Hollow Co3O4 nanospheres modified with RuCl3 as peroxidase mimics for sensitive determination of sulfide ions at neutral pH

Developing high-performance nanozymes at neutral pH is extremely necessary for the application of biological and water environmental systems. RuCl3 modified hollow Co3O4 nanospheres (Ru3+-Co3O4 HNSs) were utilized to establish a colorimetric sensor for selective determination of sulfide ions (S2-). The hollow Co3O4 nanospheres after doping of Ru3+ provide large surface area and more active sites, thereby boosting the electron transport and the affinity to the substrates. Specifically, the as-prepared Ru3+-Co3O4 HNSs exhibited remarkable peroxidase-like (POD-like) activity, which can catalyze colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxTMB at neutral pH condition. Furthermore, the Ru3+-Co3O4-based colorimetric sensor achieved a wide linear range (0.5-20 μM) and a low detection limit (0.051 μM) for S2- ions concentration, as well as good selectivity, reproducibility and practicability in sewage water. This research aims to boost the accuracy of S2- detection and shed light on application prospects in the water environmental fields.