A　series　of　porous　cubic　nanomaterials　have　been　prepared　through　a　facile　one-step　selenylation　process,　in　which　Cu-Ni-Co,　Ni-Co　and　Cu-Co　Prussian-blue　analog　nanocubes　transformed　to　Cu-Ni-CoSex,　Ni-CoSex　and　Cu-CoSex　nanocubes,　respectively.　Among　these　samples,　the　quaternary　porous　nanocubes　(Cu-Ni-CoSex)　proved　to　be　the　excellent　bifunctional　electrocatalysts　in　dye-sensitized　solar　cells　and　hydrogen　evolution　reactions.　Under　the　standard　irradiation,　Cu-Ni-CoSex　nanocubes　exhibited　a　high　power　conversion　efficiency　of　9.74%　in　solar　cells,　which　was　much　superior　than　that　of　N　(8.19%).　Cu-Ni-CoSex　nanocubes　also　delivered　superb　hydrogen　evolution　performance　in　terms　of　a　low　overpotential　(50.2　mV)　under　the　current　density　of　10　mA　cm(-2)　and　a　low　Tafel　slope　(49.6　mV　dec(-1))　in　alkaline　medium.　The　outstanding　characteristics　of　CuNi-CoSex　nanocubes　were　benefited　from　their　uniform　sizes,　porous　morphologies,　high　surface　area,　low　charge　transfer　resistances　and　good　synergies　among　multiple　elements.