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Ultrafine CuS nanoparticles anchored on nitrogen-sulfur co-doped graphene nanosheets are synthesized by a simple-green solvothermal method, the composite has excellent electrochemical performance for CO 2 reduction. [Display omitted] • The CuS/N, S-rGO was synthesized via a facile and environmentally friendly method. • The co-doping of N and S on graphene can promote the activation and conversion of CO 2. • CuS/N, S-rGO exhibits outstanding formate selectivity for CO 2 RR. Electrochemical conversion of CO 2 into hydrocarbons can effectively alleviate the energy crisis and promote carbon cycle. Herein, we report that small-size CuS nanoparticles are confined in nitrogen and sulfur co-doped reduced graphene oxide (CuS/N,S-rGO) for electrochemically reducing CO 2 to formate. Specifically, the CuS/N,S-rGO electrode achieves maximum Faradaic efficiency of 82% for formate formation at −0.63 V versus the reversible hydrogen electrode (RHE). Moreover, this catalyst exhibits a stable performance during 20 h-electrolysis. Experiments demonstrate that the doping of nitrogen and sulfur can create an abundance of active sites on the graphene nanosheets to accelerate the CO 2 reduction reaction (CO 2 RR). The CuS/N,S-rGO electrode exhibits excellent performance for CO 2 RR is attributed to the synergistic effect between N,S-rGO and CuS, and graphene can improve stability of composite. This work provides an efficient electrocatalyst for CO 2 RR and offers a facile and environmental friendly approach to synthesize small-size Cu-based composites. [ABSTRACT FROM AUTHOR]

• Hierarchical layered Fe 3 O 4 QDs@C/rGO array derived from MIL-100(Fe)/GO. • Graphene and mesoporous carbon act as conductive support for anchoring Fe 3 O 4 QDs. • Multi-porous channels increase interface contacts and facilitate ion transportation. • Synergetic effect in Fe 3 O 4 QDs@C/rGO array results in the enhanced LIB performance. Herein, a double-buffering strategy is presented to boost the lithium storage potential of Fe 3 O 4. Firstly, the skeleton of MIL-100 (Fe) MOF is grown on graphene oxide, as a self-assembled template via in-situ solvothermal approach, which transform into ultrafine, well-dispersed and mesoporous carbon coated Fe 3 O 4 QDs (4 nm) imbedded on reduced graphene oxide (Fe 3 O 4 QDs@C/rGO), by pyrolysis. Each component in such a well-designed porous hierarchical structure significantly contributes to the remarkable enhancement of lithium ion storage performance, leading to high reversible capability with excellent prolonged cyclic stability after 2000 cycles (505 mAh g−1 at 2.0 A g−1). Both, Graphene sheets and mesoporous carbon act as conductive support for anchoring uniform Fe 3 O 4 QDs with confined double buffering for cyclic volume flux. Multi-channels with uniform mesopores in the self-assembled array and 4 nm QDs of Fe 3 O 4 confined in conductive carbon shells were favorable to enhance the interfacial electron/ion transfer, leading to the excellent rate and cycling performance with released volume changes upon Li+ insertion/extraction. The present research work provides a promising outset design and synthesis strategies for metal oxide QDs based nanocomposites, which may also be extended to the other electrode material system. [ABSTRACT FROM AUTHOR]