In recent years, there has been growing interest in the potential applications of carbon-based non-metallic catalysts in various fields, such as electrochemical energy storage, electrocatalysis, thermal catalysis, and photocatalysis, owing to their unique physical and chemical properties. Modifying carbon catalyst surfaces or incorporating non-metallic heteroatoms, such as nitrogen (N), phosphorus (P), boron (B), and sulfur (S), into the carbon structure has emerged as a promising approach to improve the catalytic performance. This method enables the adjustment of the electronic structure of the carbon catalyst's surface, leading to the formation of new active sites or the reduction of side reactions, ultimately enhancing the catalyst's performance. Here, the preparation methods for doped non-metallic heteroatom carbon catalysts have been systematically explored, encompassing techniques, such as impregnation, pyrolysis, chemical vapor deposition (CVD), and templating. Finally, the existing challenges in the application of non-metallic atomic catalysts have been discussed, insights into potential future development opportunities and new preparation methods of carbon catalysts in the future have been offered.

We apply differential affine velocity estimator (DAVE) to the Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI) 12-min line-of-sight magnetograms, and separately cal- culate the injected magnetic helicity for the leading and the following polarities of nine emerging bipolar active regions (ARs). Comparing magnetic helicity ux of the leading polarity with the following polarity, we nd that six ARs studied in this paper have the following polarity that injected more magnetic helicity ux than that of the leading polarity. We also measure the mean area of each polarity in all the nine ARs, and nd that the compact polarity tend to possess more magnetic helicity ux than the fragmented one. Our results conrm the previous studies on asymmetry of magnetic helicity that emerging bipolar ARs have a polarity preference in injecting magnetic helicity. Based on the changes of unsigned magnetic ux, we divide the emergence process into two evolutionary stages: (1) an increasing stage before the peak ux and (2) a constant or decreasing stage after the peak ux. Obvious changes on magnetic helicity ux can be seen during transition from one stage to another. Seven ARs have one or both polarity that changed the sign of magnetic helicity ux. Additionally, the prevailing polarity of the two ARs, which injects more magnetic helicity, changes form the following polarity to the leading one.