NiCo2O4 crystal plane regulation applied to electrochemical non-enzymatic H2O2 sensors

Crystal plane engineering is an emerging strategy for enhancing the surface activity of catalysts, but there is little research on how crystal planes affect electrochemical non-enzymatic H 2 O 2 sensors. We synthesize four distinct NiCo 2 O 4 nanocrystals with different crystal planes and investigate their impact on electrochemical non-enzymatic H 2 O 2 sensing through a systematic combination of experimental and theoretical approaches. NiCo 2 O 4 nanosheets exposing the {3   1   1} crystal plane (311-NS) demonstrate the highest electrocatalytic activity for H 2 O 2 oxidation, with excellent selectivity, repeatability, reproducibility, and long-term stability. The H 2 O 2 detection performance of NiCo 2 O 4 with is consistent with the total amount of surface Co 3+ and Ni 3+ , indicating that the Co 3+ and Ni 3+ exhibit higher activity for H 2 O 2 oxidation. Our density functional theory calculations attribute the superior sensing performance of 311-NS primarily to its high dangling bond density of Co(III) and Ni(III) and its increased surface energy, both facilitate the oxidation of H 2 O 2 . We additionally construct a 311-NS/rotating disk electrode sensor that detects H 2 O 2 in real samples with accuracy comparable to that of high-performance liquid chromatography, highlighting its potential for applications in environmental monitoring and food safety. This study not only broadens our understanding but also demonstrates that selective exposure of specific crystal planes enhances electrochemical non-enzymatic H 2 O 2 sensing performance, an insight to guide development of future peroxide sensors.