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.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► 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