Photoelectrochemical water splitting using Cu(In,Al)Se2 photoelectrodes developed via selenization of sputtered Cu–In–Al metal precursors

•CIAS film was prepared via selenization of sputtered Cu–In–Al metal precursors.•The direct energy band gaps of CIAS samples lie in the range of 1.25–1.80 eV.•CIAS sample with [Al]/[Al+In] ratio of 0.34 has highest PEC performance.•The highest value of applied-bias-photon-to-current efficiency for CIAS is 8.99%.

Chalcopyrite p-type quaternary CuInxAl1−xSe2 (x=0.44−0.74) semiconductor photoelectrodes are prepared on various substrates via the reactive selenization of radio-frequency-sputtered Cu–In–Al metal precursors. The influence of the aluminum content in the quaternary CuInxAl1−xSe2 photoelectrodes on the structural, optical and photoelectrochemical properties of CuInxAl1−xSe2 samples is investigated. X-ray diffraction patterns and energy-dispersive analysis of X-rays results reveal that the metal precursors can be converted into the tetragonal CuInxAl1−xSe2 phase after the selenizations process under a Se atmosphere at a temperature of 570 °C for 1 h. The energy band gaps of samples are tuned by varying the aluminum content in samples. The direct energy band gap of samples increases from 1.25 to 1.8 eV when the [Al]/[Al+In] molar ratio in samples increases from 0.26 to 0.56. The mobility and carrier density of samples are in the ranges of 1.06–5.86 cm2 V−1 s−1 and 8.23×1016–2.34×1019 cm−3, respectively. The sample with an [Al]/[Al+In] molar ratio of 0.34 has the highest photoelectrochemical performance in aqueous H2SO4 solution with the applied bias photon-to-current efficiency (ABPCE) and photo-enhanced ABPCE of 8.99% and 3.61% at an applied voltage of −1.0 V vs. an Ag/AgCl electrode, respectively.

Graphical abstractCu(In,Al)Se2 sample with an [Al]/[Al+In] molar ratio of 0.34 has the highest photoelectrochemical performance in aqueous H2SO4 solution with the applied bias photon-to-current efficiency (ABPCE) and photo-enhanced ABPCE of 8.99% and 3.61% at an applied voltage of −1.0 V vs. an Ag/AgCl electrode, respectively.Figure optionsDownload full-size imageDownload as PowerPoint slide