Photoelectrode and preparation method therefor, and platinum-based alloy catalyst and preparation method therefor

A method for preparing a Pt-based nano-alloy catalyst, comprising:

• preparing a photoelectrode:
• providing a p-type monocrystalline silicon substrate as a planar silicon substrate, the p-type monocrystalline silicon substrate being a light absorption layer, with a doping concentration of 1014-1018 cm−3, and the light absorption layer having a thickness of 1-1000 μm;
• chemically cleaning the planar silicon substrate, and then performing nanostructured treatment on a front surface of the planar silicon substrate, to obtain a silicon micro-nanowire array;
• depositing a passivation layer with a thickness of 1-5 nm on the front surface of the planar silicon substrate or the silicon micro-nanowire array substrate;
• depositing an active metal layer comprising at least one of titanium, zirconium, aluminum, zinc, iron or copper and having a thickness of 10-80 nm on the passivation layer;
• depositing a rear conductive layer with a thickness of 100-5000 nm on a back surface of the planar silicon substrate or the silicon micro-nanowire array substrate;
• fixing a wire to the rear conductive layer by using an adhesive, and insulating and sealing the rear conductive layer, the adhesive, and the wire, so that the planar silicon substrate or the silicon micro-nanowire array exposes only a region in which the active metal layer is deposited as an effective operation region of the photoelectrode, to obtain the photoelectrode;
• placing the photoelectrode in an electrolytic cell with at least one light-transmitting surface and comprising an electrolyte;
• causing excitation light emitted by a light source to irradiate a surface of the photoelectrode from the light-transmitting surface of the electrolytic cell, wherein the photoelectrode comprises an active metal layer, a passivation layer, a semiconductor light absorption layer, a rear conductive layer, and an insulating protective layer that are sequentially stacked in an incident direction of the excitation light;
• based on an electrochemical workstation, and under the irradiation of the excitation light, using a Pt electrode and a reference electrode to match the photoelectrode to electrochemically treat the surface of the photoelectrode;
• and
• cleaning the electrochemically-treated photoelectrode to obtain a photoelectrode modified by an Ag—Pt nano-alloy catalyst.