Atomic layer deposition-developed two-dimensional α-MoO 3 windows excellent hydrogen peroxide electrochemical sensing capabilities

Abstract Two-dimensional (2D) α-MoO 3 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 MoO 3 nano-films were composed of flat nanoparticles with the average size of about 35 nm and possessed layered orthorhombic phase (α-MoO 3 ). The electrochemical sensor based on these 2D α-MoO 3 nano-films exhibited great sensitivity of 168.72 μA mM −1  cm −2 to hydrogen peroxide (H 2 O 2 ) 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-MoO 3 nano-films ultra-fast response/recovery time of ∼2.0 s was achieved under the wide linear H 2 O 2 detection range. Additionally, the sensor based on 2D α-MoO 3 nano-films was also demonstrated great long-term stability, excellent selectivity and high reproducibility. The 2D α-MoO 3 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.