An Ultrahigh Performance Enzyme‐Free Electrochemical H2O2 Sensor Based on Carbon Nanopores Encapsulated Ultrasmall Cobalt Oxide Nanoparticles

Abstract Small metal oxide nanoparticles (NPs) that possess abundant accessible active areas and optimal geometric/electronic structures show great promise in electrochemical detection of hydrogen peroxide (H 2 O 2 ) but remain a synthetic challenge. Herein, a simple adsorption‐annealing synthetic strategy is employed for ultrasmall Co 3 O 4 NPs using the confinement of carbon nanopores in porous carbon (PC). The characterization results indicate that Co 3 O 4 NPs with an ultrafine diameter of 3.01 nm are well distributed on PC (Co 3 O 4 /PC−H) with high density because of the carbon nanopore confinement of the support. The achieved Co 3 O 4 /PC−H can be used as an excellent electrocatalyst for H 2 O 2 detection, with a high sensitivity of 332 μA mM −1 cm −2 , a low detection limit of 1.2 μM, and an excellent linear detection ranges from 0.04 to 20 mM. This catalyst can also be employed for sensing H 2 O 2 in real samples. The large specific surface area and unique morphology and structure of Co 3 O 4 /PC−H contribute to the high performance for H 2 O 2 detection. Provided herein is a facile but efficient strategy for the synthesis of enzyme‐free electrochemical H 2 O 2 sensor for analytical applications.