Preparation And Electrochemical Behavior Of Metal Sulfides/Reduced Graphene Oxide Materials By Pyrolysis Of Molecular Precursors

The synthesis of inorganic materials and their interfaces provides numerous opportunities for material design and improvement in the field of sustainable energy conversion.Functional inorganic nanomaterials prepared using appropriate molecular precursors can effectively control particle size distribution,morphology,etc.,and obtain ideal electrochemical properties.Graphene,with large specific surface area,preeminent thermal conductivity and chemical stability,is well liked by researchers.The hybrids of inorganic nanosulfides and graphene combine the particular properties of inorganic materials with the unique advantages of graphene to produce new synergistic effects,exhibiting superior properties.It is of great significance for the development of functional materials to rational design and synthesis of metal sulfide/reduced graphene oxide mixtures with satisfactory electrochemical properties and durability by using molecular precursor method.Herein,a simple molecular precursor pyrolysis strategy is proposed to fabricate Co₄S₃,Co₉S₈nanoparticles hosted on reduced graphene oxide?rGO?nanosheets?Co₄S₃-Co₉S₈/C/rGO,CSG?using GO-supported Co-coordination polymer as a precursor for the first time.Well-dispersed Co₄S₃-Co₉S₈nanoparticles and affluent interfaces maximize the amount of catalytically active sites.The interfacial synergistic effect between the two components is propitious to the improvement of electrochemical behavior.RGO supports with high conductivity and enriched defects speed up reaction kinetics and effectively inhibit aggregation of cobalt sulfides.On the basis of the above compositional and structural superiorities,CSG has good activity in alkaline environment?1 M KOH?for hydrogen evolution reaction?HER?.CSG achieves the lowest overpotential?134 m V?as compared to the control materials at the current density of 10 m A·cm^–2.In terms of Li-ion batteries?LIBs?,CSG composite expresses a remarkable reversible capacity of 814 m Ah·g^–1at 0.2 A·g^–1after 200 cycles.The synthetic strategy as well as defective interface engineering provides a favorable direction for potential applications in HER and LIBs.Using the same ligand and synthetic route,the Bi₂S₃nanorods loaded on rGO nanosheets?Bi₂S₃/rGO,BSG-400?are prepared by replacing cobalt nitrate with bismuth nitrate.1D nanorod architecture possesses preeminent kinetic characteristics,which shortens the ion diffusion path and increases the contact area between electrode and electrolyte.RGO has a large specific surface area,and charge polarization at the interface promotes charge transfer.The LIBs properties of the composite are much better than those of Bi₂S₃alone.The anode material?BSG-400?reaches 558.4m Ah·g^–1at 0.2 A·g^–1after 200 cycles.The introduction of graphene makes up for the shortcoming of bismuth sulfide with poor conductivity,increases the specific surface area,thus improving the conductivity and stability of the material.In conclusion,the synthetic approach of sulfides/graphene with diethyldithiocarbamate as coordination ion and sulfur source,graphene as a supporting material has the advantages of universality,simple operation procedure and strong repeatability.And,the interfacial effect of the formed material improves the electrochemical performance in different degree.