NOVELTY - A titanium dioxide nanotube array is arranged in copper sulfate solution and plated, and pure copper is deposited on array to obtain a copper/titanium dioxide composite nanotube array and then electrically oxidized in sodium hydroxide alkali solution, to obtain titanium dioxide nanotube array covered with a super-thin cuprous oxide nano line. The array is arranged in selenium ion solution and stirred under illumination, to obtain a cupric selenide nanotube array.    USE - Preparation of p-type semiconductor copper-selenide/titania nanotube array (claimed) used for solar batteries, solar radiation absorbers, nano switches, thermoelectric-photoelectric transducers, superconductors, and air-sensitive sensors.    ADVANTAGE - The method provides p-type semiconductor copper-selenide/titania nanotube arrays capable of effectively extending the absorption range of titanium dioxide within an absorption range of visible region and reducing compounding rate of an electron cavity. Since more photo-production electrons and photo-production cavities are generated under visible light, it is beneficial for cupric selenide generation through the reaction between the cuprous oxide and selenium ions.    DETAILED DESCRIPTION - Pure titanium or titanium alloy is used as anode and a platinum blade is used as a cathode, and by applying 25-100 V direct current voltage a titanium dioxide nanotube is prepared in an electrolyte. The nanotubes are roasted at 400-500 degrees C for 4-6 hours and crystallized to obtain titanium dioxide nanotube array. 2x 5 cm Array is arranged in copper sulfate solution (5-20 mmol) and pure copper is deposited in a standard three-electrode system using platinum blade as electrode pair, silver/silver chloride as reference electrode, and array as working electrode, to obtain a copper/titanium dioxide composite nanotube array. The ON/OFF voltage ratio is -1/-0.00001 V and ON/OFF time ratio is 0.2/1. The composite array is used as anode and platinum blade is used as cathode, with the distance between electrodes being 2 cm, and a voltage of 0.5 V is applied and the array is electrically oxidized in 0.5-2M sodium hydroxide alkali solution for 30 minutes to obtain a titanium dioxide nanotube array covered with super-thin cuprous oxide line under no stirring condition. Selenium powder (0.015-0.03 g) and sodium hydroxide (18-12 g) are taken in a 50 ml beaker and distilled water (40 ml) is added. The beaker is arranged on a magnetic force stirrer for continuous heating and stirring, to obtain a selenium ion solution. 2x 5 cm Cuprous oxide/titanium dioxide nanotube array is arranged in the selenium solution and stirred with illumination for 30-60 minutes, to obtain a titanium dioxide nanotube array covered with cupric selenide.