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 OXD-like activity due to its unique structure and properties. Herein, Co-N-GDY with high oxidase (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, 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.

Nanozymes, as a novel form of enzyme mimics, have garnered considerable interest. Despite overcoming the main disadvantages of their natural analogs, they still face challenges such as restricted mimic types and low substrate specificity. Herein, we introduce a reactive ligand modification strategy to diversify enzyme mimic types. Specifically, we have utilized helical plasmonic nanorods (HPNRs) modified with para-nitrothiophenol (4-NTP) to create an oxygen-sensitive nitroreductase (NTR) with light-controllability. HPNRs act as a light-adjustable source of nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate (NAD(P)H), providing photon-generated energetic electrons to adsorbed 4-NTP molecules. In the presence of O₂, the activated 4-NTP transfers the captured electron to the adsorbed O₂, mimicking the electron transfer process in its natural counterpart. This enhanced O₂ activation notably boosts the oxidative coupling of para-aminothiophenol (4-ATP). Density functional theory (DFT) calculations reveal that hot electrons injected into the lowest unoccupied molecular orbital (LUMO) energy level of 4-NTP can be transferred to that of molecular oxygen. In conclusion, our findings underline the potential of the reactive ligand modification strategy in developing new types of enzyme reactions, which opens up promising avenues for the enhancement and diversification of nanozyme functionalities.