In-situ growth of micro-cubic Prussian blue–TiO2 composite film as a highly sensitive H2O2 sensor by aerosol co-deposition approach

• A PB–TiO2 composite film was in-situ prepared by an aerosol co-deposition approach.
• Micro-cubic PB and nano-round TiO2 double structures were obtained in one step.
• As-prepared biosensor can exhibit ultrasensitivity in H2O2 detection.
• High performance is due to the band gap extinction of TiO2.

Assisted by the aerosol co-deposition approach, Prussian blue (PB)–TiO2 composite film can be in-situ formed in one step. The architecture of this film is constructed by two layers: PB–TiO2 nano-particles as a ground layer and individual PB micro-cubes as a top layer. Together with the strong electrocatalytic ability from regular PB morphology, TiO2 can denote its high catalysis in H2O2 detection attributed by the extinction of band gap since the combination of PB. Under a low operation potential −0.05 V, this sensor exhibits an ultrasensitive ability (1726.8 μA mM−1 cm−2), stability and low detection limit (1.5 μM) in H2O2 analysis. The application of this composite material is hopeful to extend in complex physiological analysis, and the preparation approach is promising to extend in more composite materials in-situ synthesis.