As　a　green　and　sustainable　corrosion　protection　technology,　photoelectrochemical　cathodic　protection　(PECCP)　cannot　be　applied　to　protect　metals　having　low　corrosion　potential　(Ec)　due　to　the　insufficient　negative　conduction　band　(CB)　potential　of　the　present　semiconductor　materials.　Herein,　for　the　first　time,　PECCP　is　reported　to　indirectly　protect　metals　with　low　Ec　from　corrosion　by　introduction　of　an　interlayer　with　high　Ec　between　the　substrate　and　semiconductor.　As　an　example,　a　nickel　interlayer　was　firstly　deposited　on　magnesium　alloy　substrate　by　chemical　deposition　and　electrodeposition　to　provide　the　high　Ec,　followed　by　electrodeposition　of　Cu2O　semiconductor　layer　on　the　nickel　layer.　A　series　of　characterizations,　including　high-resolution　transmission　electron　microscope　and　X-ray　photoelectron　spectroscopy,　indicate　that　the　resultant　Cu2O　semiconductor　has　an　octahedral　structure　and　an　edge　length　of　ca.　514　nm.　The　n-type　property　of　the　semiconductor　is　determined　by　the　Mott-Schottky　curve,　and　the　photo-response　behavior,　such　as　obvious　photo-induced　potential　drop　and　stable　photocurrent　density　as　high　as　747　mu　A　cm-2　under　visible　light　illumination,　is　confirmed　by　electrochemical　and　photoelectrochemical　measurements.　The　new　proposed　methodology　described　in　this　study　is　not　limited　to　magnesium　alloy　but　also　can　be　possibly　applied　in　other　structural　metals　having　low　Ec.