The confinement can effectively overcome aggregation and detachment of polyoxometalates (POMs) from supports, thereby enhancing their energy storage properties. However, static confinement still inevitably leads to insufficient exposure of active sites, affecting the full stimulation of their activities. Herein, by tailoring the functional groups of the crosslinker, we engineered nanocages with a transition from rigid to flexible structures, enabling dynamic confinement of phosphomolybdic acid (PMo 12 ) in a hybrid hydrogel. Theoretical calculations reveal that compared to rigid nanocages, flexible nanocages with abundant structural configurations enable dynamic confinement of PMo 12 without detachment. Moreover, structural flexibility of nanocages stimulates more active sites of PMo 12 , accelerating proton-coupled electron transfer during the charge/discharge process. Thus, the flexible nanocage-based symmetrical supercapacitor delivers a high power density of 35.0 mW cm −2 at energy density of 0.052 mWh cm −2 . This work provides a flexible nanocage confinement strategy for anchoring POMs in energy-related applications
Linkai Wang,Yu Han,Jian Wei,Qingjie Ge,Shijian Lu,Yanpeng Mao,Jian Sun
Hydrogenation of CO 2 into light olefins is an important route to carbon neutrality . Most of traditional researches focus on the catalyst component, structure, and promoter to enhance the selectivity of light olefins while ignoring the diffusion of products. Here, we report a NaFeZr-MOR composite catalyst for light olefin synthesis in CO 2 hydrogenation via pore confinement. The selectivity in hydrocarbons and STY (Space-time yields) of C 2–4 = is gradually increasing maximum up to 51.3% and 12.2 (mmol·g cat −1 . h −1 ), which lie in a high level among reported Fe-based catalysts. Further characterization revealed that the essence of selectivity change period is the accumulation and evolution of carbonaceous species, which causes the change of product diffusion behavior. It suppresses the escape of heavy hydrocarbons from MOR pores, leading to an increased light olefin, especially ethylene, which is called “dynamic confinement”. These findings provide a new insight for controlling low-carbon product selectivity in CO 2 hydrogenation.
Ruixuan Zhao,Mingyang Gao,Jiajun Chen,Weijie Yi,Huijun Li,Peicheng Wang,Zejin Tian,Xiaomin Wang
Transition metal layered oxides have emerged as a prominent class of cathode materials for sodium-ion batteries. However, their cycling stability remains a critical limitation impeding further development. Recent studies confirm that lithium incorporation effectively improves the long-term cycling performance of these materials. However, constrained by the inferior initial capacity and rate capability it induces, this approach has never achieved practical and widespread application. Hence, a novel P2-Na 0.67 Li 0.1 Ni 0.23 Mn 0.62 Zr 0.05 O 2 cathode material is proposed. The structural stability of the cathode material is significantly improved through the formation of a surface Zr O polarized layer that effectively suppresses lattice oxygen loss. Simultaneously, the transition metal vacancy concentration was modulated through controlled Zr 4+ doping levels, enabling enhanced initial capacity via optimized cationic/anionic redox participation. The in situ/ex situ characterization of the system demonstrated that it achieved dynamic confinement of anionic redox activity during the entire charge-discharge process, thereby enabling reconstruction of the oxygen reaction pathways. The modified samples exhibited enhanced electrochemical performance with 152.3 mAh g −1 at initial cycling and 99.1 mAh g −1 at 10C. This work presents a novel strategy for transition metal layer optimization and dynamic confinement of lattice oxygen activity, while providing new insights for the development of layered oxide cathode for high-performance SIBs.
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