The phase transition of manganese oxides on carbon fibers via the thermal treatment is able to enhance the electrocatalytic activities for fabricating high-performance flexible all-solid-state zinc-air battery.
In this work, three-dimensional N, S co-doped carbon with high density Fe-single atom-nanoclusters of homogenous dispersion (N, S co-doped CPANI-TA-Fe Fe-SA-NC catalysts) is successfully prepared by the optimal pyrolysis of...
Although noble metal-based materials are known as favorable catalysts for electrocatalytic oxygen reduction, their scarcity and expensive prices are unsatisfactory. Hence, developing earth-abundant and efficient bifunctional oxygen electrocatalysts for rechargeable ZABs is demanded and remains grand challenging.Carbon materials with unique surface properties and high structural flexibility have been used to prepare advanced electrocatalysts by heteroatom doing and/or loading of various transition metals from nanoparticles to single atoms. [3] Currently, the strategy to improve the electrocatalytic activity of bifunctional ORR/OER electrocatalysts is proposed by the synergistic effect via the integration of multiple active components. Alternatively, the modulation of the geometric and porous structure would facilitate mass transfer and enhance the number of accessible active sites. Obviously, the uniform loading of additional metal active sites is of importance in improving electrocatalytic activity. [4] Specifically, the cobalt species were anchored on the conductive carbon supports via the thermal treatment of organic precursors with the good capability to disperse metal species (such as ZIF-67). [5,6] However, the sintering and aggregation of cobalt species during the annealing process would result in poor electrocatalytic performance. Alternatively, molecular assembly is an efficient strategy for preparing the controllable architectures of catalysts. [7] Therefore, it is highly desirable to integrate the wellshaped 3D porous carbons with cobalt active sites for high-performing electrocatalysis.Inspired by the affinity of receptors and ligands for directly targeting cancer cells, the mini biomimetic coordination of chitosan and folic acid (FA) provides a reaction platform to facilitate the anchoring of metal ions. Herein, the pre-coordination of chitosan with folic acid led to the formation of hierarchical aggregates composed of nanosheets. Their surface functional groups (e.g., carboxylic groups, amino groups) provide the anchoring sites for metal ions via the metal-nitrogen coordination and can avoid the agglomeration of excessive metal ions. During the carbonization, the presence of cobalt species promotes the selfcatalytic growth of carbon nanotubes on the carbon nanosheets of 3D hierarchical porous nanoflowers (CoCNTs/PNAs). With a low boiling point of 732 °C, the thermal release of ZnCl 2The strategy of heteroatom doping and metal active sites can synergistically promote oxygen electrocatalysis. Especially, the combination of theoretical simulations with experimental results provides new opportunities to understand the electrocatalytic mechanism. Herein, the 3D carbon nanosheets aggregate with highly branched carbon nanotubes and cobalt active sites (CoCNTs/PNAs) is prepared via the facile self-assembly-pyrolysis strategy. The CoCNTs/PNAs electrocatalysts exhibit superior bifunctional activities to oxygen reduction (E 1/2 = 0.925 V) and evolution (E j = 10 = 1.54 V) reactions, surpassing those of Pt/C-...
The rational design of robust electrocatalysts for efficient integrated devices is crucial to enhance energy conversion performance. The coordination of organic ligands with metal ions provides high flexibility to anchor metal atoms among carbon materials. Herein, the atomic anchoring of Zn and Ni atoms into N‐doped carbon networks with adjustable atomic structure is developed by the facile pyrolysis of metal‐organic framework nanoplates in the presence of dicyandiamide. Theoretical calculations reveal the descriptor‐based design principles to adjust the bridging structures of metal‐nitrogen‐carbon moieties with changing d‐band centers, thereby improving electrocatalytic performance. The resulting electrocatalyst displays good multiple electrocatalytic activities for carbon dioxide reduction, oxygen reduction, and evolution reactions, enabling the fabrication of integrated energy devices. Importantly, the CO2‐H2O overall splitting with the as‐prepared electrocatalysts has been driven by the commercial solar cell and the zinc‐air battery assembled with the same catalyst respectively, showing high CO faradaic efficiency up to 90%. Especially, the overall solar‐to‐CO conversion efficiency is up to 13% and the corresponding utilization efficiency of solar‐to‐electricity can reach 54.4%, demonstrating the large promising space to chase the limit that solar cells can possibly achieve. This work provides new opportunities to modulate the atomic bridging structure of metal‐nitrogen‐carbon for integrated electrolysis.
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