Ce-doped indium oxide nanozymes with peroxidase-like activity induced by cerium-indium synergy for colourimetric detection of HO

In this work, InCe x nanoparticles with different In-Ce ratios were synthesized by a simple co-precipitation method and InCe x nanoparticles could be used as a mimic of peroxidase to catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by H 2 O 2 and produce the typical blue ox TMB. In addition, the prepared InCe x nanoparticles showed excellent peroxidase-like catalytic properties compared with pure CeO 2 and pure In 2 O 3 . InCe 0.1 exhibited the best peroxidase-like activity, which was mainly attributed to the indium-cerium synergy, which accelerated the TMB and H 2 O 2 electron transfer rate between them. Based on the above findings, a facile and sensitive H 2 O 2 detection system with a sensitive response range of 10-100 μM and a detection limit of 5 μM for H 2 O 2 was successfully proposed. This work synthesizes nanomaterials with peroxidase-like activity by modifying In 2 O 3 through a simple co-precipitation method and offers new insights into the search for novel peroxidase mimics. InCe x has a higher catalytic efficiency due to the presence of more oxygen vacancies and higher Ce 3+ content, which can provide a wide range of binding sites for TMB, and also can accelerate the electron transfer rate.