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.