Probing the crystal plane effect of Co3O4 for non-enzymatic electrochemistry sensing performance toward hydrogen peroxide

Abstract

The crystalline structure of catalyst surfaces has an important effect on the catalytic activity. However, the crystal plane effects of Co3O4 catalysts towards H2O2 activation are rarely reported. In this work, Co3O4 hexagon nanosheets, nanosheets, nanorods and nanocubes with respective {111}, {112}, {110} and {001} dominant exposed facets were synthesized by hydrothermal synthesis, and the crystal plane effects of these Co3O4 nanocrystals were compared with respect to their viability as potential for non-enzymatic H2O2 sensors. Co3O4 as a hexagonal nanosheet with a {111} crystal plane exhibited the best performance for H2O2 detection, and exhibited a fast response of 3 s, a wide linear range from 0.0005 ∼ 8.5 mM with sensitivity of 1160.2 μA·mM-1cm-2, and detection limit of 0.049 μM. Overall, the H2O2 detection performance of Co3O4 with different exposed facets was ranked as {111} > {112} > {110} > {001}, which is consistent with the proportion of surface Co3+, indicating that the surface Co3+ exhibit higher activity for H2O2 oxidation. This study indicates that tuning of thecrystal plane of nanocrystals is important to enhancement of non-enzymatic H2O2 detection, and provides an important constraint when developing high efficiency catalysts for non-enzymatic electrochemical H2O2 sensors.