surface, Co9S8@NSC can perform more capacitive sodium storage mechanism. As a result, the electrode can exhibit a favorable reversible capacity of 226 mA h g−1 at 5 A g−1 and a favorable capacity retention of 83.1% at 1 A g−1 after 800 cycles. The unique design provides an innovative thought for enhancing the sodium storage performance.

We developed a molten salts process to prepare Co9S8 nanoparticles (NPs) entrapped, S, N co‐doped carbons. Cobalt chloride was used as the cobalt source. The melamine‐formaldehyde (MF) resin provided the carbon source and nitrogen source, and thiourea provided sulfur source. In addition, common inorganic salts were added as templates to generate pores. The characterization results showed that the prepared materials contained high contents of N, S and Co, and were mesoporous composites. At the same time, the porosity of electrocatalyst depended on the type of salt and the mass ratio of precursor to salt, which further affected the electrocatalytic activity of hydrogen evolution reaction (HER). The best prepared catalyst showed excellent HER performance. The onset overpotential of the catalyst was low (33 mV) and had a small Tafel slope (61.1 mV dec−1), in addition to good stability in alkaline media. A molten salts process was developed to prepare Co9S8 nanoparticles entrapped, S, N co‐doped carbons. CoCl2 was used as the cobalt source. The melamine‐formaldehyde resin provided the carbon and nitrogen source, and thiourea provided sulfur source. Common salts were added as templates to generate pores. The best catalyst showed excellent HER performance. The onset overpotential of the catalyst was low (33 mV) and had a small Tafel slope (61.1 mV dec−1), in addition to good stability in alkaline media.

This study develops a novel MOF‐235@Co9S8 composite via hydrothermal synthesis to overcome the limitations of MOF‐235 as a sulfur host in lithium‐sulfur batteries, such as poor conductivity and weak polysulfide adsorption. Serving as a multifunctional matrix, Co9S8 promotes MOF‐235 nucleation, resulting in smaller particles and increasing the specific surface area by 76.7% (reaching 147.6 m2 g−1) compared to pure MOF‐235. The optimized MOF‐235@5%Co9S8/S cathode delivers a high initial discharge capacity of 859.3 mAh g−1 at 0.5 C and maintains 556.4 mAh g−1 after 500 cycles, achieving a capacity retention of 64.7% and substantially outperforming the unmodified MOF‐235/S. These enhancements arise from the synergistic effects of Co9S8, which improves electrical conductivity and lithium‐ion diffusion, chemically anchors polysulfides through polar Co─S bonds, and catalytically accelerates polysulfide conversion, effectively suppressing the detrimental shuttle effect. This composite demonstrates excellent potential for high‐performance, long‐cycle‐life lithium‐sulfur batteries. This study introduces a novel MOF‐235@Co9S8 composite synthesized via the hydrothermal method to address conductivity and polysulfide issues in lithium‐sulfur batteries. Experimental results demonstrate 76.7% higher surface area (147.6 m² g−1) and stable cycling (556.4 mAh g−1 after 500 cycles). Characterization confirms Co9S8's synergistic roles in conductivity enhancement, polysulfide anchoring, and catalytic conversion, showcasing its potential for high‐performance cathodes.

Nowadays, SC is recognized as a key element of hybrid energy storage system in modern energy supply chain for electric vehicles (EVs). Co₉S₈ as a promising electrode material attracts much attention for supercapacitor owing to its superior electrochemical capacity. However, its poor stability and electronic conductivity, which result in inferior cycling performance and rate capability, have seriously limited the practical application of Co₉O₈ in supercapacitors. In this article, Co₉S₈ nanoparticles were embedded in reduced graphene oxide (rGO) via a simple anneal approach as high efficient and stable electrodes for SCs. The Co₉S₈/rGO composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The Co₉S₈ nanoparticles were inserted tightly between the rGO layers due to strong intermolecular forces, preventing the cluster in reduction process of rGO from graphene oxide (GO). The rGO provides the conductive network for Co₉S₈ and shortens the ion diffusion paths, improving rate performance and enhancing the stability of the electrode material. The as-prepared Co₉S₈/rGO takes full advantages of high capacitance performance of Co₉S₈ nanoparticles and excellent conductivity and electrochemical stability of rGO. Thus, Co₉S₈/rGO composites exhibit high specific capacity of 708.3 F g−1 with the active material mass of 2 mg at current density of 1A g−1. In addition, the asymmetric hybrid SC (Co₉S₈/rGO//rGO) delivered an excellent energy density of 41.1 Wh kg−1 and a high power density of 750.3 W kg−1. The Co₉S₈/rGO composites introduced here represent a high efficiency ideal electrode that can be easily applied in automotive field with excellent performance.

Cobalt sulfide (Co9S8) particles are compounded as the electrode materials of supercapacitors by a mechanical alloying method. They show excellent properties including good cycling stability and high specific capacitance. A supercapacitor is assembled using Co9S8 as the anode and activated carbon (AC) as the cathode. It gains a maximum specific capacitance of 55 F·g−1 at a current density of 0.5 A·g−1, and also an energy density of 15 Wh·kg−1. Those results show that the novel and facile synthetic route may be able to offer a new way to synthesize alloy compounds with excellent supercapacitive properties.

TiO2 anodes have attracted great attention due to their good cycling stability for lithium ion batteries and sodium ion batteries (LIBs and SIBs). Unfortunately, the low specific capacity and poor conductivity limit their practical application. The mixed phase TiO2 nanobelt (anatase and TiO2-B) based Co9S8 composites have been synthesized via the solvothermal reaction and subsequent calcination. During the formation process of hierarchical composites, glucose between TiO2 nanobelts and Co9S8 serves as a linker to increase the nucleation and growth of sulfides on the surface of TiO2 nanobelts. As anode materials for LIBs and SIBs, the composites combine the advantages of TiO2 nanobelts with those of Co9S8 nanomaterials. The reversible specific capacity of TiO2 nanobelt@Co9S8 composites is up to 889 and 387 mAh·g−1 at 0.1 A·g−1 after 100 cycles, respectively. The cooperation of excellent cycling stability of TiO2 nanobelts and high capacities of Co9S8 nanoparticles leads to the good electrochemical performances of TiO2 nanobelt@Co9S8 composites.