The recent progress in activating surface reconstruction by integrating advanced characterizations with theoretical calculations for high-efficiency oxygen evolution reaction is reviewed.

Figure 2. Illustration of the crystal structures of the main cathode materials: a) LiFePO 4 with olivine structure, b) LiMn 2 O 4 with spinel structure, and c) LiNi 0.5 Co 0.2 Mn 0.3 O 2 with layered structure. d) Comparison of energy density for typical cathode materials. a,b,d) Reproduced with permission. [55]

The rational design and facile synthesis of 1D hollow tubular carbon‐based materials with highly efficient oxygen reduction reaction (ORR) performance remains a challenge. Herein, a simple yet robust route is employed to simultaneously craft single‐atomic Fe sites and graphitic layer‐wrapped Fe3C nanoparticles (Fe3C@GL NPs) encapsulated within 1D N‐doped hollow mesoporous carbon tubes (denoted Fe‐N‐HMCTs). The successional compositional and structural crafting of the hydrothermally self‐templated polyimide tubes (PITs), enabled by Fe species incorporation and acid leaching treatment, respectively, yields Fe‐N‐HMCTs that are subsequently exploited as the ORR electrocatalyst. Remarkably, an alkaline electrolyte capitalizing on Fe‐N‐HMCTs achieves excellent ORR activity (onset potential, 0.992 V; half‐wave potential, 0.872 V), favorable long‐term stability, and strong methanol tolerance, outperforming the state‐of‐the‐art Pt/C catalyst. Such impressive ORR performances of the Fe‐N‐HMCTs originate from the favorable configuration of active sites (i.e., atomically dispersed Fe‐Nx sites and homogeneously incorporated Fe3C@GL NPs) in conjunction with the advantageous 1D hollow tubular architecture containing adequate mesoporous surface. This work offers a new view to fabricate earth‐abundant 1D Fe‐N‐C electrocatalysts with well‐designed architecture and outstanding performance for electrochemical energy conversion and storage.

Superior reaction reversibility of electrode materials is urgently pursued for improving the energy density and lifespan of batteries. Tin dioxide (SnO2) is a promising anode material for alkali‐ion batteries, having a high theoretical lithium storage capacity of 1494 mAh g− based on the reactions of SnO2 + 4Li+ + 4e− ↔ Sn + 2Li2O and Sn + 4.4Li+ + 4.4e− ↔ Li4.4Sn. The coarsening of Sn nanoparticles into large particles induced reaction reversibility degradation has been demonstrated as the essential failure mechanism of SnO2 electrodes. Here, three key strategies for inhibiting Sn coarsening to enhance the reaction reversibility of SnO2 are presented. First, encapsulating SnO2 nanoparticles in physical barriers of carbonaceous materials, conductive polymers or inorganic materials can robustly prevent Sn coarsening among the wrapped SnO2 nanoparticles. Second, constructing hierarchical, porous or hollow structured SnO2 particles with stable void boundaries can hinder Sn coarsening between the void‐divided SnO2 subunits. Third, fabricating SnO2‐based heterogeneous composites consisting of metals, metal oxides or metal sulfides can introduce abundant heterophase interfaces in cycled electrodes that impede Sn coarsening among the isolated SnO2 crystalline domains. Finally, a perspective on the future prospect of the structural/compositional designs of SnO2 as anode of alkali‐ion batteries is highlighted.

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