Atomic layer deposition-developed two-dimensional α-MoO3 windows excellent hydrogen peroxide electrochemical sensing capabilities

Two-dimensional (2D) α-MoO3 nano-films with thickness of 4.9 nm were fabricated via atomic layer deposition (ALD) technique for the first time on the wafer scale and were subsequently annealed at 200 °C. The developed MoO3 nano-films were composed of flat nanoparticles with the average size of about 35 nm and possessed layered orthorhombic phase (α-MoO3). The electrochemical sensor based on these 2D α-MoO3 nano-films exhibited great sensitivity of 168.72 μA mM−1 cm−2 to hydrogen peroxide (H2O2) and presented extremely wide linear detection range of 0.4 μM-57.6 mM with the lowest detection limit of 0.076 μM at the signal to noise ratio of 3. Furthermore, due to extremely thin nature of 2D α-MoO3 nano-films ultra-fast response/recovery time of ∼2.0 s was achieved under the wide linear H2O2 detection range. Additionally, the sensor based on 2D α-MoO3 nano-films was also demonstrated great long-term stability, excellent selectivity and high reproducibility. The 2D α-MoO3 nano-films fabricated via ALD technique in this work represent a great opportunity for development of high-performance electrochemical sensors based on 2D transition metal oxides.