Cd2Ta2O7,　which　showed　high　photocatalytic　activity　for　overall　water　splitting,　was　synthesized　by　sol-gel　method.　Its　maximum　activity　increased　from　462　mu　mol-H-2/h　and　23.0　mu　mol-O-2/h　into　173.0　mu　mol-H-2/h　and　86.3　mu　mol-O-2/h　when　0.2　wt.%　NiO　was　loaded　as　co-catalyst.　The　band　structure　of　Cd2Ta2O7　was　calculated　by　a　plane-wave-based　density　functional　theory　(DFT).　The　valence　band　is　mainly　formed　by　O　2p　AO＇s,　and　the　conduction　band　predominantly　consists　of　Ta　5d,　O　2p　and　Cd　5s5p　AO＇s.　Cd　atoms　endue　new　features　different　from　other　tantalates,　and　its　effect　on　the　band　structure　of　Cd2Ta2O7　was　discussed.　(C)　2012　Elsevier　B.V.　All　rights　reserved.