The development of nanozymes with excellent intrinsic oxidase-like activity and specificity has received increasing interest. Graphdiyne (GDY) could be a promising choice for designing nanozymes with enhanced oxidase (OXD)-like activity due to its unique structure and properties. Herein, Co-N-GDY with high OXD activity but no peroxidase (POD) activity was synthesized by codoping of cobalt (Co) and nitrogen (N) into GDY and compared with other GDY-based nanozymes (including GDY, Co-GDY, and N-GDY). Upon analyzing the doping effect of Co and N on the OXD-like and POD-like activities, we found that the combination of Co and N in GDY played a significant role in enhancing the OXD-like activity, and even reversed the POD-like activity of N-GDY to OXD-like activity of Co-N-GDY. The electrochemical experiment and the theoretical calculations provided an explanation for the mechanism and showed that the activity was closely linked to the reduction ability of O₂ or H₂O₂ on the nanozyme substrates, which was determined by the rate-determining step of the catalytic reaction.

Fluorinated and nitrogen-doped graphdiyne (F/N-GDY) have been used in the active layer of perovskite solar cells (PSCs) for the first time. The introduction of heteroatoms turns out to be an effective method for boosted solar cells performance, which increases by 32.8% and 33.0%, better than the pristine or GDY doped PSCs. The enhanced performance can be attributed firstly to the superiority of F/N-GDY originated from the unique structure and optoelectronic properties of GDY. Then, both can further reduce surface defects and improve surface and bulk crystallinity than pristine GDY. What's more, efficiency increase caused by F-GDY is mainly attributed to the improvement of fill factor (FF), while the higher short-circuit current (J_SC) plays more important role by N-GDY doping. Most importantly, the detailed mechanism brought about by doping of F-GDY or N-GDY is expounded by systematical characterizations, especially the synchrotron radiation technique. Doping of F-GDY causes Pb^II+x and forms new Pb–F bonds between F-GDY and Pb ions. Doping of N-GDY or GDY brings about Pb^II-x (N-GDY doping induces more deviation than that of GDY due to the participation of imine N), improving its electron density and conductivity.

A new Gd@C_2v(9)-C₈₂·2.5(S₈)·0.5(CS₂) co-crystal was prepared for the first time and characterized by single-crystal X-ray diffraction (XRD). The analysis clearly showed that, even though the C_2v(9)-C₈₂ cage is fully ordered, the endohedral Gd atoms are highly disordered. This result indicates the presence of highly delocalized endohedral Gd atoms, which has never been reported before. Density functional theory (DFT) calculations were used to rationalize the XRD results. The calculations reveal the presence of two local energy minima, a and b, with the latter existing as four conformers b1–b4. Whereas the energy difference between the two minima is calculated only ~ 10 kcal/mol, their interconversion is almost impossible due to a high energy barrier, of up to 35.98 kcal/mol. This suggests the existence of multiple low-energy positions for the endohedral Gd atom. In addition, a remarkable electron transfer from the C_2v(9)-C₈₂ cage to the S₈ moieties was demonstrated, which might result in a modified endohedral environment and further contribute to the occurrence of delocalized endohedral Gd atoms.

Novel carbon nanohybrids based on unmodified metallofullerenes have been successfully fabricated for use as a new magnetic resonance imaging (MRI) contrast agent. The nanohybrids showed higher R₁ relaxivity and better brightening effect than Gd@C₈₂(OH)_X, in T₁-weighted MR images in vivo. This is a result of the proton relaxivity from the original gadofullerenes, which retained a perfect carbon cage structure and so might completely avoid the release of Gd³⁺ ions. A "secondary spin-electron transfer" relaxation mechanism was proposed to explain how the encaged Gd³⁺ ions of carbon nanohybrids interact with the surrounding water molecules. This approach opens new opportunities for developing highly efficient and low toxicity MRI contrast agents.