Powder-Based Cu ₃ VS ₄ Photocathode Prepared by Particle-Transfer Method for Water Splitting Using the Whole Range of Visible Light

Powder-based Cu ₃ VS ₄ photoelectrode with 1.5–1.6 eV of a band gap that was responsive to whole range of visible light was fabricated by a particle transfer method, aiming at enhancement of the photocathodic performance. The particle-transferred Cu ₃ VS ₄ photoelectrode with a Au-contacting layer (Cu ₃ VS ₄ /Au) showed much higher photocathodic performance for water reduction to produce H ₂ under simulated sunlight irradiation (AM-1.5 G) than previously reported Cu ₃ VS ₄ /FTO prepared by a conventional drop-casting method. This drastic enhancement is due to the good contact between photocatalyst particles and the Au-contacting layer of the substrate electrode. Loading of a Pt cocatalyst was effective for further enhancement of the photocathodic performance of the Cu ₃ VS ₄ /Au photoelectrode. Pt(1 nm)-loaded Cu ₃ VS ₄ /Au gave about 4 mA cm ⁻² of the cathodic photocurrent at −0.41 V vs NHE at pH7 that was four times higher than that without a Pt cocatalyst under simulated sunlight irradiation (AM-1.5 G). When Cu ₃ VS ₄ particles with a small particle size were prepared by a flux method, better durability was obtained compared with a solid-state reaction. Efficient photoelectrodes based on a powdered metal sulfide utilizing whole range of visible light have successfully been developed by a particle transfer method, loading of a Pt cocatalyst, and a flux method on photoelectrochemical performance.