Co4+ in Porous ZIF-67-derives Intercalating-Bridging Adsorption of 2-Reaction Sites for Simultaneous 2-Electron Transfer Toward Sensitive Detection of Uric Acid

Metal -organic frameworks (MOFs) have been used to detect uric acid (UA), but still very challenging to achieve a low detection limit due to the low inferior conductivity of MOFs. Herein, three different N -doped ZIF-67-derived carbons were synthesized for the first time by one-step co -pyrolysis of 2-methylimidazole with cobalt nitrate (CN), cobalt acetate (CA) or cobalt chloride (CC) toward UA sensing. Afterwards, the cobalt nitrate -derived Co particle (Co/CN) supported by N -doped ZIF-67-derived carbon displays extremely low detection limit and high sensitivity for UA, outperformed all reported MOFs-based UA sensors. More interestingly, it was discovered that the high valence Co 4+ within the Co/CN sample produced in high -acidic environment can intercalate in the frame for a bridge adsorption between two reaction sites, which boosted simultaneous 2 -electron transfer, while Co 3+ only allows an end -adsorption structure for one -electron transfer being the rate determining step. Furthermore, the bridge adsorption mode of UA on Co 4+ -based catalyst was also verified by theoretical DFT calculations and XPS experiment. This work holds great promise for a selective and sensitive UA sensor for practical bioscience and clinic diagnostic applications while shedding lights in fundamental research for innovative designs and developments of high -sensitive electrochemical sensors.