Abstract
The layered structure MoS2, an n-type conductor (bandgap of 1.9-2 eV), can be excited under irradiation with visible light. However, its valence band energy (-4.2 eV) is closed to the minimum energy required to reduce water into hydrogen (- 4.2 eV at pH = 7). The p-type semiconductor Cu2O (a bandgap of 2 eV) has a valence band energy of - 4.0 eV, higher than that of MoS2 and therefore has potentially as photocatalytic for water splitting. In this work, the heterojunction of Cu2O/MoS2 is prepared on a conductive FTO-coated glass substrate by electrodeposition methods. We conduct initially the MoS2 thin film on FTO by cyclic voltammetry (CV). Then, the Cu2O thin film is deposited on the MoS2/FTO thin film by double-potential pulse chronoamperometric (DPPC) to form a p-n junction Cu2O/MoS2/FTO photo-electrode which play an anodic role in a photoelectrochemical cell. The structure, morphology and composition of heterojunction electrode are characterized by powder X-ray diffraction, SEM, TEM, IR, Raman spectroscopy, electrochemical impedance spectroscopy (EIS). The optical properties are determined by UV-VIS spectroscopy and Photoluminescence (PL) spectroscopy. The photoelectrochemically catalytic activity of the electrodes is performed in dark condition and light condition with 1.5 AM from a solar simulator system by Linear-sweep voltammograms and Transient photocurrent-time methods. The H2-generation yield is evaluated by gas chromatography. The effect of the structure and the composition of the Cu2O/MoS2 thin films on the kinetics and mechanism of the photoelectrochemical water splitting is also considered.
Published Version
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