Intensive oxidase-like activity of carbon dots nanozymes modulated with phosphoric acid for sensing

Development and modulation of carbon dots based nanozymes (CDNs) with pleasing oxidase-like activities remains a challenging and meaningful endeavor. Herein, aiming at enhanced photocatalytic capabilities of CDNs, a phosphoric acid (H 3 PO 4 ) synthesis strategy was proposed through series of remarkable CDNs development and elaboration, named as P-CDNs. In this modulated strategy, reagent of H 3 PO 4 not only provides P atoms into the carbon dots’ backbone, generating defects for π-electron; but also functionalizes as interbedded phosphate, providing active electron sites to further promote electron efficacy and oxidase-like activities. The capacity of catalytic TMB was used to exemplify the oxidase-like activities of CDNs, and the results confirmed that the catalytic performance of P-CDNs was 3.25 times than that of the reference CDs. Based on the crackajack oxidase-like activity of P-CDNs, a smartphone remote analysis system was readily constructed to sensitive colorimetric/fluorescence dual mode response to diazotization reaction represented by nitrite. Our synthesis strategy not only provides guidance for the design of highly active CDNs but also offers directions for synthetic chemistry and materials science.