Rapid microwave-assisted synthesis of ball-in-ball CuO microspheres and its application as a H2O2 sensor

Novel ball-in-ball hollow CuO microspheres have been synthesized by a one-step microwave-assisted process in mere 10 min without any surfactant. The as-prepared product shows uniform spherical morphology with diameters of 2.5–4 μm. The shell thickness of the outer and inner balls is around 200 and 460 nm, respectively, and the spacing between the two shells is about 150 nm. The formation mechanism for the ball-in-ball CuO architectures has been discussed. When evaluated as an enzyme-free sensor, the ball-in-ball CuO microspheres display an excellent electrocatalytic response to H2O2 with the advantages of good sensitivity, short response time, and low detection limit.

► Ball-in-ball hollow CuO microspheres were first prepared by a microwave-assisted method.
► The CuO shells were composed of many taped CuO nanoflakes with a width of ∼40 nm.
► Four growth stages were proposed for the formation of CuO microspheres.
► The CuO microspheres exhibited excellent sensing performance in H2O2 detection.