Nano-Micro Letters最新文献

Highlights

Highlights

Highlights

Highlights

Electrochemical reduction of CO₂ into high-value hydrocarbons and alcohols by using Cu-based catalysts is a promising and attractive technology for CO₂ capture and utilization, resulting from their high catalytic activity and selectivity. The mobility and accessibility of active sites in Cu-based catalysts significantly hinder the development of efficient Cu-based catalysts for CO₂ electrochemical reduction reaction (CO₂RR). Herein, a facile and effective strategy is developed to engineer accessible and structural stable Cu sites by incorporating single atomic Cu into the nitrogen cavities of the host graphitic carbon nitride (g-C₃N₄) as the active sites for CO₂-to-CH₄ conversion in CO₂RR. By regulating the coordination and density of Cu sites in g-C₃N₄, an optimal catalyst corresponding to a one Cu atom in one nitrogen cavity reaches the highest CH₄ Faraday efficiency of 49.04% and produces the products with a high CH₄/C₂H₄ ratio over 9. This work provides the first experimental study on g-C₃N₄-supported single Cu atom catalyst for efficient CH₄ production from CO₂RR and suggests a principle in designing highly stable and selective high-efficiency Cu-based catalysts for CO₂RR by engineering Cu active sites in 2D materials with porous crystal structures.

Lithium (Li) metal electrodes show significantly different reversibility in the electrolytes with different salts. However, the understanding on how the salts impact on the Li loss remains unclear. Herein, using the electrolytes with different salts (e.g., lithium hexafluorophosphate (LiPF₆), lithium difluoro(oxalato)borate (LiDFOB), and lithium bis(fluorosulfonyl)amide (LiFSI)) as examples, we decouple the irreversible Li loss (SEI Li⁺ and “dead” Li) during cycling. It is found that the accumulation of both SEI Li⁺ and “dead” Li may be responsible to the irreversible Li loss for the Li metal in the electrolyte with LiPF₆ salt. While for the electrolytes with LiDFOB and LiFSI salts, the accumulation of “dead” Li predominates the Li loss. We also demonstrate that lithium nitrate and fluoroethylene carbonate additives could, respectively, function as the “dead” Li and SEI Li⁺ inhibitors. Inspired by the above understandings, we propose a universal procedure for the electrolyte design of Li metal batteries (LMBs): (i) decouple and find the main reason for the irreversible Li loss; (ii) add the corresponding electrolyte additive. With such a Li-loss-targeted strategy, the Li reversibility was significantly enhanced in the electrolytes with 1,2-dimethoxyethane, triethyl phosphate, and tetrahydrofuran solvents. Our strategy may broaden the scope of electrolyte design toward practical LMBs.

Autonomously self-propelled nanoswimmers represent the next-generation nano-devices for bio- and environmental technology. However, current nanoswimmers generate limited energy output and can only move in short distances and duration, thus are struggling to be applied in practical challenges, such as living cell transportation. Here, we describe the construction of biodegradable metal–organic framework based nanobots with chemically driven buoyancy to achieve highly efficient, long-distance, directional vertical motion to “find-and-fetch” target cells. Nanobots surface-functionalized with antibodies against the cell surface marker carcinoembryonic antigen are exploited to impart the nanobots with specific cell targeting capacity to recognize and separate cancer cells. We demonstrate that the self-propelled motility of the nanobots can sufficiently transport the recognized cells autonomously, and the separated cells can be easily collected with a customized glass column, and finally regain their full metabolic potential after the separation. The utilization of nanobots with easy synthetic pathway shows considerable promise in cell recognition, separation, and enrichment.

Highlights

Highlights

Regulating the local configuration of atomically dispersed transition-metal atom catalysts is the key to oxygen electrocatalysis performance enhancement. Unlike the previously reported single-atom or dual-atom configurations, we designed a new type of binary-atom catalyst, through engineering Fe-N₄ electronic structure with adjacent Co-N₂C₂ and nitrogen-coordinated Co nanoclusters, as oxygen electrocatalysts. The resultant optimized electronic structure of the Fe-N₄ active center favors the binding capability of intermediates and enhances oxygen reduction reaction (ORR) activity in both alkaline and acid conditions. In addition, anchoring M–N–C atomic sites on highly graphitized carbon supports guarantees of efficient charge- and mass-transports, and escorts the high bifunctional catalytic activity of the entire catalyst. Further, through the combination of electrochemical studies and in-situ X-ray absorption spectroscopy analyses, the ORR degradation mechanisms under highly oxidative conditions during oxygen evolution reaction processes were revealed. This work developed a new binary-atom catalyst and systematically investigates the effect of highly oxidative environments on ORR electrochemical behavior. It demonstrates the strategy for facilitating oxygen electrocatalytic activity and stability of the atomically dispersed M–N–C catalysts.