With the development of high-performance electrode materials, sodium-ion batteries have been extensively studied and could potentially be applied in various fields to replace the lithium-ion cells, owing to the low cost and natural abundance. As the key anode materials of sodium-ion batteries, hard carbons still face problems, such as poor cycling performance and low initial Coulombic efficiency. Owning to the low synthesis cost and the natural presence of heteroatoms of biomasses, biomasses have positive implications for synthesizing the hard carbons for sodium-ion batteries. This minireview mainly explains the research progress of biomasses used as the precursors to prepare the hard-carbon materials. The storage mechanism of hard carbons, comparisons of the structural properties of hard carbons prepared from different biomasses, and the influence of the preparation conditions on the electrochemical properties of hard carbons are introduced. In addition, the effect of doping atoms is also summarized to provide an in-depth understanding and guidance for the design of high-performance hard carbons for sodium-ion batteries.

Catalytic oxidation can be effectively promoted by the presence of oxygen vacancies on the catalyst surface. In this study, the effect of oxygen vacancies on the catalytic wet air oxidation (CWAO) of phenol was investigated with CeO₂ and MnO_x–CeO₂ as catalysts. CeO₂ and MnO_x–CeO₂ catalysts with different amounts of oxygen vacancies were obtained via hydrothermal methods and applied for the CWAO of phenol. It was found that CeO₂ and MnO_x–CeO₂ nanorods were much more active than the cubic nanorods. The physicochemical properties of the samples were characterized by TEM, XRD, BET, XPS, and H₂-TPR techniques. The results revealed that the presence of oxygen vacancies in CeO₂ and MnO_x–CeO₂ catalysts could increase the oxidizing ability of the catalysts surface. The addition of Mn could greatly improve the adsorption ability of CeO₂ and more efficiently oxidize phenol and its intermediates. The synergy between Mn and Ce could further improve the catalyst redox properties and produce a larger amount of active oxygen species, which is the reason why MnO_x–CeO₂ nanorods are the most active catalysts among the catalysts investigated in this study.