Electrochemistry of CuO/In2O3 p–n heterojunction nano/microstructure array with sensitivity to H2 at and below room-temperature

We report a facile template-free procedure to synthesize CuO/In2O3 p–n heterojunction nano/microstructure array on Si substrate. It was synthesized by electrodeposition in quasi-2D ultra-thin liquid layer combining with annealing treatment. By applying a special square potential across the electrodes, Cu2 + and In3 + were selectively and periodically deposited according to their reduction potentials. The array is well-ordered with strictly periodic arrangement in hundreds of microns, and it shows a reasonable sensitivity and selectivity to H2 at and below room temperature due to the tunneling modulation of heterojunction array. And the mechanisms of electrodeposition and tunneling modulation obtained rational explanation.

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► An H2 sensing system at and below room-temperature, CuO/In2O3 p–n heterojunction nano/microstructure array, is proposed.
► The electrochemical mechanism bases on the selective deposition of each component in quasi-2D liquid layer.
► The gas sensing mechanism relies on tunneling modulation of heterojunction nano/microstructure array.
► The breakthrough in H2 sensing application of tunneling modulation eventually realized