Polyoxometallate Cluster Induced High-Entropy Oxide Sub-1 nm Nanosheets as Photoelectrocatalysts for Zn-Air Batteries.

The lack of highly efficient and inexpensive catalysts severely hinders the large-scale application of Zn-air batteries (ZABs). High-entropy oxides (HEOs) exhibit unique structures and attractive properties; thus, they are promising to be used in ZABs. However, conventional high-temperature synthesis methods tend to obtain microscale HEOs with a lower exposure rate of active sites. Here, we report a facile solvothermal strategy for preparing two-dimensional (2D) HEO sub-1 nm nanosheets (SNSs) induced by polyoxometalate (POM) clusters. Taking advantage of the special 2D sub-1 nm structure and precise element regulation, these 2D HEOs-POM SNSs exhibit enhanced bifunctional oxygen evolution and oxygen reduction reaction activity under light irradiation. Further applying these 2D HEOs-POM SNSs to ZABs as cathode catalysts, the CoFeNiMnCuZnOx-phosphomolybdic acid SNSs-based ZABs deliver a low charge/discharge voltage gap of 0.25 V at 2 mA cm-2 under light irradiation. Meanwhile, it could maintain an ultralong-term stability for 1600 h at 2 mA cm-2 and 930 h at 10 mA cm-2. The 2D sub-1 nm structure and fine element control in HEOs provide opportunities to solve the problems of low intrinsic activity, limited active sites, and instability of air cathodes in ZABs.

Hybrid Sub-1 nm Nanosheets of Co-assembled MnZnCuOx and Polyoxometalate Clusters as Anodes for Li-ion Batteries.

Transition metal oxide (TMO) anode materials in lithium-ion batteries (LIBs) usually suffer from serious volume expansion leading to the pulverization of structures, further giving rise to lower specific capacity and worse cycling stability. Herein, by introducing polyoxometalate (POM) clusters into TMOs and precisely controlling the amount of POMs, the MnZnCuOx -phosphomolybdic acid hybrid sub-1 nm nanosheets (MZC-PMA HSNSs) anode is successfully fabricated, where the special electron rich structure of POMs is conducive to accelerating the migration of lithium ions on the anode to obtain higher specific capacity, and the non-covalent interactions between POMs and TMOs make the HSNSs possess excellent structural and chemical stability, thus exhibiting outstanding electrochemical performance in LIBs, achieving a high reversible capacity (1157 mAh g-1 at 100 mA g-1 ) and an admirable long-term cycling stability at low and high current densities.

In Situ Fabrication of Porous Cox P Hierarchical Nanostructures on Carbon Fiber Cloth with Exceptional Performance for Sodium Storage.

Superior high-rate performance and ultralong cycling life have been constantly pursued for rechargeable sodium-ion batteries (SIBs). In this work, a facile strategy is employed to successfully synthesize porous Cox P hierarchical nanostructures supported on a flexible carbon fiber cloth (Cox P@CFC), constructing a robust architecture of ordered nanoarrays. Via such a unique design, porous and bare structures can thoroughly expose the electroactive surfaces to the electrolyte, which is favorable for ultrafast sodium-ion storage. In addition, the CFC provides an interconnected 3D conductive network to ensure firm electrical connection of the electrode materials. Besides the inherent flexibility of the CFC, the integration of the hierarchical structures of Cox P with the CFC, as well as the strong synergistic effect between them, effectively help to buffer the mechanical stress caused by repeated sodiation/desodiation, thereby guaranteeing the structural integrity of the overall electrode. Consequently, Cox P@CFC as an anode shows a record-high capacity of 279 mAh g-1 at 5.0 A g-1 with almost no capacity attenuation after 9000 cycles.