Silver microelectrode arrays are fabricated by photolithography for a one‐step analysis of H2O2 in low ionic strength samples. The effects of electrode length, width, band‐to‐band separation, connection height, and adhesion layer are evaluated. The developed sensor shows excellent repeatability (RSD=1.20 % (n=5)) and reproducibility (RSD=1.12 % (n=5)) with the linear range of 0.0–10.0 mM, the sensitivity of 9.84±0.34 μA mM−1, and the detection limit of 22.69 μM. The sensor has been successfully applied to detect H2O2 directly without the addition of supporting electrolyte in synthetic urine, tap water, drinking water, and milk samples.

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In this work, we study and compare the photo-induced conductivity of a two-dimensional electron gas (2DEG) at the bare surface of SrTiO3 (STO) and in the heterostructure of BiFeO3 (BFO) and STO, where BFO was deposited by radio frequency magnetron sputtering. The photo-induced conductance of the BFO/STO interface shows a large increase which is 20.62 times more than the sum of photo-induced conductance from each individual BFO thin film and STO crystal. Since this photo-induced conductance of the BFO/STO heterostructure can be adjusted to become higher and lower by applying an electric field to the top surface, we attribute this large increase to the strong photo-induced electrical polarization of BFO. With the two-point setup of positive bias and negative bias, the conductivity also exhibits diode-like behavior where the forward and backward resistances are different. This work provides methods to interplay between light irradiation, electric field, and conductivity in all-oxide electronics.